1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. PowerPoint to accompany Krar Gill Smid Technology of Machine Tools 6 th Edition Contour Bandsaw Operations Unit 37

2. 37-2 Objectives Set up the machine and saw external sections to within.030 in. (0.8 mm) of layout lines Saw internal sections to within.030 in. (0.8 mm) of layout lines Set up a contour bandsaw to file to a layout Know the purpose of special cutting tools used on a contour bandsaw

3. 37-3 Contour Bandsaw Provides ability to cut material close to form required quickly –At same time removes large sections that can be used for other jobs Versatility increased by using various attachments and cutting tools –Operations: sawing, filing, polishing, grinding, and friction and high-speed sawing Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

4. 37-4 Procedure to Mount a Saw Band 1.Select and mount proper saw inserts in upper and lower saw guides using proper gage for thickness of blade used Allow.001 to.002 in. clearance 2.Lower upper saw band carrier wheel to ensure blade will slide over wheels when installed 3.Mount blade over upper and lower wheels with teeth pointing down toward table

5. 37-5 4.Adjust upper wheel until some tension registered on blade-tension gage 5.Set gearshift lever in neutral position and turn upper saw band wheel by hand to make sure saw band rides on center of crown 6.Re-engage gearshift lever and close doors on upper and lower carrier housings 7.Replace filler plate in table 8.Lower upper saw guide very close to work 9.Start machine and adjust saw band to proper tension

6. 37-6 Procedure to Cut an External Section 1.Study print and check layout on workpiece 2.Check job selector and determine proper blade to use for job 3.Mount proper saw blade and guides on machine 4.Place work on table and lower upper saw guide until just clears work by.250 in. and clamp in place

7. 37-7 5.Start machine and check band tracking 6.Consult job selector dial and set speed 7.Place material against work-holding jaw or against block of wood 8.Carefully bring work up to blade and start the cut 9.Carefully feed workpiece into saw but do not use too much force 10.Saw to layout lines

8. 37-8 Most Common Sawing Problems TooTooImproperImproper HeavyLightBladeBlade ProblemFeedFeedTrackingTension Blade wandersXXX Blade not cuttingXX Blade dulls quicklyX Poor finishXX Small portion of Table 37.1 in text

9. 37-9 Sawing Internal Sections Starting hole must be drilled through section to be removed to allow saw blade inserted and welded Good practice to drill hole at every point where sharp turn must be made to allow workpiece to be turned easily

10. 37-10 Butt Welder Adds to versatility of bandsaw Permits convenient welding of blade for removal of internal sections Blades cut from coil stock and welded into continuous band –Broken blades may be welded and used again –Resistance-type welders fuse ends of blade –Butted ends of welded blade must not overlap in width, set or pitch of teeth

11. 37-11 Procedure to Weld a Bandsaw Blade 1.Select proper blade for job by checking chart on machine 2.Determine length of blade required Add twice center-to-center distance of the wheels plus circumference of one wheel Subtract 1 in. if upper wheel extended full distance to allow for stretch of blade 3.Place blade in cutoff shear, cut to length

12. 37-12 4.If ends of blade are straight but not square, hold them firmly with teeth reversed and grind both ends in one operation 5.To get proper tooth spacing after blade welded, grind off some teeth at ends of blade to depth of gullet prior to welding Welding operations consume about.250 in. of blade length Number of teeth ground off depend on pitch of blade

13. 37-13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Amounts to grind off various blades to achieve proper tooth spacing

14. 37-14 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

15. 37-15 6.Clean welder jaws and position inserts for blade size and pitch 7.Adjust jaw pressure by turning selector handle for width of blade being welded 8.Clamp blade (centered between jaws) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

16. 37-16 9.Depress welding switch or lever and hold it until weld has cooled 10.Release movable jaw clamp and release welding lever 11.Remove blade and check weld for Flash material should be uniform on both sides Spacing of teeth should be uniform Weld should be in center of gullet Back of blade should be straight

17. 37-17 12.Move reset lever to anneal position and clamp blade, with weld in center of jaws and teeth to rear and clearing jaws 13.Set selector switch at proper setting for annealing blade Push anneal switch button and jog it intermittently until band reaches dull red As cools, jog anneal switch so cools slowly 14.Remove blade and grind to same thickness as blade 15.After blade ground, anneal it to blue color

18. 37-18 Procedure to Saw Internal Sections 1.Drill hole slightly larger than width of saw blade near edge of section to be cut 2.Cut saw blade and thread it through one of drilled holes in workpiece 3.Weld blade and then grind off weld bead to fit saw thickness gage 4.Anneal weld section to remove brittleness and prevent blade from breaking

