High School Metals Processes Packet :1 Ritchie

Hayward Community School District 715-634-2619 #HurricaneStrong Made with PosterMyWa!:LCorn

Metals Processes- Home Coursework Packet Mr. Ritchie, 4th Quarter 2019

Hello!

I’m starting offthis distance learning packet with some information about how I’d like you to proceed with your Coursework. I’d prefer to be working in the shop, but this is great knowledge to have!

My first questions of everyone are, Do you have access to a stable and reliable internet -connection?

Your first assignment is to call me at (715) 651-7188. My office hours are 9 am. to 1 p.m.

Daily. The purpose of this call is to discuss the options for you to turn in your completed work. I am providing assignments for 6 weeks of lessons even though we are scheduled to be back in school on Monday, April 27th. (At the time this was written.)

This packet coursework is REQUIRED and will be graded on a pass/fail grade scale. You have will have assignments worth 75 points weekly and extra credit activities will be available throughout the course.

Expectations:

• I would like you to work on this course for at least 20-30 minutes every weekday. I often give extra credit to those that choose to go above and beyond.

• I would like you to keep a journal of what you have completed during the week, any questions, comments, etc. The details are listed at the top of the next page.

• I would like you to call, Facetime, Video Chat or otherwise contact me once a week after you have completed your assignment. We will schedule a day of the week so that we can be consistent. My office hours are 9 am. to 1 p.m. Daily. Please leave a

message if I happen to be on the other line.

Enrichment Activities • Enrichment activities and other fun stuff will be posted on Google Classroom. These may be links to videos, tutorials, etc. • You may spend extra time and effort in developing your skills with an experienced family member. Please follow local and national health recommendations and be safe! ALWAYSREMEMBER! Ifyou are stuck, have questions, want to learn more, or need help in any way, I am here for you. Save my number (715) 651-7188 or send an email jfitchiehayward.k1 2.wi.us

Accountability Journal: The purpose of this document is for you to write, in at least three well-written sentences, your own daily notes to narrate your progress in this course.

Photo Journal Daily Requirements: 1. At least 3 well-written sentences. 2. Save these reports weekly and turn in with your assignments.

Example:

(Have your photos available to turn in separately)

Day & Date Journal Entry

Monday Today I took time to read pages 5-15 in the text and underlining words

4/13/2020 I thought were the main ideas. I was able to complete the chapter

worksheet for chapter three. I thought the video about steel making was interesting. Metals Processes Week I

As a three-time winner of the “Teacher of the Year” award, Gerald Mason has a firm hold on the interest, affection, and re spect of his students and supervisors. At various times during his 27 years as an Industrial Technology Instructor, Gerald’s city, school district, and state have each awarded him that high honor. It all started for Gerald when he was a boand used an old dining room table to mount some woodworking machines, a sin gle electric motor, a line shaft, and a set of pulleys. He has been interested in almost anything mechanical ever since. To his basic high school education, he added several vocational courses—welding, machining, and auto mechanics. Then he earned a BS degree in Education and a MA degree in Industrial Education. Now Gerald, who teaches metalworking in one of the largest school districts in his city, is sharing his interests with his stu dents. In addition to learning the metalworking skills, Gerald and his students study safety precautions, discuss metalworking procedures in industry, do market surveys for metal products, and examine publicity for ob openings. Chartes Zilch Gerald seldom rests, even in the summer. He helps an Industrial Arts Club raise money to buy ex tra equipment for the class room. The students have sold 20 can crushers and 40 computer tables that they ;t , made on their assembly lines. The money they raised was spent for a com puter-controlled typesetter and several other teaching tools. From Gerald, students learn that metalworking technology is a “good, steady area for future work and an excellent skill for both careers and hobbies.”

Gerald Mason Industrial Technology Instructor

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3. How well does the occupation pay? length of training needed to perform the re 4. Is steady employment available? quired work. The following occupational clas 5. Is the work dangerous? sifications are commonly used: 6. Is there opportunity for advancement? 1. unskilled workers 7. What is the chance of starting your own 2. semiskilled workers business? 3. skilled workers 8. What other opportunities, such as teaching, 4. technicians might be available? 5. technologists To get answers to these questions, ask 6. engineers. your parents, teachers, guidance counselor, These general occupational classifications and relatives about them. Read all you can will be explained in the following sections. about the occupation, beginning with infor mation you will find in this unit. Further more, a good source of information concerning all types of careers, including metalworking careers, is the Occupational Outlook Hand book. This book is brought up-to-date every Unskilled Workers two years by the U.S. Department of Labor. It . This classification includes workers who is in many school or public libraries. available require little or no special training for the tasks they perform. This classification in cludes laborers who handle and move materi als manually, floor sweepers, and others who 1—3dClassflcatlon of require little training or application of knowl Occupations edge. The percentage of unskilled workers in the labor force is decreasing and will probably An occupation is the kind of job or work decrease further in the years ahead. at which a person is employed to earn a living. Occupation means the same as job or voca tion. Many kinds of occupations can become S rewarding careers. Semiskilled Because of space limitations, only the de iI5 scriptions of the more common metalworking Workers occupations are included in this book. A com This classification includes workers re plete listing is provided in the Dictionary of quiring some special training. The training pe also published by Occupational Titles. It is riod for semiskilled jobs may range from sev and is available in the Department of Labor eral days to as much as one year. Examples of many libraries. semiskilled metalworking jobs include assem The amount of education and training re bly line workers, machine tool operators, in quired for different metalworking occupations spectors, maintenance mechanics, and punch varies widely. The training period may range press operators. from several days to five years or longer. For Machine tool operators are generally in example, a drill press operator may be trained cluded in the semiskilled classification. This to perform simple drilling operations with a group includes drill press operators, lathe op small drill press in several days. On the other erators, milling machine operators, and opera required for train hand, four years is generally tors of nearly every kind of specialized produc ing an engineer or a machinist. tion machine tool. Machine tool operators are generally employed to operate one kind of ma General Classifications chine tool. As the operators become skilled, Metalworking occupations are broadly they can perform all of the operations that can classified by the knowledge, kind of skill, and be performed on one machine. Unit 1—Careers in Metalworking 15

Because the skill and required training Methods of Learning a Trade varies, semiskilled workers are further classi Apprenticeship is a highly recommended fied for job promotion and pay purposes. It is method for learning a skilled trade. An ap practice to classify machine tool op common prentice is someone who is employed to learn erators as Class A, Class B, or Class C opera a trade, usually in an apprentice training pro tors. The Class A operator possesses more gram. See Fig. 1—2.The length of the appren skill, and experience than the knowledge, ticeship training period may vary for different B or Class C operator. Class trades, anywhere from two to five years. The High school or vocational school metal apprenticeship period for becoming a machin work or machine shop classes provide valu ist or tool-and-die maker, for example, is usu able experience not only for securing employ ally four years. ment but also for advancing more rapidly as a To qualify for apprenticeship training in a tool operator. This kind of machine experi skilled metalworking trade, you must gener ence is also valuable in securing employment ally be a high school graduate or have equiva other kinds of semiskilled jobs in the in many lent trade or vocational school education. You metalworking industry. must have better-than-average mechanical ability. High school or vocational school grad uates are frequently in demand as apprentices for skilled metalworking trades. However, they must have a good background in science, mathematics, English, drafting, and metal working. Skilled Workers An apprentice is paid while learning a Workers in this classification include trade. A graduated pay scale is provided so those employed in the skilled trades. A trade that earnings increase as experience increases. is a job that generally requires from two to On completion of the apprenticeship, the ap five years to learn. A person generally learns a prentice becomes a journeyman. A journey skilled trade through a combination of shop man is a worker who has met minimum qual instruction, classroom instruction, and on- ifications for employment as a skilled the-job training. The classroom instruction in tradesman. cludes mathematics, blueprint reading, tech nical theory, science, and instruction in any other subject required for the trade. Fig. 1-2 An apprentice program often provides Examples of skilled trades among the met ‘one-on-one’ instruction from a journeyman alworking occupations include the following: machinist. Cincinnati Mi1acron machinist, layout worker, tool-and-die maker, instrument maker, boilermaker, welder, sheet metalworker, molder, and heat-treater. De scriptions of these trades, the nature of the work involved, and educational training re quirements are explained in Section 1—7. A tradesman (a level of skill identified by trade unions), also caBed a craftsman, must be able to perform all of the tasks that are com mon in the trade. For example, a machinist is a skilled worker who must be able to set up and operate the machine tools used in the trade. The machinist must know shop mathe matics, blueprint reading, and the use of pre cision measuring tools. 16 Part 1—Introduction A certificate is issued upon completion of the trade. It takes two to four years to learn the apprenticeship training program. This doc the trade. ument is recognized by employers and labor To qualify for employment in jobs that re unions throughout the country as qualifica quire an FAA license, an aircraft-and-engine tion for entrance into the trade. The new jour mechanic must pass tests given by the Federal neyman must continue studying the tools, Aviation Agency. processes and procedures in the trade to be The airplane mechanic must guard against come more highly skilled and to advance fur gasoline fumes, explosions, and the danger of ther. inhaling poisonous carbon monoxide gas. The pickup method is a second way to ac quire the broad knowledge and experience re Auto Body Repair Mechanic quired for employment as a skilled tradesman. This method involves working in one occupa Auto body repair requires such metal tional area until sufficient knowledge and ex working skills as spot welding, arc welding, perience are obtained to qualify as a skilled flame cutting, soldering, and riveting. Skillful worker. use of straightening and smoothing tools is Workers who choose to learn a skilled also required to be able to restore damaged trade by the pickup method will find that it bodies to like-new condition. Formal training usually takes longer than serving an appren in auto body repair can usually be obtained at ticeship. Frequently they must attend voca vocational schools. tional or technical schools to learn blueprint reading, shop mathematics, and technical Boilermaker theory of the trade they are learning. The boilermaker assembles prefabricated It is becoming increasingly difficult to parts made of iron and steel plates to make learn skilled metalworking trades by the boilers, tanks, and machines. A boilermaker pickup method. The apprenticeship method is can also repair these assemblies. The boiler recognized as a more efficient method for maker must drill and punch holes, use ma learning a skilled trade. chines for cutting and bending the plates, drive hot rivets, and read blueprints. Boilermakers work at the site where the boiler, tank, or machine is to be assembled. They must be skilled in using tools and equip i1-7J Descriptions of ment for installation and repair. There is the Occupations danger of being burned by hot boilers and riv ets. It takes about four years as a helper to The following descriptions of skilled and be a boilermaker. semiskilled metalworking occupations are ar come ranged in alphabetical order. Coremaker Aircraft-and-Engine Mechanic A coremaker makes cores used to form An aircraft-and-engine mechanic inspects, holes or hollow parts in castings. Coremaking repairs, and overhauls airplanes. The person is described in Unit 32. The coremaker should learn mathematics and also learn how to read must be able to use hand tools, run basic ma A person may learn the trade in a chine tools, and use precision measuring in blueprints. foundry during an apprenticeship of about four struments. Some of the work is greasy and dirty, and some work has to be done outdoors. years. The coremaker’s job is closely related to the molder’s trade. Aircraft-and-engine mechanics should have a high school education and must attend a Diemaker technical institute. They will learn engine theory, electricity-electronics, sheet metal The diemaker makes metal forms or pat work, welding, and other subjects needed in terns, called dies, that are used in punch Unit 1—Careersin Metalworking 17

Fig. 1-3 An expert machinist used a precision boring machine to make several hundred holes in this nuclear reactor core. Each hole was located precisely within a few ten-thousandths of an inch. (Litton Industries, Inc.)

Forge Operator A forge operator runs a forging press, on which automobile axles, wrenches, etc. are forged. The forge operator must have a knowl edge of iron and steel and must be able to read blueprints. He or she should have at least a high school education and must be strong and healthy. The work is hot, heavy, dirty, and presses to stamp out forms in metal. Auto noisy. The danger of being burned by hot mobile fenders and other sheet metal parts are metal is always present. made with such dies. Diemakers can set up and run all standard machine tools. They Gagemaker or Instrument Maker must read blueprints, make sketches, use lay The gagemaker, sometimes called an in out tools, and measure with micrometers Fig. strument maker, makes and repairs all kinds 1-3). of gages and is a type of toolmaker. To do this Diemakers use most of the information in a person must be able to set up and run any this book. They must have good eyesight to machine in the shop. Good eyesight is re make fine measurements. Diemakers should quired to make accurate measurements. The have at least a high school education. They gagemaker must read blueprints, make will learn the trade and progress faster, how sketches, lay out the work, and use most of ever, if they are technical school or trade the information in this book. school graduates and are good at mathematics The worker will learn the trade much and drafting. It takes four to five years to learn quicker and progress faster as a technical the trade as an apprentice. school or trade school graduate. It takes at A diemaker is seldom without work and is least four years to learn the trade. one of the last persons to be laid off. The die maker’s, diesinker’s and toolmaker’s trades Heat-treater are closely related. A heat-treater is one who performs heat- Diesinker treatment operations on steel and other met als. A knowledge of how to harden, temper, The diesinker makes drop forgingdies that case-harden, anneal, and normalize metal is are used in drop hammers to hammer hot required. This work is usually learned by steel into the desired shape. working in the heat-treating department of a The diesinker must have good eyesight, factory. A heat-treater should have at least a read blueprints, make sketches, use layout high school education. The work is hot and tools, and measure with micrometers. A die- there is danger of being burned by hot metal sinker should have the same educational prep and hot liquids. The heat-treater must some aration as the diemaker. times guard against poisonous fumes.

