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1)Chromizing (surface diffusion process)

Like boronizing process, chromizing is also used for surface hardening of both carbon and tool steels. There are two types of chromizing: pack chromizing and gaseous chromizing. The components to be chromizedare packed with fine chromium powder and additives. A typical chromizing mixture consist of 60 percent chromiumor ferro chrome (with carbon content not exceeding 0.1%), 0.2 percent ammonium iodide, and 39 percent kaoinpowder. Diffusion of chromium carbide is formed on the surface of steel. The threatment time needed for achievinga case depth of 0.02-0.04 mm is 12 hours at 900-1020 centigrade degree. Hardness of chromium carbide layeris about 1500 VHN.
(T. V. Rajan, C. P. Sharma, A. Sharma, Heat Treatment: Principles and Techniques, pp.164)

Chromizing(new)(better)

A surface diffusion process, whereby chromium is alloyed with iron to give a chromium-rich surface layer.
Application range MILD STEEL AND LOW ALLOY STEEL
The process is analogous in many ways to carburizing, but more similar to certain types of alumining and other techniques where a metal diffused into the surface of steel.
The process generally involves the through cleaning of the components, which are then placed in a heat resistant box with a proprietary powder of an unstable chromium compound. This box is then sealed and taken to above 1000 C. The compound is decomposed, releasing chromium in an active state which will then react with iron, producing the necessary alloy. This will diffuse away from the surface towards the core.
The time involved and, to certain extent the temprature, controls the depth of the chromium-rich layer. With treatments in excess of 4 h, the layer at the surface will contain up to 30 per cent chromium with an even merge to the core which contains no chromium. As an alloy of steel with more than 12 percent chromium has excellent corrosion resistance, it will be seen that the chromizing process results in a corrosion-resistant surface. Steel with chromium above about 25 percent is austenitic and thus has excellent corrosion resistance, comperable to that of the18-8 austenitic steels, and the same time can have the mechanical strength of low alloy medium carbon steel.
On completion of the treatment , the components are removed from the powder which can beregenerated for further use. Under certain circumstances the components can if desired be welded, and provided distortion is not a serious problem, the component can be hardened and tempered. In general, howewer, chromizing is used on components such as studs or fasteners, where corrosions resistance of a high standart is essential. On sheet metal, it is possible to carry out some cold working on the treated strip, provided the dies used are in good condition, and thus do not damage the surface.
(Handbook of Metal Treatments and Testing, Robert B. Ross, p.60)

2)Optical Properties ( material property )

The wide-ranging optical properties observed in solid-state materials can be classified into a small number of general phenomena.The simplest group namely reflection,propagation, and transmission.
(Fox M.,Optical Properties of Solids ,p. 1)


Optical Properties (new)(better)

By ‘‘optical property’’ is meant a material’s response to exposure to electromagnetic radiation and, in particular, to visible light. This chapter first discusses some of the basic principles and concepts relating to the nature of electromagnetic radiation and its possible interactions with solid materials. Next to be explored are the optical behaviors of metallic and nonmetallic materials in terms of their absorption, reflection, and transmission characteristics. The final sections outline luminescence, photoconductivity, and light amplification by stimulated emission of radiation(laser), the practical utilization of these phenomena, and optical fibers in communications.
(Fundamentals of Materials Science and Engineering, William D. Callister, Jr. , p.298)

3) Carriage ( about lathe) (machine part)

Carriageis mounted on the outer guideways of lathe bed and it can move in a direction parallel to the spindle axis. It comprises of important parts such as apron, cross slide, saddle, compound rest and tool post. The lower part of the carriage is termed the apron in which there are gears to constitute apron mechanism for adjusting the direction of the feed using clutch mechanisms and the split half of nut for automatic feed. The cross slide is basically mounted on the carriage, which generally travels at right angles to the spindle axis. on the cross slide , a saddle is mounted in which the compound rest is adjusted which can rotate and fix to any desired angle. The compund rest slide is actuated by s screw, which rotates in a nut fixed to the saddle.
(Rajender Singh, Introduction to basic manufacturing processes and workshop technology, page 410)

Carriage ( about lathe)(new) (better)

