What is the Machinability index? Are there anycriteria for evaluating machinability?

What is the Machinability index?

                   

Machinability defines the ease with which a material (mainly metal) can be cut or shaped while providing a satisfactory surface finish. A material with good machinability requires little power to cut, produces a smooth surface finish, and minimises wear on the tooling. By contrast, a material with poor machinability requires more power to cut, gives a poor surface finish, and wears the cutting tool. As such, materials with poor machinability cost more to process.

 

 

Corrosionpedia Explains Machinability

 

The machinability of a material depends on its physical and mechanical properties as well as its condition. Some physical and mechanical properties that can determine a metal’s machinability include hardness, yield strength, modulus of elasticity, and compressive strength. "Condition" refers to the composition of the material, including but not limited to its microstructure, chemical composition, grain size, and heat treatment process. The American Iron and Steel Institute has adopted standards for measuring the machinability of metals. AISI No. 1112 carbon steel is arbitrarily assigned a machinability rating of 100%. All other machinability ratings are, therefore, rated against this value.

 

 

Are there any criteria for evaluating machinability?

Following are parameters needs to considered for machinability measurement.

• Tool life, and types of wear tool subjected to. Crater wear, flank wear etc.

• Cutting forces Power consumption.

• Shape, size, type of chips. Tendency to burr. Cutting ratio of chip.

• Efficiency and rate of chip removal.

• Quality and properties of workpiece material.

• Quality of surface finish and dimensional accuracy.

• Temperature at cutting zone.