MIM process flow MIM process scheme .
Step 1: Feedstock
· Very fine metal powders usually (<15 microns) are mixed with a primary paraffin material and a secondary thermoplastic polymer. Together they act as binders
· Unlike standard powder metalurgy, which can achieve only 80-90% of theoretical density, MIM results in 95-100%. This means we can achieve close tolerances and reduce costs by producing small, complex parts over high production runs
Step 2: Molding
· The feedstock is fed into either our multi-slide MIM machinery or standard molding equipment, then heated and injected into a mold cavity under high pressure
· Our proprietary multi-slide tooling can produce extremely complex shapes and allow for shorter cycle times
· Once molded, the component is referred to as a “green” part
· Our multi-slide process routinely produces green parts in 3 seconds as opposed to 25-40 seconds on a standard MIM system
· Its geometry is identical to that of the finished piece, but to allow for shrinkage during the sintering phase, it’s about 20% larger in size than the finished component will be
Step 3: Debinding
· Binder removal or “debinding” involves a controlled process to remove most of the binders
· The process removes the binders and prepares the part for the final step – sinterin
· Once debinding is complete, the component is referred to as “brown”
Step 4: Sintering
· The “brown” part is held together by a small amount of the binder, and is very fragile
· Sintering eliminates the remaining binder and gives the part its final geometry
· During sintering, the part is subjected to temperatures near the melting point of the material
· The entire sintering process takes 15-20 hours