Design and Fabrication of a Wear Testing Machine – Mechanical Project

Abstract
This study was carried out to design and fabricate a cost effective and efficient wear tester (pin on disc) used in the metallurgy research field. Design and calculations were established and the machine was fabricated with well selected materials and components all sourced locally. The performance of the fabricated machine was finally evaluated against a standard wear machine in the Standards Organization using statistical methods and the result showed that the locally fabricated machine is 97% effective.

Introduction
Wear testing is a method for assessing erosion or sideways displacement of material from its “derivative” and original position on a solid surface performed by the action of another surface. This test is commonly used as a simple measure of work ability of material in service. Materials behave differently in friction state so it may be important to perform mechanical tests which simulate the condition the material will experience in actual use. Wear testing is typically carried out on the A356 alloy. Wear tests of the selected alloy is a critical parameter for determining the quality of these materials. The loads and forces acting on these materials while in service are compressive in nature and their ability to withstand such loads and forces without failure is a measure of their reliability. The availability of a wear testing machine for materials is the first step to effective quality control and good manufacturing practice. The establishment of quality control facilities by manufacturers for continuous assessment of product quality is a necessary requirement for ensuring compliance with relevant standard and maintaining product quality that will continue to meet the needs of the uninformed users.

In Egypt today, there is no effective locally fabricated wear testing equipment that is readily available and affordable for the researchers in the metallurgy filed. The foreign wear machines are expensive, rarely available and beyond the reach of the researchers. In line with the need to evolve a dual purpose effective wear machine with 100% locally sourced materials and components which will be cheap and readily available to surface study and will improve productivity, quality control, good manufacturing practice in the building material industry and also spur National economic growth, the design and fabrication of a wear testing machine is carried out. Pin on disc wear test machines were designed and constructed.

Description of the Machine
The wear machine consists of a load frame and an electric motor with control unit as illustrated in Figure.

The flexible arm is connected to electromagnetic key (center lock) by means of a steel wire, which worked as a brake to stop the experiment at required time and the time was controlled by digital timer. The load varies by changing the location of weight and the size of weight (10 gm to 500 gm).

fabrication of wear testing machine
fabrication of wear testing machine

Wear Test
The wear test was performed on Pin-on-Disc apparatus shown in figure . In this test the flat end of cylindrical specimen 8 mm in diameter and 12 mm length was fixed in chuck jaws to prevent specimens from rotation during the test. Axial load was applied to the pins against the plane surface of the rotating disc. The specimen’s ends were polished with 1200 grit SiC emery paper and cleaned with acetone. The wear test reported is the average of two readings and was carried out at room temperatures. The standard disc used for testing was made of hard steel ASE 1045 with hardness of 263BHN whose surface roughness was 0.2 μm.
The materials chosen for the present study was A356 having the chemical composition shown in Table . The material was received in the form of bar. Each specimen was weighed before the experiment and after it by a digital balance having sensitivity of 0.001gm. The duration of the experiment was controlled by digital timer.

Conclusion
The values of the Statistic methods showed the range of accuracy of the locally fabricated tester. The locally fabricated wear tester can be applied to attest the quality of alloy, in accordance to the requirements of the Standards Organization, and will give values which would compare well with those from the standard (foreign) wear tester for alloy under the same test conditions. The wear rate decreases as the load decreases from 29.4-49 N also, the wear rate decreases as the time increases from 240 to 120 second. Considerable saving in terms of cost and time could be obtained from using the locally fabricated tester. It is successful analytical tools which can be used to measure the wear behaviour of materials.

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