MACHINE TOOLS INTRODUCTION

 

MACHINE TOOLS INTRODUCTION

MACHINE TOOLS: - Tools, which operated by machine power, for removing of excess metal to attend desire shape and size is called machine tools.

Factor affecting Metal Cutting: -

1.   Properties of Work Material.

2.   Properties and Geometry of cutting tools.

3.   Interaction between the tool and work.

• TYPES OF METAL CUTTING PROCESS: -

  1.   ORTHOGONAL CUTTING (Two dimensional cutting)-

  In this cutting process, the tool is perpendicular to the direction of feed motion.

  There are two types of force is involved.

  Cutting edge clears the width of the work piece on either side.

  Chip flow velocity is normal to the Cutting edge.

  Cutting tools prepare a surface parallel to the work face.

  Less metal removed.

  Application is rare – Knife turning, Broaching etc.

   

  2.   OBLIQUE CUTTING (Three dimensional Cutting) –

  In this cutting process, major edge of the cutting tool is presented to the work piece at an angle which is not normal (angle ≠ 90⁰) to the direction of feed motion.

  The cutting edge of the tool may not clear with the width of work piece.

  Maximum chip thickness may not occur at the middle.

  Cutting tool may or may not prepare a surface parallel to the work face.

  More than one cutting edge are in action.

  Application is wider.

TYPES OF CUTTING TOOLS: -

1.   Single Point Cutting Tools –

• Has one effective cutting edge.
• Commonly used in Lathe, Planner, Shapper, Boring, Slotter etc.
• Types – a. Ground type, b. Forged type, c. Tripped type, d. Bit type.
• This tool may be Left handed or right handed.

 

LEFT HAND TOOL           Tool cut the job from left to right         i.e. from Head stock to Tail stock.

RIGHT HAND TOOL               Tool cut the job from left to right   i.e. from Head stock to Tail stock.

 

Fig. 1 | Left Hand and Right Hand Cutting Tools

2.   Multi Point Cutting Tools –

These tools have more than one effective cutting edge.

Examples – Milling Cutter, Drill, Reamers etc.

 

IMPORTANT PROPERTIES OF CUTTING TOOL: -

1.   Hot Hardness

2.   Wear Resistance

3.   Toughness

• CUTTING TOOLS MATERIAL: -

1.   Carbon Steel:-     

• Hot hardness – 250⁰C
• Cutting Speed –12m/min.

2.   High Speed steel (HSS):-       

• Hot hardness – 900⁰C
• Cutting speed – 30m/min.

3.   Stellite (Trade name of non-ferrous cast alloy):-     

• Hot hardness – 1000⁰C
• Cutting speed – 24m/min.

4.   Cemented Carbide:-     

• Hot hardness – 1500⁰C
• Cutting speed –150 m/min.

5.   Ceramics:-

• Hot hardness – 1200⁰C
• Cutting speed – 600 m/ min.

6.   Diamond:-

• Hot hardness – 1650⁰C
• Cutting speed - 1000 m/ min