MIM Molds New Expectations
Increasingly the manufacturing process of choice for small metal parts is Metal Injection Molding or MIM. MIM is complex but highly effective. Its inherent design flexibility provides the same benefits and features of plastic and rubber molding, but produces a much stronger end product. MIM parts have densities and mechanical properties approaching those of forged or machined components.
MIM starts with mixing. Metallic powders – selected for inherent abilities such as impact strength, low and high temperature characteristics, and hardness – are blended together, often with a binding agent. The goal is to create a composite with the strengths and benefits of all the incorporated metals, while offsetting the independent weaknesses.
The composite material is injected into a mold just as it would be if you were using a plastic or rubber mold. MIM material can leak outside cavity areas through gaps of .0005 inches or even less in some situations, necessitating extremely tight tolerances in the manufacture of the mold components.
The molded part itself, sometimes called "the green part," is fragile. It emerges from the mold in a semi-liquid state with the consistency of a melted crayon, and solidifies in a matter of seconds.
With this in mind, the action of the mold – whether it's something as simple as ejector pins or more complicated such as slides or unscrewing cores – must be timed and actuated so that the "green part" survives the process. Things such as parting line, shut offs, gating, ejection, polish and venting all play a crucial role in the success of the mold.
The ejected pieces are sent to a finishing stage where burrs and surface imperfections are removed via high-speed machining centers and precision surface grinders. Finished parts can also be hardened, painted, drilled, or tapped before shipping.
The key to using MIM well is a manufacturer's ability to produce a mold specifically fit to the customer's part, and to ensure a closely controlled MIM process that achieves satisfying results.
AFT has the capabilities and professionals to help you with your MIM needs. Our experienced staff understands the mold build and we are experts in the MIM process. We have the latest technology in the design and mold-making areas, and when needed, can call on the expertise of some of the best mold-making shops in the United States to engineer, design and build first-class molds. Let us help you with your next project 303-833-6000 or visit www.pcc-aft.com. |
