1. Manufacturing Science
MACHINABILITY
DYNAMOMETER
MACHINE TOOL VIBRATION
Presented By
AMIT KUMAR
ME-1 (3rd)

2. CONTENT INTRODUCTION MACHINABILITY Machinability of ferrous metal
Machinability of non ferrous metal
Thermally Assisted Machining
SURFACE FINISH
DYNAMOMETER
Mechanical dial gauge type
Strain gauge type
MACHINE TOOL VIBRATION

3. INTRODUCTION
We all know that the term machinability refers to the case with which a metal can be machined to be acceptable surface finish..
Machinability is a term that describes the ease or difficulty with which a metal can be machined. It can be measured by the life of the cutting tool or the material removal rate in relation to the cutting speed used. The good machinability indicates;
1. Good surface finish and integrity.
2. Long tool life.
3. Low surface and power requirement

4. Machinability Machinability is defined in terms of:
Surface finish and surface integrity
Tool life
Force and power required
The level of difficulty in chip control
Good machinability indicates good surface finish and surface integrity, a long tool life, and low force and power requirements
Machinability ratings (indexes) are available for each type of material and its condition

5. Build Thread Hafco HM52 CNC Conversion -
Liquid cutting
Build Thread Hafco HM52 CNC Conversion -

6. Machinability: Machinability of Ferrous Metals
Steels
If a carbon steel is too ductile, chip formation can produce built-up edge, leading to poor surface finish
If too hard, it can cause abrasive wear of the tool because of the presence of carbides in the steel
In leaded steels, a high percentage of lead solidifies at the tips of manganese sulfide inclusions
Calcium-deoxidized steels contain oxide flakes of calcium silicates (CaSO) that reduce the strength of the secondary shear zone and decrease tool–chip interface friction and wear

7. Machinability: Machinability of Ferrous Metals
Effects of Various Elements in Steels
Presence of aluminum and silicon is harmful, as it combine with oxygen to form aluminum oxide and silicates, which are hard and abrasive
Thus tool wear increases and machinability reduce
Stainless Steels
Austenitic (300 series) steels are difficult to machine
Ferritic stainless steels (also 300 series) have good machinability
Martensitic (400 series) steels are abrasive

8. Machinability: Machinability of Nonferrous Metals
Aluminum is very easy to machine
Beryllium requires machining in a controlled environment
Cobalt-based alloys require sharp, abrasion-resistant tool materials and low feeds and speeds
Copper can be difficult to machine because of builtup edge formation
Magnesium is very easy to machine, with good surface finish and prolonged tool life
Titanium and its alloys have very poor thermal conductivity
Tungsten is brittle, strong, and very abrasive

9. Machinability: Thermally Assisted Machining
In thermally assisted machining (hot machining), a source of heat is focused onto an area just ahead of the cutting tool
Advantages of hot machining are:
Reduced cutting forces
Increased tool life
Higher material-removal rates
Reduced tendency for vibration and chatter

10. Surface Finish
Surface finish influences the dimensional accuracy of machined parts, properties and performance in service
Surface finish describes the geometric features of a surface while surface integrity pertains to material properties
The built-up edge has the greatest influence on surface finish

11. Surface Finish A dull tool has a large radius along its edges
In a turning operation, the tool leaves a spiral profile (feed marks) on the machined surface as it moves across the workpiece
Typical surface roughness is expressed as

12. Surface Finish and Integrity
Factors influencing surface integrity are:
Temperatures generated
Surface residual stresses
Plastic deformation and strain hardening of the machined surfaces, tearing and cracking
Finish machining is considering the surface finish to be produced
Rough machining is to remove a large amount of material at a high rate

13. DYNAMOMETER
It is a device which measures cutting forces accurately during cutting process
It should have rigid body to avoid deflection in cutting process
Commonly used tool dynamometer are
Strain gauge type
Mechanical dial gauge type

14. Strain gauge
The dynamometers being commonly used now-a-days for measuring
machining forces desirably accurately and precisely (both static and dynamic
characteristics) are
• strain gauge
strain gauge may be of one, two or three dimensions capable to monitor all of PX, PY and PZ.
For ease of manufacture and low cost, strain gauge type turning
dynamometers are widely used and preferably of 2 – D (dimension) for
simpler construction, lower cost and ability to provide almost all the desired force values.

15. Mechanical force gauge
Mechanical dial gauge
Mechanical force gauge

16. MACHINE TOOL VIBRATION
In machine tool and cutting processes, machine stiffness plays important role in accuracy and surface finish.
Low stiffness creates vibration.
Effect Of Vibration
Poor surface finish
It damages tool component
It creates noise pollution
Losses of dimensional accuracy of the workpiece

17. FORCED VIBRATION SELF EXCITED VIBRATION
It is caused by some periodic force present in the machine tool i.e. from gear drives, misalignment of motors and pump and due to improper balance of machine tool component.
The function of forced vibration is to remove the forcing elements , change the cutting speed and the tool geometry..
SELF EXCITED VIBRATION
Self excited vibration is generally caused by the interaction of the chip removal process and the structure of the machine tool. These vibrations generally have high amplitude than forced vibration.
This vibration is removed by increasing the dynamic stiffness of the system and by damping.

18. THANK YOU