The Development of Lead-Free Sliding Contacts Based on Bronze-Graphite Composites through Powder Injection Moulding

Abstract:

Sliding electrical contacts are traditionally produced by conventional compacting technologies. Employing the powder injection moulding process (PIM) as a new manufacturing method can offer several advantages such as the fabrication of complex net-shaped parts, cost-effectiveness and high volume productions. The PIM process route consists of the following steps: powder processing, compounding, injection molding, debinding and sintering. A two-stage process consisting of solvent debinding and thermal debinding is often used to remove the moulding binder. In the present paper, the suitability of the powder metallurgical processes: mechanical alloying and powder mixing for the preparation of bronze-graphite powder mixtures for the compounding and injection moulding of sliding contacts is discussed. The use of a suitable binder is of central importance for the preparation of injection-moldable feedstocks. For this purpose, two commercial ready-to-use binder systems were utilized and evaluated. The essential challenge of the process route is to optimize all parameters of the subprocesses to achieve a damage-free debinding and sintering of the injection-moulded parts. First results on the influence of the graphite content, the binder fraction, the debinding and sintering parameters are presented and discussed.

• Periodical: Key Engineering Materials (Volume 742)
• Pages: 205-212
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.742.205
• Online since: July 2017
• Authors: Husam Ahmad*, Robert Stelzer, Daisy Nestler, Wolfgang Nendel, Lothar Kroll, Guntram Wagner
• Keywords: Brushes, Debinding, Powder Injection Molding, Powder metallurgy, Sintering, Sliding Electrical Contacts

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