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A machinist uses most of the information given in this book. Good eyesight is essential, because the machinist must make fine measurements. A machinist must also have superior judgment of depth and distance, and also have good co V ordination. A high school education is pre ferred. The trade will be learned quicker and progress made faster if the machinist is a tech nical school or trade school graduate. It takes four years to learn the trade as an apprentice. There is the danger of being cut by sharp tools and metal, and some of the work is greasy and dirty. Maintenance Mechanic A maintenance mechanic is skilled in working with machines and in shaping and joining materials by using tools and instru ments. Preventive maintenance is a major part of the job. Maintenance mechanics inspect Fig. 1-6 This machine operator is responsible equipment, oil and grease machines, and clean for the precision drilling of holes. (CBI Industries, Inc and repair parts, thus preventing breakdowns or work delays.

There is the danger of being cut by sharp tools Fig 1-7 This machinist is turning a part for a and sharp metals. Some of the work is greasy liquid storage tank. The numerically controlled and dirty. This job is related to the machin machine required an investment of several ist’s, described below. hundred thousand dollars CBI Company) Machine Setup Workers The machine setup worker specializes in 41’ getting machine tools ready for operation, and .1 instructs machine operators in their use. He 1 or she keeps an eye on the machines run by the machine operators, and keeps them ad (us’ced.The machine setup worker may be a fully aualified machinist or may have learned how to set up these machines while employed as a machine operator. An ability to read blue prints and to use all kinds of measuring tools and gages is required. Machinist Machinists make precision metal parts, and repair and construct machine tools. They can set up and run standard machine tools (Fig. 1-7),read blueprints, make sketches, use layout tools, and measure with micrometers.

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about

and

factory,

such

must

advertising,

must

dirty

must

and

sell.

pipefitter’s,

and

related.

apprentice.

mathemat

sell.

something

personnel

is

territory,

and

of

school

made

they

and be

how

repairs

It

usually

buffing

venti

as

metal

There

pleas work.

sheet know

Some

them,

these

stud

They pass

belts,

must

often

takes

air

die-

and

on

The

are

by

to

or

or a Unit 1—Careersin Metalworking 21

Fig. 1-8 Many sheet metal workers are needed to build aircraft bodies. While the techniques are specialized, aircraft sheet metalworkers use the basic principles of assembling and fastening sheet metal. (Boeing)

Toolmaker The toolmaker makes and repairs all kinds of special tools, cutting tools, figs, and gages. Because these are measured with fine instru ments, the toolmaker’s eyesight must be good. The toolmaker can set up and run all standard machine tools. He or she must read blue prints, make sketches, use layout tools, and measure with micrometers. The toolmaker uses most of the information in this book. Toolmakers should have at least a high school education, but they will progress faster Sheet metalworkers must know how to if they are technical school or trade school solder, and read blueprints. They should rivet, graduates. Knowledge of mathematics and have a high school or trade school education, drafting is necessary. It takes four to five years know geometry, drafting, and how to make to learn the trade as an apprentice. patterns. This trade takes three to four years is the danger of being cut by to learn. There sharp tools and metals. The toolmaker’s, Spring and fall are the busy seasons for diemak er’s, diesinker’s, and gagemaker’s trades are outdoor work. Factory work is more steady. closely related. The work is noisy at times, and there is the danger of falling from high places and of being cut by sharp edges of metal. The sheet metal worker must also guard against lead poison Fig. 1-9 Structural steel workers assemble used in commercial ing, caused by solder made of lead and tin. girders and beams and industrial buildings. They join the structural sheet metalworker’s and tinsmith’s trades The shapes with welds, rivets, or bolts. are closely related (Fig. 1-8). Structural Steelworker You have seen the great steel frames that form the skeletons of large buildings or sky scrapers. Fastening the many steel beams and frames together is called structural steelwork (Fig. 1-9). You may have seen a structural steelworker stand on a steel beam and swing high in the air. The structural steelworker also builds bridges and ships on which the big parts are welded or riveted together. Blue prints must be read, and it is necessary to be a careful and strong outdoor worker and a good climber. There is the danger of falling from high places. 22 Part 1—Introduction Tool Programmer, Numerical The welder should know about different Control metals and how to read blueprints. A beginner can learn to do simple welding jobs in a few A tool programmer analyzes and schedules However, becoming skilled in welding the operations involved in machining metal hours. with several different processes may take from parts on numerically controlled machine six months to several years. There is danger of tools. Numerically controlled machine tools being burned by the torch or hot metal. Weld process parts automatically, with little effort ers must be licensed in many states. or control on the part of the machine tool op The welder is very important in industry erator (Fig. 1-10). today and will continue so in the future. The tool programmer reads and interprets the blueprint of a part to be machined. Then, the programmer analyzes and lists on a pro. gram sheet in proper sequence, the machine operations involved in machining the part. 18 The programmer must indicate (1) the Technicians kinds of operations to be performed, (2) the tools to be selected and used, (3) the correct Technician occupations are among the cutting speeds and feeds, and (4) when cutting fastest growing in the United States. Techni fluids are to be used. Hence, a tool program cians are workers whose jobs often require the mer must have a good knowledge of mathe application of scientific and mathematical matics, blueprint reading, and machine shop principles. They usually work directly under operations. With large, complex, multipurpose scientists, engineers, or industrial managers. machine tools, a knowledge of a computer-as Industry needs several technicians for every sisted programming language is necessary. professional engineer (Fig. 1-12). In general, the educational requirements Welder for technicians include high school graduation and two years of post-high school training. The welder joins metal parts by melting This kind of technical training is available in the parts together with the use of the oxyace many types of schools, including technical in welding process, the electric-arc weld tylene stitutes, junior colleges, community colleges, or with other welding processes ing process, area technical schools, armed forces schools, 1-11). A highly skilled welder knows how (Fig. and extension divisions of colleges and univer a of different welding to use number pro sities. cesses, and is able to weld many different met occupations generally require als. Technician technical education and training that ranks between the requirements of the skilled tradesman and those of the technologist. Technicians usually possess more knowledge of drafting, mathematics, science, and techni cal writing than a skilled craftsman. However, they are not expected to know as much about these subjects as technologists or engineers.

Fig. 1-10 This numerically controlled laser measuring machine is being checked by an experienced technician. (Hewlett Packard Company)

I Unit 1—Careersin Metalworking 23

Fig. 1-12 Using a standard tensile test machine, this technician subjects an aircraft engine bolt to a force of 600,000 pounds. (Fairchild Industries) Fig. 1-11 This welder is arc welding a tank to be used for liquid storage. (CBI Company) Industrial Technicians Industrial technicians are also called mam ufacturing technicians or production techni cians. Industrial technicians assist industrial Technicians usually train in only one area engineers, manufacturing engineers, and tool of technology, such as the following: mechan engineers in a wide variety of problems. They ical technology, tool technology, industrial or are particularly important in metals manufac manufacturing technology, aeronautical tech turing industries. nology, automotive technology, civil engi They assist engineers with problems con neering technology, metallurgical technology, cerning the efficient use of employees, mate instrumentation technology, and safety tech rials, and machines in the production of goods nology. Technicians usually are not required and services, These problems may involve to perform as skilled craft workers however, plant layout, development and installation of a knowledge of skilled trade practices and pro special production machinery, planning the cedures is often required. The following de flow of raw materials or parts, developing ma scriptions are for technicians in metalworking terials-handling procedures, and controlling industries. inventories. Industrial technicians are also concerned with time-and-motion studies, Aeronautical Technicians analysis of production procedures and costs, quality control of finished products, and pack Technicians in this area assist engineers aging methods. and scientists with problems involving the de sign, production, and testing of aircraft, rock Instrumentation Technician ets, helicopters, missiles, and spacecraft. They aid engineers by preparing layouts of struc The instrumentation technician assists tures, collecting information and making cal engineers in designing, developing, and mak culations, checking drawings, and performing ing many different kinds of special measuring many other duties. instruments and gages. Such instruments and

I

ist performance

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graphs,

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ments

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Technician

efficiency

(Fig. technicians technician

time,

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kinds

of

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machinery.

performance

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parts

measurement

the

and

parts

sketches

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1-13).

design

designs

temperature, used

technicians

a

tools,

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well-known data

must

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measuring

the

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for

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assist

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production

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tools,

be

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automatic

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also

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including

and

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als proved

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Metallurgical production

supervise

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24

serve

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technologist

Engineering

1-9

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Metallurgical

much

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studies,

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mathematics,

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durability,

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category

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technologist

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Technologists

the

technologists

in

of are

valuable

managerial

performed

laboratory

personnel

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mathematical

may

engineer

to

the

the

technologists

positions

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chemical

of

practical,

of

technicians

toughness,

graduates

Technician

periods

receive

technologists

obtain

devices

internships. and

making

professional

technician,

computer

engineer development

Some

also

classification

be technologists

of

extracting

physics,

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called

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machinability.

professional

degree

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manager;

in

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types

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content,

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or

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engineers.

becoming

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chemistry,

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metals

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missiles,

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metalworking

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1-15).

largely

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(Textron,

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products,

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(Fig.

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1—Careers

engineers

and

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built.

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metal

Unit

metals

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engineering.

metal

manufacturing

are

visualize

constructed

be

and

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waterways,

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when

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design

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properties

1-15

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the

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dams,

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structural

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homes

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aluminum

engineering

and

analyst,

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and

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tunnels,

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technician

labor

quality

service,

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may physics,

electrical

be

in

spacecraft,

estimating,

capacities

engines.

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obtain

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Company)

and

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bridges,

manufacturer’s

of

They

and

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plan,

drafting,

Engineers

specialist

Metals

as

quality

1-14).

roads,

in

quality

aircraft

engineer,

equipment,

and

required

of

or

technical

This

the

sales

planning,

power

(Fig.

is

production

machinery,

Engineers

buildings,

(Reynolds

sales

of

purchasing,

Engineers

1-14

14O

try.

cation

mathematics,

electronic tions, gree.

roads,

tomobiles,

office

building

ing,

manager

tive,

area

cilities

designer;

studies

rector1

director;

checking

sheet. Fig. 26 Part 1—Introduction 4. Electrical and electronics engineers de them for practical use. They also develop sign and develop electrical machinery, elec new alloys with new properties. trical switches, controls for machines and 8. Tool and manufacturing or industrial appliances, radios, televisions, automatic engineers generally start with the model, controls for industrial machinery, electric or prototype, of a product created by a prod power generators, and many other electron uct engineer. They analyze and plan the in ically controlled products. dustrial processes needed to economically 5. Marine engineers develop new designs for manufacture the product. They design the commercial and military ships, subma special manufacturing machines, equip rines, and other types of marine equip ment, assembly lines, and any packaging ment. system required. They also supervise the 6. Mechanical engineers design many differ construction and installation of the ma ent kinds of machines, appliances, and me chines and equipment needed for produc chanical equipment for industrial and con tion, and they organize the work force. sumer use. Finally, they supervise and control produc 7. Metallurgical engineers develop and im tion through manufacturing and assembly prove methods of extracting metals from operations to the finished and packaged their ores, refining them, and preparing product.

WORDS TOKNOW

apprentice heat-treater metallurgist skilled worker boilermaker inspector metal patternmaker steamfitter carbon monoxide instrument maker metal spinner structural coremaker jeweler millwright steelworker diemaker journeyman molder technician diesinker layout worker pipefitter technologist engineer lead poisoning plumber toolmaker forge operator machine operator polisher trade foundry machine setup semiskilled worker unskilled worker gagemaker worker sheet metalworker welder machinist

REvIEwQUESTIONS

1. List several factors that you should consider in selecting your occupation, 2. List several school subjects that are generally needed to learn a trade or become a technician, technologist, or engineer. 3. List several kinds of semiskilled metalworking jobs. 4. What is the length of the training period for semiskilled metalworking jobs? 5. List several skilled metalworking trades. 6. In what two government publications can you find further information about skilled trades or occupations? 7. Describe the apprenticeship method of learning a trade. 8. What is a journeyman? 9. What education is required to become a technician? A technologist? An engineer? 10. List several kinds of work done by (1) technicians, (2) technologists, (3) engineers.

27

What are metals? Usually they are shiny, Fig. 2-1 Metalworking and metal products are solid materials that conduct heat and electric important in every part of modern life. ity; They come from ores that are mined from the earth, then melted and refined to separate each metal. Except for mercury, most metals are solid and hard at room temperatures.

