Requirements for die casting tendon design:
Tendon is used to improve strength and rigidity of parts when reduce wall thickness in case of die casting shrinking and deforming. It also prevents work piece from deforming when the piece is ejected out from the mould. The tendon is also used to assist loop (access of metal flowing) during filling. The thickness of tendon is less than the wall thickness, general 2/3~3/4 of wall thickness.
Requirements for wall thickness design:
Wall thickness of die casting is one of specific factors in die casting mould technology. The thickness has closed relationship with the whole process specifications, such as filling time calculation, flow gate speed, setting time calculation, mould temperature gradient, function of pressure, molding time, ejection time and operational efficiency;
a. Thick thickness makes mechanical properties of die casting
descend significantly; thin thickness has good compactness, relatively improving strength and pressure resistance of die casting;
b. Thickness cannot be too thin. Too thin causes molten aluminum poor filling, difficult for forming. And it also results in poor welding on aluminum alloy. Cold shut and other defects may be easily caused on the surface, which also bring difficulties to die casting. The thicker thickness is, the more internal porosities, shrinkage cavities and other defects are. Under enough strength and rigidity, the thickness should be descend as much as possible and brought into correspondence with the thickness of cross section. In case of shrinkage porosity, wall thickness should be reduced and tendon is increased; for large flat die casting, tendon is set to reduce thickness.
Requirement for shape structure design:
a. Eliminate internal undercutting;
b. Prevent or decrease loose core;
c. Avoid core crossing.
Rational structure of die casting cannot only simplify structure, but also can reduce cost and improve quality of die casting.