DIE CASTING

Die Casting



Contents

Introduction2

Die Casting: Concepts and Principles3

Cold Chamber Process3

Hot Chamber Process3

Equipments Used for Die Casting4

Principles of Die Casting4

Advantages and Disadvantages of different Solidification Processes6

Sand Casting6

Shell Moulding6

Investment Casting7

Die Casting7

Examples of Products Manufactured Using Die Casting8

Conclusion11

Die Casting

Introduction

The starting state of material is either liquid or highly plastic. In order to bring this material to stable and solid form, various solidification processes are being used. Casting is the first step of the solidification process. During the casting processes, the molten metal is poured into the cavity, and the metal takes the shape of mould cavity (Zulkepli, 2010). Casting processes usually take place in a factory which has all the necessary equipments for manufacturing of molds, handling and melting molten metal, and cleaning processes after casting process completes. The sequence of steps included in casting processes include preparation of die or mould, melting of metal, pouring of metal into the mould, solidifying the poured metal, and finally conducting the finishing processes. Figure 1 summarizes the steps involved in manufacturing of materials; it also highlights the importance of casting.

Figure 1: Material Production Steps

Solidification actually starts when the temperature of the material falls below its point of freezing. The process of solidification involves phase change of the material; this phase change depends on various factors; for example, the material is a pure element or an alloy. For pure elements, the solidification happens at its melting point (it remain constant for every casting), while for the alloys, a temperature range can be considered as a solidification point.

This paper discusses the major principles of die casting, advantages and disadvantages of various casting processes, and finally presents some examples of the products manufactured by the process of die casting.

Die Casting: Concepts and Principles

The Die casting is done using either of old chamber or hot chamber processes. These processes are explained briefly in the following (efunda, 2013):

Cold Chamber Process

In this process, for each shot, the cold chamber is used to ladle the molten metal. The plunger or plunger walls are exposed to the melt for lesser time as compared to other processes. This process is useful particularly for the metals including Copper, Aluminum, and alloys of Copper.

Hot Chamber Process

In this process, the die cavity remains immersed in the molten metal permanently; the de cavity is connected with the pressure chamber. As the plunger moves to the open position, the pressurizing cylinder's inlet port uncovers. This step ensures that the new charge of molten metal fills the cavity at a faster rate, in comparison to the cold chamber process. This process is used for the metals with the characteristics of high fluidity and low melting points. Examples of such metals include lead, zinc and tin.

Equipments Used for Die Casting

The most common equipments used for carrying die casting activities include Cold Chamber Machine, Aluminium Die Casting Machine, and Rotor die casting machine. Figure 2 shows a glimpse of these machines.

Figure 2: Die Casting Equipment

Principles of Die Casting

The general principles of Die casting which must be taken care of ...