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Types of Metal Saws Session 4. Shop Tools and Techniques2 Cutting Off Materials Five most common methods of cutting off material Hacksawing Bandsawing.

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Presentation on theme: "Types of Metal Saws Session 4. Shop Tools and Techniques2 Cutting Off Materials Five most common methods of cutting off material Hacksawing Bandsawing."— Presentation transcript:

1 Types of Metal Saws Session 4

2 Shop Tools and Techniques2 Cutting Off Materials Five most common methods of cutting off material Hacksawing Bandsawing Abrasive cutting Cold sawing Friction sawing

3 Shop Tools and Techniques3 Power Hacksaw Reciprocating type of saw Frame and blade travel back and forth Pressure applied automatically on forward stroke Limited use in machine shop work Usually permanently mounted to floor

4 Shop Tools and Techniques4 Power Hacksaw

5 Shop Tools and Techniques5 Power Hacksaw

6 Shop Tools and Techniques6 Horizontal Bandsaw Flexible, belt like "endless", blade that cuts continuously in one direction Thin, continuous blade travels over rims of two pulley wheels and passes through roller guide brackets Support blade and keep it running true Popular for high production and versatility

7 Shop Tools and Techniques7 Horizontal Bandsaw

8 Shop Tools and Techniques8 Abrasive Cutoff Saw Cuts by means of thin, abrasive wheel revolving at high speed Well suited for cutting most metals and materials such as glass and ceramics Can cut to close tolerances Can be performed under dry conditions Use of cutting fluid keeps work and saw cooler and produces better surface finish

9 Shop Tools and Techniques9 Abrasive Cutoff Saw

10 Shop Tools and Techniques10 Cold Circular Cutoff Saw Uses circular blade similar to one used on wood-cutting table saw Generally made of chrome-vanadium steel Suited for cutting aluminum, brass, copper, machine steel, and stainless steel

11 Shop Tools and Techniques11 Cold Circular Cutoff Saw

12 Shop Tools and Techniques12 Friction Sawing Burning process by which saw band (with or without) saw teeth, is run at high speeds to burn or melt its way through metal 10,000 to 25,000 sf/min Cannot be used on solid metal Amount of heat generated Excellent for cutting structural and honeycombed parts of machine or stainless steel

13 Shop Tools and Techniques13 Horizontal Bandsaw Parts Frame - hinged at motor end with two pulley wheels over which continuous blade passes Step Pulleys - Used to vary blade speed Roller guide brackets - Provides rigidity for section of blade Blade tension handle - Used to adjust tension on saw blade Vise - Mounted on table, holds work

14 Shop Tools and Techniques14 Saw Blades Commonly made of high-speed tungsten and high-speed molybdenum steel Hardened completely for power hacksaw Flexible blades on bandsaws have teeth hardened

15 Shop Tools and Techniques15 Saw Blades Manufactured in various degrees of coarseness, ranging from 4-14 pitch 10-pitch blade used for general-purpose sawing Always select saw blade as coarse as possible Always have two teeth of blade in contact with work at all times

16 Shop Tools and Techniques16 Installing a Blade Make sure teeth are pointing in direction of saw travel or toward motor end of machine Adjust blade tension to prevent blade from twisting or wandering during cut Rotate work ½ turn in vise, if need to replace blade before cut finished Prevent new blade from jamming

17 Shop Tools and Techniques17 Sawing Important that correct type and pitch of saw blade be selected and run at proper speed Blades Finer tooth when cutting thin cross sections and extra-hard materials Coarser tooth used for thick cross sections and soft, stringy material Speed Should suit type and thickness of material Too fast will dull saw teeth quickly

18 Shop Tools and Techniques18 Advantages of the Vertical Bandsaw

19 Shop Tools and Techniques19 Advantages of the Vertical Bandsaw

20 Shop Tools and Techniques20 Advantages of the Vertical Bandsaw

21 Shop Tools and Techniques21 Contour Bandsaw Parts Fabricated from steel Basic parts Base Column Head

22 Shop Tools and Techniques22 Bandsaw Applications Notching Sections of metal removed in one piece Slotting Quick and accurate without expensive fixtures