21 The Importance of Metals Metals are essential to the conduct of our daily lives, to our industrial society, and to our national defense (Fig. 2-1). Metals are ev erywhere around us. They are widely used in the manufacture of aircraft and spacecraft, au tomobiles, buses and trucks, railroad cars, bi cycles and motorcycles, and ships and subma rines. Structural steel and other structural metals are used in the construction of roads, bridges, tunnels, and buildings. Many metals are used in the construction construction of home appliances. These include familiar la bor-saving devices such as stoves, washing machines, clothes dryers, and dishwashers— and convenience items such as toasters, refrig erators, furnaces, and air conditioners. Also included are entertainment items such as ra dio and television sets, stereo phonographs, tape recorders, cameras, and projectors. Metals are used extensively in the manu facture of hand tools, portable power tools, machine tools, farm and manufacturing ma chinery, and roadbuilding equipment. Sports equipment such as fishing reels, pleasure boats, outboard motors, golf clubs, and guns also make use of metals. Valuable or precious metals are often used in making coins, jew elry, tableware, and cutlery. 28 Parc i—Introduction

Fairchild Corporation

Allcgheny International

• Lt

_ . . •.--- Combustion EngioiLting, Inc Fairchild Corporation our daily lives Talley Industries Florida Power & Light Co.

defense

Fairchild Corporation Unit 2—Introducing Metals 29

2-2 Properties of Metals Metals have different characteristics, called properties. When an engineer selects the metals for a product, he selects them on the basis of their properties. Metal properties fall into three groups: (1) Chemical properties are characteristics of the chemical composition of metals and their chemical reactions to other metals. Corrosion resistance, for example, is the ability to resist rusting (oxidation) or other chemical actions. Gold, stainless steel, aluminum, and copper are much more corrosion-resistant than iron and steel. (2) Physical properties are characteristics of Fig. 2-2 Drill rods are removed from a heat metals when they are not being acted upon by treating furnace. The heat treatment is being done outside forces. Color, density, weight, and to stress relieve the rods. (Allegheny International) electrical and heat conductivity are physical properties. Density is expressed as the weight in grams of one cubic centimeter of material (the mass per unit volume). Conductivity is the ability to absorb and transmit heat or elec tricity. Hardenability is the property of a metal to harden uniformly and completely. A (3)Mechanical properties are characteristics ex metal with poor hardenability will hibited by metals when outside forces are ap harden on its sur plied to them. Metalworkers must have an un face only, while its center will be left rela soft. derstanding of the mechanical properties of tively metals when they make or shape metal prod Brittleness refers to how easily a metal will ucts. break with little or no bending. Hardened tool steels and gray cast iron are brittle compared to unhardened steels. Ductility is the property of a metal to be bent, rolled, or otherwise changed in shape Mechanical without breaking. Metals high in ductility in clude soft steel, copper, and aluminum. They Properties can be drawn into fine wire and rolled into Metaiworkers are often concerned with thin sheets without breaking. the following mechanical properties of metals Malleability permits a metal to be ham and how they affect their work. mered or rolled into shape without breaking. Hardness means resistance to penetration Most malleable metals are ductile. A few met by other materials. Steel, for example, is much als, such as lead and malleable cast iron, can harder than lead or pure aluminum. Hardness not be stretched very far without breaking and may be increased by cold working such as are therefore not ductile. bending, hammering, or rolling at room tem Toughness in metal refers to its ability to perature. Hardness may also be increased or withstand sudden shock without breaking decreased by treating the metal in different (fracturing). A metal high in toughness will ways with heat (Fig.2-2). usually bend or deform before fracturing. 30 Part 1—Introduction When steel is made extremely hard by heat metal. Metals high in fusibility are usually treatment, it loses much of its toughness. high in weldability (Fig. 2-4). Welding is dis Cutting tools hardened by heat treatment will cussed in Unit 26. usually break before they bend very much. Strength is the resistance of a metal to de However, a special kind of heat treatment, formation (Fig. 2-5). Tensile strength is resis called tempering, reduces hardness and in tance to being pulled apart. Compressive creases toughness. strength is resistance to being squeezed to Toughness is often more important than gether. Shear strength is resistance to cutting hardness. For example, it is more important or slicing forces. Torsional strength is resis for steering knuckles, springs, axles, and other tance to twisting forces. critical auto parts to rank high in toughness Elasticity is the ability of a material to than to rank high in hardness. return to its original size and shape after the Machinability refers to the ease with external force causing a change in shape has which metals may be machined, or cut by a been removed. Elastic limit is the maximum machine tool (Fig. 2-3). Machinability ratings load per square inch or square centimeter that are expressed as a percentage in comparison can be applied to a material without forcing it with AISI 1112 steel, which is rated at 100%. to change shape permanently. AISI stands for the American Iron and Fatigue is the characteristic that causes a Steel Institute, a trade association of compa metal to fracture (break) under a repeated load nies that sell or work with iron and steel. The that is well below the tensile strength of the AISI develops and sets ratings or standards for metal. Parts subjected to repeated bending or making, selling, and using different kinds of vibration sometimes break because of fatigue iron and steel. failure. Fusibility enables a metal, when in its liquid state, to join easily with another liquid

Fig. 2-4 The fusibility of metal, or the Fig. 2-3 Facing, a common machining ease with which Ii may be melted, affects operation, is done on a lathe. A cutting fluid the strength of its welds. helps the cutting action of the tool bit. Metals rated high in machinability can be cut more easily, leaving a smoother surface than with harder, tougher metals. ___

Unit 2—IntroducingMetals 31

... E.. :r:I •‘.• —- Fig. 2-5 Types of strength in metals. The A. TENSILE STRENGTH colored views show what happens when the stress on a metal exceeds its strength. 1+—

B. COMPRESSIVE STRENGTH Alloys The properties of a pure metal can be C. SHEAR STRENGTH changed by melting and mixing one or more other pure metals with it. This process pro duces a new metal which is called an alloy. Nonmetallic elements may also be included in alloys. An alloy may have characteristics very different from the pure metals from which it was formed. Stainless steel is a fa miliar alloy composed of steel, nickel, and 0. TORSIONAL STRENGTH chromium. It is strong, tough, and much more corrosion-resistant than plain steel (Fig. 2-6). The many kinds of alloys may also be classified as either ferrous alloys or nonferrous alloys. Alloys are named after the main, or principal, metal, called the base metal. Thus, 24 Classification steels that are intentionally alloyed with of Metals nickel, chromium, or tungsten are called steel Metals are classified as pure metals or as alloys. When aluminum is alloyed with other alloys. metals, aluminum alloys are formed. Other metals may also be added to copper to form Pure Metals copper alloys or to zinc to form zinc alloys. A pure metal is a single chemical element that is not combined with any other chemical Fig. 2-6 Space shuttles and the equipment element. A chemical element is a fundamen necessary to launch them contain more than 45 tal substance that cannot be decomposed (bro basic metals in several thousand different alloys. ken down) by chemical reaction into sub (Morton Thiokol Inc.) stances of simpler composition. The earth is made up of more than 100 elements. Pure metals are generally too soft, low in strength, or low in some other desired prop erty to be used in many commercial applica tions. Thus, their use in the pure state is lim ited to laboratory experiments and a few construction applications. Metals may be further classified as either ferrous or nonferrous metals. The word “fer rous” is derived from the Latin word “fer rum,” which means iron. The main element in all steel is iron. Thus, all steels are called ferrous metals. Examples of nonferrous metals are aluminum, copper, lead, tin, and zinc. 32 Part 1—Introduction

is important to the intelligent selection and 2-5 Selection processing of metals for each product. For ex ample, various aluminum alloys are used in of Metals the construction of spacecraft, aircraft, small Engineers, product designers, technicians, engines, lawn furniture, storm windows, and and skilled workers in metalworking occupa small boats. Aluminum alloys are desirable tions must understand the properties of var for these products because they are light ious metals and their alloys. This knowledge weight, corrosion-resistant, and strong. The

Showing Off: A Ladder to the Sky For forty years (1889- find a suitable design. Eu the 7300 tons (6,636 metric 1929), the Eiffel Tower in fel’s design was chosen af tons) of metal used in the Paris was the tallest struc ter he convinced the Min tower. It combined strength ture in the world. Today it ister that a stone structure with rigidity and still was is still one of the tallest of that height would be im relatively light. towers. It was built to show practical. Eiffel completed the off the new materials and After his design was tower in time for it to be methods used during the chosen, Eiffel had only two used as the entrance to the first century of the Indus years to finish the tower. Paris Exposition. At that trial Revolution. The He had to plan every detail time, it was seen as an en “new” material was iron. carefully and devise whole gineering marvel. While Iron had been used for new building methods to other structures may climb many years for tools and make the grand idea a real higher today, the Eiffel weapons, but never before ity. Tower still stands as a sym had an iron project as great One major design prob bol of great technological as the Eiffel Tower been at lem was to determine the advances. tempted. type of metal to he used. The tower is named for Eiffel could choose either Gustave Eiffel, the engineer cast iron, steel, or wrought who built it as part of the iron for the tower’s girders. Paris International Exposi Cast iron was too brittle tion of 1889. The Exposi and lacked tensile strength. tion was a type of indus Steel was lighter and more trial fair with exhibits and flexible, but Eiffel feared demonstrations spotlight that steel’s greater elastic ing new inventions. In the ity would produce too early stages of planning the much sway in high winds. fair, France’s Minister of The wind was a very im Commerce and Industry portant factor to consider proposed a grand 1000-foot when building a tower that tall [305 meters) structure would reach 984 feet [300 that would be a symbol of metersj into the sky. France’s pride and prosper Eiffel chose wrought ity. A contest was held to iron as the best material for

French Government, Tourist Office)

There

loys specialty

minum structural

are

steels. blades,

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treatment.

manufacture

REVIEW

WORDS

15.

14. 12.

13. 11.

10. corrosion

base AISI

brittleness alloy

compressive

More

9.

8. 3.

6. 4.

5. now

7. 2.

I.

are

strength

What How

How Explain Why

What

What

In

What Explain other

Name Name

Name

Name

List

are

drills,

and

metal

alloys

also

steels

available

what steels.

than

steels,

ten

Steels

hundreds

are

many does

alloy

is

QUESTIONS

happens

are resistance

is

cutting

and

two

two

TO the

of

available.

chisels,

the

meant 20,000

the

and

meant

kinds

important

pure

that

the

tools

More

an

three

alloy

explain

KNOW

principal

metals

different

tool

difference

of

difference

for

more

alloy

causes

can

metals

of

to

tools

by this

by

different

used

of

thread-cutting

than

use

groups

steels,

steels.

metal

a

Many

the

be

fusibility

considered

each

than

fracture

differ ferrous

products fatigue

elasticity

elastic density

ductility

metal

different

type

of

kinds

ways

in

for

are

of

350

hardened

base

between

between

metal

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machinability hardenability

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tain

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or

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there

nonferrous

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hardness.

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is

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important

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are

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metalworking

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hardness?

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cer

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who

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safety

cause Safety

every

shops,

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injured

securely.

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31

3-2

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Council

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glasses

cause

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cedures,

work machinery.

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Fig.

painful or

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have tools

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metals

concern:

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personal the

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avoid

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yourself

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tools,

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unprotected

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working

care

discussed.

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safety.

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Ginding produced

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and Fig.

rake ticles

metalworking

in

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metals

sonal sharp

items

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Safe

into 2. Unit 3—Personal Safetyin Metalworking 35

Fig. 3-3 Handle hot liquid metals carefully and wear the correct safety clothing.

laboratories, and factories. Your eyes can not be replaced. Protect them at all costs. 2. Close-fitting clothing made of hard, C smooth-finished fabrics should be worn. Such fabric will not catch easily on sharp edges or rotating tools. Fuzzy sweaters are Fig. 3-4 Choose the right equipment to protect especially bad and should only be worn un your eyes and face. (A) Safety glasses with side der a hard-finished shop coat or jacket. shields. (B) Goggles. (C) Face shield for full-face Long shirt sleeves should be close protection. fitting or rolled up past the elbow. Neck ties should be removed or tucked into the shirt. A close-fitting or .SlOPr H.S!P OR .E.R apron shopcoat will SMA. CAP protect street clothes from the usual grime S4Kfy GLASSES of metalworking (Fig. 3-5). wTH S!DE SHiELDS 3. Feet should be protected against hot, sharp .—NO S2,EATER chips, heavy falling objects, and liquid -SCARF OR P5 TUCKED hot BATWERN THE 1ST AND metals. Safety shoes are best (Fig. 3-6), but 2ND OJTTLtIs ordinary leather shoes offer considerable -- SLEEVES ROL’_ED U OR CUT OFF AOOJE protection. Canvas shoes and open-toed THE ELSOWS sandals offer no protection and should -‘O T: PCCF ETS never be worn when doing metalwork. ,LAU APR C THAT 4. Always take off all jewelry before working CTS C_OSELY AROUC HE SOD. with metals. Wrist watches, rings, neck NO Ri WATCH, RiNG. laces, and bracelets can get caught on OP CLOVES equipment and cause serious injury. -ARDN HANGS DOWN TA THE KNEES STRO.i A—HOC 5TRNCS SACK SAFETy SHOES 4 Fig. 3-5 Dressing safely for metalworking. / Fig. 3-6 Safety shoe with steel-reinforced toe. 36 Part I—Introduction

5. Long, loose hair can be caught in rotating tools. Wear long hair under a close-fitting cap or tie it back tightly. 6. Never wear gloves when operating metal working machines. They are easily caught in moving parts and may cause serious in jury to the hands. (Workers must wear gloves, however, when handling hot mate rials or containers and when arc welding.)

