Single Point Cutting Tool
Terminology or Nomenclature of Single Point Cutting tool.
This specification is according to the American Standards Association (ASN) Systems.>
- The angle between the end cutting edge or flank to the plane perpendicular to the side of the shank is known as the end cutting angle.
- This angle usually varies from 5 to 15 degree
- The angle form to smooth flowing of chips from the face, known as rack angle. It allows to smooth flow of chips.
- The back rack angle is the angle between the face and the plane perpendicular to the end cutting edge.
- Softer the material, greater should be the positive rake angle.
- The back rake angle may be positive negative or neutral.
9. Side Rack Angle:
- The angle between the face and plane perpendicular to the side cutting edge is known as the side rack angle. It allows chips to flow smoothly when material cut by side cutting edge.
- The amount by which a chip is bent depends upon this angle. When the side rack angle increases, the magnitude of chip bending decreases. Smoother surface furnish is produced by a larger side rake angle.
- It is also known as a clearance angle. It is the angle that avoids tool
wear. It avoid the rubbing of flank with a workpiece.
- End cutting angle made by end flank to the plane perpendicular to the base.
- This angle may vary from 6 to 10 degrees.
11. Side Relief Angle:
- It is the angle made by the side flank to the plane perpendicular to the base. It avoid rubbing of side flank with a workpiece.
- This angle allows the tool to fed sideways into the job in order to cut the work material without rubbing.
- When the side relief angle is very small, the tool will rub against the job and therefore it will get overheated and become blunt and the surface finish obtained will be poor.
Factors influencing rake angle of the single point cutting tool:
2. Type of tool material being used: tool material like cemented carbide permits turning at a very high speed. It has been observed that in machining at a very high cutting speed rake angle has a little influence of cutting pressure.
3. Depth of cut: in rough turning, a high depth of cut is given to withstand severe cutting pressure. so the rake angle should be decreased to increase the lip angle that provides strength to the cutting edge.
4. The rigidity of the tool holder and condition of the machine: an improperly supported tool on an old and worn out machine can’t take up severe cutting pressure. so machining under such conditions the tool used should have a larger rake angle than that at the normal condition to reduce the cutting pressure.
End relief angle (βy) =60
Side relief angle (βx) =60
End cutting edge angle (φe) = 60
Side cutting edge angle (φs) = 100
Nose radius = 0.2mm
Single Point Cutting Tool Examples :
- Turning tool
- Shaping tool
- Planing tool
- Slotting tool
- Boring tool
- Fly Cutter
Material Used For single Point Cutting tools :
Tool bits generally made of seven materials
- High-speed steel
- Cast alloys (such as stellite)
- Cemented carbides
- Cubic Boron Nitride
- Polycrystalline Diamond
High Carbon Steel
These are usually plain carbon steel containing 0.6 to 1.5 % C. Method of fabrication for High Carbon Steel (HCS) is forging. HCS has a hot hardness temperature of about 250°C. Also, its maximum cutting velocity is about 5 m/min. Hence, HCS is generally used for machining soft materials like aluminum, copper, magnesium, etc. HCS is harder and the cheapest tool material.
High-Speed Steel (HSS) is usually carbon steel containing 1.5 to 2% carbon, 18 % tungsten, 4% chromium, 1% vanadium, and rest is iron. Tungsten is added to increase hardness. Chromium is added to increase hot hardness. Vanadium is added to increase wear resistance. The method of fabrication for HSS is forging. The cutting velocity of HSS is 40-60 m/min. It gives a higher speed than HCS. The hot hardness temperature of HSS is about 600°C.
Sometimes 18% molybdenum is added instead of tungsten to increase the wear resistance of the tool. Then this HSS is called as molybdenum based HSS. But tungsten-based HSS is commonly used. HSS has the only disadvantage that during machining of pure carbon work material, diffusion of carbon atoms into iron is much more because iron has a stronger affinity to attract carbon.
Advantages of Single Point Cutting Tool :
- Single Point Cutting tool is simple in construction hence easy to Design and Manufacture.
- As compare to multipoint cutting tool single point cutter are cheaper.’
- Resharpening of cutter is easy
Disadvantages of Single-point Cutting Tools :
- These tools have low material removal rates ( MRR ) hence productivity is low.
- The tool wear rate is high.
- Tool life is short.
- High Cutting temperature
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