Degreasing of zinc aluminum low pressure casting

Zinc aluminum alloy die casting is a kind of powder aluminum die casting parts with zinc as the key component. The surface of such parts is a very high density surface, the inside is porous material for fire evacuation. It is allowed to use acid-base degreaser, but only use partial alkali degreaser to carry out degreasing in Zhejiang low-pressure casting processing plant. Most zinc die castings must be rolled with Ni Cr alloy double-layer coating, which has a high requirement for decorative art. Before degreasing, they are all ground polished. Therefore, dewaxing (polishing wax with Paraffin) is the first step, followed by chemical degreasing electrolytic degreasing. Because the melting point of paraffin is about 70%, in order to emulsify paraffin, the temperature of paraffin removal water is higher than 70 ℃. In the past, we only used general chemical degreasing solution to raise the temperature to remove wax. This kind of way has a long time low efficiency. Now there is a professional supply of dewaxing water, time is reduced, the actual effect is good. If ultrasonic wave is applied, the actual effect is stronger. Generally, dewaxing water can only remove wax without degreasing, chemical degreasing should also be carried out.

The chemical specificity of zinc alloy material is very strong, the partial alkali of chemical degreasing solution can be too strong, otherwise it will etch the surface of Hangzhou Auto parts casting aluminum parts processing plant. The temperature is generally controlled between 50-70 ℃ for 3-5min. The products supplied in the market are also degreasers that combine degreasing wax removal, they are very effective in combination with ultrasound. The composition of degreaser for zinc alloy parts by electrolysis is similar to that of chemical degreaser. But it must have complexing agent. When the zinc alloy die casting is degreased by electrolysis, it should be placed on the negative electrode degreased. The temperature is 50-70 ℃, the current intensity is 3-5a / DM2, the time is 1-2min. In the selection of dewaxing degreasing two in one process, under the effect of ultrasonic wave, sometimes the surface of casting will cause dark brown etch film in Zhejiang auto parts casting aluminum processing plant. This kind of degreaser is suitable for application. The degreaser specially used for zinc die casting shall be replaced. This should be noted.