Linde, a leading global industrial gases company, and Megamet Solid Metals, a custom metal-injection molding company, have shown that the quality of metal-injection molded (MIM) parts could be significantly enhanced by following a ‘Best Practice’ in controlling the carbon potential in the sintering zone.
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Linde’s advanced SINTERFLEX® Atmosphere Control System helped achieve the improvements, and Linde is to feature them at a commercial presentation and tabletop sessions during February 23-25 at MIM 2015 to be held in Tampa, FL. The Metal Injection Molding Association (MIMA), which is a trade association of the MPIF, and APMI International, its affiliate, are sponsoring the International Conference on Metal Injection Molding of Metals, Ceramics and Carbides (MIM).
Using Linde’s advance control system, Megamet was able to decrease the carbon content’s standard deviation in MIM parts; reduce rejects and prevent rework due to carbon content; boost productivity; and improve the number of parts in specification.
Bruce G. Dionne, who co-chaired MIM 2014, commented:
Homogeneity and consistency in the furnace atmosphere are pivotal to the success of MIM manufacturing. The highest accuracy carbon control is achieved by regulating the carbon potential at the sintering temperature to the value that will lead to the desired final surface carbon concentration in the sinter body upon cooling.
"The SINTERFLEX atmosphere supply system maintains the low CO+H2 concentration atmosphere necessary to stabilize carbon potential.
Dionne, as the General Manager of Megamet Solid Metals, had explained the Best Practice findings in June at PM2014 - the 2014 World Congress on Powder Metallurgy and Particulate Materials. The dynamics involved in measuring the atmosphere carbon potential and the reasons for decarburization were also reviewed.
The presentation was titled, “An Approach to Carbon Control of Sintering Furnace Atmosphere: Theory and Practice,” and this has been published in the Proceedings of the PM2014 World Congress. This paper can be purchased through the Metal Powder Industry Federation (MPIF).
In 2010, Linde and Megamet had commenced their collaboration on the sintering atmosphere control system.
After the first SINTERFLEX ACS was installed at the Earth City facility, we identified opportunities for improving the control system and conducted follow-up tests
Grzegorz Moroz, Linde Program Manager, Heat Treatment & Atmospheres
In December 2013, the unit was modified by the Linde project team and the advanced SINTERFLEX system was installed. Linde and Megamet had partnered to assess the capabilities of the unit, and they tracked numerous parameters to increase the effectiveness of its performance.
When compared to other manufacturing processes such as CNC machining and casting, MIM is a cost-effective option. It is suitable for low-volume prototyping as well as for volume production of high-quality parts. This method allows production of complex shapes with exceptional strength and outstanding surface finish, which allows it to be used for making parts for electronics, automotive components, aerospace, medical devices, tools and machines.
Plastic-injection molding process enables formation of shapes with high precision. This powder metal process provides the durability and strength of metals, along with the advantages of plastic-injection molding. In MIM, the final step is sintering, which is a high-temperature hardening process. This process is performed in a controlled atmosphere, and it involves application of heat below the melting point, which causes the high-density alloyed powders to fuse. During the sintering process, decarburization is avoided by the MIM parts due to the carbon-neutral atmosphere. Decarburization prevents the carbon content from meeting the specification.