Analysis of Aluminum Die Casting Crack

During aluminum die casting manufacturing,die casting surface crack might happen the surface over thick and deep area.We need to differ suface crack from other cracks and analyze the reason why surface crack happen.We can eliminate surface crack by controlling mold temperature,release agent spray,optimizing die casting parameters.Contact us for professional die casting service.

die casting surface crack
die casting surface crack

Die casting featured high efficiency,simple processing,tight tolerance,lower surface roughness,high strength,which can reduce quite amount of machining and save a lot of raw material.Therefore,die casting widely used for various of industries.However,it is really hard to design die casting parts without any deep cavities because of structure and wall thickness requirement of die casting parts.Therefore,die casting can not avoid porosity,cold shut,cracks etc.In many kinds of cracks,there is one kind of surface crack which is normally in 0.1-0.3mm deep and can be removed.The surface crack usually happen to deep cavity.By analysis of surface crack,it will be useful to differ surface crack from other kinds of cracks.

The housing was produce via high pressure die casting.The material is ADC12.By view of 3D drawing,the size of housing is 56x351x202mm and max wall thickness is 30mm and min wall thickness is 4.0mm and weight is 5.36kg.The injection temperature is 635-660℃.One important technical requirement is leakage proof under 0.1-0.1Mpa for 10s.In red arrow pointed area,there is surface crack.Leakproof test passed.The crack do not become worse by outer pressure.It can be removed by grinding.

(a)It shows crack.(b)It shows crack on cross section.The defect happen to area A where the thickness is quite big.By view of cross section,the defect do not damage the substrate.The difference between surface crack and other kinds of crack is quite visible.

Crack over surface :caused by shrinkage,not deep,not damage the substrate.

Other kinds crack:penetrate into substrate.

By microscope,the crack does not affect substrate.However,other kinds of crack affect substrate badly.

The reason for crack:

There is nonuniform wall thickness for deep cavity andt tmperature over tooling is not same.Alloy were metled in unproper method.The tooling temperature,die casting processing and ventilation system are main factors for crack problem.During solidification,surface crack might happen but it is not deep and about 0.3mm thick.

To avoid crack,we suggest to increase radius and make molten alloy fill smoothly.Meanwhile,the temperature of molten alloy need to be controlled.The surface crack might happen if molten temperature is too high.The cold shut might happen if molten temperature is too low.Release agent should be used during die casting,which can avoid cold shut,crack etc.The injection temperature should be about 645℃ and release agent should be 1:(80-120).

WEIHENG is professional die casting supplier and provide full die casting service for Automobile Industry,Lighting Industry,Mechanical Equipment Industry etc.If any inquiries for die casting,please feel free to contact us.

Leave your comment

Your email address will not be published. Required fields are marked *