32 Safe Work Practices Fig. 3-7 Cutting tools and workpieces must be General tightened securely for safe operation.

1. Get approval from your instructor or super visor before using any equipment. 2. Make it a habit to stop, look, and think in unfamiliar situations. When in doubt, ask your instructor or supervisor for help. 3. Give serious and undivided attention to your work. 4. Do not walk through restricted areas marked by barriers or floor markings. With Machinery and Machine Tools

1. Be sure all safety devices are in place and working correctly before using any ma chine or equipment. - -- 2. Be sure to tighten workpieces and cutting Fig. 3-8 Mark out-of-order equipment with a tools securely in machine tools, so that blue sign. cutting pressures cannot loosen them (Fig. 3-7). 3. Always keep hands away from moving 8. Always stop machines to adjust, clean, machinery. oil, or repair them. When making hazard 4. Never use your hands to stop moving ma ous repairs, disconnect the machine from chines or parts such as a lathe or drill its power source so that it cannot be press chuck. turned on. 5. When closing electric switches, use the 9. Disconnect out-of-order equipment and insulated handle if available. Avoid touch identify it with a blue sign (Fig. 3-8) as ing the metal parts of the switch or recommended by the National Safety switch box. Council. 6. Never leave a running machine. Someone 10. When changing speeds on a cone pulley else may not expect it to be running and drive system, wait until the machine may be injured by it. comes to a full stop before shifting the 7. Always stop a machine before making belt. measurements with tools that may catch 11. Replace projecting setscrews on rotating in the machinery, such as a caliper. equipment with flush setscrews. Unit 3—Personal Safety in Metalworking 37

Fig. 3-10 Brushing is a safe way to remove Fig. 3-9 Learn to lift heavy objects by using the sharp chips. Never pick up chips with your hands. strength in your legs, not your back. (Manual High School, Roger Bean)

With Other Students or Co-workers With Shop Materials 1. Always try to be alert, patient, courteous, 1. Handle materials carefully to avoid being and willing to help. This is especially nec cut. essary in school shops where you may have 2. Do not touch metal you suspect is hot. to wait to use a tool or get help from your Test it first by sprinkling a few drops of instructor. water on it. 2. When working with someone, agree before 3. Get help in lifting or moving heavy pieces hand on how the work will be done and of metal or machine parts. Remember to who will do each part so that there will be lift with your legs, not your back (Fig.3-9). no confusion that could lead to injury. 4. Get help also when handling long pieces of 3. Do not disturb someone who is actively in metal, so as to avoid injuring someone or volved in operating a machine or other po damaging equipment. tentially hazardous equipment. You may 5. Return large pieces of metal to their proper cause them to make a mistake which could storage racks immediately after cutting off cause an accident. the pieces needed. With Scrap and Waste 1. Use a brush, a piece of cardboard, or a stick 3-3 Safe Use to sweep up or push away sharp metal of Hand Tools chips (Fig. 3-10). Never use your hands. 2. Never use compressed air to blow metal The improper use of hand tools frequently re chips from a machine or work station with suits in personal injury. The following safe out approval. work practices should be followed when using 3. Keep aisles clear of small metal pieces, hand tools: chips, and other waste. These are hazards 1. Use the right tool for the job to be per to safe travel. formed. 4. Keep floors clear of oil, grease, and other 2. See that tools and your hands are clean liquids that could cause someone to slip and free of grease or oil before use so that and fall. the tools can be held firmly. 38 Part 1—Introduction 3. Cutting tools should be sharp when using them. Dull tools cause accidents because they require greater force to use them. Dull tools also leave jagged edges that may cut someone. 4. Sharp-edge tools should be carried with their points and cutting edges pointing downward. 5. Heads of cold chisels and punches should not be allowed to mushroom or crack; they should be properly dressed or re paired. 6. When using a chisel, always chip in a di rection which will prevent flying chips from striking others. 7. Choose the correct size and type of wrench for the 1ob and use it properly. You can injure your knuckles or hand if the wrench slips. 8. When using a file, be sure that it is equipped with a snug-fitting handle. Oth erwise, the sharp tang on the file could in jure your hand. 9. When you hand tools to others, give them with the handle first (Fig. 3-11). 10. Always report damaged tools to the in structor. Damaged tools can cause inju 34 ries. FirstAid be free of 11. Tools should always wiped 1. Always notify the instructor immediately grease or dirt after use and then returned when you or another student are injured, to the proper storage place. no matter how slight the injury. 2. Get first aid as soon as possible (Fig. 3-12). It is good practice to let slight or moderate cuts bleed for a few moments before stop ping the flow of blood. Free bleeding carries a tool to someone, Fig. 3-11 When you give infectious particles out of the wound. Se always offer it handle first. The scriber being vere cuts or bruises should receive the handed to the student in this picture is needle im sharp and hard enough to cut steel. mediate attention of a doctor. 3. Burns should also be treated promptly. A first-degree bum is one in which the skin is merely reddened. In a second-degree burn, the skin is blistered. In a third-degree burn, the skin is charred. Treat first-degree burns with applications of ice or cold wa ter. Then apply a sterile dry bandage. Sec ond- and third-degree burns should receive a doctor’s attention immediately. 4. If you are concerned about an injury or an illness, don’t be foolishly brave and “tough it out.” Get professional help as soon as possible.

Fig.

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Part 1 Introduction Name Score

UNITI Careers in Metalworking

1-12. Multiple Choice. Write the letter of the correct response to each statement or question in the space at the left.

1. A book published by the U.S. Department of Labor that provides current information about all types of careers is the A. Dictionary of Occupational Titles C. Career Quarterly B. Occupational Outlook Handbook D. Career Outlook Review

2. There are over 20,000 occupational titles described in the U.S. Department of Labor book called the A. Dictionary of Occupational Titles C. Career Quarterly Handbook B. Occupational Outlook Handbook D. Annual Survey of Occupational Titles

3. The length of time usually required to train an engineer or a machinist is A. 2 years C. 4 years B. 3 years D. 5 years

4. Workers in occupations that require little or no training are classified as A. unskilled C. skilled B. semi-skilled D. technicians

5. An example of a semi-skilled occupation would be a(n) A. engineer C. machine tool operator B. floor sweeper D. technologist

6. An example of a skilled occupation is A. technician C. engineer B. technologist D. tradesperson (such as machinist)

7. A person learning a trade in a systematic way under a master of the trade or under the direction of a company is called a(n) A. beginner C. trainee B. learner D. apprentice

8. Becoming a skilled tradesperson without the benefit of a formal educational program is called A. the pickup method C. an apprenticeship B. on-the-job training D. an internship

Continued on next page

7 ______

9. Workers whose occupations require two years of technical education beyond high school are called A. engineers C. technicians B. technologists D. skilled workers

10. Which occupational classification requires four years of college and prepares indus trial workers for either technical or middle-management positions? A. journeyman C. technologist B. technician D. engineer

11 . The occupational classification requiring the highest level of education in mathe matics, physics, and chemistry is A. technician C. technologist B. engineer D. skilled tradespcrson

12. The kind of engineer who organizes people, materials, and machines for mass pro duction in an industrial plant is the A. tool engineer C. industrial engineer B. manufacturing engineer D. all of the above

8 ______

Part I Introduction Name Score

UNIT2 Introducing Metals

1-16. Multiple Choice. Write the letter of the correct response to each statement or question in the space at the left.

1. Characteristics of metals when they are not being acted upon by outside forces are called A. chemical qualities C. physical properties B. attributes D. traits

2. Characteristics of the chemical composition of metals are called A. mechanical properties C. chemical properties B. physical properties D. molecular properties

3. Characteristics that describe how metals behave when outside forces are applied are called A. mechanical properties C. chemical properties B. physical properties D. molecular properties

4. What property of metal refers to its ability to resist penetration’ A. hardness C. elasticity B. toughness D. elastic limit

5. What property of metal refers to its ability to withstand shock without cracking’ A. hardness C. strength B. toughness D. elasticity

6. The property that causes metal to break with little or no bending is A. hardness C. fatigue B. toughness D. brittleness

7. The property of metal that refers to its resistance to being pulled apart is A. ductility C. tensile strength B. toughness D. compressive strength

8. Metals high in weldability are usually high in A. fusibility C. malleability B. ductility D. meltability

9. The property that causes metal to fracture under a repeated load that is less than the tensile strength of the metal is called A. elastic limit C. toughness B. brittleness D. fatigue

Continued on next page)

9 ______

10. Ferrous metals are metals that contain A. copper C. aluminum B. iron D. zinc

11. A combination of two or more metals, one of which is intentionally added to the base metal, is called a(n) A. mixture C. blend B. compound D. alloy

12. Steels that can he hardened to make such items as files, drills, wrenches, and ham mers are called A. alloy steels C. specialty steels B. structural steels D. tool steels

13. About how many different kinds of metals and metal alloys are now available? A. 1,000 C. 20,000 B. 10,000 D. 30,000

14. About how many different kinds of aluminum alloys are available? A. 400 C. 300 B. 350 D. 250

15. About how many kinds of copper alloys are available? A. 100 C. 300 B. 200 D. 400

16. About how many different kinds of metals are used in a modern automobile? A. 50 C. 150 B. 100 D. 200

10 ______

Part 1 Introduction Name Score

UNIT3 Personal Safety in Metalworking

1-13. Short Answer. In the spaces provided below, write 13 things that the boy pictured needs to correct to be dressed safely for work.

1.

2.

3.

4.

5.

6.

7.

8. 9

10.

11.

12.

13.

14-24. Multiple Choice. Write the letter of the correct response to each statement or question in the space at the left.

14. Clothing made of which kind of fabric is safest to work in? A. soft and smooth C. hard and smooth B. soft and fuzzy D. hard and ribbed

15. Next to safety shoes, what shoes offer good protection for metalworking? A. ordinary leather shoes C. open-toe sandals B. canvas shoes D. any of the above

(Continued on next page)

11 for

wet

you

most

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person

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12 Metals Processes Week 2

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they

the way

Supervisor a

make machines workers.

finishing. Larry

Larry It

his

the

industry.

Numeri

works

to

business

division

lots Division

emphasizes

time

industry,

and

Barton

to

project, applied of

including

was

metal

main

in

do,

busi Larry

up opportunity

course,

con

will And

stay he

and

ability has foundry Barton

the which

on

ad

easy

his

of

he in

through

with

enrolled

satisfaction

Larry

steel

is

spends

Larry workers

for

responsible

he

cutting

was

he

and

production,

company,

young

shafts. most

him

learned

worked

is

to in

the

always

enjoyed

most

supervisor

become

shop

participate

to

internal

enjoys

of

Although

ranks,

people,

recognize

many

his

of

for

part

with

fixing

and

but

working

his

job. guiding

a

skilled

threads

just

of vocational

wide

of

of

not 17

he

time

something

in

Larry

the the his

early

workers

as

a

has

at

variety

the

threaders

with

with

machine skills

coopera

day

on

he

the has

in

youn

many

cast

pro

in

was

life

his

the

his

ex

re on

or

of

a

Fig.

hand. Internal.

clockwise

advances Fig.

on

ing

clockwise

(Fig.

are nut

a

internal Threads

and

face

that

right-hand

the

19-1 The

19-2 right-hand.

Threads

wheels

A

that

screws

winds

of

19-2B).

(A)

screw

right

a

shaft

with

A

threads

Screw

Threads

rotation.

on

is

cylinder

right-hand

onto

screwed at

(Fig.

are

may

the

side

thread

thread

counterclockwise

on

a

threads.

A

I..,

I

constant

external

are (Fig.

a inside

44-1)

a

and

(B)

be

nut

or

grinder

bolt

is

either

(Fig.

clockwise

A

right-hand

thread

a

19-1B).

left-hand

that

a

(A)

left-hand

has

cone.

of

ridge

has

angle

19-2A).

threads

right-hand

External.

a

is

that

right-hand

advances

•.

hole

left-hand

screwed

Threads

of

rotation.

onto

around

threads

has

or

thread

uniform

Most

or

(Fig.

left-hand.

(B)

Screw

two

or

a

with

a

counter

bolt

on

left-

the

threads

threads nut

threads

19-IA).

on

grind

shape

bolts

sur

the

has

are

UNIT

A

Threads

lathes,

drilling

chines

precision

with

manually,

in

machinery.

fine

vise user

vantage.

advantage Threads

screw

a

riage

motion.

change easy

them

such

left-hand.

sumed left

metal

detail.

Hand

Screw

jaws.

side.

to

adjustments

as

machine

to

in and

apart.

all

apply

automatic

rotary

to

lathe.

bolts,

machines,

are

A

It

put

a

measurement

taps

On

Screw

can

be

because

However, threads

a

multiplies

good

vise

cutting

The

often

process

great

working

Screw

right-hand

parts

Threads

Made

How

make

(turning)

Threads

and

Uses As

nuts,

tools.

provides

screw

threads

example

it

used

on

are

dies

clamping

lathes,

they

revolves,

and

together

and

threads

tool

threads

Units

most

instruments,

widely

the

drawings,

Ordinary

Screw

of

in

to

are

motion

possible.

act

are

screws.

unless

great

thread-grinding

is

increase

turning

in

micrometers

used

milling

20

Screw

threads

also

like

routinely. the

force

Are

are

used

it

quickly

a

mechanical

and

to

marked

drives

to

lead

lathes,

threads

straight

used

They

a

also

between

straight-line

effort

on

wedge.

mechanical

cut

21

tools,

machines,

are

screw

fasteners

to

used

make

the

or

threads

discuss

makes

LH

of

are

turret

make

made

line.

take

The

ma

and

car

the

the

ad

on

for 155

as

to it 156 MOVING DIE Pitch: The distance from a point on one screw thread to a corresponding point on an adjacent thread, measured parallel to the thread axis (Fig. 19.4). The pitch of a thread is a measure of the size of the thread. For inch- based threads, pitch is equal to 1 divided by the number of threads per inch. For metric threads, pitch is expressed in millimeters. The pitch of a thread may be determined STATIONARY with a steel rule or with a screw pitch gage DIE (Fig. 19-6).Be sure to use customary inch tools Fig. 19-3 The technique of thread rolling used for measuring inch-based threads, and metric in cold heading machines. tools for measuring metric threads. Lead: The distance a thread moves along Most standard threaded fasteners are made its axis in one revolution. On a single thread, from wire on automatic machines called cold the lead and pitch are the same. On a double headers. Cold headers use flat thread-rolling thread, the lead is equal to twice the pitch. On dies to form threads (Fig. 19-3). Cylindrical a triple thread, the lead is equal to three times thread-rolling dies are available for use on the pitch (Fig. 19-7). lathes. Lead, or helix, angle: Angle made by the helix of a thread at the pitch diameter, mea sured in a plane perpendicular to the axis of the thread (Fig. 19-4). Multiple thread: A thread having the same 19$ ©Tew The.d thread form produced with two or more heli Terrn cal grooves, such as a double or triple thread (Fig. 19-7). The following screw thread terms are adapted from American National Standards Crest: The top surface that joins the two of a thread (Fig. 19-4). Institute (ANSI)definitions:’ sides Major diameters The largest diameter of a Root: The bottom surface that joins the straight external or internal thread (Figs. 19-4 two sides of adjacent threads (Fig. 19-4). and 19-5). The nominal, or basic size is similar to the major diameter, and is used for general Fig. 194 The principle parts of a screw thread identification, such as identifying the thread size as /4” or 1/2” diameter. Minor diameter: The smallest diameter on a straight external or internal thread (Figs. 19-4 and 19-5). Pitch diameter: On a straight thread, the diameter of an imaginary cyiinder that passes through the thread profile where the width of the thread and the width of the groove are equal (Figs. 19-4 and 19-5). The amount of clearance between mating threads is con trolled by maintaining close tolerances on their pitch diameters.

