Aas Mohammad

A review of turning of hard steels used in bearing and automotive applications

Hard turning is a recent technology that involves machining of hard steels using modern machine tools. Hard machining presents challenges in terms of selection of tool insert with improved tool life and high-precision machining. Turning of hardened steels using single-point cutting tool has got considerable interest among manufacturers of ball bearings, automotive, gear, and die industry. Hard turning in the automotive industry and bearing applications typically has a number of potential benefits over traditional form grinding including lower equipment costs, shorter setup time, and fewer process steps which in turn provides high flexibility and ability to cut complex geometries. Moreover, the hard turning process is usually carried out without coolant/lubricant and thus, the problem of storage, handling, and disposal of cutting fluid is eliminated, and at the same time, it probably favors the health of operators. This paper presents an overview of the past research hard turning using hard turning tools such as PCBN, cubic boron nitride, Ceramics, Carbide, etc. Major hard turning cutting materials and effect of hard turning process parameters on cutting forces, heat generation during cutting, surface finish and surface integrity, and tool wear have been discussed in light of the findings of the past research.

Investigation of surface integrity during wet turning of hard alloy steel

This paper presents a study that investigates the effect of the CNC hard turning parameters on the surface integrity (SI), defined in terms of surface roughness average (Ra) and the micro-hardness MH, of hard steel (AISI 52100) under wet cutting conditions. Nine experimental runs based on an orthogonal array of Taguchi method are performed and grey relational analysis method is subsequently applied to determine an optimal cutting parameter setting. The SI parameters, i.e., surface roughness average and micro-hardness are selected as the quality targets. An optimal parameter combination of the turning operation is obtained using grey relational analysis. By analysing the grey relational grade matrix, the degree of influence for each controllable process factor onto individual quality targets can be found. The feed rate is identified to have the most influence on the roughness average and also on the micro-hardness. Further, the analysis of variance (ANOVA) is also applied to identify the most significant factor; the feed rate is the most significant controlled factors for affecting the SI in the turning operations according to the weighted sum grade of the surface roughness average and micro-hardness.

Dimensional synthesis of a planar five-bar mechanism for motion between two extreme positions

Abstract This paper suggests the dimensional synthesis of a planar five-bar mechanism of variable topology using dyadic and triadic techniques. The mechanism consists of two binary links with two offset tracing points and transmits motion between two extreme positions. Synthesis of mechanism for standard kinematic task is considered. The analytical displacement equations have been written using complex numbers. The effectiveness of mechanism synthesis has been demonstrated on a numerical example. The equations are solved and verified using MATLAB. The main attractions of method are simplicity, reduced solution space, non-iterative results and better accuracy due to non-dependence on graphical techniques.

Dimensional synthesis of six-bar Stephenson III mechanism for 12 precision points path generation

The technological advancements require sophisticated manufacturing procedures wherein requirement to design mechanisms that can precisely follow a specified path through a given number of precision points are to be fulfilled. With these objectives, a six-bar Stephenson III linkage mechanism, having one degree of freedom has been dimensionally synthesised for 12 precision points. The complex number dyadic and triadic loop closure equations have been used to synthesise the mechanism for path generation. In this approach, loop closure equations are solved simultaneously for 12 displacement positions of coupler tracing point and 12 orientation positions of various links for which the output link oscillates. The prescribed parameters are displacement vector (δj) and coupler link motion and the designer is not constrained to restrict the remaining orientation angles of links. Finally, a code has been developed in MATLAB to solve these loop closure equations for determination of the dimensional length of each link.

Machining parameter optimization using Taguchi approach

Among several industrial CNC machining processes, Turning is a fundamental machining process. Turning operation is widely used in industry including the aerospace and automotive sectors because of its versatility and efficiency. In order to get desired quality of the product by machining operation proper selection of process parameter is essential. Taguchi method is an effective tool for optimizing process parameters. The aim behind present work is to find surface roughness, which is key parameter to justify quality of machining operation. By this approach process parameter and their optimal settings is investigated. During machining operation influence of process parameter and their interaction during machining is also analyzed by ANOVA. Al-Alloys are universally acceptable materials due to their excellent corrosion resistance, formability, high strength-weight ratio that is unaltered at elevated temperatures. This work reflects the Depth of cut as the key factor for surface roughness optimization.

Investigations on the Effect of CNC Dry Hard Turning Process Parameters on Surface Integrity: A Multi-performance Characteristics Optimization

Abstract The cutting parameters such as the cutting speed, the feed rate, the depth of cut, etc. are expected to affect the two constituents of surface integrity (SI), i.e., surface roughness and micro-hardness. An attempt has been made in this paper to investigate the effect of the CNC hard turning parameters on the surface roughness average (Ra) and the micro-hardness (μh) of AISI 52100 hard steel under dry cutting conditions. Nine experimental runs based on an orthogonal array of the Taguchi method were performed and grey relational analysis method was subsequently applied to determine an optimal cutting parameter setting. The feed rate was found to be the most influential factor for both the Ra and the μh. Further, the results of the analysis of variance (ANOVA) revealed that the cutting speed is the most significant controlled factor for affecting the SI in the turning operation according to the weighted sum grade of the surface roughness average and micro-hardness.