Machine Tools
Madan Lal Chandravanshi Assistant Professor Indian School of Mines Dhanbad
1 Manufacturing Processes
•Material Removal Processes (Machining) •Joining Processes (Welding, Brazing, Soldering) •Casting Processes •Forming Processes
2 Material Removal Processes (Machining)
•Cutting tools •Machine Tools •Lathe turning •Drilling •Milling •Grinding •,Sawing, filing •Nontraditional machining process (EDM)
3 Cutting Tool
In the context of metalworking , a cutting tool , is any tool that is used to remove metal from the workpiece in form of chips. It frequently refers to a tool bit . Tool material should be harder than the material which is to be cut They must be able to withstand the heat generated in the metal cutting process. They also must have a specific geometry, designed so that the cutting edge can contact the workpiece without the rest of the tool dragging on its surface. The angle of the cutting face is also important .
4 Classification of Cutting tools
single point cutting tool multiple point cutting tool.
5 A single-point cutting tool
Has only one cutting edge used for increasing the size of holes, or boring, thread making, turning etc.
6 A single-point cutting tool
Cutting speed = πDN/1000 meter per minutes
7 8 Single Point Cutting Tool geometry
9 Know the Single Point Cutting Tool Shank: Main body of tool, it is part of tool which is gripped in tool holder Face: Top surface of tool b/w shank and point of tool. Chips flow along this surface Flank: Portion tool which faces the work. It is surface adjacent to & below the cutting edge when tool lies in a horizontal position . Base: Bearing surface of tool on which it is held in a tool holder. Nose radius: Cutting tip, which carries a sharp cutting point. Nose provided with radius to enable greater strength, increase tool life & surface life. Typical Value : 0.4 mm – 1.6 mm Nomenclature of Single Point Lathe Tool The most significant terms in the geometry of a cutting tool angles are:
Relief or clearance angle . Side relief . End relief Rake angle . Back Rake angle . Side Rake angle Cutting edge angle . Side Cutting edge angle . End Cutting edge angl . Nose Radius 11 Cutting-Tool Terms Relief or Clearance angle: Ground on the end and side faces of a tool to prevent it from rubbing on the work piece. To enable only the cutting edge to touch the work piece .
Side Relief angle: • Angle ground directly below the cutting edge on the flank of the tool End Relief angle: • Angle ground from the nose of the tool
12 Cutting-Tool Terms Rake angle:
Ground on a tool to provide a smooth flow of the chip over the tool so as to move it away from the work piece Back Rake angle • Ground on the face of the tool • Influences the angle at which chip leaves the nose of the tool • Generally 8 - 10 0 Side Rake angle • Ground on the tool face away from the cutting edge • Influences the angle at which the chip leaves the work piece • A lathe tool has 14 0 side rake.
13 Back Rake
Angle formed between top face of tool and top of tool shank
Positive Top face slopes downward away from point
Negative Top face slopes upward away from point
Neutral
14 Cutting-Tool Terms Nose Radius: • Rounded tip on the point of the tool Functions: • Strengthens finishing point of tool • Improves surface finish on work • Should be twice amount of feed per revolution • Too large – chatter; too small – weakens point
15 Tool Angle Application
Factors to consider for tool angles
The hardness of the metal
Type of cutting operation
Material and shape of the cutting tool
The strength of the cutting edge Multiple-point cutting tools
have two or more cutting edges. Example:- milling cutters, drills, and broaches.
17 Milling cutters
18 Milling tool geometry
Face cutter
Chamfering cutter Cutting Tool Materials
•Tool Steels •High Speed Steel (HSS) •Carbides •Coated Carbide •Ceramics and cermet •TiN Coated High-Speed Steel •CBN •Diamond tool
20 Machine Tool
21 Machine tools
Lathe turning
Drilling
Milling
Shaper
Planer
Grinding
Broaching, sawing, filing
Nontraditional machining process (ex EDM)
22 Lathe Turning
23 Lathe Turning
Turning
24 Lathe
25 Gear System
26 Tailstock
27 Long Job is supported by tailstock
28 Drilling in lathe machine
29 Cutting parameters
Speed Cutting speed is defined as the speed at which the work moves with respect to the tool (usually measured in feet per minute).