19. 37-19 5.Mount saw band on upper and lower pulleys and apply proper tension for size of blade 6.Insert table filler plate 7.Set machine to proper speed for type and thickness of material being cut 8.Cut out internal section (within 1/32 in.) 9.Remove saw band from pulleys 10.Cut blade at weld point on cutoff shear 11.Remove workpiece and blade

20. 37-20 Trimming and Blanking Dies Possible to use internal cutting technique to make short-run trimmings and blanking dies Internal section (slug) becomes punch and external material forms the die Table must be tilted to provide proper clearance for die

21. 37-21 Friction Sawing Fastest means of sawing ferrous metals up to 1 in. in thickness Metal fed into bandsaw traveling at high velocity (up to 15,000 sf/min) Tremendous heat generated by friction brings metal immediately ahead of saw teeth to plastic state and teeth easily remove metal –Blade remains cool (time to cool as it travels)

22. 37-22 Friction Sawing Used on hardened ferrous alloys, armor plate, stainless-steel alloys –Cannot cut aluminum, brass, thermoplastics because materials weld to blade and clog teeth Machines resemble vertical band machine but of heavier construction Bands made of standard carbon-alloy steel but thicker Widths of.250,.750 and 1 in (10, 14 pitch)

23. 37-23 Friction Sawing Saw band almost completely covered to protect operator from sparks Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

24. 37-24 High-Speed Sawing Performed at speeds ranging from 2000 to 6000 sf/min Used on nonferrous metals and wood, plastic and rubber Same machine setups and procedures apply as for conventional sawing Chips must be removed rapidly –Buttress of claw-tooth blades most efficient

25. 37-25 Band Filing Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Produces better finish than conventional sawing Band file –Steel band onto which are riveted number of short, interlocking file segments –Form continuous loop –Obtained in flat, oval, and half-round cross sections; bastard and medium cuts; and in widths of.250,.375, and.500 in.

26. 37-26 Procedure to Set Up for Band Filing 1.Select proper band file for job by consulting job selector dial 2.Set gearshift lever into neutral position 3.Remove saw guides and filler plate 4.Mount proper file guide and backup support 5.Lock ends of file blade together 6.Mount file band (teeth pointing in right direction) on bandsaw carrier wheels

27. 37-27 7.Lightly add tension to band 8.Check alignment and tracking of file band 9.Lower upper guidepost to proper work thickness 10.Mount proper table-filler plate 11.Set gearshift lever into low gear and start machine 12.Adjust band file to proper tension 13.Adjust machine to proper speed for material being filed

28. 37-28 Procedure to File on a Contour Bandsaw 1.Consult job selector and set machine to proper speed Best filing speeds between 50 and 100 ft/min 2.Apply light work pressure to file band 3.Keep moving work back and forth against file to prevent filing grooves in work 4.Use file card to keep file clean

29. 37-29 Knife-Edge Blades Available with knife, wavy, and scalloped- edge blades Special roller guides must be used Used for cutting soft, fibrous materials Scalloped-edge blades suited for cutting thin corrugated aluminum Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

30. 37-30 Spiral-Edge Blades Round and have continuous helical cutting edge around the circumference Provides a cutting edge of 360º Permits machining of intricate contours and patterns without work having to be turned Require special guides Two types: spring-tempered and all-hard Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

31. 37-31 Line-Grinding Bands Have abrasive bonded to thin edge of steel band –Aluminum oxide or silicon carbide Used to cut hardened steel alloys and other materials which could not be cut by bandsawing Requires high speed (3000 to 5000 sf/min) Requires coolant

32. 37-32 Diamond-Edge Blades Used to cut superhard space-age materials as well as ceramics, glass, silicon, and granite Has diamond particles fused to edges of saw teeth Generally require coolant Very expensive Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

33. 37-33 Polishing Bands Used to remove burrs and provide good finish to filed or sawed surfaces Continuous loop of 1-in-wide abrasive cloth manufactured to specific machine length Available in several grain sizes –Aluminum-oxide and silicon-carbide abrasive Mounted in same manner as saw band Marked with arrow to indicate direction of travel

34. 37-34 Electro-Band Machining Used to machine materials such as thin-wall tubing, stainless steel, aluminum and titanium honeycombing Low-voltage, high-amperage current fed into saw blade –Workpiece connected to opposite pole of circuit Work comes close to band; continuous electric spark passes from knife edge to work Arc disintegrates work –Blade does not touch workpiece Coolant used to prevent damage to work

35. 37-35 Electro-Band Machining Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

36. 37-36 Bandsaw Attachments: Work-Holding Jaw Device used by operator to hold and guide work into saw Connected to weight-type power feed so operator merely steers work Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

37. 37-37 Other Band Attachments Disk-cutting attachment –Permits cutting of accurate circles from approximately 2.5 to 30 in. in diameter Cutoff and mitering attachment –Used to support work when square or angular cuts are made Ripping fence –Provides means for cutting long sections of flat bar stock or plate into narrow parallel sections