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Defect Reasons and Quality Control of Die Castings

Source: Junying   Author: Junying   Posted: 2015-04-07 16:42:04   Hits: 449

Die casting is a special casting process. Compared with other casting processes, die casting process is basically characterized by the filling up and shaping of die casting mould with liquid metal under high speed and pressure conditions. Injection during mould filling process and fast cooling of metal moulds are detrimental to the forming of die casting moulds, resulting in many defects of die castings. Some defects are inevitable, but others can be avoided. Some defects have no effect on properties of die castings, so such die castings can still be used. However, some defects affect properties of die castings, and such die castings should be disposed of as wastes. 

Thus, quality is the lifeblood of enterprises, an important pillar of enhancing enterprises’ competitiveness as well as an important condition of increasing economic benefits. Therefore, improving the quality of die castings is advantageous for enterprises to increase economic benefits or reduce waste of resources.

Quality of die castings includes appearance quality, internal quality and quality in use. Appearance quality refers to surface roughness, surface quality, dimensional tolerance, geometric tolerance, mass deviation, etc. Internal quality refers to chemical components, physical and mechanical properties, metallographic structure as well as impurity and cracks of internal die castings. Quality in use refers to such features of die castings like abrasion resistance, corrosion resistance, machinability and weldability, which can meet various working requirements and performance. The direct reasons for causing defects of die castings can be classified into several kinds below:
1. Unreasonable design of die casting structure
2. Improper use of die casting moulds
3. Wrong use of materials or improper melting process
4. Wrong use of die-casting machines or improper control of die casting conditions
5. Improper manual operations during die casting process

Besides, there are several indirect reasons for causing defects, including imperfect management like poor on-site quality management, and malpractice or irresponsibility of operators and so on.

Defect Reasons and Quality Control of Die Castings - Junying