Die Casting Defects Causes and Solutions Part Two

From more than a decade of professional die casting process experience, Sieg-Huao has summarized 10 types of common die casting defects and obtained a complete set of preventive measures.

Six: Adhesive material

Appearance Inspection: Small pieces of material in metal or non-metal is fused with metal matrix part, which will be peeled off under the action of external forces.

The reason for this phenomenon:

1) There are metal or nonmetallic residues on the surface of the diecast cavity.

2) When pouring, the impurities are attached to the surface of the cavity.

 

The solution and prevention methods:

1) Before die-casting, the cavity pressure chamber and pouring system should be cleaned to remove metal or non-metallic adhesives.

2) Clean the casting alloy.

 

Seven: Layering

Appearance Inspection: There is a distinct layer of metal in the diecast product.

The reasons for this phenomenon:

1) The die has no enough rigidity.

2) During the injection process, the head appears to be crawling.

3) Improper design of runner system.

 

The solution and prevention methods:

1) Strengthen die casting mold rigidity.

2) Adjust the injection punch and pressure chamber to eliminate the crawling phenomenon.

3) Design reasonable sprue.

 

Eight: Friction and Ablation

Appearance Inspection: The surface of the die casting part is roughened in some positions.

The reasons for this phenomenon:

1) The position and shape of the inner runner are not correct.

2) The diecast part where is brushed strongly by metal liquid has not got enough cooling.

 

The solution and prevention methods:

1) Correct the position and direction of the sprue.

2) Improve the cooling condition, especially for the position which got strong brush.

3) Adjust the velocity of the alloy liquid to avoid cavitation.

4) Remove the alloy adhesive on the casting mould.

 

Nine: Wash out

Appearance Inspection: Several positions of the die casting are pitted or embossed.

The reasons for this phenomenon:

1) Improper positioning of sprue.

2) Poor cooling condition

 

The solution and prevention methods:

1) The thickness of the inner runner should be appropriate.

2) Modify the position, direction and setting method of the inner runner.

3) Strengthen the cooling of the eroded part.

 

Ten: Cracks

Appearance Inspection: When place the die casting products into alkaline solution, the crack seems dark gray. The linear or wavy cracks are narrow and long, and there is a trend of development under the action of external forces.

The reasons for this phenomenon:

1) The alloy has high iron content or too low silicon content.

2) The casting wall thickness has changed dramatically.

3) The local compaction force is too tight, and the force is not equal when the top is out.

 

The solution and prevention methods:

1) Proper control of alloy composition.

2) Change the casting structure, and adjust the core mechanism.

3) Increase the draft Angle.

4) Increase retention time.

 

So these are the ten common die casting defects causes and solutions, and we hope this article will bring you help. For more information on die casting(aluminum and zinc die casting), investment casting and other casting process, please check out the article and product list on our website.