tamilkamathaigal

Extrusion Process Principles Extrusion process is very common in the plastic industry. It is used for high volume plastic production. In extrusion process the color pigments along with other performance enhancing additives are combined with resin which is then pushed through the rotating screws. The heat and pressure generated within the barrels of screw is dispersed and melts the plastic

Plastics can be classifies into two broad categories - Thermosets and Thermoplasctics. A brief description of these two classes will be discussed here. Thermosets are the kind of plastics which are not recyclable. They undergo a kind of chemical change at the time of heating. As a result they can be shaped once because of this permanent chemical change. This process is known as heat hardening.

Cope and drag in Sand Mold : Cope and Drag are the two parts of the casting flask. Cope is the upper part and drag is the lower part. Even if the casting process is flaskless , the same terms are used for the upper ans lower parts. Generally the flask is made of wood or metal. It contains molding sand. When metal is poured into the mold cavity the flask supports the mold. Gating system:

Investment or lost-wax castings: The Lost-wax method, sometimes, also called simply as precision-investment casting has been used for many years by jewelers and dentists. Since world-war-II, the method has been adapted to the production of small and precise, industrial fasting. Basically, the method involves the use of expendable (heat disposable) pattern unrounded with a shell of refractory

Die casting process is very different from sand casting as the mould used here is permanent. The mould is not expandable and need not to be broken after the cooling and solidification. Here the mould is called the die. Please Read : Comparison of different casting process A complete Guide to casting process Gravity die casting: When the molten is metal is poured under a gravity

Sand casting: In sand casting which is also known as sand molded casting, an object is produced by sand mold. The process involves pouring of the molten metal in to the mold cavity. The molten metal is then cooled to the room temperature. The metal is solidified. After cooling, the metal object is separated from the mold. Sand casting process has its advantages and disadvantages. So care

We know that casting is the process of pouring molten metal in a desired shaped cavity and allowing it to solidify. After the solidification we get the desired shaped object. Please read : Comparison of different casting processes. What is casting ? Main application of castings Basic Steps of Sand casting Basic Operation of the casting process First we have to make a pattern Then the

Pattern allowances: There are some allowances which are responsible for the difference in the dimensions of the casting and the pattern. These allowances are considered when a pattern is designed for casting. In this article we will discuss those allowances - 1. Shrinkage allowance: After solidification of the metal from further cooling (room