Feature article: PIM International, Vol.2 No. 2 June 2008, pages 50-54, 2928 words

Author: Joseph Tunick Strauss, HJE Company Inc, USA

Engineer, President, HJE Company Inc., 820 Quaker Rd., Queensbury, NY 12804, USA

Introduction

In the following review, Joe Strauss of HJE Company, Inc., Queensbury, NY, USA, discusses the factors affecting the utilisation of the powder injection moulding process (PIM) for the production of precious metal jewellery. Jewellery, defined here as objects that have no function but are purely decorative, is a potentially major market that appears to be able to use PIM’s advantages to maximum effect. Current applications and opportunities for growth are presented.

PIM has proven to be a viable manufacturing alternative to investment casting of small parts with respect to achievable tolerances, material properties, and economy of scale. The cost benefit of PIM is amplified by complex geometries and very high cost materials. For these reasons PIM should be of great advantage to jewellery manufacturers as many of their products are investment cast and possess these attributes. However, applications of PIM in the jewellery manufacturing sector are isolated and discontinuous.

The PIM industry has been growing steadily since its inception. Although the area responsible for the bulk of the industry is iron-based alloys, there has been steady expansion into more exotic materials such as thermal management materials, magnetic materials, hard materials, and titanium. The diversity of these materials indicates that the PIM industry can accommodate a myriad of materials.

The structure of the PIM industry is that most PIM companies act as job shops. That is, the part design does not originate at the PIM facility and the part does not go directly to the end user. PIM facilities manufacture parts of someone else’s design for someone else’s use or marketing. This is mostly true for captive PIM operations as well. Thus, the environment between the jobbing PIM companies is highly competitive and they are always looking for new opportunities. They must also evaluate different markets and materials.

PIM’s main competitors are the long established investment casting and discrete machining industries. The primary reason for choosing PIM over these competing processes is cost. The reduction in process steps, quality and quantity of labour, and greater material utilisation are prime advantages that offset the high cost of PIM feedstock.

The jewellery sector is a mature industry with well-established markets. In the US market alone, the quantity of investment cast jewellery is conservatively estimated to be in excess of ......