High School Metals Processes Packet 3 Ritchie Hayward Cornrnunity School District 715-634-2619 #HurricaneStrong Made with PosterMyWaiLcom Metals Processes Week 5 91 UNIT : . - Linear Measurement Accurate measurement is the key to the of linear (straight line) measurement. How production of interchangeable parts and mass ever, gradual adoption of the modern form of production of metal products. Every part of a the metric system, the International System product must be accurately made to the size of Units (abbreviated SI) has begun. Many and shape specified by the designer. Parts that large corporations have converted completely are not made accurately will not fit properly or in part to the SI Metric system of measure with other parts of the product. As a result, ment. Many companies are dimensioning the finished product may not work properly or their drawings in SI metric (millimeter) units. it may wear out sooner than it should. It is important, therefore, to learn both sys Good workmanship depends greatly upon tems of linear measurement. accurate measurement and layout work. Therefore, learning to read and use the com mon measuring and layout tools is important in metalworking. These tools are presented in The U.S. Units 12-14, after linear measurement is ex Customary, plained here. or Inch, System The inch is divided into the common frac tions of ½”, ‘/4”, Yb”, /16”, /32”, and ‘/64” (Fig. Linear 11-I). With practice, parts can be measured ac curately to ¼4th of an inch using steel rules Measurement having 1/64th graduations (Fig. ll-2(. Steel The United States is the last industrial rules are also made with decimal fractions of ized nation to continue using the inch system an inch such as Y,o” and ‘/rno” (Fig. 11-3). Fig. 11-1 The common 6 32 48 customary inch rule 8 24 40 56 divisions. I 8 4 8 2 8 4 8 1 9 II 13 15 16 6 16 16 16 6 16 6 92 Part 4—Measuring and Laying Out T Fig. 11-3 A rule marked decimal of Fig. 11-2 A steel rule (actual size) with 1/32” in fractions graduations along the top edge and 1/64” an inch (actual size). The smallest division on the graduations along the bottom edge. upper scale is .100”, on the lower scale .010”. Decimal fractions of an inch, however, are Table 11-1 gives the decimal equivalents normally written on technical drawings in the of all the common fractions of an inch, to following way: gether with their equivalent in millimeters. 1 one tenth inch = — = 0.100” How big is one-thousandth of an inch? To give you an idea of .001” (‘/iooo”), paper 3/iooo” one hundredth inch = —i-- 0.010” this is about thick, and thin tis sue paper is about Yiooo” thick. A hair on your head is about 3/iaoo” thick. one thousandth inch j-j = 0.001” one ten-thousandth inch 1 = 10 000 Measurement of common fractions with a steel rule frequently cannot provide the accu racy required. Therefore, precision measuring instruments, such as micrometers and ver SI Metric System niers, have been developed that measure ac The SI Metric system is a base ten, or dec curately to Yiooo” and even ‘/io,ooo”. (These are imal, system. Its units of measurement are re described in Unit 14.) Since these instruments lated to each other by powers of ten. Each of measure in decimal fractions, it is important the main units can be changed to a unit of to learn the decimal equivalents the com of more convenient size, when desired, by mul mon fractions. tiplying or dividing by powers of ten. Table Decimal equivalents. The decimal equiva 11-2 lists the names of several basic SI metric lent of a common fraction may be found by units, their symbols, and their relationship to dividing the numerator of the fraction by its each other. It is important to learn the metric denominator. - symbols because they are used whenever met Example: Y2 = 1 2, or .500 ric measurements are written or printed. The 2)1.000 same symbol is used for singular and plural. Table 11-1 Fractional and Decimal Inch and Millimeter Equivalents To 4 To 3 To 2 Milli- To 4 To 3 To 2 Miii 4ths Sths l6ths 32nds 64ths places places places meters 4ths 8ths l6ths 32nds ó4ths places places places meters 33 0156 .016 .02 .397 .5156 .516 .52 13.097 64 17 64 .0312 .031 .03 .794 .5312 .531 .53 13.494 32 3 32 35 .0469 .047 .05 1.191 .5469 .547 .55 13.891 64 9 64 .0625 .062 .06 