Feature article: PIM International, Vol.1 No. 4 December 2007, pages 17-25, 3290 words

Author: Prof. Dr. Yimin Li, Central South University, China

State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, China

Introduction

In this specially commissioned feature for Powder Injection Moulding International Prof. Dr. Yimin Li of the Powder Metallurgy Research Institute, Central South University, Changsa, China, presents an insight into current PIM production in China and identifies the markets and applications that are driving the technology forward.

Powder injection moulding (PIM), a combination of traditional powder metallurgy (PM) and plastic injection moulding, has been a major focus of attention in China because complex-shaped high performance parts can be economically manufactured by this technology. The earliest application of PIM in China was an alumina spark plug body for automobile engines in the early 1960’s. The earliest injection moulded metallic component was a tungsten eccentric weight for a vibration motor in mobile phones in the early 1990’s. Before 1995, the number of PIM parts manufacturers and associated powder and equipment suppliers in China was small. Although a rapid growth of production volumes has been recorded since 1995, the economic situation is still difficult for most Chinese PIM manufacturers.

The unfamiliarity of designers with PIM processes, the lack of awareness amongst potential customers and the limited number of orders have been the three major limitations. Manufacturers have to pay close attention to determine whether PIM is an economically feasible alternative to conventional production techniques for an individual product, and if it is, they need to persuade the customer to recognise it. Towards the end of 2005, their efforts finally came to fruition. PIM had gradually become accepted by Chinese customers and it is now regarded as a competitive materials shaping process in China.

Characteristics of Chinese PIM are systematically outlined in this report. It is regretful that there are currently no PIM associations in China and many companies were unwilling to directly provide statistical data for this report. The statistics that are provided here are well founded but not guaranteed to be accurate. It is however hoped that this feature will give a deeper understanding of the Chinese PIM industry.....

Figures and Tables:

Fig. 1 Fishing sinkers are one of the major high volume MIM products in China (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 2 Buccal tubes. Population growth is stimulating the market for orthodontic instruments, many of which are now incorporating MIM parts (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 3 MIM Bayonet lugs (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 4 MIM Fastener (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 5 Estimation of PIM material usage in China

Fig. 6 MIM sintering facility (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 7 Injection moulding facility (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 8 Biopsy forcep components (Courtesy HuNan Injection high technology Co, Ltd.)

Fig. 9 Schematic of the 3D Biopsy forcep components (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 10 Eccentric weights produced for mobile phones (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 11 Injection moulding machine (Courtesy HuNan Injection High Technology Co, Ltd.)

Fig. 12 State Key Laboratory of Powder Metallurgy at Central South University, China

Fig. 13 Effects of various MW addition on the tensile strength and shrinkage of binder weights

Fig. 14 The curve of strength versus debinding time

Fig. 15 Effect of moulding pressure on the percentage of distorted compacts

Fig. 16 Effect of moulding temperature on the percentage of distorted compacts

Fig. 17 The density changes versus different frequency of vibration

Fig. 18 The density changes versus different amplitude of vibration

Fig. 19 Housing part formed from Fe-Ni alloy by MIM. Taken from the Technical Paper 'Research on Metal Injection Moulding of Housing for the Semiconductor Industry' published in this issue.

Table 1 Different processing conditions for biopsy forceps and eccentric weights

Table 2 Powder particle size and the mechanical properties

Table 3 Examples of new developing materials