Investigation of the relationship between tool wear and residual stress in high feed milling of DIN1.2344 ESR mold steel with 55 HRC hardness


Thesis Type: Postgraduate

Institution Of The Thesis: Bursa Uludağ University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2013

Thesis Language: Turkish

Student: SELİM KOCA

Supervisor: Mustafa Cemal Çakır

Abstract:

In this study, test samples prepared from the hardened tool steel with 55 HRc hardness were subjected to pocketing operation in a CNC vertical machine. 3 different cutting speeds and 5 different feed rates were used. At the end of the machining, tool wear was determined by a microscope. After that, residual stress on the machined test specimens was determined by using X-Ray deflection and hole drilling methods. The experimental results indicated that; - As tool wear and residual stresses considered together, an optimum processing parameters have not been obtained in a single experiment. - It is concluded that; the increase in cutting speed affects residual stresses more than the increase in feed rate. - It is thought that tool wear affects temperature as well as mechanical impact. The increase in tool wear effects the temperature increase and friction and hence creates surface tensile residual stresses. It also attempts to suppress with a mechanical load causing plastic deformation as the ball nose endmills that causes compressive residual stresses. - Regardless of tool wear, increase in cutting speed has found to effect the depth from the surface of residual stresses significantly. - Although tool wear has a significant effect on the residual stresses, it is decided that prediction of residual stresses can not be made just by looking into the tool wear.