Machinability Of Work Materials Research Articles

Optimum surface roughness evaluation of dies steel H-11 with CNC milling using RSM with desirability function

Machinability aspect is of paramount importance for efficient process planning in manufacturing. Machinability of work materials is an imperative aspect which may affect the different manufacturing phases including product design, process planning and machining operation. Machinability of engineering materials may be evaluated in terms of process output variables like surface roughness (SR), material removal rate, cutting forces etc. CNC milling has become one of the most competent, productive and flexible manufacturing methods, for complicated or sculptured surfaces. With the more precise demands of modern engineering products, the control of surface texture has become more important. This paper reports mathematical model for correlating the milling machining parameters such as spindle speed, table feed rate, depth of cut, step over and coolant pressure, with the response characteristic, SR, while machining hot die steel, H-11 with titanium coated carbide end mill cutter. The response surface methodology in conjunction with face centered central composite rotatable design has been used to develop the empirical model for the response. The significance of the mathematical model developed was ascertained using desirability functions and confirmation experiments. The results obtained depict that the mathematical model is useful not only for predicting optimal process parameters for achieving the desired quality but also for achieving the process optimization.

Experimental Study on Material Removal Capability with Vibration-Assisted WEDM

Wire Electrical Discharge Machining (WEDM) is a thermal process that involves melting and vaporisation of work material by a wire electrode in order to obtain the required size. The present work covers a study to improve the material removal rate (MRR) and to machining required slot size by varying frequency lateral vibration of wire while WEDM machining on AISI H13. The machining experiments were conducted by means of two electrode wire materials such as brass and zinc coated wires. The experiments mainly focused on surface integrity aspects like surface/sub surface microstructure, kerf width and surface roughness modification of surfaces machined with Wire Electrical Discharge Machining. The experimental results present the machinability of work material with WEDM process with varying frequency of vibration of wire electrode materials.

Investigation of the machinability of commercially pure titanium in ultrasonic machining using graph theory and matrix method

Any type of machining operation is well influenced by the machinability of work material under processing. This work proposes a graph theory and matrix method based technique for the assessment of machinability of titanium in ultrasonic machining. Identification of various machining attributes along with their relative importance has been considered and analyzed by developing a mathematical function by employing graph theory and matrix method. An attribute digraph is developed, which provides a visual illustration of considered attributes with their relative interactions. This digraph is further represented by using matrix expression. A permanent machinability index for all the experimental runs is also obtained from matrix form demonstration based on attribute digraph. The combination of all the attributes for any machining operation makes this method quite versatile. The results reveal that an experimental run having the combination consisting tool material of titanium, grit size of 500, and power supply of 300 W yields optimized results for machinability.

Machinability evaluation of dies steel H-11 with CNC Milling using digraph and matrix method

Machinability aspect is of considerable importance for efficient process planning in manufacturing. Machinability of work materials is an imperative aspect which may affect the different manufacturing phases including product design, process planning and machining operation. Machinability of engineering materials may be evaluated in terms of process output variables like surface roughness (SR), material removal rate, cutting forces etc. In this paper, graph theoretic approach is proposed to assess the performance of die steel H-11 using titanium coated carbide cutter, together with spiral type cutter path strategy. SR is considered as machinability attribute to evaluate the effect of several factors and sub-factors. Factors affecting machinability and their interactions are analyzed by developing a mathematical model using digraph and matrix method. Permanent function is obtained from the matrix model and the function value aids in quantifying the influence of considered factors on machinability. Factors affecting SR are grouped into five factors namely work-piece, tool coating, tool geometry, cutter path strategy and machine tool. The results reveals that machine tool has the highest index value and hence the most influencing factor and feed rate is the most significant sub-factor influencing SR of H-11 using titanium coated carbide cutter on CNC Milling.

Machinability Prediction of Workpiece Material with a Diagraph Method

This work presents a diagraph method for the description and predication of the potential machinability of work materials. In the method, a radar chart with five axes was used to examine the machinability of different work materials and each axis representing a behavior or property, i.e. abrasiveness or hardness of workpiece material by grading the 5 different machinability properties. Such charts are seen to be helpful in the setup work to machine the new materials or unknown materials when choosing suitable tool properties and the cutting data suitable for the new material machining.

Effect of Coolant of Water-solution in Superfinishing. Application of Electrolytic In-process Dressing.

In order to simplify the treatment of coolant in production systems, the superfinishing characteristics under the condition of water-solution type coolant are investigated experimentally. This type of coolant is inferior to an oil type coolant in removing chips from the stone because of its poor permeability. Electrolytic in-process dressing is applied to promote the self-dressing of diamond stone. As work materials, alumina which is sintered under atmospheric pressure and soft steel (equivalent to 0.15% carbon steel) are used. The results obtained are as follows. Electrolytic in-process dressing makes it possible to use the coolant of water-solution in superfinishing. The suitable conditions in electrolytic in-process dressing depend on the machinability of work materials. The soft steel whose chips are easy to make a loading on the working surface of stone needs the stronger dressing. A concentration of some percent is sufficient for a coolant to maintain its essential properties. The electrolytic in-process dressing is more effective for harder or finer stone, because it can control the cutting ability of the stone.

ファインセラミックスのホーニング加工 被削性と切りくず生成機構

The mechanism of chip formation and the machinability of fine ceramics are investigated by both honing operation and scratching test using a conical diamond tool. The workpieces are alumina Al2O3, silicon nitride Si3N4 and silicon carbide SiC which are sintered under atmospheric pressure, and borosilicate glass (SiO2). Based on the experimental results which were done by the authors, the specification of the diamond sticks is decided to obtain superior honing performance. The results are as follows. The machinability of work materials is best in SiO2 and deteriorates in the order of Al2O3, Si3N4, and SiC. Comparing the shape and size of chips made by honing with the grain structure of Al2O3 and Si3N4, it can be estimated that the chips are mainly formed by the fracture occurred along the grain boundary, although chips of Si3N4 are also formed by the fracture occurred through the grain. Two types of material removal are observed depending on the load acting on the cutting grits. When the load is small, the cutting grits are in the condition of wear and the surface roughness of the work material is improved. When the load is set above the critical value, a lot of chips are created and there remains many large craters on the surface honed.

Honing Conditions for Effective Use of Diamond and Cubic Boron Nitride Sticks

Based on the honing theory developed earlier [12], the nominal depth of cut a¯i, was found to express the severity of honing conditions when using diamond and CBN sticks. The critical nominal depth of cut a¯ic is the important factor in evaluating the cutting ability of sticks, the machinability of work materials, and optimum operational conditions. Good honing performance can be obtained in the case where a¯ic > a¯i.