MET 33800 Manufacturing Processes Chapter 25 Other Machining Processes Before you begin: Turn on the sound on your computer. There is audio to accompany this presentation. Other Machining Processes Shaping Planing Broaching Sawing Filing Chapter 25-2 Materials Processing Chapters 11-13 Chapters 20-27 Chapters 15-17 Chapters 30-33 Chapter 25-3 1
Shaping and Planing Among oldest single-point machining methods. Largely replaced by milling and broaching for production operations. Chapter 25-4 Shaping and Planing Types of geometry commonly machined using shaping or planing methods. Chapter 25-5 Shaping and Planing Chapter 25-6 2
Shaping Workpiece feed at right angle to cutting motion. Single point cutting tool held in ram and reciprocates across workpiece. Cutting occurs on forward stroke only (clapper box prevents tool drag). Chapter 25-7 Shaping Chapter 25-8 Shaping Machines Machine types: Horizontal: push-cut or pull (draw)-cut Vertical: regular (slotter) or keysetter Special Chapter 25-9 3
Shaping Machines Chapter 25-10 Shaping Cutting Parameters Cutting parameters: V = cutting speed L S = length of stroke (in) N S = #strokes/min (rpm) R S = stroke ratio (no units) L = length being cut W = width being cut t = depth of cut f c = feed in/stroke 2 L N S S V = 12 R S cutting stroke angle R = S o 360 L W t MRR = CT W T = m N f S c o Chapter 25-11 Planing Workpiece feed at right angle to cutting motion. Workpiece is moved past multiple single point cutting tools that are held stationary. Tool heads can be arranged for cutting in both directions. Very slow process applicable to only very large workpieces. Chapter 25-12 4
Planing Machines Chapter 25-13 Broaching Entire surface generated in single pass of broach. Broach composed of series of teeth, each tooth slightly higher. Feed per tooth is change in height of successive teeth. Feed per tooth is built into cutting tool (unique to process). Chapter 25-14 Broaching Broach may be stationary or move past work. Internal & external broaching possible. Used for mass production due to cost of broach ($15-30K). Better accuracy and finish than drilling, boring or reaming. Speed relatively low 20 25 sfpm. Chapter 25-15 5
Broaching Chapter 25-16 Broaching Chapter 25-17 Broach Design Chapter 25-18 6
Broach Design Chapter 25-19 Broach Design 1. Each tooth is single-edge cutting tool. Chapter 25-20 Broach Design 2. Rise per tooth (RPT) or step - determines amount of material removed. Chapter 25-21 7
Broach Design 3. Pitch (P) distance between teeth. Minimum of two teeth engaged in work. L W = length of cut P 0.35 LW Chapter 25-22 Broach Design 4. Tooth style: Roughing (depth of cut t r ) 0.006 RPT Semi-finishing (depth of cut t s ) 0.003 RPT Finishing (depth of cut t f ) 0.001 RPT Burnishing rounded disks with no cutting edge. 0.001-0.003 RPT. Chapter 25-23 Broach Design 4. Tooth style (continued): DOC = depth of cut n = number of teeth t = rise per tooth n = r DOC - n t - n t t r f f s s Chapter 25-24 8
Broach Design 5. Broach design: a) Rotor-cut (Jump-cut): Two or three teeth have same height with cut-away so each tooth machines only a portion of the surface. Allows deeper and narrower cuts. Reduces force and power requirements. Chapter 25-25 Broach Design 5. Broach design (continued): b) Double-cut: Four teeth have same height and progressively get wider. c) Progressive: First few teeth machine to center, remaining teeth offset and finish remaining surface area. Chapter 25-26 Broach Design 5. Broach design (continued): d) Chip-Breakers: Same function as other chipbreakers on other cutting tools. Break long continuous chips in ductile materials. Chapter 25-27 9
Broach Design 6. Tooth angle: Normal to direction of cut to 5-20º angle (shear-cut broach). 7. Hook: Primary rake angle. 8. Back-off: End clearance to prevent rubbing. 9. Front pilot: Aligns broach in hole before cut begins. 10. Rear pilot: Keeps broach square as tool leaves workpiece. Chapter 25-28 Broach Design Chapter 25-29 Broach Design Chapter 25-30 10
Broach Design Chapter 25-31 Broach Design Chapter 25-32 Machining Parameters MRR = 12 t r W V n r W = width (circumference) of tooth t r = roughing teeth RPT n r = # roughing teeth T m = L / 12V L = length of stroke Chapter 25-33 11
Broach Design Parameters Allowable Pull (AP) area of min section Y.S. AP = S Y.S. = yield strength of broach S = safety factor Chapter 25-34 Broach Design Parameters Allowable Load (AL) 13.5 x 10 D AL = S L 6 4 r 2 D r = root diameter S = safety factor L = length from push end to first tooth Chapter 25-35 Machining Parameters Pull Force F CB 5 S nt r W S = shear stress of material W = width (circumference) of tooth t r = roughing teeth RPT n = #total teeth Chapter 25-36 12
Broach Design and Machining Parameters Example Process: Pull Broaching Part Configuration: 1.0 diameter ID shape x 3.0 long 0.125 depth of cut Part Material: 1018 Annealed Carbon Steel V = 20 fpm S = 2972.5 psi Broach Y.S. = 260,000 psi Chapter 25-37 Broach Design and Machining Parameters Example Chapter 25-38 Broach Design and Machining Parameters Example Chapter 25-39 13
