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Metal Cutting Saws III

Metal Cutting Saws III. Types of Blades used on Cutoff Saws and Tips on using Saws. Cutoff blades are usually made of:. Carbon alloy- used in the toolroom and maintenance shop and in light manufacturing where accuracy is needed

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Metal Cutting Saws III

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  1. Metal Cutting Saws III Types of Blades used on Cutoff Saws and Tips on using Saws

  2. Cutoff blades are usually made of: • Carbon alloy- used in the toolroom and maintenance shop and in light manufacturing where accuracy is needed • High speed steel- often alloyed with tungsten or molybdenum, used in heavy duty and full-time production work • Tungsten carbide- used for heavy production and for rough cutting through tough materials

  3. Cutting speed refers to the amount of workpiece material that passes by a cutting tool in a given amount of time. Cutting speeds are measured in feet per minute (fpm) or metres per minute (mpm)

  4. Saw tooth forms have a great impact on the cutting process. Certain angles and the size and shape of the gullet dictate the type of material and speed of the cutting process.

  5. The bandsaw has a thinner blade and wastes less metal on each cut.

  6. Tooth forms used on cutoff saws: • Precision tooth form –is the most widely used form. The tooth has the following features: 0° rake angle, 30° back clearance angle, deep gullet and a radius at the bottom

  7. Buttress tooth form- also known as skip tooth. Features: 0° rake angle, 30° back clearance, widely spaced teeth for greater chip clearance for thick work sections, deep cuts and soft materials

  8. Claw Tooth form- also called hook tooth, it has a positive rake angle and a smaller clearance angle than the precision or buttress forms. It can cut at a faster rate at a reduced feed pressure which will provide longer tool life.

  9. Tungsten carbide tooth form- has a positive rake angle and a smaller clearance angle than any of the other tooth forms. The tungsten carbide teeth are fused into a fatigue-resistant blade that is necessary for heavy, tough cutoff sawing.

  10. Saw blade pitch refers to the number of teeth per inch or the number of teeth per 25 mm. The thickness of the material determines the pitch of the blade. Ideally you want to keep three teeth in contact with the blade at all times.

  11. The set of the saw blade refers to the amount the teeth is offset from the center of the blade. It will influence the size of the kerf.

  12. The width of a saw blade is determined by the smallest radius you are required to cut on the workpiece.

  13. The gauge of the blade is a measurement of blade thickness. • Up to ½ width : .025 thick • 5/8th to 3/4th width: .032 • One inch and over: .035

  14. Most companies now order their blades a specific length already welded. The blade length formula is: BL= (2 x center distance) + (pulley diameter x )

  15. Some machines have band welders attached to the front panel of the machine.

  16. Butt Welder – welds and anneals a butt joint on a band

  17. Performance & Troubleshooting • For maximum blade life, break in for 20 minutes at half normal feed rate. Other tips – lower speed, or use blade with more teeth per inch • Watch the chips – fine powder: increase feed, blue colour: reduce feed • To get more pieces per hour, try higher speed, heavier feed, blade with fewer teeth per inch or with hook teeth

  18. To improve finish of cut, try higher speed, lighter feed or blade with more teeth per inch. • To improve accuracy of cut, try higher speed or less feed. • Blade breaking: guides not set close enough to work, out of alignment or too tight; continued tension on the blade when not in use; too little or too much tension; sawing dry; blade too thick; brittle weld; speed too slow; feed too high; too few teeth per inch

  19. Blade running off – forcing the cut; guides improperly spaced or out of vertical alignment; teeth dull on one side of blade • Premature dulling of teeth – cutting speed too great; feed pressure too light; guides touching tooth set; too few teeth; too short a break in period for blade; sawing dry • Burrs on Back of blade – only one of two back edge rollers in contact with blade; not enough blade tension; guides not set right

  20. Teeth ripping out – feed pressure too heavy; too few of teeth per inch (chip too larger per tooth or teeth straddling work of thin section); too many teeth per inch (chips loading in gullet); starting cut on corner of material; sawing dry • Grooves in side of blade – guide of out alignment; too tight; dirty or worn blade.

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