Oğuzhan Paçal, 030070031, 9th week

Broaches (Cutting Tools) 07-04-11 01:07
Broaches are used for broaching which is one of the most productive of the basic machining processes. The machine tool is called a broaching machine and the cutting tool is called the broach. The broaches compete economically with milling and boring and is capable of producing precision-machined surfaces. The broach finishes an entire surface in a single pass. Broaches are used in production to finish holes, splines, and flat surfaces.
A broach is composed of a series of teeth, each tooth standing slightly higher than the last. This rise per tooth, also know as step or the feed per tooth, determines the amount of material removed. There is no feeding of the broaching tool required. The frontal contour of the teeth determines the shape of the resulting machined surface. As the result of these conditions built into the tool, no complex motion of the tool relative to the workpiece is required and the need for highly skilled machine operators minimized.
(Mikell P. Groover, Fundamentals of Modern Manufacturing, Materials, Processes and Systems, p. 748)

Pyrometer 07-04-11 10:18
A pyrometer is an instrument for measuring high tenperatures. As mercury boils at about 660°, we can estimate the temperature of fused metlas, and the like, only by the expansion of solids. The only instrument of this sort which we need mention, as it is the only one susceptible ıf accuracy, is Daniell's Register Pyrometer. It consists of a hollow case of black lead, or plumbago, into which is dropped a bar of platinum, secured to its place by a strap of platinum and a wedge of porcelain. The whole is then heated, as, for instance, by placing it in a pot of molten silver, whose temperature we wish to ascertain. The metal bar expands much more than the case of black lead, and being confined from moving in any but an upward direction, drives forward the arm of a lever over a graduated arc, on which we read the degrees of Fahrenheit's scale: this instrument gives very acurate results; by it the melting point of cast iron has been found to be 2786°F, and of silver 1860°F.
(Benjamin Siliman, First Principles of Chemistry, p.78)

Film stacking process 07-04-11 15:53
Film stacking consists of interleaving layers of reinforcement fibres inthe form of tape or fabric with layers of thermoplastic polymer films or powder. Wetting of the fibres is achieved during the consolidation process. To obtain a high quality laminate (low void and good impregnation of the fibres), the stack has to be consolidated under severe conditions (high pressure and temperature, and a protracted molding cycle).
(Sylvie Béland, High Performance Thermoplastic Resins and Their Composites, p.101)

Resin transfer molding(RTM) 07-04-11 16:07
High volume production of FRP component demands automation of the molding process for efficiency, component quality, and safety issues. Automated high volume production of processes due to the simplicity and maturity of such techniques, SMC and BMC, for example, are used extensively inthe automotive industry. A disadvantage of these methods is that short fibre orientation is difficult to control during injection, causing a wide variation in the component mechanical properties. As a result, short fibre reinforced components are limited to non-structural application.
Rtm is a closed-mould FRP process which can utilize low moulding pressures and low cost flexible tooling. RTM can be used to produce complex components with high fibre volume fraction and a good surface finish. The process involves the placement of dry reinforcement in closed matched moulds followed by the injection of a liquid thermosetting resin. The resin is polymerized either at ambient or elevated temperatures and the component is removed with a smooth surface on both sides. Several types of resin system are available including polyesters, vinyl esters, urethane methacrylates, phenolic resin and epoxy resins. The choice depends on both cost and application. Prior to moulding the reinforcement is often shaped to produce a fibre preform in a seperate process. The preform can consist of different hypes of fibres such as glass, polyester, aramid or carbon in several forms such as woven fabric, continuous filament random mat, non-crimp fabric or chopped strand mat.
(P.W. Dufton,Lightweight Thermoset Composites: Materials in Use, Their Processing and Application, p. 151)