‘Unified Screw Threads (ANSI Bi. 1-1960) Published by the American Society of Mechanical Engineers, New York, NY

pitch

Fig.

inch.

internal

the clearance

Fig. diameters

.

same

19-6

19-5

gage.

ilL1HlIiHiLHHi

(A)

lp[IFIlIIIIIIfJF[IfT1TfTfTHHIiHJI1I

threads

Using

basic

Measuring

A

between

of

comparison

a

screw pitch

-

a

I

of

steel

them.

matching

OLSi?F.V/

C.

the

diameters.

and

rule.

);

‘1.11

number

between

1’;

External

a

nut,

(B)

bolts

2

Using

showing

of

the

threads

and

CLEA;IC

threads

minor

a

nuts

screw

the

and

per

have

Fig.

threads

thread.

measured

the

single

measured

(Fig.

of

thread

the

a

19-7

Height

major

Clearance: Side

crest

19-5).

thread

depth

are

(Fig.

The

or

related

and

with

perpendicular

perpendicular

of

19-4).

flank:

and

pitch

SI\JGLE

of

DOUE3LE

2

minor thread:

TRIPLE

The

thread.)

the

the

23

as

PITCH and

L.EAD--

The

shown

distance

Unit

root

root

diameters

leads

JHREA[)

THF?EAD (Sometimes

-

The

Tf PITCH

LEAD-H

19—Screw

surface

H

to

to

here.

on

of

1EAD

of

distance

between

a

the

multiple

the

either

mating

of

that

Threads

axis

thread

the

called

side

connects

the

between

thread,

thread,

of

crest

of

axis

the

the

157 a 158 Part s—Threads and Thread Cutting Development objections to this sharp V-thread form, the United States Standard Form Thread was de of Screw Threads veloped (Fig. 19-8). It was developed during in the the 1860s, and was first adopted by the United United States States Navy in 1868. This thread form was widely adopted by American industries. Some manufacturers, however, continued to make The cross-sectional shape of a screw threads according to their own systems. of thread is called its profile or form. Early ten, bolts made by one manufacturer would threads had no flat crests. To overcome the not fit nuts made by another. i. i;. ‘; WiNim SeVers: Standard Setter of American Manufacturing Imagine that you have Sellers (1824-1905). Trained practical designs and added lost an important metal as a machinist and rnechan weight for durability. Ma part---—say, the nut that ical engineer, Sellers chines made by Sellers’ holds your bicycle tire to opened and operated a ma company gained a reputa the frame. You go to the bi chine tool manufacturing tion for excellent perfor cycle shop and find that plant in Philadelphia. He mance. His insistence on none of the nuts they have insisted on accuracy in all precision, standardization, will fit your bike. In fact, of the company’s work. If a and simplicity helped ad youi lost part is one of a measurement was off by vance the general standard very limited number of even a “hair’s breadth,” he of manufacturing. And it parts, and it will be very saw that it was adjusted. was Sellers’ influetice that difficult to get another one. In 1864 Sellers pro made shopping for replace Maybe you’ll never be able posed to standardize screw ment parts a simple task, to get your bike back to threads, He suggested that instead of a cause for alarm. gether! all screw threads be made This imagined scene with a sixty-degree angle. will give you some idea of He also said that threads what American manufac should be made with flat turing was like in the rmd crests and roots instead of l800s. Mass production had with the sharp V-shaped begun, but the industrial form then common. system had a lot of “bugs” Sellers’ two ideas were in it. For one thing, there used in designing the Stan were no standards for screw dard Form Thread, which th1-eads, so a part made by was adopted by the U.S. one manufacturer often Navy in 1868. Within ten wouldn’t fit a machine years, Sellers’ screw thread made by another. The lack was used all over the coun of a standard thread greatly try. By 1894, this screw troubled those who were thread had become the concerned about precision standard for international and quality in machine tool use. production. Sellers set other trends One of these people in machine tool manufac was manufacturer William turing, including simple,

while ferences

form,

rounded

flat Thread

threads. American

instead the Great

Fig.

approved Institute

modifications)

Screw

neers National

SAE thread

United profile

Form

Screw

agencies

thread gress

Commission

19-8).

more

19r.%

The

In

This

crests

19-8

During

Extra-Fine

countries

Thread established

the Britain

(SAE)

standardization

American The

Thread

1948,

Thread

standards.

form

so

was

(ANSI)

roots

Unified

States

from

of

The

in

Fine

committee

produced

that

English

(Fig.

industry

Commission

World

1933.

had

the

the

American

named

the

to

Threads

agreed

Unified

and

and

the Standard

-

Thread.

threaded

Form

Standard

19-9).

Thread

to

Standard

develop would

C’’

Screw

Society

recommended

United

industries

may

older

the

was

prefer

American

now

War

the

for

to

the

the

These

National

and

National

of

have

much

Series

use an

This

Thread

that

parts

uses

and

I

be

in

American of

rounded

American

also

States,

screw

American

American

Form

external

Screw

the

other

the

Automotive

are

either 1924.

‘7

the

adopt

use

form

National

interchangeable.

the

was

made

Unified

established

need

Standards

Unified

generally

the

Screw

in

threads.

Commission

Thread

Canada,

same

added

flat

crests.

thread.

cooperating

The

rounded

was

new

1911.

in

main

National

National arose

National

National

threads

each

Thread

crests,

thread

thread

Screw as

like

screw

(with

Engi

Con

The

(Fig.

The

dif

has

and

the

the

for

or

of

a

and

Engineers, 2Unified

2. following Thread

vided

1960), cluded formulas

Form be

however,

be and

same. American rounded

these Thread

The

Fig.

1.

Flat

Depth

Pitch

Unified

adopted Unified

adopted

used rounded.

19-1.)

19—1.)

The

later

The

the 19-9

published

depth

thread

two

by

at

Production

and

in

number

is

is

internal

interchangeably

edition,

New

calculations

root

depth

crest

the

= (See

The

for

the

equal

common

slightly

American

kinds

P

National

National

from

from

D

National

York.

may

of

number

= some

Unified

by

Unified

is Figs.

=

Unified

of

number

of

to

optional

the

threads

the

of

0.61343

0.6

F

the

tL

be

threads

0.5

less

tolerances

the

Screw applications

19-8

American

screw threads

=

Unit

1343

Screw

made

Form

of

1427 external

Screw

for

Coarse

NC

NF

Screw

internal

Fine than

of

and

for

threads 19—Screw

in

Threads

on

an

x

thread

per

Thread

threads

thread.

with

thread.

most

x

Thread. most

are

Society

Threads

P

Threads2:

both

19-9):

the

1

external

P,

permit

Thread

inch

Thread

essentially

Unified

(ANSI

the

Unified

or

per

the

depth

instances.

series

applications;

Threads

Form.

the

of

per

0.5

(See

(See

(ANSI

root

inch.

following

However,

Mechanical

‘ROUND

Bl.l.1949)

them

external

ROOT

1427

inch

Unified

(UNC):

(UNF):

for

are

Table

Table

Form must

Form

B1.1-

The

the

the

in 159

di to of

is

of

the

Un

the

the

per

and

ma fits,

have

lead

jobs

Pipe

ridge

NPT

mated

many screw angle

of

liquid

square

groove

product

types ranking

any

threads

for

the

fittings.

mm

a

be types on

jacks

threads.

Thus,

The sealant

each

fit the

The The

mated,

the

on

Taper angle

threads

pitches, pipe or

of pipe of

requirements.

like

as

against

may used

four

are

[62.48

acme

house

equal. used The

pipe-fitting

and

following thread.

However,

19-12).

3B

fits. long

fit Forms seal

fit

also in squares. for

use

about

width

width mated

foot Handbooks

fit

for

the also

as Common

formed Standard thread

type Standard

of

tools.

(Fig.

are pipes

and

tightness

and

two per

in

and

intermediate compound

close

usually loose

free close is used

are

mated.

used

this

2A is

an class, 19-11). ¾”

are

and

are

They

pipe

form

1B:

depth

2B:

3B:

result classes

are

allowances pipefitters

external

height

A

and

National machine

thread Othe’ Threod with

National information

low-pressure

diameter

(Fig.

threads.

free

grooves

a of necessary and and

and

The

of

assembling

ridge

permit that

classes tapered and

lathe,

The and

internal

threads

Thred

the

29°

threads the

a used the

IA

pipe (NPT)

2A

have Th’ec 3A

for

the

applications. strong

are

and

is

square

on

of

class 2B Thres

leakage.

any

kinds

following

19-10).

require When

A equal.

Acme

American American

used

194

very

gas

class ified meets with The tolerances fit: Classes Classes

Classes

tolerances between

Squwe

(Fig. are groove between is Acme similar screw thread other chinists tolerances,

Pipe

are Plumbers standard

Threads that or threads normally

meter]

8

are

32 in. 32 28 six 32 28 32

24 (FF1 24 24 20 20 20 20 be 20 Ta

3.

(NEF) and

and flts, UNEF

(UN

series

the

thread

inch

2A

The

(See The

and

as

per

called

72 80

64 56 (16UN) 48 44 40 18 18 28 32 16 36 24 24 28 14 14 20 20

(NFl

UNF

)SAE) 3A,

classes 2B,

class

tightness

Thread

Cutting

such

Threads

thread. of

and

12-thread external

lB,

threads.

series

9 8

Threads 64 48 56 40 18 40 16 .32 14 21 12 24 13 11 32 10 20

Thed

(NC)

UNC

(USS)

formerly

2A,

Thread

19-1

NEF

the

The

external

series,

degree

screw

Normally,

IA,

and

ExtraFine

the

ed

Screw

the

16-thread

Table

:Lsgnated

1900

threads, .0600 .0730

.0860 .0990 .1120 .1250 4150 .1380

.2160 .1640 .2500 .3125

.3750 .4375 (SUN), .5000 t’ree .5625 .6250 .7500

1.0000

from

CiaS5S.

Decimal Equivalent the

of

Uniftod

arc

Unit

threads.

means

6—Threads

Urifd

National

and

deoc

series

less-common

0

1

¼

½ with

¾ 5/ ½ 3/4

Vio ‘/16 9/

fit”

Part Inch ‘I/Is 13/ 13/

include

included. adopted classes

are

19-1.)

classes

internal

mating

Six

used

Diameter

Unified EF) ble Other thread also

(12UN),

1

0 2 S 4 3 6 8

i96

No. 10 12

160

3. 4.

are classes “Thread

three classes ternal tween

between

vides

the

Taper ther

3. Threads

chanical,

2. construction.

4.

Fig.

1. Fig.

The

The The

The free-fitting

joints chanical

American

American

tighter

19-11

19-10

P

D

WIDTH

W

the

basic

D

P

R

Pipe C

NPSC

NPSH

NPSL

NPSM

Pj

(NPS)

tapered

the

.500 DEPTH

PITCH

in

tapered

The

The

W

FLAT

DEPTH

FLAT

PITCH

the

Threads data

joints

hose

MAKE

PITCH)

sides

OF

X

thread

mechanical

National

National

Acme

square

have

is

is

joint

thread

ON

ON

PITCH

THREAD

for

threads

.500

couplings.

NO.

thread

for

.001

for

with

of

NO. +

-

TOP

BOTTOM

different

several

(NPTR)

.001

thread.

THREADS

becomes. the

is

PITCH

thread.

use

loose-fitting

TO

X

THREADS

OF

is

used

locknuts.

GROOVE

Standard

Standard

PITCH

joint

TO

thread

.003

are

THREAD

in designed

joints.

+

.002

(P

types:

make

in

screwed

.010

sizes

PER

loose-fitting

OVERSIZE

for

X

PER

Table IN

pipe

is

.3707)—

INCH

INCH

use

Straight

INCH

Railing

NUT

600.

INCH

of

P

a

mechanical

for

couplings.

rigid, X

CLEARANCE

pipe.

in

19-2

together,

The

.3707

TO

.0052

(.500

use

railing

Joint

FIT

Pipe

pro

me

me

far

X

in

32

Fig.

for

types

NPSI—Dryseal

NPSF—Dryseal

PTF-SAE

NPTF—Dryseal

listed joint

sealant. tions

per

Size

Nominal PAREECT

TQ

machinists.

