Metal Injection Molding - Wax Removal

Metal Injected Molding (MIM) is fast becoming an important part of manufacturing.

One of the most important aspects of metal injection molding (MIM) is "debinding" or "dewaxing" the part once molded. In the past, the debinding or dewaxing process was time consuming and somewhat tedious... but with solvent vapor degreasing, dewaxing becomes fast and easy. Solvent vapor degreasing handily takes the wax into solution and reduces debinding times from hours to minutes.

Metal injection molding uses binders (like wax additives) to hold the metal powder together during the injection molding process. The Metal Injected Molded (MIM) parts, also known as green bodies or green parts need to have the additive waxes removed prior to sintering. Sintering is the process of making (a powdered material) coalesce into a solid or porous mass by heating it. The "green bodies" are heated to harden. However, if the additive waxes are not removed prior to sintering, the entire part could "melt" or collapse in the sintering process; making a mess and causing lost production.

Benefits of Solvent Vapor Degreasing to Dewax

Enter solvent vapor degreasing, which has the two-fold benefit of using solvents that take the wax into solution, and heat to create solvent vapor that penetrates deep within the green part to "pull" the wax out of the deep blind holes and other cavities that are unique to the MIM part.

• Solvent vapor degreasing reduces the debinding process time from 100 hours (as used in thermal binder degradation) to minutes.
• An additional benefit of Solvent Vapor Degreasing is that the solvents used are non-flammable, fast evaporating, do not leave a residue and are effective...unlike some of the debinding solvents of the past.

The Dewaxing Process

1. Green bodies are placed in the cleaning basket and lowered into the vapor degreaser.
2. The MIM parts are heated while the solvent condenses around the entire part and moves into blind-holes and grooves to take the wax into solution (dissolve the wax).
3. If needed, the MIM parts can be immersed into the boiling solvent for additional wax removal.
4. After 5-30 minutes (depending on the amount of wax to be removed), the parts are brought to the refrigeration zone - where they are cooled and ready for sintering.