What is the difference between metal powder injection MIM plastic base and wax base binder?

At present, in the MIM technology process, the most used binders are two: metal powder injection MIM plastic based binders and waxy based binders. What is the difference between MIM and wax based adhesive for injection of metal powder? A brief analysis of the difference between MIM and waxy - based adhesive was made by guangdong da-hong new materials today.

First，The new material of guangdong da-hong introduces the way of removing the binder

Removal mechanism of binder. The binders are removed mainly through two processes: one and two, and the corresponding process of debonding and sintering is known through the finishing of guangdong da-hong new wood. During the first tripping process, the filler in the binder is removed, making the green billet into a porous brown billet. At this point, most of the binder is removed. In the process of secondary debonding, the high temperature skeleton agent is removed to completely remove the binder.

Second，Analysis of guangdong da-hong new materials in composition, plastic base, wax base binders

The binder generally includes metal powder injection accelerator (low temperature area), matrix agent (high temperature area), filler and other additives. The biggest difference between metal powder injection MIM plastic base binder and wax base binder lies in the difference of filling agent, followed by the difference of proportion of other additives.

1.Metal powder injection MIM accelerator

The metal powder MIM accelerator literally means that the feed viscosity is too large to be injected, and the addition of such additives can greatly reduce the feed viscosity. Commonly used MIM promoters are stearic acid (SA) and paraffin (PW). Stearic acid is technically known as octadecanic acid. Stearic acid is widely used in cosmetics, plastic cold-resistant plasticizers, mold release agents, stabilizers, surfactants, can play a very good lubrication effect. Paraffin is a mixture of solid higher alkanes, whose molecular formula of main components is CnH2n+2, where n=17 ~ 35. Paraffin can make detergent, emulsifier, dispersant, plasticizer, grease and so on, also be a kind of lubricant with good effect.

2.Skeleton agent

In the process of degreasing, as the binder is slowly removed, the green billet is very easy to collapse, because the metal particles at the degreasing stage have not reached sufficient temperature to melt and stick together, and at this time, the skeleton agent to maintain the skeleton is needed. Matrix agents mainly include PE (high density, medium density and low density), PP, EVA and POM.

Skeleton agent are considered in the selection of two aspects: first, the skeleton agent in degreasing temperature (110 ℃) can't melt softening, otherwise can't keep fixed shape; Secondly, the matrix is easy to be removed under sintering conditions, and the simpler the molecular structure, the more likely it is to be decomposed into gaseous small molecules.

3.Main filler

The main filler refers to the substance accounting for at least 50vol% of the binder. For MIM plastic base binder injected with metal powder, the main filler is POM. Therefore, in the MIM plastic-base binder injected with metal powder, POM is used as both skeleton and filling agent. For waxy binders, the main filler is paraffin (PW). In waxy binders, paraffin (PW) ACTS as both an injection accelerator and a filler.

4.Other additives - dispersion and deodorization

Dioctyl ester (DOP) is a common dispersant with good compatibility with most synthetic resins and rubber used in industry. Of course, formaldehyde and other gases are produced during degreasing and sintering, and a small amount of deodorant and antioxidants are added.

The above is about the difference of MIM plastic base and waxy base binder for metal powder injection made up by guangdong dahong new material. Is it helpful for you to choose the binder better? If you want to know more about metal powder injection molding technology, welcome to consult the professional team of MIM injection molding technology of guangdong dahong new materials metal powder injection molding!