MIM plastic-based adhesive, wax-based which type is better?

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1.Mixing stage

The wax-based binder is mainly paraffin, with low viscosity and easy volatilization; therefore, it is easy to mix, but it should be noted that the temperature should not be too high (below 120 ℃), and it has an air-tight design to reduce volatilization loss. The plastic-based binder is mainly POM,with high viscosity and low volatility; a mixer with high shear force is required, and the temperature setting is higher (greater than 150 ℃) to reduce the viscosity of the binder; due to the higher temperature In order to prevent some special metal powders from being oxidized, nitrogen protection is required in special cases.

2.Injection stage

Wax-based binders have low viscosity, good lubricity, and low pressure, low firing rate, and low mold temperature. Injection molding machines can meet the requirements. On the contrary, fast firing rate can easily lead to separation of powder and glue, resulting in sand hole defects in the final product. The plastic-based adhesive needs a high-speed electric injection molding machine,the screw should be short, the injection rate, injection pressure, mold temperature are high, and the pressure holding time is long; POM Cracking!

3.Degreasing stage

Wax-based binders are mainly degreasing by solvent or hot atmosphere.The solvent will deteriorate the skeleton proppant. Drying after dissolution often causes the green body to warp and deform.The corresponding solvent also needs to be fireproof. The recovery of the solvent and the safety performance of the degreasing furnace need to be paid attention to. The plastic-based binder is mainly degreased by the catalysis of acid. This method is fast,and the attached products are all CO2 and N2 safe gases. The equipment is simple and easy to manage.

4.Sintering stage

The wax-based binder takes a long time before sintering (<600°C), resulting in snot-like and yellow wax residue; due to the deterioration of the skeleton agent during degreasing, the product deformation is large; although the price of thermal debonding wax-based binder is high, it can be Using a degreasing and sintering integrated furnace, the labor cost is low, and it is popular in Japan.The plastic-based binder has a short time in the first stage of sintering (<600°C), resulting in asphalt-like, dark green-yellow wax slag, which is not easy to clean. In addition, the plastic-based adhesive is relatively small in deformation.

Summarizing the differences between the above four processes, it can be seen that the wax-based binder mixing and injection molding process has simple requirements, but the deformation of the sintered part is large; the plastic-based binder mixing and injection molding process requires higher requirements,  precisely because of its Due to the relatively large viscosity and other reasons, the deformation of the sintered parts is small. Of course, the specific parameters of different companies are different, and there will be some discrepancies.

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