The carriage supports the lathe cutting tool and provides the tool with the movement neede to perform machining operations. It slides along the ways and contains two primary sections called the saddle and apron. Figure 5.1.12 shows the carriage of a lathe and identifies the saddle and apron.
The saddle is an H-shaped casting that slides back and forth on the ways. The apron is suspended from the saddle.The sliding motion of the saddle is parallel to the ways and is called longitudial feed. The saddle supports both the cross slide and the compound rest.
The apron is attached to the bottom of the saddle and hangs down in front of the bed. The apron contains a hand wheel that engages a gear with the feed rack to move the carriage along the ways. Some apron hand wheels have a graduated micrometer dial to allow precise control of the longitudinal carriage movement.
Also on the apron is the feed control clutch. The clutch causes machine-powered movement of either the carriage or the cross slide when engaged.
(Precision Machining Technology, Peter J. Hoffman, p.358)

4)Multiplexer (electronic device)

Amultiplexer or MUX , also called a dta selector , is a combinational circuit with more than one input line , one output line and more than one sellection line .There are some multiplexer ICs that provide complementary outputs. Also , multiplexers in IC form almost invariably have an ENABLE or STROBE input , which needs to be active for the multiplexer to be able to perform its intended fuction. A multiplexer selects binary information presents on any one of the input lines , depending upon the logic status of the selection inputs , and routes it to the output line.

(Digital electronics: principles, devices and applications ; Anil Kumar Maini , pg. 269 ; 2007)

Multiplexer(new)(better)

Multiplexers allow multiple devices to be connected to a single device. These are very popular for telephone systems. A telephone switch is used to determine which telephone will be connected to a limited number of lines to other telephone switches. This allows telephone calls to be made to somebody far away without a dedicated wire to the other telephone. In older telephone switch boards, operators physically connected wires by plugging them in. In modern computerized telephone switches the same thing is done,but to digital voice signals.
In figure 6.13 a multiplexer is shown that will take one of four inputs bits D1, D2, D3 or D4 and make it the output X, depending upon the values of the address bits, A1 and A2.
(Automating Manufacturing Systems with PLCs, Hugh Jack, p.128)

5)Optical Encoder (sensor)

Very often, it is required to detect the position, velocity, acceleration and direction of movement of rotors, shafts, pistons, of the actuating devices such as rotary machines and translational systems. This is achieved by the use of optical encoders. The optical encoder is a device, which provides encoded pulsed signals in response to the movement. Continuous optical signals are modulated (coded) by the use of a specially designed rotating disk containing code patterns called 'track'. The pattern or track on the disk consists of alternate appearance of opaque and transparent segment and the pattern is circular. Basically, two types of encoders, such as incremental encoder and absolute encoder exist.

(Mahalik N.P., Mechatronics, 2nd reprint, 2006, pg.170)


Optical Encoder(new)(better)

The detection of angular and linear motion is a key of function in a multitude of systems such as machine tools, industrial robots, variety of instruments, computer mice etc. Although they are one of many techniques capable of such measurements, the ease with which they are interfaced to digital systems has made them very popular.

Optical encoders are used to measure either angular or linear positions. Those for angular detection are commonly caled rotary or shaft encoders, since they usually detect the rotation of a shaft. Opticalencoders encompass a variety of devices, all of which use light as the means to transform movement into electrical signals. All devices have two basic building blocks: a main grating and a dedect,on system. It is the position of one with respect to the other that is dedectied. The main grating represents the measurement standart.

For linear measurements, the main grating, commonly called the scale, is one or more sets of parallel lines of constant or specially coded pitch supported by a substrate. Similarly, a rotary encoder has a grating with radial lines on a disk.

Both linear and rotary encoders can, in principle, be absolute or incremental, Although in practice, linear absolute encoders employing optical principles are quite uncommon and have drastically limited performance chraracteristics ( accurancy, resolution, and/or maximum operating speed).Figure 6.66 shows a simplied classification of optical encoders.This classification refers to the nature of information generated. The incremental encoder dedects movement relative to a referance point. As a result, some form of referance signal is usualy supplied by the encoder at a fixed position in order to define a reference position. The current position is then incremented (or decremented) as appropriate. Multiple reference marks can also be used, where the distance between successive marks is unique so that as soon as two successive marks have been dedected, it becomespossible to establish absolute position from then on. The reference point can also be mechanical.Should power be lost or signal transmission error occur, then the absolute position is lost and the encounter must return to one or more reference points in order to reset its counters. Unfortunately, a loss of count may not be detected until a reference point is reaccessed. Furthermore, reading errors may accumulate. On the other hand, absolute encoders produce a set of binary signals froms which the absolute position can be deduced without the kowledge of the previous motion history. The current position is known right from powering-on. In the case of absolute rotary encoders, single and multiturn devices are avaible. Multiturn devices use an internal mechanical transmission system to drive a second grating that serves as turn counter.
(The measurement, instrumentation, and sensors handbook, John G. Webster, p.6-98)