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Types of Metal Saws. Unit 35. Methods of Cutting Off Material. Five most common methods of cutting off material Hacksawing Bandsawing Abrasive cutting Cold sawing Friction sawing. Power Hacksaw. Reciprocating type of saw Frame and blade travel back and forth
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Types of Metal Saws Unit 35
Methods of Cutting Off Material • Five most common methods of cutting off material • Hacksawing • Bandsawing • Abrasive cutting • Cold sawing • Friction sawing
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
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
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
Cold Circular Cutoff Saw • Uses circular blade similar to one used on wood-cutting table saw • Generally made of chrome-vanadium steel • Carbide-tipped blades used for some applications • Suited for cutting aluminum, brass, copper, machine steel, and stainless steel
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
Horizontal Bandsaw Parts • Frame - hinged at motor end with two pulley wheels over which continuous blade passes • Step Pulleys - Used to vary speed of blade • Roller guide brackets - Provide rigidity for section of blade • Blade tension handle - Used to adjust tension on saw blade • Vise - Mounted on table, adjusted to hold work
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 • 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
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
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
Sawing Hints • Never attempt to mount, measure, or remove work unless saw is stopped • Guard long material at both ends to prevent anyone from coming in contact with it • Use cutting fluid whenever possible to help prolong life of saw blade
When sawing thin pieces, hold material flat in vise to prevent saw teeth from stripping • Use caution when applying extra force to saw frame • Generally causes work to be cut out of square • Set stop gage when several pieces of same length are required • Place short piece of same thickness in opposite end of vise when holding short work