MIM feeding process in which binders used plastic base, wax base which good?

Metal powder injection MIM feed process inside the binder with plastic based binder or wax based binder? What are the differences between plastic and waxy binders in mixing, injection, degreasing and sintering processes? The following is a brief introduction of the differences from the new materials of guangdong dahong.

First,Mixed phase

Waxy base binder:

1. Blending temperature below 120 ℃, shorter mixing time;

2. Sealed mixing and air-tight design to reduce the heating loss of paraffin;

3. Can use plastic base mixing equipment, but shear force should pay attention to temperature control.

Plastic based binder:

1. The mixing temperature greater than 150 ℃, soft time long;

2. Using open mixture kneading;

3. The waxy - based mixing mixer cannot be used;

4. Special powder mix shall be protected by nitrogen;

5. High shear force is sufficient to soften the plastic-based adhesive.

In general, the waxy base binder is mainly paraffin with low viscosity and volatile. So the easy mixed, but also should pay attention to the temperature shoulds not be too high (below 120 ℃), reduce the volatilization loss with air tightness design. Plastic-base binder is mainly POM with high viscosity and low volatility. With the shear strength of mixer, and the temperature setting of higher (greater than 150 ℃), in order to reduce the adhesive viscosity; Since the temperature is high and usually open, nitrogen is required to protect special metal powders from oxidation.

Second,The injection stage

Waxy base binder:

1. Good lubrication, slow shooting speed can also be achieved, oil press can also be metal powder injection MIM;

2. Mold and metal powder injection MIM material tube temperature low;

3. It is easy to cause the shell effect in the separation of powder and glue due to the low viscosity of wax.

Plastic base binder:

1. High speed motor can make plastic base feed;

2. Metal powder injection molding machine injection rate, high injection pressure, long time pressure;

3. Screw compression ratio is very important, screw length is shorter;

4. Die temperature to high (> 120 ℃), in order to reduce metal powder injection residual stress;

5. The temperature control of the feed tube should be more strict, the injection should be lowered immediately to avoid POM cracking!

The injection stage is similar to the mixing stage, and the high viscosity of the plastic-base binder brings difficulty to the injection molding of metal powder. Due to low viscosity and good lubrication, low pressure, low injection rate and low mold temperature metal powder injection molding machine can meet the requirements. On the contrary, rapid injection rate can easily lead to separation of powder and glue, which leads to the sand hole defect of the final product. The plastic-base binder needs high speed electric metal powder injection molding machine, the screw should be short, the injection speed, the injection pressure, the mold temperature is high, and the pressure keeping time is long. In addition, the temperature control of the feed tube should be more strict, the injection should be immediately cooled to avoid POM cracking!

Third,Skim phase

Wax base (dissolution/heat removal) :

1. Dissolution makes the product easy to change;

2. In addition, low efficiency, poor safety of dissolving equipment, fire prevention of solvent and recycling all cause environmental and safety problems;

3. Dissolving is suitable for large parts. The structure should have a supporting plane.

Plasticizer (acid catalytic deactivation) :

1. Rapid catalysis, suitable for meat thickness below 5mm, high efficiency;

2. Simple equipment and high security;

3. The by-products are gases (CO2, N2) that are easy to manage.

The above is about the difference of metal powder injection MIM plastic base and wax base binder in mixing, injection molding, degreasing and sintering process, 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 MIM professional team of new material metal powder injection molding in guangdong province!