2½

1½

1V

Pipe

¾

¾

19-12

Further

½ inches

Vs

¼

2 1 American

Pipe

Pipe

of

without

that

below:

2

diameters

Straight

Pipe

THREADS

pipe

The

Threads

BDTTD.’,

Taper

Short—Dryseal

require Threads,

/_‘

Actual

and

Thread

information

inside

0.62.3 0.270

0.824 0.494

2.468 0,364

2.067

1.610 1.048

1.380

/,,

threads four C30

National

the

pipe

Standard

Pipe

Standard

Standard

Table

Tap forms

LT—-.

Pipe

(NPTF)

a

use

Unit

threads

Thread

gas

is

Pipe

outside

Actual

0.840

2.375 0.675

2.875 0.540

0.405

1.315

1.660

1.900

1.050

Drill

I

Thread

available

19-2

of

19—Screw

of

Standard

Intermediate or

L

Fuel

Pipe

about

are

Dimensions,

I

Dryseal

pipe

Sizes (NPT).

SAE

liquid

Internal

used

\

Thread Threads

..

inch

T—READS

11½ 11½ 11½

11½

compound

in

Per

the

27

Threods

14

18

14 18

Short 8

Dryseal

tight

handbooks

threads

TO

in

different

Internal Straight applica

.

thread

Taper

drill

1W31

2¾e Tap

size 1½z

Wit

‘Vt,

2½

1½

Ta

161

are or 162 Part 6—Threads and Thread Cutting

pitch in millimeters nominal size nominal size threads 194 ISO Metric in millimeters — — — —- per inch Threads ISO thread symbol In 1949, the International Standards Orga nization (ISO) recommended worldwide adop tion of three series of metric threads, These M24 x 3 threads are based on the same 60-degree M20 x 2.5 thread form adopted for the ISO Inch (Unified) 3/4 - 10 are (1)ISO x threads, (Fig. 19-9).The three series MiS 2 —f.—5/8 - 11 Metric coarse pitch, (2) 150 Metric fine pitch, M14 x 2 9/16 - 12 and (3) ISO Metric constant pitch. ISO Metric 1/2 - 13 and ISO Inch threads have the same thread M12 x 1.75 form but are not interchangeable because of 7/16 - 14 Mb x .5 differences in diameters and pitches. 3/8 - 16

Figure 19-13 compares the ISO Metric M8 x 1.25 f.:.... 5/16 - 18 coarse series thread sizes with the Unified Na- M5.3x1 . 1/4-20 tional (ISO Inch) coarse series thread sizes. Ta 12 - 24 ble 19-3 gives a complete listing of ISO Metric M5 x 0.8 -----— coarse and fine pitch thread sizes. -- 10 - 24 Only ISO Metric coarse pitch threads are M4 x 0.7 8 - 32 commonly used on fasteners. ISO Metric fine M3.5 x 0.6 6 - 32 pitch threads are used mostly on precision 5 - 40 M3 x 0.5 tools and instruments. The constant pitch se 4 - 40 ries threads are used mainly on machine parts, M2.5 x 0.45 3 - 48 but are also used on all spark plugs. .-==-fr=- 2 - 56 M2 x 0.4 Meffic Th’eod 1 - 64 Ge o O M1.6 x 0.35 Basically, there are three ISO Metric classes of fit: fine, medium, and coarse. The Fig. 19-3 A comporLon of the common sizes classes of fit are more accurately identified by of ISO Metric Coarse threads with Unified giving the tolerance grade and the tolerance National (ISO Inch) Coarse threads. position of the mating threads. Tolerance grades are specified by a number that can be applied to both pitch and major diameter. Tol erance position is specified with a lower case (small) letter for external threads and with a diameter in millimeters is given. This is fol capital letter for internal threads as follows: lowed by the thread pitch in millimeters, sep External Threads: Internal Threads: arated from the first number by a “times” be when e = large allowance G = small allowance mark (x). The pitch may omitted designating coarse threads. Therefore, an ISO g = small allowance H = no allowance h no allowa:ice Metric 16 mm coarse thread with a pitch of 2 mm would simply be designated Ml6. The for Table 19-4 shows the tolerance classes same diameter in a fine thread would be des and matches external and internal threads, ignated M16 x 1.5. Complete designations for fit. them with the three classes of ISO Metric threads include identification of the tolerance class. Thread Designation Additional information on ISO Metric All ISO Metric thread designations begin threads can be found in handbooks for engi with the capital letter “M.” Next, the major neers and machinists.

Nominal

WORDS

Dryseal double

dies acme

depth

internal class external 24 22 27

20 18 12 mm 16 14

10

3 4 8 6 5 2

2.5

1.4

1

6

size

of

thread

of

thread

thread

thread

threads

threads

thread

TO

KNOW

3

3 Pitch 2 2.5 2.5 2 2.5 0.8 07 0.5 045

0.4

0.35 03 1.5 1.25 mm I 1.0

75

Coarse

Medium

Fine

nominal major ISO

multiple left-hand Iso

minor

lead

Class

of

fit

ISO

Inch

Metric

of Identified

.‘

diameter

Approximately diameter

.

thread Tolerance ..

.

size

thread

threads

thread

Tap

Coarse

threads

ISO (Review 24.00 21.00 19.50 17.50 15.50 1400 12.00

10.25 mm

4.2 8 6.75 3.3 5.0 2.5 2.05

1.6 1,25 1.1

5

drill

Metric

Table

with

series

Table

75%

threa&

E’i4rna1 Classes

‘..

4h

Continued) 8g

6g

thread the

.

19-4

root pitch

single right-hand pipe

pitch

screw-pitch

19-3

Threads

Tolejance

Class

diameter

compound

of

diameter

of

Clearance thread 22.80 24.60 27.95 20.50 18.20 16.45 14.2 122

10.2

mm

drill Threads 6.2 3.2 42 2.2 8.2 5.2 2.6 1.8

1.55

thread

of

class

thread

gage

Fit

Internal

threads

6H 5H

7K

Unit

Unified

square

tolerance tapered

thread

triple taps Pitch 2

2

mm 19—Screw 1.5 1.5 1.5 1.5 1.5 1 1.25 1 — — — — — — —

25

thread

designation

thread

Form

Fine

class

Threads

series

thread Tap 25.00 22.00 20.50 18.50 16.50 10.50

14.50 1250 mm 8.75 7.0 — — — — — —

—

drill 163 164 Parc 6—Threads and Thread Curcing

REvIEw QUESTIONS

1. Are most screw threads right-hand or left-hand? 2. How carl you tell whether the thread on a bolt is right-hand or left-hand? 3. What is a double thread? Triple thread? Multiple thread? 4. What is meant by major diameter? 5. What is meant by minor diameter? 6. What is the pitch diameter? 7. What is the pitch of a thread’ 8. What is the lead of a thread? What is the difference between lead and pitch? 9. Describe two ways to measure the pitch of a thread. 10. Describe a square thread and give an example of where it is used. 11. Describe an Acme thread and give an example of where it is used. 12. List the four types of pipe threads. Which is used for general purpose plumbing? 13. How do NPT threads differ from Unified screw threads? 14. Why aren’t iso Metric threads interchangeable with Unified National threads? 15. Explain how ISO Metric threads are designated. 16. Where can additional information be obtained on screw threads?

. UNIT External Threading with Dies

Most threads are made with machine placeable cutters (Fig. 2.0-2).The main body of tools. However, skilled metaiworkers some this type of die is called a collet. The cutters times find it necessary to cut threads by hand are held in place with a threaded ring called a with dies. guide. The hole in the center of the guide is a close fit with the rod being threaded. This helps to guide the die so that it will go on the rod squarely. Rethreading dies are square or hexagonal in shape so they can be turned with an ordi nary wrench (Fig. 20-3). They are used only for Threcdirig Dies rethreading of damaged threads. A threading die is a tool for cutting exter Left-hand dies cut left-hand threads. They nal threads on a round rod, such as those on a are stamped with either an “L” or an “LH,” bolt. Small diameter threads are cut with Right-hand dies are unmarked. small round dies that are either solid or ad A screw plate is a set of threading tools justable (Fig. 20-1). Larger diameter threads that includes dies, taps, and the tools needed are cut with dies that use adjustable and re to use them (Fig. 20-4). Unit 20—External Threading with Dies 165

A B ADJUST ‘A SAFE Fig, 20-1 Threading dies. (A) Solid. (B) 4 A djus table.

CO..*ET /

Fig. 20-3 Rethreading dies. (A) Square. (B) Hexagonal. (Greenfield Tap & Die/Div. of TRW, Inc.)

GUDE 5T SAFE’.’, Fig. 20-2 An adjustable die with replaceable cutters.

A diestock is a tool for holding and turn ing a threading die (Fig. 20-5(. Diestocks are made in several sizes to fit dies of different di- ameters.

‘ 2O2 Sizes of “I/il Threading Dies The diameter and pitch of the thread that is produced are stamped on each die, together with the kind of thread. For example, /4-2O Fig. 20-4 A screw plate (a set of taps and dies, UNC means die that the will cut a Unified die stock, and tap wrenches). Greenfield Tap & National Coarse thread with a major diameter Die/Div. of TRW, Inc.) of ¼” and 20 threads per inch. The sizes of inch-based threads are given in Table 19-1. A die marked M8 x 1.25 is a metric die that will cut a thread with a major diameter of 8 Fig. 20-5 A diestock. mm and a pitch of 1.25 mm. The sizes of met ric threads are given in Table 19-3. It should be noted that the diameter of the rod on which a thread is to be cut should be the same as the major diameter of the die. 166 Part 6—Threadsand Thread Cutting

Fig. 20-7 Adjusting a threading die to a standard bolt.

5. Place the tapered, or starting side, of the die on the rod (Fig. 2O8). Fig. 20-6 Beveling the end of the workpiece 6. Hold before threading. the diestock with both hands near the die (Fig. 209). Keep the die as square as paseFble with the rod. Press down firmly and at the same time slowly rotate the die How k Cut oakwiee. Larger die sizes require more o Thread pressure to got the die started. After two or 20$ wi’h c CNe three thresds have been cut, heavy pressure o on the di.e is rio longer necessary. The die Destock will continue to screw itself onto the rod 1. Bevel the end of the rod to be threaded (Fig. as it is rotated. 20-6). (“Bevel” means to slant or taper the 7. Shift the position of your hands to the ends edge.) This makes it easier for the die to of the diestock, add a little cuttlng flu.d, start the thread. and continue to cut the thread (Fig. 20-10). 2. Hold the rod tightly in a machinist’s vise Back up toe de a haiLturn every two or so that it cannot turn. three threa.s to brcak and clean away the 3. Adjust the die to fit a standard bolt, that is, chips, This helps keep chtps from clogging a bolt with threads of the same size you the die and rcu!ghcnin up the thread. want to make (Fig. 20-7). Threading to a shooidee, A shoulder is a 4. Mount the die in the diestock. Secure it diameter larger than the thread diameter. with the tightenhig screw (Fig. 20.5). When fuiJ. threads are needed as close to a

Fig. 20-8 The starting side of the threading die has the most tapered threads.

—2 TO 3 TH?EADS

cial

minum.

other fluids

eral

side

usually partly

20-Il). shoulder. will

the shoulder

Fig.

the

20:4

When

threading diestock

20-9

usual

of

leave

oil

metals

partially

Fig.

shoulder.

made

finished

the

Never

result

or

Cutting

as

Placing

20-11

Then

threading

several

manner

die,

especially

is

one

possible,

are

for

Cutting

cut

cut

fluids

in

important

Turn

threads

since

Cutting

turn

given

broken

the

of

threads

fluid

full

partly

Threading

the

as

steel,

hands

are

the

the

the

first

for

threads

in

up

die

described

threads

recommendations

when

also

die

near

stress

Table

die

cut

commercial

threading

to

use

near

over

cut

Fluids

teeth.

the

available

over

the

threads

starting

with

sulfurized

to

to

the

of

the

50-2.

shoulder

shoulder.

a

finish

above.

cutting

and

die

steel.

the threads

a

near

on

for

cutting

cut

thread.

the

wrong

min

This

Spe

(Fig.

alu

will

the

the

for

in

SIAii’i

D

3.

4.

2.

can

1. too Fig.

thread rect

thread. ends

DE

2CJ5

With

With

crometer.

with

ing By

By

standard

SDE

The

be

loosely.

External

20-10

depth

of

testing

the

measuring

determined

fits

the

If

Unit

a

a

a

fit

thread

thread

thread-roll

the

three-wire

The

DlESTOCK

diestock

to

too

or

mating

20—External

SDE

GPPOS:TE

RE

STARTING

threads

how produce

hands

pitch

Measurements SSiED

External

class

tightly.

CUT

Q;

ring micrometer

the

the

in

after

nut

TH

‘‘,TH of

diameter

may

snap

method

THE

SIDE

must

the

gage

the

THREADS

threaded

If

external

Threading

pitch

or

D

cutting

be

it

THE

following

proper

gage

threaded

(Fig.

is

be

moved

Thread

(Fig.

with

diameter

too

is

several

cut

(Fig.

93-13).

with

piece

screw

too

fit

small,

to

14-4)

a

to

ways:

hole.

