Typical Parts Made with These Processes

Size: px

Start display at page:

Download "Typical Parts Made with These Processes"

Agatha Jacobs
5 years ago
Views:

1 Turning

2 Typical Parts Made with These Processes Machine Components Engine Blocks and Heads Parts with Complex Shapes Parts with Close Tolerances Externally and Internally Threaded Parts

3 Products and Parts Made By These Processes

4 Alternative Processes Precision Casting Powder Metallurgy Powder Injection Molding Abrasive Machining Thread Rolling

5 The Turning Process Using Engine Lathes Operate on all Types of Materials Use of single-point tools Skilled Labor Low Production Rate

6 Tool Geometry Rake Angle Side Rake Angle Cutting-Edge Angle Relief Angle Nose Radius

8 Typical Lathe and Its Various Components

9 Lathe Components Bed: Usually made of cast iron. Provides a heavy rigid frame on which all the main components are mounted. Ways: Inner and outer guide railsn that are precision machined parallel to assure accuracy of movement. Headstock: mounted in a fixed position on the inner ways, usually at the left end. Using a chuck, it rotates the work. Gearbox: inside the headstock, providing multiple speeds with a geometric ratio by moving levers.

10 Spindle: Hole through the headstock to which bar stock can be fed. Chuck: 3-jaw (self centering) or 4-jaw (independent) to clamp part being machined. Tailstock: Fits on the inner ways of the bed and can slide towards any position the headstock to fit the length of the work piece. An optional taper turning attachment would be mounted to it. Tailstock Quill: Has a Morse taper to hold a lathe center, drill bit or other tool. Carriage: Moves on the outer ways. Used for mounting and moving most the cutting tools. Cross Slide: Mounted on the traverse slide of the carriage, and uses a handwheel to feed tools into the workpiece.

11 Tool Post: To mount tool holders in which the cutting bits are clamped. Compound Rest: Mounted to the cross slide, it pivots around the tool post. Apron: Attached to the front of the carriage, it has the mechanism and controls for moving the carriage and cross slide. Feed Rod: Has a keyway, with two reversing pinion gears, either of which can be meshed with the mating bevel gear to forward or reverse the carriage using a clutch. Lead Screw: For cutting threads. Split Nut: When closed around the lead screw, the carriage is driven along by direct drive without using a clutch.

12 Quick Change Gearbox: Controls the movement of the carriage using levers. Steady Rest: Clamped to the lathe ways, it uses adjustable fingers to contact the workpiece and align it. Can be used in place of tailstock to support long or unstable parts being machined. Follow Rest: Bolted to the lathe carriage, it uses adjustable fingers to bear against the workpiece opposite the cutting tool to prevent deflection.

13 Lathe Accessories Carriage and Cross Slide Stops Devices for Turning Parts with Various Tapers Milling, Sawing, Gear-Cutting, and Grinding Attachments Various Attachments for Boring, Drilling, and Thread Cutting

14 More Tool Geometry

15 Lathe Operations Form Tools Boring Drilling Parting Grooving Thread Cutting Knurling

16 Cutting Operations Performed on a Lathe

17 Above Left: Example of Boring Below Left: Example of Thread Cutting Above Right: Example of Drilling Below Right: Example of Grooving

18 Types of Lathes Bench Lathes Special Purpose Lathes Tracer Lathes Automatic Lathes Automatic Bar Machines Turret Lathes Computer-Controlled Lathes

20 Turret Lathe

21 Computer-Controlled Lathe

22 Things to Remember About Machining Parts on Lathes Takes considerable amount of time High Production Costs Wastes Material Not as Economical as Forming or Shaping

23 Boring and Boring Machines

24 What is Boring Performed to enlarge a hole made previously. Used for circular internal profiles in hollow workpieces

25 Boring Machines Small pieces lathe Large pieces boring mill Horizontal vs Vertical Boring mills Perform various operations: TURNING, FACING, GROOVING, CHAMFERING

26 Horizontal Boring Mill

27 Vertical Boring Mill Large pieces can be machined on a vertical mill

28 Jig Boring Machines Vertical machines High precision bearings Used to make jigs and fixtures Being replaced by CNC boring machines

29 Considerations Through holes, rather than blind holes, should be specified. Smaller length-bore diameter ratios Interrupted internal surfaces should be avoided.

30 Milling and Milling Machines

31 Milling The Process of cutting away material by feeding a workpiece past a rotating multiple tooth cutter.

32 Types of Milling

33 Peripheral Milling Peripheral Milling is when the cutter is longer than the width of the cut. a.k.a.- Slab Milling The axis of the cutter is usually parallel to the work piece surface.

34 Face Milling the cutter is mounted on a spindle having an axis of rotation perpendicular to the workpiece surface. Leaves feed marks on the machined surface.

35 End Milling The cutter 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. Can produce a variety of surfaces at any depth.

36 Conventional Milling a.k.a- Up Milling The Direction of cutter rotation opposes the feed motion.

37 Climb Milling a.k.a.- Down Milling The direction of cutter rotation is the same as the feed motion.

38 Other Types of Milling Straddle Milling Form Milling Slotting and Slitting Uses circular cutters

39 Tool holders Arbor Cutters Mounted on an arbor Used in peripheral, face, straddle and form milling.

40 Shank-Type Milling Cutter and shank are one peice

41 Design and Operating Guidelines Basic cutters should be used as much as possible. Avoid expensive special cutters. Chamfers should be specified instead of radii. Chamfer-A furrow or groove, as in a column. Avoid internal cavities and pockets with sharp corners. Due to the difficulty of doing them.

42 Troubleshooting Tool Breakage Tool material lacks toughness, improper angles. Excessive Tool Wear improper tool material, improper tool fluids. Rough Surface Finish Feed per tooth too high, tool chipped or worn. Chatter Marks Insufficient stiffness of system, external vibrations. Breakout Lead angle too low, feed and depth of cut too high.

43 Milling Machines First Milling Machine Built in 1820 by Eli Whitney

44 Column-and-Knee type Most common milling machines.

45 Basic Components Work Table Saddle Knee Overarm Head

46 Bed Type Work table is mounted is mounted directly on the bed. Not versatile High Stiffness Used for high production work

47 Other Milling Machines Planer-Type Several heads and cutters able to mill different surfaces Rotary-Table One or more heads for face milling. Computer Numerical Control Able to mill, drill, bore and tap with repetitive accuracy Profile Milling Machines 5 axes of movement.

48 Planning and Shaping Planning Large workpieces 25m X 15m Work piece is mounted on a table and travels back and forth along a straight path. Cutting speeds can get up to 120 m/min with 150 hp Shaping Tool does the moving Small less than 1m X 2m

49 Gear milling Uses a rotating form cutter Gear blanks are indexed after each cut Is a low production process Gear teeth are produced individually

TURNING BORING TURNING:

TURNING BORING TURNING: FACING: Machining external cylindrical and conical surfaces. Work spins and the single cutting tool does the cutting. Done in Lathe. Single point tool, longitudinal feed. Single