1.588 .5625 .562 .56 14.288 16 5 16 37 .0781 .078 .08 1.984 .5781 .578 58 14.684 3 64 19 64 .0938 .094 .09 2.381 .5938 .594 .59 15.081 32 7 32 39 .1094 .109 .11 2.778 .6094 .609 .61 15.478 64 5 64 .1250 .125 .12 3.175 .6250 .625 .62 15.875 8 9 8 41 1406 .141 .14 3.572 .6406 .641 .64 16.272 5 64 21 64 .1562 .156 16 3.969 .6562 .656 .66 16.669 32 11 32 43 .1719 .172 .17 4.366 .6719 .672 .67 17.066 64 11 64 3 .1875 .188 .19 4.762 .6875 .688 .69 17.462 16 13 16 45 .2031 .203 .20 5.159 .7031 .703 .70 17.859 7 64 23 64 2188 .219 .22 5.556 7188 .719 .72 18.256 32 15 32 47 • 2344 .234 .23 5.953 .7344 .734 .73 18.653 64 3 64 .2500 .250 25 6.350 .7500 .750 .75 19.050 4 17 4 49 .2656 .266 .27 6.747 .7656 .766 .77 19.447 9 64 25 64 .2812 .281 .28 7.144 .7812 .781 .78 19.844 32 19 32 51 .2969 .297 .30 7.541 .7969 .797 .80 20.241 5 64 13 64 .3125 .312 .31 7.938 .8125 .812 .81 20.638 16 21 16 53 .3281 .328 .33 8.334 .8281 .828 .83 21.034 11 64 27 64 .3438 .344 .34 8.731 .8438 .844 .84 21.431 32 23 32 55 .3594 .359 .36 9.128 .8594 .859 .86 21.828 64 7 64 3 .3750 .375 .38 9.525 .8750 .875 .88 22.225 25 8 57 8 3906 391 .39 9.922 .8906 .891 .89 22.622 13 64 29 64 .4062 .406 41 10.319 .9062 .906 .91 23.019 32 27 32 59 .4219 .422 .42 10.716 .9219 .922 .92 23.416 64 15 64 7 .4375 .438 .44 11.112 .93 75 .938 .94 23.8 12 16 29 16 61 .4531 .453 .45 11.509 .9531 .953 .95 24.209 15 64 31 64 4688 .469 .47 11.906 .9688 .969 .97 24.606 32 31 32 63 .4844 .484 .48 12.303 .9844 .984 .98 25.003 64 64 .5000 .500 .50 12.700 1.0000 1.000 1.00 25.400 Table 11-2 Metric Si Units Property Unit name Symbol Relationship of units Length millimeter mm 1 mm = 0.001 m LINEAR centimeter cm 1 cm = 10 mm MEASURE decimeter dm 1 dm = 10 cm or 100mm meter m 1 m = 100 cm or 1000mm kilometer km 1 km = 1,000 m Area square centimeter cm’ 1 cm’ = 100 mm’ SQUARE square decimeter dm’ 1 dm’ = 100 cm’ MEASURE square meter m’ 1 m’ = 100 dm’ ale a I a = 100 m’ hectare ha 1 ha = 100 a square kilometer km2 1 km’ = 100 ha milligram mg I mg = 0001 g MASS gram g 1 g = 1,000 mg kilogram kg 1 kg 1,000 g metric ton 1 1 t = 1,000 kg • U. 7I••fl fl ,..,,,,,,,W’ H H fl ,,fl,I Ia p ,, Fig. 11-4 A One meter, the basic unit of 1 length in SI. Metrics, and B one yard, a II 1111111111111111111 linear unit in the U.S. Customary system. STHS ii 21 3! C The sizes of inches and millimeters are compared at right. 210 310 410 510 110 Il1iIIlHllHhIlIIIIll)I1I1IIIHIIIlIH(lI1LHh(1IIlIUIuh11iIllIllhII11.llhI[ We are mainly concerned here with the basic SI Metric units of linear measurement, The meter is the basic unit of length. It mea 39.37”, roughly equal to the yard (Fig. sures full range of metric micrometers and into decimeters A 11-4). The meter is divided vemiers are available for making measure (0.1 meter], centimeters 10.01 meter], and mil ments finer than ‘/2 mm. Unit 14 explains [0.001 meter]. It has been agreed limeters how to read these instruments. worldwide that metric dimensions on techni cal drawings for metalwork will be given in millimeters. Most metric rulers and tapes are divided into millimeters, abbreviated “mm,” and are 114 Use of Conversion numbered at every 10 mm mark (Fig. 11-5). Tables 300 mm rules are used instead of the familiar 12” rules, and 150 mm steel rules replace the Conversion tables are included in this 6” pocket rule. Precision steel rules are avail book for convenience in convering dimen able with graduations as fine as 0.5 mm 1½ sions in inches to dimensions in millimeters. mm] (Fig. 11-6). Table 11-3 can be used for converting decimal ______ ________________________________________ Unit I I—Linear Measurement 95 parts of an inch to millimeters. Thus, if the Table 11-3 a decimal figure such as metric equivalent of Conversion Table desired, it may be found by using the .835” is Parts of an Inch to Millimeters following procedure: Decimal Inches Millimeters Inches Millimeters Inches Millimeters 0.8” = 20.32 mm 0.03” = 0.762 mm 0001 0025 001 0254 0.1 2.54 0.002 0 051 002 0508 0.2 508 0.005” 0.127mm 0003 0.076 003 0.762 0.3 7.62 0.835” = 21.209 mm 0.004 0102 004 1.016 0.4 1016 0.005 0127 005 1.270 0.5 12.70 Table 11-1 lists fractions of an inch, their 0.006 0.152 006 1.524 0.6 15.24 778 07 17.78 decimal equivalents, and their equivalents in 0,007 0 178 007 1 millimeters.