Anıl Uzal, 030070012, 4th Week

Pre-Alloyed Powders:

In the pre-alloyed powders, each particle is an alloy composed of the desired chemical composition. Pre-alloyed powders are used for alloys that cannot be formulated by mixing elemental powders; stainless steel is an important example. The most common pre-alloyed powders are certain copper alloys, stainless steel, and high-speed steel. (Groover M.P., Fundamentals of Modern Manufacturing: Materials, Processes, and Systems 3^rd Edition, page 355)

Integrated Circuits (IC):

An integrated circuit (IC) is a collection of electronic devices such as transistors, diodes, and resistors that have been fabricated and electrically intraconnected onto a small flat chip of semiconductor material. The IC was invented in 1989 and has been the subject of continual development ever since (Historical Note 35.1). Silicon (Si) is the most widely used semiconductor material for ICs, due to its combination of properties and low cost. (Groover M.P., Fundamentals of Modern Manufacturing: Materials, Processes, and Systems 3^rd Edition, page 798)

Electroplating:

Electroplating, also known as electrochemical plating, is an electrolytic process (section 4.5) in which metal ions in a electrolyte solution are deposited onto a cathode workpart. The setup is shown in Figure 29.1. The anode is generally made of the metal being plated and thus serves as the source of the plate metal. Direct current from an external power supply is passed between the anode and the cathode. The electrolyte is an aqueous solution of acids, bases, or salts; it conducts electric current by the movement of plate metal ions in solution. For optimum results, part must be chemically cleaned just prior to electroplating. (Groover M.P., Fundamentals of Modern Manufacturing: Materials, Processes, and Systems 3^rd Edition, page 670)

Tumbling (mechanical surface cleaning method):

Tumbling (also called barrel finishing and tumbling barrel finishing) involves the use of a horizontally oriented barrel of hexagonal or octagonal cross-section in which parts are mixed by rotating the barrel at speed of 10-50 rev/min. Finishing is performed by a “landslide” action of the media and parts as the barrel revolves. As pictured in Figure 28.1, the contents rise in the barrel due to rotation, followed by a tumbling down of the top layer due to gravity. This cycle of rising and tumbling occurs continuously and, over time, subjects all of the parts to the same desired finishing operation. However, because only the top layer of parts is being finished at any moment, barrel finishing is a relatively slow process compared to other mass finishing methods. It often takes several hours of tumbling to complete the processing. Other drawbacks of barrel finishing include high noise levels and large floor space requirements. (Groover M.P., Fundamentals of Modern Manufacturing: Materials, Processes, and Systems 3^rd Edition, page 663-664)