Group #3 Erica Velarde, Sean Clifton David Pincus, Ruben Sosa Machining Processes Group #3 Erica Velarde, Sean Clifton David Pincus, Ruben Sosa

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

Products and Parts Made By These Processes

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

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

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

Typical Lathe and Its Various Components

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.

• 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.

• 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.

• 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.

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

Typical Lathe and Its Various Components

More Tool Geometry

Lathe Operations Form Tools Boring Drilling Parting Grooving Thread Cutting Knurling

Cutting Operations Performed on a Lathe

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

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

Turret Lathe

Computer-Controlled Lathe

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

Boring, Drilling, Reaming, and Tapping Machining Processes Boring, Drilling, Reaming, and Tapping

Boring and Boring Machines

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

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

Horizontal Boring Mill

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

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

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

Drilling, Drills, and Drilling Machines

What are Holes used For? Typical for assembly with fasteners i.e. screws, bolts, rivets Weight reduction Ventilation Access to inside parts Appearance

Drilling is a Common Process!!! THE COST OF HOLE MAKING IS AMONG THE HIGHEST MACHINING COSTS IN AUTOMOTIVE ENGINE PRODUCTION

Properties Burring on the bottom surface upon breakthrough requires further machining Diameters of holes are usually oversize Quality of drill Thermal properties Reaming and honing improve dimensional accuracy

Standard-Point Twist Drill Point angle (118-135deg) Lip-relief angle (7-15deg) Chisel-edge angle (125-135deg) Helix angle (15-30deg) Diameter range from 0.5-150mm

Other Types of Drills Step Drill Core Drill Produces 2 or more different diameters Core Drill Makes an existing hole larger Counterboring & Countersinking Produce depressions on the surface to accommodate the heads of screws/bolts

More Drill Types Center drill Spot drill Spade drill Produces small hole on the end of a workpiece Spot drill Starts a hole at the desired location Spade drill Removable bits, produces large-diameter or deep holes Higher stiffness (absence of flutes) Straight-flute drill Gun drill

Gun Drill

Trepanning Removes a disk to create a hole

Material-Removal Rate MRR=(pi*D^2)f*N / 4 Pi*D^2 / 4= cross sectional area F = the distance penetrated per revolution N = rotational speed

General Troubleshooting Problem Probable causes Drill breakage Dull bit, chips clogging flutes, feed to high, lip relief angle too small Excessive drill wear Cutting speed to high, ineffective fluid, rake angle too high, drill burned when sharpened Tapered hole Drill misaligned or bent, lips not equal Oversize hole Same as above, machine spindle loose, chisel edge not central, side force on workpiece Poor hole surface finish Dull bit, ineffective fluid, welding of workpiece on drill margin, improperly ground drill, improper alignment

Reaming and Reamers

Considerations Drilling should be perpendicular to the surface Interrupted holes should be avoided Hole bottoms should match standard drill point angles Through holes preferred to blind holes Preexisting holes or dimples help center the drill Blind holes must be drilled deeper than subsequent reaming or tapping operations

What is Reaming An operation used to make an existing hole dimensionally more accurate and/or to improve surface finish For further accuracy and surface finish, holes may be burnished, ground or honed.

4 Steps to Accuracy Centering Drilling Boring Reaming

Tapping and Taps

Tapping Produces threads May be done by hand or machine Chipless tapping is a process of internal thread rolling

Milling and Milling Machines

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

Types of Milling

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.

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.

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.

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

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

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

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

Shank-Type Milling Cutter and shank are one peice

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.

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.

Milling Machines First Milling Machine Built in 1820 by Eli Whitney

Column-and-Knee type Most common milling machines.

Basic Components Work Table Saddle Knee Overarm Head

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

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.

Planning and Shaping Planning Shaping 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

introduction Broaching and Broaching machines Sawing Filing Gear Manufacturing by Machining

Broaching and Broaching machines Broaching is a similar technique to shaping with a long multiple-tooth cutter and is used to machine internal an external surfaces.

Broaching is just as effective as Boring Milling Shaping Reaming

Broaching machines are very expensive but these machines yield a very high quantity of production runs.

Uses a single pass for finished shapes or sized Produces close tolerances and good surface finish Uses a multipoint cutting tool (broach) Has the roughing and finishing teeth on the same tool

Sawing Sawing is an old common operation dating back to around 1000 B.C Sawing is an efficient bulk removal process and can produce near net shape materials The process wastes little material Most common use of saws Hacksaws Circular saws Band saws Friction sawing

Samples of various sawing operations

Hacksaws Hacksaws were developed in the 1960’s. Good for cutting off bars, rods, and structural shapes

Power hacksaws Fast They work smoothly and efficiently even under heavy-duty operation. With normal care these machines are indestructible.

Circular sawing Circular sawing is a multipoint cutting process in which a circular tool is advanced against a stationary workpiece to sever parts or produce narrow slots. Uses thin circular blades with teeth on periphery Rotating blade is fed into a stationary workpiece Produces a narrow cut and a good surface finish

Diamond Saw Blades For Marble And Limestone Circular saws also called cold saws when cutting metal They are used for high production rate sawing Cold sawing is used in industry very commonly particularly for cutting large crossed sections. Diamond Saw Blades For Marble And Limestone saw blade for plastics

Types of cold sawing machines

Band saw Uses a flexible steel band with a toothed edge Workpieces are fed into the cutting edge on vertical machines Can produce straight, irregular, or curved cuts

Friction sawing Workpieces are fed into a continuously moving band Produces fine, accurate work Is a finishing operation in which small amounts of material are removed

Gear Manufacturing by Machining Several processes for making gears Form cutting (form-milling) Gear generating (Hobbing, Shaping)

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

Gear generating This particular machine removes over 17 lb of 8822 steel from a 100-lb, 18-in.-diameter gear in under 12 min

Gear Hobbing Is a gear generating process that uses a helical hob cutter Cuts several teeth on a progressive basis Is used for high production runs

Gear shaping Cutters rotate in timed relationship with the workpiece Produces internal gears, external gears, and integral gear-pinion arrangements

References http://www.manufacturingcenter.com/tooling/archives/0604/0604cooling.asp http://www.mfg.mtu.edu/marc/primers/milling/ http://www.americanmachinetools.com/How_to_use_a_Milling_Machine_files/Fig8-33.gif http://www.advantagefabricatedmetals.com/images/slittingprocess.gif http://www.eliwhitney.org/inventor.htm http://www.cncmasters.com/images/bps-1649.jpg http://www.lagun.com/products/gbm/gbm22e-42e.html

http://www. manufacturingcenter. com/tooling/archives/0604/0604cooling http://www.manufacturingcenter.com/tooling/archives/0604/0604cooling.asp http://www.mfg.mtu.edu/marc/primers/milling/ http://www.americanmachinetools.com/How_to_use_a_Milling_Machine_files/Fig8-33.gif http://www.advantagefabricatedmetals.com/images/slittingprocess.gif http://www.eliwhitney.org/inventor.htm http://www.cncmasters.com/images/bps-1649.jpg http://www.lagun.com/products/gbm/gbm22e-42e.html

http://www.ohiobroach.com http://www.broachingmachine.com/ http://class.et.byu.edu/mfg130/processes/mechanicalreduction.htm http://www.doringer.com