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In the manufacturing and daily maintenance of precision injection molds, sandblasting treatment is an indispensable surface treatment technology. It uses compressed air to spray fine abrasive materials onto the mold surface, achieving a series of process goals such as cleaning, roughening, or finishing, providing a strong guarantee for the efficient and stable production of the molds.

1. Efficient cleaning, removing stubborn stains

During the long-term use of injection molds, the surface is prone to accumulate oil stains, rust, oxide layers, and difficult-to-remove release agents and carbon deposits. Especially in the exhaust slots and deep cavity structures, the problem of carbon deposits is particularly prominent. The sandblasting process can quickly and uniformly remove these contaminants, restoring the mold to a clean state, and is the preferred solution for pre-treatment before mold maintenance and repair.

2. Surface roughening to enhance coating adhesion

When the mold needs to undergo spraying, electroplating or other surface coating treatments, an appropriate surface roughness is crucial for ensuring a firm bond between the coating and the substrate. Sandblasting can create uniform micro-roughness on the mold surface, significantly increasing the mechanical adhesion between the coating and the base material, effectively preventing coating peeling and prolonging the mold's service life.

3. Eliminating processing stress and enhancing mold lifespan

CNC milling and electrical discharge machining (EDM) generate microscopic residual stress concentrations on the mold surface. During the sandblasting process, the impact of high-speed abrasives forms a beneficial compressive stress layer on the mold surface, which helps to release some of the processing stress and improve the fatigue resistance of the mold, thereby extending the overall lifespan of the mold.

4. Achieve a beautiful matte finish

Some customers have very high requirements for the appearance of the product. For instance, they prefer a smooth matte effect rather than a shiny one. In such cases, sandblasting can directly create a uniform matte texture in the mold cavity.

Moreover, sandblasting has another advantage. It can cover minor processing marks. After CNC or electro-discharge machining, there are usually some tool marks or discharge marks. After sandblasting, those tiny lines are covered by the uniform matte finish, making the product look more beautiful. Many customers in the fields of consumer electronics and automotive interiors prefer this treatment. 

5. Different sands, different effects

The materials used for sandblasting are also different, and the resulting effects vary significantly:

•Glass beads are our most commonly used material. They are gentle and do not damage the mold. They are relied upon for daily cleaning and 

removing carbon deposits.

•White corundum and brown corundum are slightly harder and are suitable for removing thick rust or for roughening.

•Steel sand is mainly used for stress strengthening. This is a more specialized material.

•Soft materials like walnut shells are suitable for cleaning soft molds that are sensitive to scratches.

What material to choose depends on the effect you want to achieve. It cannot be generalized.

6. Although sandblasting is effective, there are certain areas that must be avoided:

•There is no need for excessively high air pressure: If the air pressure is too high, the sand particles will cut into the surface of the mold like knives, 

        which can damage the mold instead. We usually control the pressure within 0.3 to 0.6 megapascals; it's better to be lower rather than higher.

•After spraying, it cannot be used directly: After spraying, it must be thoroughly cleaned to remove all the sand particles from the gaps. Otherwise, 

        these hard particles will enter the product and become foreign matter defects. The customer will definitely not approve it.

•Do not spray on the textured surface randomly: If the mold has a textured surface, sandblasting will flatten and distort the texture. For this, it is 

        necessary to seek professional texture repair services; do not attempt to do it yourself. 

Sandblasting is a seemingly simple process that actually involves numerous technical details. Correct and reasonable application of sandblasting technology can effectively extend the lifespan of molds, improve product appearance quality, and reduce maintenance costs. For every user and maintainer of injection molds, understanding the true function of sandblasting and mastering its operation procedures is an important part in ensuring smooth production.

If you have any questions regarding the mold processing technology, please feel free to contact us at Shenzhen Hainai Precision Mold Co., Ltd.:

Contact - hainamould Mould Company Limted

Our website: https://www.hainamould.com/

Contact us: ciky@hainamould.com