Dies

or

93-10).

plain

large,

the

threads.

fits

the

threads

class

either

or

it

in

mi cor

us

fits

the

167

of a ______

168 Part 6—Threads and Thread Cutting

WORDS TO KNOW

adjustable die diestock screw plate threading die bevel left-hand die solid die thread-roll gage collet rethreading die thread micrometer starting side cutting fluid right-hand die thread ring gage

REVIEWQUESHONS

1. What tool is used for cutting external threads? 2. Describe three kinds of dies for cutting new threads. 3. What kind of die is used for recutting damaged threads? 4. What is a screw plate? 5. What does ‘/4-20 UNC on a die mean? 6. What is a diestock? 7. Why should the end of a rod be beveled before threading? 8. Why is it necessary to back up the die when threading? 9. What kind of cutting fluid should be used when threading steel? 10. List several ways in which the fit or class of thread can be determined.

UNIT

I . ,—--., -:. . ------. . ‘1.. Internal Threading with Taps

Most threaded studs, bolts, and screws four flutes (grooves) cut across the threads have mating parts that have a hole with inter (Fig. 21-1) The edges of the thread formed by nal threads. Metaiworkers sometimes cut the flutes are the cutting edges (Fig. 2 1-2).The these threads by hand with threaded taps. shank end of the tap is square so that it can be This unit describes the use of taps for internal turned with a wrench. threading, a necessary skill for most metal- Taps are made from carbon steel or high- workers. speed steel and are hardened and tempered. A set of taps includes a taper tap, a plug tap, and a bottoming tap (Fig. 21-1). The taper tap has about six threads ta 211 pered at the end so that it will start easily. The taper also makes it easier to keep the tap Taps straight as the cut is begun. The threads are A tap is a tool for cutting internal threads cut gradually as the tap is turned into the It has threads like a bolt with two, three or hole. Unit 21—Internal Threading with Taps 169 __J,,,/,,,,,,,,,,, to the center line of the tap (Fig. 21-5A). Chips tend to collect in the flutes of these taps. Un less the tap is backed out to clear it of chips, A the tap may bind in the hole and break. Gun g! taps and helical-fluted taps are designed for ef ficient chip removal, thereby permitting rapid thread cutting with a minimum of tap break B age. Gun taps are straight-fluted, with two, three, or four flutes depending on the size of the tap (Fig. 21-3). The cutting edges are ground at an angle to the centerline of the tap. - C The angular cutting edges cause the chips to Fig. 21-1 A set of hand taps. (A) Taper. (B) shoot ahead of the tap. Plug-type gun taps are P]ug (C) Bottoming. (Greenfleld Tap & Die/Division designed for tapping open, or through, holes. of TRW Inc.) Bottoming-type gun taps are designed for tap ping blind holes (holes that go only part-way Into a workpiece), producing fine chips that can readily escape. Helical-fluted taps, commonly known as spiral-fluted taps (Fig. 21-4), are designed to lift the chips out of the hole being tapped. For

.4

Fig. 21-2 How the cutting edges of a tap cut. B

The plug tap has three or four threads ta a pered at the end and is used as starting tap Fig. 21-3 Gun taps. (A) Plug-type. Note the on easily cut metals. chip formation. (B) Bottoming-type (Greenfleld Tap The bottoming tap has full threads except & Die/Division of TRW Inc. for the first thread and is used to cut full threads as close as possible to the bottom of a hole. Fig. 21-4 Spiral-fluted taps. (A) Low-angle. (B) High-angle. (Greenfleld Tap & Die/Division of TRW, Inc.) 2i2 Tap Styles Taps are made in many styles to suit var B ious hand- and machine-tapping operations. Hand taps are straight-fluted, have three or four flutes, and have a cutting edge parallel _

170 Part 6—Threads and Thread Cutting this reason, they are well suited for tapping blind holes. Low-angle spiral-fluted taps are best for tapping ductile materials like alumi num, copper, or die-cast metals (Fig. 21-5B). High-angle spiral-fluted taps work best on tough metals, such as carbon and alloy steels. They are made with two, three, or four flutes, depending on the tap diameter, and are avail able in plug and bottoming types. Serial taps are usually made in sets of three. They have one, two, or three identifying rings cut at the end of the shank (Fig. 21-6). These taps are designed for cutting threads in Fig. 21-6 A set of serial taps. (Greenfleld Tap & very tough metals. The taps are similar in ap Die/Division of TRW, Inc.) pearance to the taper, plug, and bottoming taps, but they differ in pitch diameter and ma jor diameter. Each tap is designed to remove part of the metal that must be cut away to .:- .-.- -•---t”” produce the thread. The No. 1 tap is used first to make a shallow thread, then the No. 2 tap Fig. 21-7 A thread-forming tap. Greenuleld Tap is used, and the No. 3 tap cuts the thread to & Die/Division of TRW, Inc.) final size. Thread-forming taps (Fig. 21-7) have no cutting edges and therefore produce no chips. ventional taps. Tap drills used with thread- Threads are formed by forcing the metal to forming taps (drills used to make the holes to flow around the threads on the tap. This pro be tapped) must be larger than those used with duces a strong thread, because the grain of the comparable conventional taps. The manufac metal is forced to follow the thread profile and turer’s tap drill size recommendations should the surface is somewhat work-hardened, Be be carefully followed. cause of the high pressures involved, thread depths are less than those produced by con- Left-hand taps cut left-hand threads. They are stamped with an “L” or an “LH.” Right- hand taps are unmarked.

Fig. 21-5 The cutting action of straight.fiuted taps compared to spiral-fluted taps. (A) Straight- fluted hand tap. (B) Low-angle, spiral-fluted tap. Greenfield Tap & Die/Division of TRW, Inc.) Sizes of Taps Taps are made the same sizes as bolts and screws. The major diameter, pitch, and kind of thread are stamped on the shank of the tap. For example, 1/420 UNC means that the out side diameter of the tap is Y4”,there are 20 threads per inch, and the thread is Unified Na tional Coarse. Table 21-1 gives the sizes of inch-based taps. A tap marked M6 x 1 is a metric tap with an outside diameter of 6 mm and a pitch of 1 mm. The sizes of metric taps are given in Ta ble 19-3. Unit 21—Internal Threading with Taps 171

21-4 21-5 Internal Thread Tap Size Limits Measurement The size of the pitch diameter of a tap de Internal threads are checked for the cor termines the depth and the fit of a tapped rect fit or class of thread with thread plug thread. Internal threads may be tapped for var gages, as shown in Unit 93. ious classes of threads, such as classes 1B, 2B, and 3B. The thread may be either a loose or tight fit, depending on the pitch diameter of the tap. 2i6 Taps are available with either cut threads or ground threads. The ground threads pro Tap Drills duce tapped threads to a very accurate size. The hole to be tapped must be the right Taps with ground threads are made with stan size. If the hole is too large, the thread will be dard, oversize, or undersize pitch diameters. too shallow; if it is too small, the tap may The size limits of the pitch diameter are indi break. The drill that is used to make the hole cated by a pitch diameter limit number, such before tapping is called the tap drill. as LI, H2, or H6, on of Hl, the shank ground The tap drill should be a little larger than thread taps. When purchasing taps of this the diameter at the bottom, or root, of the type, the limits code number and the fit or thread, known as the minor diameter Fig. class of thread to be tapped should be speci 21-8). To save the time of figuring, tap drill fied, If are not specified, the supplier they gen sizes are put in the form of a table such as erally taps sends with pitch diameter limits Table 21-1. The tap drill recommended for av for either of two sizes. One produces tapped erage work produces threads that are about threads for a Class 2 fit for National Form 75% of the depth of external threads. threads. The other produces threads for a Class 2B fit for Unified Form threads. These fits are used on most commercially available bolts, screws, and nuts. The recommended taps for specific types of threads, including limits code numbers for various thread fits and classes of threads, are given in standard handbooks for machinists. For example, a /8-16 UNC ground thread tap for a Class 2B thread would be identified with the letter G and with the additional number H5; for a Class 3B thread, the code number would be GH3.

Fig. 21-8 This drawing shows how the size of a tap, the size of a tap drill, and the minor (root) diameter of the thread compare to each TAD DRLL other. SZE OF TAP - a

T

on

drill cor

0075

0080

0156

0156

then

0156 0156

a

0.0055 0.0070 close 0 0.0055 0.0075 0.0075 0.0080 0.0075 0 0.0110 0.0110 0.1)115 (inches) 111)115 0.0130 small 1)0)30 0.013! 00131 00027 0.0027 0 0.0156 00156 00156 0.0156 0 0.0156 0.0156 0.0156

0.0156 0.0156

00156 0 Clearance 0.0156 0.0156 0.0156 0 0.0156 0.0156

0.0156

(The

get

the

to firmly

hole,

of

hands

1-9).

sure

2

holding 200

156

1065

0935 1

1360 tap the 1495 1770

drill

2656

4531 Be

6406

8906 0156

down 0.0785 00670 0.0785 0 0.0935 0 0.1200 0.1065

0 0.1360 0 0.1495 0 0 0.1770 0.2031 0.2187 0.2031 Decimal 0.2656 0.2187 0 0.3281 0.3281 0.3906 03906 0 0.4531 0.5 1 0.5156 0.578) 0.6406 0.5781 1.0156 0.7656 0 0.7656 0.8906 0

both

equivalent

for it

in

Fig.

to

(inches) plug

tap Press

drill. a

Clearance with used

Taps

Size #51 #47 #47

#42 #42 #36 #36 #31 7/32 7/32 #29 #31 #29 #25 #25

#16 #16 or is nearest

13164 13/64

17/64 17164

21/64 25.64 21/64 2.5/64 29/64 .19/64

37/64 .1.1/64 .17/64 .1.1/64 41/64 the 41/64 49/64 49/64 1-I/6 57/64 57/64 1-l/6

wrench

drill

of

tap

clearance

21-10).

of

a

tap

wrench

1

a

12

wiench

end

size

0700

1360

(Fig.

3680 42)9 4844 tap 7656

8750

0.0595 taper 0.0469 0.0700 0.0595 0

0.0820 0.0785 called 0.0890 in 0.0935 0.1015

0.1040 0.1065 0.1130 0.1360 0 Decimal 0.1495 01770 0.1590 0.1820 0.2010’ 0.2130 0,2570

03125 0.272(1 03320 0.3906 0 0

0.45.31 0 0.53

0.5(56 0.578 0.6875 0.6562 0.8125 0 0 0.9375

equivalent

the Inch-Based

ra

tap a

the

tap

inches)

the

depth

find size

for

(in

to

the ...... - - .

. through ...... - - . - . . . - - - - . Install rect

thread handle taps.) drill . Insert grasp to .

3/64

drills ......

. 5/16 - . - - ......

7/8 .

21-1 25/64 17/32

27/64 11/16 29/64 31/64 13/16 pass 21/32 15/16 33/64 37/64

49/64

Fractional

Sizes,”

tap

Drills2 3.

4.

75%

of

may

for

“Drill

Size

Table . . . .

letter

screw / 7 the

3

53 53 . 50 50

( 1 .

45 47 43 42 F .

38 . 37 16 36 14

29 . 29 54-2 25

33 , 2)

. U Q

drills ... .

... drill......

or ......

Number

and

Table bolt

tap Clearance

with

a

set

that

size

and

vise 0955

Root

5528 7307

here, so

00438 0.0527

0.0628 0.0550 0.0657

0.0758 0.0719 11.1)795 0.0925 0.06)9 (inches) 0 0.0974 0.1055 0.1234 0.1279 0.1359 0.1494 0.1619 0.1850 0.1696 diameter 0.2403 0.2036 0.2938 0.2584 0.3209 0.3447 0.3725 0.400) 0.4350 0.4542

0.5069 0.4903 0 0.6201 0.6688 0.7822 0

0.8376 0.9072

a

thread

Threads

given

the

in

proper

Tap Drills1

of

drill workpiece

1120

0860

1380 1380

a

a the

0.0730 00600

0 0.0730 0.0860

0.0990 00990 position. Outside 0 0.1250 0.1120 (inches)

0.1250 0. 0

0.1640 0.1640

0.1900 0.1900 02(60

diameter 0.2160 tap 0.2500 0.3125 0.2500

0.3750 03125 0.3750 0.4375 0.4375

0.5000 0.5000 1.0000 0.5625 Tap 0.5625 0.6250 1.0000 0.6250 0.7500 0.7500

0.8750 0.8750 in

of

diameter

hole with

size

a . . - -

workpiece root

(((1 -

. . HowtoCut Internal

172 . .

- with - . ,

NF upright -

the .

UNF ..

# -

#264 #3-56 .

#4-48 (SAL)

#5-44 .

#0 ...

#6-40 #8-36 ......

the ......

... hole

1-14

tap 1/4-28

#10-32

#12-28 1/2-20

3/8-24

3/4-16

5/8-18 7/8-14

7/16-20 5/16-24

makes

9/16-18 get the

an

of

than

the

in

that

Size

cannot

I))

NC larger

drill

#1-64

UNC #2-56

#3-48 #4-40 (USS)

#5-40

#6-32

#832

1-S

21 Clamp

Drill hole

1/4-20 #10-24 7/8-9 #12-24 you 1/2-13

172 3/8-16

5/8-il

5/16-18 .1/I’-

7/16-14

9/16-12

‘If

little

2The

1.

2.

the ting

change

hole plug

the lecting

bottom

6.

5.

Fig.

(L.S. handle.

when

ing

required.

the

the

turn the

ting Lubricate

longer

Once

ken

as and

angle

ment or grees

hole.

parallel

It started.

