Study of Chip Formation in Hard Turning of AISI 4340 Alloy Steel in Different Cutting Environments

Abstract

The hardened alloy steel like AISI 4340 is known to be difficult to cut material. In order to increase the flexibility and ability to manufacture complex geometry's, hard turning was introduced where the necessity of grinding operation can be eliminated. Generally hard turning requires large quantities of coolants and lubricants. The cost of procurement, storage and disposal of coolants and lubricants increases the total cost of production. In the present study minimal quantity lubrication ( MQL) is used for cooling in turning of hardened alloy steel AISI 4340 with CBN insert. The effect of MQL environment on chip formation is studied and compared with dry and wet environment. The experiments were conducted using Taguchi L18 (2' x 3 7 ) mixed orthogonal array. It is observed that the chip thickness in turning of hardened AISI 4340 in MQL gives the higher cutting ratio than dry and wet turning. MQL turning gives acceptable chips that can handle easily. The cost of procurement, storage, reconditioning and disposal of coolants and lubricants can highly reduce which reduces the total cost of production considerably. This technique can form a viable alternative to conventional wet turning, as it can be implemented without any drastic alternations in existing facilities available on shop floor.