Feed Feed rate is defined as the distance the tool travels during one revolution of the part.
Depth of Cut
30 Cutting speed and feed determines the surface finish, power requirements, and material removal rate. The primary factor in choosing feed and speed is the material to be cut. However, one should also consider material of the tool, rigidity of the workpiece, size and condition of the lathe, and depth of cut.
31 Lathe Turning
Facing
32 Lathe Turning
33 Specification of Lathe Machine
1. Swing over carriage 2. Distance between centers 3. Hole through spindle 4. Travel of cross-slide 5. Taper of tailstock spindle 6. Length overall 7. Width overall 8. Height overall 9. Shipping weight 10. Motor/Speed Control 11. Spindle speed range
34 Milling Machine tool
35 Milling Machine Tool
Milling is one of the basic machining processes. Milling is a very versatile process capable of producing simple two dimensional flat shapes to complex three dimensional interlaced surface configurations.
36 Process
The milling process:
Typically uses a multi-tooth cutter
Work is fed into the rotating cutter
Capable of high MRR
Well suited for mass production applications
Cutting tools for this process are called milling cutters
37 Vertical Mill
38 Horizontal Mill
39 40 Classification of Milling
Peripheral Milling (SLAB Milling) Face Milling End Milling
41 Peripheral Milling (SLAB Milling)
The milled surface is generated by teeth located on the periphery of the cutter body. The axis of cutter rotation is generally in a plane parallel to the workpiece surface to be machined.
42 Face Milling
The cutter is mounted on a spindle having an axis of rotation perpendicular to the workpiece surface. The milled surface results from the action of cutting edges located on the periphery and face of the cutter
43 End Milling
The cutter in end milling generally rotates on an axis vertical to the workpiece. It can be tilted to machine tapered surfaces. Cutting teeth are located on both the end face of the cutter and the periphery of the cutter body.
44 METHODS OF MILLING
Up Milling Down Milling
45 UP MILLING (conventional milling)
The direction of the cutter rotation opposes the feed motion. For example, if the cutter rotates counterclockwise , the work-piece is fed to the right in up milling.
46 47 DOWN MILLING (climb milling)
The direction of cutter rotation is same as the feed motion. For example, if the cutter rotates clockwise , the work-piece is fed to the right in down milling.
49 Grinding Machine
The primary purpose of a grinding wheel is to sharpen tools (eg. drill bits). The hard abrasive of the wheel is made for removing very hard materials like high speed steel.
Never grind on the side of the wheel.
Never grind a soft material such as Aluminum. The material will coat the wheel and prevent the abrasive from working properly. (SHOW)
50 51 52 Cavity
53 Grinding Wheel Specification
54 Safety Measures
Safety Glasses EVERYONE MUST WEAR SAFETY GLASSES IN THE SHOP.
Clothes and Hair Check your clothes and hair before you walk into the shop. In particular: IF YOU HAVE LONG HAIR OR A LONG BEARD, TIE IT UP. If your hair is caght in spinning machinery, it will be pulled out if you're lucky. If you're unlucky, you will be pulled into the machine. NO LOOSE CLOTHING. Ties, scarves, loose sleves, etc. are prohibited
55 Safety Measures (Cont..)
NO GLOVES REMOVE JEWELERY WEAR APPROPRIATE SHOES No open toed sandals. Wear shoes that give a sure footing. Safe Conduct in the Shop Be aware of what's going on around you. For example, be careful not to bump into someone while they're cutting with the bandsaw (they could lose a finger!).
56 Safety Measures (Cont..)
Machining IF YOU DON'T KNOW HOW TO DO SOMETHING, ASK! BEFORE YOU START THE MACHINE:
Study the machine. Know which parts move, which are stationary, and which are sharp.
Double check that your work-piece is securely held. Remove chuck keys and wrenches.
DO NOT LEAVE MACHINES RUNNING UNATTENDED! CLEAN UP MACHINES AFTER YOU USE THEM!
A dirty machine is unsafe and uncomfortable to work on.
57