Tapping

taps the

the

tap

now

21-9

Starrett

tap

it

is

steel

A

tap.

tap

tap

in

chip.

to

tap.

deeper

fluid. tap

the

gets

partially

of

very

require

in Greenuield

several

using

(Fig.

from

to

to

and

the

necessary

Tap

up

the

wrench

a

rule

Company)

with

as

tap

while

the

the

deeper.

blind

If

It

the

bottom blind

important

every

then.

Shift

21-11).

wrenches.

far

bottoming

a

thread

a

until

going

top

is

can

hole

threads

more

hand

the

cut

gun,

B

tap

Tap

as

(Fig. turning

holes.

not

two

your

hole

In

of

This

be

to

it

the

hole.

threads

A

of

with

&

is

helical,

on

this

to

tap

the

pressure

press

will

21-12),

used

Die/Division

necessary tap

or

the

(A)

forced

that

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threads

hands

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are

often

tap, one

the

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is

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workpiece, If

way,

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Adjustable.

that

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go.

to

down

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at

being

clockwise.

desired,

been

appropriate

side

or

and

and

results

bottom.

to

check

Clean threads

the to

is

turns

the

to

will

are

hole

tap

thread

cut

started

to

of

continue

the

cut,

finish

on of

get

used,

bottom

chips

as

TRW,

be

not

back

its

run to

the

a is

in

a

out (B)

the

ends

deep

it

the

to

started

deeper

square

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form

break 90

Larger

a

align

keep

back

is

at T

Inc.)

cut

col

hole

cut

bro

the tap.

the

the

up

of

de

tap

no

as

an

to

of

Fig.

tap

hole

Fig.

keep

Fig.

TAP

wrench

21-12

21-li

to

21-10

your

minimize

Unit

Shift

hands

The

after

When

21—Internal

tap

your

the

near

the

starting

must

thread

hands

chance

the

be

Threading

tap a

has

to

parallel

thread

of

on

the

been

tap

the

ends

breakage. with

with

to

started.

tap

the

of

Taps

a

wrench.

the

tap, 173 174 Part 6—Threads and Thread Cutting

Cutting fluids for tapping Taps are very A tap extractor is a tool designed to re hard and brittle and are easily broken. Cutting move broken taps (Fig. 21-14). It is made with fluids greatly reduce the strain on the tap, and slender steel fingers that fit into the flutes of should be used when tapping most metals. the tap, so that a twisting force can be applied Cutting fluids for tapping are the same as for to remove the broken tap. external threading, and are explained in Unit Electrical discharge machining, explained 20. in Unit 83, can be used to cut away the bro ken tap if the above methods fail.

18 Causes of Broken Taps 2140 Taps break for the following reasons: Thread nert too small 1. A hole that has been drilled Thread inserts are threaded steel bushings, remove more metal than forces the tap to They are used to replace worn or damaged breaks. it is able to; therefore, it jams and threads. They arc also used to provide strong an angle to the hole 2.. A tap that is started at wear-resistant threads in low tensile s rcngrh breaks. sticks tight and then metals, such as cast aluminum and magne a it, a 3. The tap wrench acts like levet With sium. Special tools are required for installing force can he put upon the great twisting some types of thread inserts. However, some this force breaks many taps. tap. Misuse of types of thread inserts are installed without pressure to one side of the Applying more special tooling (Fig. 2 1-15). tap wrench than the othet may also break the tap. 4. Lack of cutting fluid where required will cause a tap to stick tight and break. 5. Failure to back up the tap will cause the chips to crowd in front of the cutting edges or to pack tight in the flutes of the tap. More force is then needed to turn the tap, and this extra force is often more than the tap can stand. Fig. 21-13 Removinga broken tap with a cape 6. Turning a tap after the bottom of the hole chisel and hammer. is reached will cause it to break.

Fig. 21-14 A tap extractor can sometimes be Iemovfrg a used to remove a broken tap. (Thr Wator Compacy) 219 Broken Tap from a Hole A broken tap is usually difficult to remove because the broken part is jammed tightly in the hole. A tap broken near the top of the hole may sometimes be removed by placing a dull cape chisel in the flute of the tap and striking light blows with the hammer, as shown in Figure 21-13. Apply penetrating oil first, then work the broken tap both clockwise and counter clockwise until it is loose.

WORDS

REvIEw

gun

bottoming

hand blind

13.

15. 12. 10.

14. 11.

3.

9. 4.

6.

5. 2.

8.

7.

I.

Name

What Why

What What What

How When What What

What How Describe

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tap

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tap

hole

is

do

can

does

QUESTIONS

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kind is does

size does

is is

hand-tapping,

TO

six

tap

it

a

a

the

thread-forming

a

a

thread

necessary

causes tap tap

tap

a

KNOW

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of

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machine name

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wrench?

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drill

i

inserts?

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tap;

of

UNC

of

tap

plug

right-hand

left-hand

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1.75

broken

to

why

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plug

used

tap

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stamped

tap

stamped

taps

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tool

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removed should

tap;

for

taps.

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up

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used

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¼”-20

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the

the

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thread

cutting

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21-15

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conventional

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taper serial

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tapping

insert.

kept

tap?

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extractor

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of

of

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tapping?

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insert.

square

a

a

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steel?

Unit

tap

tap

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M6

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21—Internal

threads?

each Step

mean?

basic

mean?

with

insertion

Drill

thread?

Aluminum?

2.

used

steps

r’i

the

out

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Step

thread worn

T-handle tool.

work? for?

thread-forming for

Threading

I/i

3

wrench

thread

installing

thread

insert

with

insert.

tap

and

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tap 175 to

his his

the

op

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tech

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they interpret

surgery.

spent

EBW

programs.

of

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how

pedals

both

the

are

welder

aircraft

and

EBW

four

tanks,

who brain

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intensity and

jobs

in

Donald

manager

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young

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machine. telescopes,

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products on Technical

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of com regu

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equipment (EBW)

trained in

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aircraft.

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him no

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farm, Donald

wings

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company

for

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space

work

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says welding

off

on the

position

controls

box

pacemakers production

in

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welders

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company

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invested

years

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learned

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the

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machining

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cone tron for be life. younger chines nicians ers erate Many Donald’s cial operate

weld hard-vacuum electron change EBW ing is which One in the rays. heavy ble lations. dents pany, latest tional and portunity He satisfaction. it ______

Part 6 Threads and Thread Cutting Name Score

UNIT19 Screw Threads

1-15. Multiple Choice. Write the letter of the correct answer to each statement or question in the space at the left.

1. The threads on most standard threaded fasteners are made on cold-heading machines with A. ordinary thread-cutting dies C. flat thread-rolling dies B. round thread-rolling dies D. single-point threading tools

2. The largest diameter of a straight external or internal screw thread is called the A. outside diameter C. inside diameter B. major diameter D. minor diameter

3. The smallest diameter of a straight external or internal screw thread is called the A. outside diameter C. minor diameter B. major diameter D. inside diameter

4. The diameter of a screw thread that determines the fit or clearance between mating threads is the A. major diameter C. pitch diameter B. minor diameter D. actual outside diameter

. The distance from a point on one thread to a corresponding point on the next thread is called the A. lead C. travel B. pitch D. gap

6. Two ways to measure the pitch of screw threads are A. with a plain micrometer and a screw C. with a rule and a plain micrometer pitch gage D. with a screw pitch gage and a rule B. with dividers and a micrometer

7. The thread form that was first adopted by most American industries was the A. American National C. United States Standard B. Unified National D. ISO Metric

8. The form of screw thread most widely used in the United States today is the A. American National C. United States Standard B. Unified 0. ISO Metric

9. The thread angle of the Unified Screw Thread is A. 3Q0 C. 60C 45C B. 0. 90°

Continued on next page

45 in

12

20

the

seal

of

of

on

Thread

thread

thread

differences

finish

of

Pipe

Thread

low-pressure

a

the

metric

metric

M

rn

Pipe

of

Taper

thread

fine

because

require

coarse

a

pitch

letter letter

pitch

Taper

a the

fasteners?

Joint

the

C

for

the

that

the

the

thread

of

for

drawings?

is

with

and

pitch?

metric

jobs

left.

pitch? threads smoothness

Acme lead pipe

Railing

Dryscal pitches constant

B with

variable

with do

tools

on

to

mm C.

C.

D. D. the

C.

D. C. C. D.

D. C.

D.

working

mm

interchangeable

at

designation

has

designation

on

used

1.25

2.5

not

machine

and and

are

blanks

thread

thread

on Thread

general-purpose

the

the

the

dcs[gnated for

commonly

in

is

is

Standard

threads

is

diameter diameter

mostly

used

National

mm threads What rum

What

used

ISO

thread

answers 1

Metric

Thread

16. 17. National

thread

thread

Thread

Unified

ISO

your

thread

Metric

a

thread

letter letters

the

Pipe

National

pipe

Metric

angle

of

pitch

Pipe

of and

the

of

ISO

the the

Metric

pitch

Write ISO

of

American

are

class

type Inch

fit

pitch Unified ISO

Straight

diameters thread Taper coarse fine with with

29-degree

the

B. A.

B. A. The

A

11. A. B. A.

is ISO their A. B. B. The A.

Which

How

Answer.

.1.

10.

11.

I

12. 14.

15.

Short — ______

1617.

46 ______

Part 6 Threads and Thread Cutting Name Score

UNIT20 External Threading with Dies

1-7. Multiple Choice. Write the letter of the correct answer to each statement or question in the space at the left.

1 Cutting threads by hand on a round bar is done with a tool called a A. threading tap C. thread chaser B. threading die D. thread cutter

2. A set of taps and dies is called a A. tap-and-die set C. thread-cutting kit B. threading set D. screw plate

3. The tool for holding and turning the threading die is called a A. die wrench C. diestock B. die lever D. die holder

4. To make it easier to start a threading die, the end of the rod should be A. beveled C. squared off B. rounded off D. reduced in diameter

5. The starting side of a die A. has smaller teeth C. has straight teeth B. has three or four tapered teeth D. has oversized teeth

6. Why is it recommended to back up the die every two or three turns when threading A. to break the chip into small pieces C. to help make a smoother thread B. to make it easier to turn the die D. both A and C

7. A good cutting fluid to use for threading steel is A. soluble oil C. sulfurized mineral oil B. inactive mineral oil D. all of the above

8-1 1. Short Answer. List four ways of measuring an external thread for correct pitch diameter or fit,

8.

9.

10.

11.

47 to

the

holes

holes

in

correct

order

in

blind

the

of

through

is

tap

question

a

turns

or

that

size

the

the

tapping

tapping

tap

tap three tap

tap

called

is

is

tap

drill

for tap

is

or

for

Taps

certain

statement

a the

chips

two

used nut,

extractor

tap tap

used

tap

tap

is

ground

a

tap is for

is

materials eliminator

ordinary

each

in

every

die helical-fluted cam to

and hand

helical-fluted hand

helical-fluted

hand

helical-fluted

gun serial size an

hand stock

tool

screw tap

as

and with

produce

it

tough

______B.

C.

D. C.

D. by

C. 1).

C.

______D. C.

D.

B. C.

D.

C. D.

turn

hole

not

of

in

such

a

the

tap

answer

the

s

a

up

Name

Score

use

21

does

of

hole,

the

ahead

tap

for a

taps

turn

is

out

and correct

UNIT

chip

size

backed

and

the

inside

be

chips

pieces the

flutes broken

of

hold

especially

the no

certain

to

Threading

a

small

letter

should

threads

shoots

tap

has

lifts

for

used removing

the

into

cut

that

that

designed

that

that

is

to

drill for

Cutting

tap

is

tap

tap

chip

tap

tap

tap

tap

Write tap

tap

tap that

of

tap

tap

of tap

tap

of

of of

used

extractor remover

made

the

drill

Thread

special

tool

tap

hand gun

serial gun

serial

gun serial gun thread-forming

hand

a holder wrench

tap tap

tool

style

the style

the

style style

style tap

tool

Internal

and

Choice.

A.

A B. A A. break

A. B.

is A B. A.

is A A. B.

A. A B.

A. A

A. A B.

A. B. The

A

left.

1.

2.

3.

4.

5.

6. 7.

8.

9.

the

Threads

to

Multiple

6 ______

Part

1-10.

space

48

provided.

20.

18-20. 19. 18.

______

blanks.

Name Unit

______11-17. ______

______

UNC: 20:

‘/4:

21 Short

______

Matching.

(continued)

16.

17.

14.

15. 13.

12. 10.

11.

Answer.

Thread-forming

Bottoming

Serial Threaded

Plug Helical-fluted

thread

Taper

Gun B. A.

rings

inserts

Match

tap

tap

tap

tap

A

tap

steel

tap

the

is

tap

bushings

taps

marked

tap

shown (Continued

—

¼20 that - TRW

_____

with

are UNC.

----_-—--—_.

c

used

on their ______

next

Explain

to names

J-I’.’

repair page) ______liuuImIuIilh1z

1-141/v

D.

C.

what damaged

I

by collars

/ plugs ..

,./,‘...-

writing the ______

‘‘“

markings

or

stripped

the

A

correct

B

mean

threads

C

letters

D

in

the

E

are

in

space called

the 49 ______

21-26. Short Answer. List six causes of broken taps.

21.

22.

23.

24.

25

16.

27-2). Short Answer. Look up the correct tap drill size for each of the following taps. Write the in the blanks at the left.

27. /4-20 UNC tap

28. Y-24 UNF tap

29. M8 x 1 tap

50