23 Shop Tools and Techniques23 Three-dimensional shaping Radius cutting Internal or external contours Internal sections removed in one piece Bandsaw Applications

24 Shop Tools and Techniques24 Bandsaw Applications Splitting Accomplished quickly with minimum waste Angular cutting Work clamped at any angle Table may be tilted

25 Shop Tools and Techniques25 Bandsaw Blade Types Three kinds of blades commonly used Carbon-alloy High-speed steel Tungsten-carbide tipped For best results, must consider Kind of saw-blade material and tooth form Pitch set Width Gage needed

26 Shop Tools and Techniques26 Tooth Forms Precision (regular) Most generally used 0º rake angle, 30º back clearance Used for fine finish

27 Shop Tools and Techniques27 Tooth Forms Claw (hook) Positive rake on cutting face Faster cutting, longer lasting than buttress

28 Shop Tools and Techniques28 Tooth Forms Buttress (skip) Teeth spaced farther apart Tooth angles same as precision teeth Used on thick work sections

29 Shop Tools and Techniques29 Pitch Numbers of teeth per standard reference length Inch standard = No. teeth/inch Metric standard = No. teeth/25 mm Thickness of material to be cut determines pitch of blade to use Coarse: thick, Fine: thin Two teeth in contact with work at all times

30 Shop Tools and Techniques30 Set Amount teeth offset either side of center to produce clearance for back of band Wave set Group of teeth offset to right and next to left Structural steel or pipe Straight set One tooth offset to right and next to left Light nonferrous castings Raker set One tooth offset to right, one to left, and third tooth straight

31 Shop Tools and Techniques31 Width Wide blade used for straight, accurate cuts Narrow blades used to cut small radii Radius charts show proper width of blade are found on all bandsaws Choose widest blade that can cut smallest radius

32 Shop Tools and Techniques32 Gage Thickness of saw blade Thick blades stronger than thin blades Thickest blade possible should be used for sawing tough material Standardized according to blade width ½ in wide are.025 in. thick 5/8 in. and ¾ in. wide are.032 in. thick 1 in. wide are.035 in. thick

33 Shop Tools and Techniques33 Calculate Length of Saw Blade Packaged in coils 100 to 150 ft. in length Cut length required and weld ends Twice center distance between each pulley and add it it one pulley's circumference Blade length = 2 (CD) + µ D

34 Shop Tools and Techniques34 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

35 Shop Tools and Techniques35 Butt Welder 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 Resistance-type welders fuse ends of blade Butted ends of welded blade must not overlap in width, set or pitch of teeth

36 Shop Tools and Techniques36 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

37 Shop Tools and Techniques37 Friction Sawing Fastest means of sawing ferrous metals up to 1 in. in thickness Saw traveling at hi-velocity (15,000 sfm) 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)

38 Shop Tools and Techniques38 Friction Sawing Used on hardened ferrous alloys, armor plate, stainless-steel alloys Cannot cut aluminum, brass, plastics - 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)

39 Shop Tools and Techniques39 Friction Sawing Saw band almost completely covered to protect operator from sparks

40 Shop Tools and Techniques40 High-Speed Sawing Performed at speeds ranging from 2000 to 6000 sfm 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

41 Shop Tools and Techniques41 Band Filing Better finish than conventional sawing Band file Steel band of short, interlocking file segments Forms continuous loop Obtained in flat, oval, and half-round cross sections; bastard and medium cuts; and in widths of.250,.375, and.500 in.

42 Shop Tools and Techniques42 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

43 Shop Tools and Techniques43 Spiral-Edge Blades Round blade has continuous helical cutting edge around the circumference Provides a cutting edge of 360º Permits machining of intricate contours and patterns Require special guides Two types: spring-tempered and all- hard

44 Shop Tools and Techniques44 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 sfm) Requires coolant

45 Shop Tools and Techniques45 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

46 Shop Tools and Techniques46 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

47 Shop Tools and Techniques47 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

48 Shop Tools and Techniques48 Electro-Band Machining

49 Shop Tools and Techniques49 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 Start Hole

50 Shop Tools and Techniques50 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

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