Optimization of Cutting Data and Tool Inclination Angles During Hard Milling with CBN Tools, Based on Force Predictions and Surface Roughness Measurements

This work deals with technological considerations required to optimize the cutting data and tool path pattern for finishing the milling of free-form surfaces made of steel in a hardened state. In terms of technological considerations, factors such as feed rate, workpiece geometry, tool inclination angles (lead and tilt angles) and surface roughness are taken into account. The proposed method is based on calculations of the cutting force components and surface roughness measurements. A case study presented in the paper is based on the AISI H13 steel, with hardness 50 HRC and milling with a cubic boron nitride (CBN) tool. The results of the research showed that by modifications of the feed value based on the currently machined cross-sectional area, it is possible to control the cutting force components and surface roughness. During the process optimization, the 9% and 15% increase in the machining process efficiency and the required surface roughness were obtained according to the tool inclination angle and feed rate optimization procedure, respectively.

Optimization of fatigue strength of selective inhibition sintered polyamide 12 parts using RSM

Selective inhibition sintering (SIS) is a powder based that fabricate functional parts through fusion of powder bed on a layer by layer basis. Being a new fabrication method, the correlation between process variables and part properties are not fully comprehended. Polyamide 12 (nylon 12) is one of the widely used materials in powder based AM processes including SIS. Therefore, in this work, the effect of critical SIS process parameters on the fatigue behavior of polyamide 12 parts was experimentally investigated, and the parameter settings were optimized to maximize fatigue strength. The number of experimental runs was determined based on Box-Behnken design, and specimens were fabricated as per ASTM D7791. Specimens were tested by subjected them to fluctuating loading at a frequency of 3 Hz. The test results were analyzed using Minitab statistical analysis software. From the ANOVA result, it was identified that the fatigue life of SIS parts is significantly influenced by layer thickness, heater temperature, and heater feed rate. Optimization of process variables settings was performed using the Minitab response optimizer and maximum fatigue strength of 17.43 MPa was obtained. The verification experiment resulted in 17.93 MPa fatigue strength which is comparable to the predicted value and with the result from the literatures.

Machining Efficiency Increase when Nickel Based Alloy Machining

Paper presents some investigations, concerning simulation of the nickel based alloy machining. The aim of the research was an optimization of the cutting data for the purpose to increase the machining efficiency and stabilization of the tangential component of the total cutting force at the assumed level. A dedicated physical material model was built and then included to the simulation strategy. Authors demonstrated the influence of the feed rate optimization on the tangential component of the total cutting force value changes and the chip area and in this way the improvement of the cutting process.

Considering Machining Tolerances in High Speed Corner Tracking

Growing industrial demand for faster machine tools, makes feed-rate and trajectory optimization a challenging problem in machining processes. One of the most challenging machining operations for computer numerically controlled (CNC) machine tools is corner tracking. In this scenario, most of the conventional feed-rate optimization approaches sacrifice speed for accuracy. This paper, proposes a new feed-rate and trajectory optimization algorithm for CNC machines. At each corner of the trajectory, the presented algorithm regenerates the trajectory, using a circular move within a desired tolerance limit. Then, a new feed rate optimization method is employed, which enables the machine tool to travel at the maximum feasible velocity through the corners, while taking acceleration constraints into account. Experimental results for different desired tolerances indicate that the new algorithm achieves significantly shorter travel times than the theoretical minimum time trajectory with zero tolerance.