26-07-2012, 03:42 PM
Cutting tool
Cutting_Tools.ppt (Size: 1.43 MB / Downloads: 394)
Cutting Tool Properties
Hardness
Cutting tool material must be 1 1/2 times harder than the material it is being used to machine.
Capable of maintaining a red hardness during machining operation
Red hardness: ability of cutting tool to maintain sharp cutting edge
Also referred to as hot hardness or hot strength
High-Speed Steel
May contain combinations of tungsten, chromium, vanadium, molybdenum, cobalt
Can take heavy cuts, withstand shock and maintain sharp cutting edge under red heat
Generally two types (general purpose)
Molybdenum-base (Group M)
Tungsten-base (Group T)
Cobalt added if more red hardness desired
Carbide Cutting Tools
First used in Germany during WW II as substitute for diamonds
Various types of cemented (sintered) carbides developed to suit different materials and machining operations
Good wear resistance
Operate at speeds ranging 150 to 1200 sf/min
Can machine metals at speeds that cause cutting edge to become red hot without loosing harness
Blending
Five types of powders
Tungsten carbide, titanium carbide, cobalt, tantalum carbide, niobium carbide
One or combination blended in different proportions depending on grade desired
Powder mixed in alcohol (24 to 190 h)
Alcohol drained off
Paraffin added to simplify pressing operation
Cemented-Carbide Applications
Used extensively in manufacture of metal-cutting tools
Extreme hardness and good wear-resistance
First used in machining operations as lathe cutting tools
Majority are single-point cutting tools used on lathes and milling machines
Cutting_Tools.ppt (Size: 1.43 MB / Downloads: 394)
Cutting Tool Properties
Hardness
Cutting tool material must be 1 1/2 times harder than the material it is being used to machine.
Capable of maintaining a red hardness during machining operation
Red hardness: ability of cutting tool to maintain sharp cutting edge
Also referred to as hot hardness or hot strength
High-Speed Steel
May contain combinations of tungsten, chromium, vanadium, molybdenum, cobalt
Can take heavy cuts, withstand shock and maintain sharp cutting edge under red heat
Generally two types (general purpose)
Molybdenum-base (Group M)
Tungsten-base (Group T)
Cobalt added if more red hardness desired
Carbide Cutting Tools
First used in Germany during WW II as substitute for diamonds
Various types of cemented (sintered) carbides developed to suit different materials and machining operations
Good wear resistance
Operate at speeds ranging 150 to 1200 sf/min
Can machine metals at speeds that cause cutting edge to become red hot without loosing harness
Blending
Five types of powders
Tungsten carbide, titanium carbide, cobalt, tantalum carbide, niobium carbide
One or combination blended in different proportions depending on grade desired
Powder mixed in alcohol (24 to 190 h)
Alcohol drained off
Paraffin added to simplify pressing operation
Cemented-Carbide Applications
Used extensively in manufacture of metal-cutting tools
Extreme hardness and good wear-resistance
First used in machining operations as lathe cutting tools
Majority are single-point cutting tools used on lathes and milling machines