MAYURBHANJ SCHOOL OF ENGINEERING
SUB- Manufacturing Technology
SEM- 4th
BRANCH-Mechanical
By- ER. S KAR
Cutting tool materials
CONTENTS
Cutting tool materials
Today the cutting tools play an important role in improving production rate and product quality, different types were used in industrial applications for machining materials and metals, then the cutting tool materials must possess the main following characteristics:
1- Hardness
2-Toughness
3-Wear resistance
4-Impact resistance
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The first and important cutting tool which has high wear resistance and hot hardness in composition. It tool perform high speed of cut and metal removal rate, improve the cutting performance. This steel maintain it hardness up to 900 degree centigrade. The alloy element such as chromium, tungsten, Cobalt, vanadium and molybdenum are improve the wear resistance and hot hardness. The high speed Steel used for manufacturing drill, tap, ,turning tools and milling cutters.
High speed Steel
High-performance cutting tools depend on excellent raw materials, which require the following:
(1) high hardness and wear resistance
(2) sufficient strength and toughness
(3) high heat resistance
(4) Good manufacturability
(5) Good thermal conductivity and small expansion coefficient.
The different types of high speed Steel used in cutting tools:
18 – 4 – 1 high speed Steel
The composition of following material,
It made by mixing of tungsten powder and carbon at high temperature( 1500 degree centigrade), the ratio of weight like that 94 and 6 respectively. the tungsten carbide combined with Cobalt, then compacted and sintered in furnace about 1400 degree centigrade. It mainly used at Higher cutting speed. The composition of material like that:
Cemented Carbide
The straight tungsten carbide have more strongly and higher wear resistance. But, that provide rapid cracking take place in the machining Steel. To improve the resistance of Cratering, alloyed tungsten carbide must be used with adding Titanium and molybdenum carbide
Titanium carbide material used to reduce the tendency of chip to weld and improved hot hardness to the tools. Titanium carbide addition to improve the resistance to crater wear and made of structure fine grained.
This carbide should be used for machining the very hard steel and machining brittle metal like as bronze and cast iron.
The mixing of Boron nitride powder and Aluminium oxide are sintered 1700 degree centigrade. This type of material having very hard with good compressive strength. The ceramic are used to made of tips and clamped on metal shank of tool. It perform at high cutting speed as two to three times than tungsten carbide. They cannot used in shock and vibration occur because it is brittle.
The material composition of ceramics tool as follows,
Ceramic cutting tools
It have excellence surface finish of work material, high compressive strength, longer life of tool and grater machining flexibility. It withstand the temperature up to 1700 C°. It materials are used to made of Single point cutting tool to machining the work materials such as cast iron and plastic. During the machining process no coolant is needed but tool must be strongly supported.
The different condition for effectively use of ceramics on carbide tools,
It is a hardest cutting material as compare to other. For polycrystalline diamond is made by sintering under high temperature and pressure. It material has high compressive strength, low coefficient of friction and it is extremely wear resistance. That is used for machining of very hard material like as plastics, class, ceramic etc. The deformation during the machining process very less due to high compressive and bending strength, high hardness. The Diamond tool provide good surface finish at high speed with good dimensional accuracy. The tool is a very small and best suited for Lightning of cut and finishing operation. Diamond tool can resist temperature up to 1250 degree centigrade.
Diamond cutting tools
The properties of diamond tool for generally,
It suitable for high tool life, 50 to 100 time more than cemented carbide. the disadvantages of diamond tool are higher cost and brittleness.
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