Broach Design and Machining Parameters Example Chapter 25-40 Broach Design and Machining Parameters Example Chapter 25-41 Broach Design and Machining Parameters Example Chapter 25-42 14
Machining Parameters Example Chapter 25-43 Broaching Machines 1. Vertical a) Broaching press - arbor press with guided ram. b) Pull down (internal) - broach elevator above and pulling mechanism below table. c) Pull up (internal) - pulling mechanism above and handling mechanism below table. d) Surface - broach mounted in guide slides. Chapter 25-44 Broaching Machines Chapter 25-45 15
Broaching Machines Chapter 25-46 Broaching Machines Chapter 25-47 Broaching Machines 2. Horizontal - longer lengths. a) Internal typically push / not used for small holes since broach must be self-supporting. b) Surface - broach supported in guides. c) Continuous - broach stationary and work pulled past on conveyor. 3. Rotary - broach stationary and work rotated past on table. Chapter 25-48 16
Broaching Machines Horizontal Surface Broaching Machine Turbine Wheel Blade Roots Rotary Broaching Machine Chapter 25-49 Broaching Machines Horizontal Internal Broaching Machine Gun Barrel Bore Chapter 25-50 Broaching Machines Chapter 25-51 17
Broaching Machines Chapter 25-52 Sawing Chips generated by teeth located on periphery of blade. Chapter 25-53 Sawing Chapter 25-54 18
Sawing Chapter 25-55 Blade Types 1. Hacksaw blades: a. Hand: 0.025 thick (gage) 10 or 12 inch length ½ wide b. Power: 0.050 0.100 thick 12 to 24 inch length 1 2 wide Chapter 25-56 Blade Types 2. Bandsaw blades: a. 1/16 and greater width 3. Circular (cold) saw blades: a. Teeth cut into disk up to 18 dia. b. Segmented or inserted teeth used for larger diameter blades. Chapter 25-57 19
Blade Types Circular (cold) saw blades: segmented or inserted teeth larger diameters. Chapter 25-58 Blade Types Cold saw blade with carbide teeth Chapter 25-59 Blade Types Cold saw blade: segmented teeth Chapter 25-60 20
Blade Nomenclature Chapter 25-61 Blade Design 1. Blade Material: a. Hacksaw: Tungsten or molybdenum HSS. b. Bandsaw: HSS, Brazed Carbide, TiN Coated. c. Cold Saw: HSS, Brazed Carbide, TiN Coated. d. Friction Saw: Abrasive. Chapter 25-62 Blade Design 2. Tooth forms: a. Regular tooth: general purpose, ferrous materials. b. Skip tooth: softer, non-ferrous materials. c. Hook tooth: harder, non-ferrous materials. d. Variable pitch: wider range of applications including tubing. Reduced vibration. Chapter 25-63 21
Blade Design 3. Tooth spacing: a. Determines how many teeth engage work (minimum two required). b. Controls size of teeth. c. Determines gullet. Chapter 25-64 Blade Design 4. Tooth set - how teeth are offset from centerline controls size of teeth. a. Raker-set: General purpose, uniform thickness, steel and iron. b. Straight-set: Brass, copper, plastic. c. Wave-set: Thin sheet or wall tubing, non-uniform thickness. d. Cluster-set: Thin sheet or wall tubing, non-uniform thickness. Chapter 25-65 Blade Design 5. Gage: measure of blade thickness. 6. Width: controls the minimum radius bandsaw blade is capable of cutting. Chapter 25-66 22
Sawing Machines 1. Reciprocating saw - hand or power with optional automatic power bar feed mechanisms. 2. Bandsaw: a. Vertical cutoff - single stationary workpiece on table. b. Horizontal cutoff - can incorporate optional automatic power bar feed mechanisms. c. Combination cutoff and contour - like DoAll in lab. d. Friction - blade brings metal to melting point and pulls material from kerf. Chapter 25-67 Sawing Machines Chapter 25-68 Sawing Machines Chapter 25-69 23
Sawing Machines Chapter 25-70 Sawing Machines Chapter 25-71 Sawing Machines Chapter 25-72 24
Sawing Machines Chapter 25-73 Sawing Machines Friction Bandsaw Chapter 25-74 Sawing Machines 3. Circular saw : a. Cold saw - cutoff work exclusively. b. Steel friction disk - similar to bandsaw. c. Abrasive disk - technically not sawing but machine function is the same. Chapter 25-75 25
Filing Metal removal action same as sawing except chips are very small and cutting teeth are wider. Cutting action is very slow and easily controlled with high accuracy. Includes manual and machine-based operation. Chapter 25-76 File Characteristics 1. Type or cut of teeth: a. Single-cut - rows of parallel teeth at 65-85 angle. b. Double-cut - two series of parallel teeth. c. Vixen-cut - parallel curved teeth. d. Rasp-cut - teeth short and raised out of file. Chapter 25-77 File Characteristics 2. Degree of coarseness: a. Swiss - #00 to #8 roughness increasing b. Dead Smooth c. Smooth d. Second Cut e. Bastard f. Coarse g. Rough Chapter 25-78 26
File Characteristics 3. Construction a. Tang for file handle. b. Cross-section: a. Flat b. Round c. Square d. Triangle e. Half-round Chapter 25-79 Filing Machines Die filing - reciprocate file. Band filing - bandsaws with special blades. Lower accuracy. Disk-filing machines - files in form of disk. Low accuracy. Chapter 25-80 Filing Machines Chapter 25-81 27
The End See Oncourse for Videos Chapter 25-82 28