Causes analysis  and improvement methods of washout  of die casting products

Posted on : March 24, 2022 By  GREFEE

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What is washout in die casting?

The local area on the casting surface has pitting or embossing patterns, which can be removed by polishing. However, sometimes, it will have sinks at the accordingly areas and are often the area around the in-gate.

Causes:

1.improper position of in-gate – direct impact on the steel wall of mold.

2.The filling direction of in-gate is incorrect, such as flushes the according areas in cavity.

3.The in-gate is too thin and the filling speed is fast – flushes the in-gate areas.

4.Poor cooling conditions, especially the overheated areas.

5.The mold cavity material is unqualified with poor resistance to thermal fatigue.

6.The heat treatment in cavity is improper, and the surface hasn’t  been treated with nitrogen desalination or oxidation.

7.Alloy pouring temperature is too high.

How to improve the die casting parts’ surface washout issue?

1. The gate has long trip protrusion and crazing. — improves the in-gate and avoid directly impacts on the mold wall.

2. The in-gate has long strip profusion and regional fatigue crazing away the in-gate area.

3. In this case, the crazing and washout issues are most likely happened around in-gate. Increases the thickness of gate properly.

4.In production, find the high-temperature area by the mold thermoprobe. Adds point cooling in the high-temperature areas, and the spray painting time should be longer in this area and forced cooling.

5. Takes the sample of the mold cavity material and examines the composition — replace the mold cavity material.

6.Check the surface stiffness of the cavity. If there are smaller deficiencies, we can solve them by surface nitriding or oxidation treatments. If there are serve defects, we need to rece the height and then carry out surface nitriding or oxidising treatment to reproduce the mold cavity.

7. Checks the temperature of liquid aluminum by the new thermoprobe. Lowers down the pouring temperature of alloy.

Key inspection areas for washout

Washout usually is found in the sealing groove or the edges of corners.

How does washout affect the products?

It mainly affects the appearance of products and airtightness of sealing groove.

How to evaluate whether a die casting part with washout issue is qualified or not?

1. The surface washout generally can be removed by the blasting or grinding. The parts with washout removed are seen as qualified parts.

Unqualified if washout be found in those areas

1) washout is found at the deep groove of heat sinks on baking paint side is hard to remove.

2). Washout in sealing groove is hard to remove. It affects the finish of sealing groove.

Improves the washout issue for your die casting parts

Washout is mainly caused by the improper design of the gate. Experienced die casting mold design combined with scientific die casting mold flow analysis is extremely essential. When GREFEE designs the parameters of the die casting runners, we will carry out a multi-analyze about the die casting mold flow to find the most suitable feeding solution.

GREFEE has over 30 professional die casting design engineers and 5 die casting experts. Contact us now! Let’s turn your idea into a reality.

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