This Post describe about introduction to metal cutting process, different types of cutting tools, Nomenclature of single point cutting tool, Angle of single point cutting tool, Signature of cutting tools.
Introduction to metal cutting process
By using various types of process, the metals are removed from work piece to obtain require shape and size. That are classified as below (i) non cutting process (ii) cutting process. For generally, the metals are shaped in require form under the action of force and heating. That is no any cutting of metal, chip formation removal. So, this method of no cutting process. The process such as forging,drawing, spinning, rolling, extrusion are non cutting process. The metal of removed and become with required shape and size to be obtained. So the unwanted metal removing from the work piece is called the form of chip. The various cutting process obtained such as turning, drilling, boring, shaping, milling and etc.For generally edge of cutting tools having harder than the work piece metal. The various metal cutting process done by the relative motion between work piece and cutting tools.
The relative motion may be occurred during metal cutting process as follows,
- The rotation of work again the cutting tools. Example – turning
- The rotation of tools against the work piece. Ex: milling and drilling
- The linear motion of work again the cutting tool. Ex: planning
- The linear motion of tools obtain again the work. Ex: shaping.
The single point cutting tool is mainly used to metal remove from work piece become with require shape and size of product. It remove large amount of metal in quickly again rotating the work piece. Boring, turning are performed by using single point cutting tool in lathe machine.
Different types of cutting tools
The different types of cutting tools used to metal cutting process depends upon the materials and machining method used. There are classified into two types.
- single point cutting tool
- Multi point cutting tool
The single point cutting tool geometry or nomenclature:-
It is a body of tools, which is not Grained is known as shank.
The surface over the chip of metal side is known as face.
The Cutting tool surface is facing the work metal is known as Flank. There are two types like as end flank and side flank.
It is a bottom surface of shank. Generally it having flat farming in naturally.
It is a Junction of side and end of cutting edge is known as nose.
It is a junction of face and Flank.It having two types,
- end cutting edge
- side cutting edge
Angle of single point cutting tool:
Back rake angle:
There is also known as Top rack angle. The angle between tool face and line parallel to basic of tool. The slope is given in the tool surface (or) face. In the slope is given from nose along with length of tool. The angle may be positive or negative for depends upon amount of cutting edge.
Side rake angle:
The angle between face of tool and line parallel to the base of tool. The slope is given the face (or) tool top position. Also the slope is given from nose along with length of tool. When the angle is considered for positive, the slope is given toward cutting edge and the rack angle is consider for negative, the slope is given from cutting edge.
Relief angle or clearance angle:
When the slope is given download from cutting edge. That is divided in two types of clearance angle. They are
- side relief or side clearance angle
- end relief or end clearance angle
The angle between side of Flank and perpendicular line to tool base, it is known as side relief angle. Which is provided to help of avoid rubbing when tool is feed sideways into job. In case the side relief angle is large, the Tool cutting edge will be breakdown because of insufficient support. So it will be avoid the side relief angle is having very small.
When the cutting tool cannot be feeding into the work job. but it also rubbing against the job. So the overheating of tool will be done. This reason to affect the job surface finish.
The angle between flank of end and line perpendicular to tool base measuring along right angle to flank of end is called as and relief angle. This angle is used to prevent the cutting tool from rubbing again work job. If the relief angle is very large, it will be break down due to insufficient support of cutting tool. So the cutting of job will not be properly and the poor surface finish will be done. For generally it angle from 6 degree to 10 degree. So it provided in very small angle.
Cutting edge angle:
The cutting edge angle having two types such as side cutting edge and end cutting edge. The side cutting edge angle is the angle between side of cutting edge and side of tool Shank. Alternatively, the angle between side of cutting edge and longitudinal axis of tool. It side cutting edge used to control the flow of chip, avoid the formation of built up edge and distributing of cutting force.
The end cutting edge angle is the angle between end of cutting tool and line of perpendicular to tool Shank. Alternatively, the angle between tool face and plane perpendicular to shank side. Allow only for small question of end section edge to contact the machining surface, and also the vibration and chatter are prevented. The angle will be from 5 degree to 15 degree.
The nose radius is the angle between side of cutting edge and end of cutting edge. Which the side cutting edge and end cutting edge to joining a line by point lead to high heat concentration. When the joining by means of the small radius is good configuration to increase in the cutting tool life and to obtain better surface finish. By the large radius, strengthening the tool and it used on cast iron and also the casting where the cuts are interrupted.
Effects of back rake angle:
The angle size selection depends upon the material to be machined. If the material having softer, greater angle will be given. When the material is harder, the smaller of angle will be required. For example, the aluminium require more back angle than cast iron. Which back rack angle may be positive or negative or neutral according to the material selection.
For consider the above diagram show the tool with positive, neutral and negative back rack angle respectively. When the back Rake angle is higher of value the cutting edge will be weaken together. The negative back angle will be increase the tool forces to some extending. This type of difficult may be rectified by give additional support to cutting edge. For generally the carbide tools designed with negative rake angle.
The positive rake Angle whereas used as follows,
- To machining the hardened work material.
- To machining the low strength of ferrous and nonferrous material.
- To turn the long shaft with small diameter
- Machining the metals having lesser recommended the cutting speed
- The machining the job metal using small machine tool include low horsepower
The negative rake Angle whereas used followed by,
- Machining the high strength alloy
- Machine tools are more rigid
- To given the heavy and interrupted cuts
- The feed rate will be highly
Effects of side rake angle:-
During the machining operation the chip curling or amount of chip bends depends upon the side rake angle. If the side rake angle is larger, cut and bending of chip and power requirement will be decreased. Hence that providing better surface finish of machining surface.
Signature of metal cutting tool:-
The tool angle given in definite pattern is called tool signature. It tool angle have standardized by American standard Association (ASA). As per American standard Association the tool signature are presented as follows
- Back rake angle
- Side rake angle
- End relief angle
- Side relief angle
- End cutting edge angle
- Side cutting edge
- Nose radius
There are presenting in degree and mm.
The tool having the signature forming like as 8, 8, 5, 5, 6, 6 and 1 as per ASA. So the angle of tool explained for,
- Back rake angle = 8 degree
- Side rake angle = 8 degree
- End relief angle = 5 degree
- Side relief angle = 5 degree
- End cutting edge angle = 6 degree
- Side cutting edge = 6 degree
- Nose radius = 1 mm