* Types of cutting tools materials and their properities * (By/Omar mehrem)
No one
can denay that the importance of the materials which is used for manufacturing the cutting tools that has agreat effect on the industry.
introd:- the cutting metals process consists of two mecanisms , the cutting tool and the work piece metal .the work piece metal is which we want to become in aneeded form , but the cutting tool must have properties that enable it to do its required function.
** The properties of an ideal tool material can be summerized as follows :-
* Hot hardness :- as far as possible, the cutting tool should maintain its hardness at elevated temperature.
* Hardness and toughness :- the tool must be harder than the workpiece material. Also, it should be tough enough to withstand shocks.
*
Wear resistance :- the tool should provide a large resistane to the weaing ation so that excessive wear doesnt occur.
*Thermal resistance :- the thermal conductivity and specific heat of the cutting tool should be high
.
** The material commonly used for making the cutting tools :-
*High carbon steel (
HCS) :- this material contains 0.7to1.4 carbon . a disadvantages of thecarbon steel tool is their comparatively low heat and wear resistance,so they may only used in the manufacture of tools operating at low cutting speed .Its cutting speed is 5cutting speed, m/min.
*
High speed steel (
HSS):- are widely used in metal cutting.they have a relatively high percent of alloying elements (w,c andv). It retains its cutting properties even when the tool point is heated up to 600 C degree . So tools made of HSS can be operate at cutting speed 5 or 6 times higher than for HCS
* there are another types of the cutting tools materials such as
Cemented carbides which is 150 m/min cutting speed . and
Ceramics which is 600 m/min cutting speed .
There are a cutting fluids which is used during the cutting process for:-
* Remove heat generated during the cutting.
* Lubricate and reduce friction .
* Wash away the chips and to clean the machining zone.
* The direct effect of using it :-
- Reducing the energy consumption
- Increasing the tool life
- Improving the surface finish