The design of die castings must consider seven aspects: die casting wall thickness, casting fillets and draft angles, reinforcing ribs, casting holes and minimum distance from holes to edges, rectangular holes and slots, inserts, and machining allowances.
Casting Fillet Design Specifications
Generally, all parts of a die casting should intersect with fillets (except at parting surfaces). This allows for smooth metal flow during filling, facilitates gas escape, and prevents cracks caused by sharp angles. For die castings requiring electroplating and coating, fillets allow for uniform plating and prevent paint buildup at sharp corners. The fillet radius R of die castings should generally not be less than 1 mm, with a minimum radius of 0.5 mm.
Design Specifications for Inserts in Die Castings
First, the number of inserts in a die casting should not be excessive. Second, the connection between the insert and the die casting must be firm, and the insert should ideally have grooves, protrusions, or knurling. Third, inserts must avoid sharp corners to facilitate placement and prevent stress concentration in the casting. If there is severe electrochemical corrosion between the casting and the insert, the insert surface needs a protective plating layer. Finally, castings with inserts should avoid heat treatment to prevent volume changes caused by phase transformations of the two metals, which could loosen the insert.
Design Specifications for Die Casting Wall Thickness
Thin-walled die castings have higher strength and better density than thick-walled ones. Therefore, the design of die castings should follow the principle of minimizing wall thickness and maintaining uniform wall thickness while ensuring sufficient strength and rigidity.
Design Specifications for Machining Allowances in Die Castings
Generally, due to the limitations of the die casting process, when certain dimensional accuracy, surface roughness, or geometric tolerances of die castings do not meet the requirements of the product drawings, companies should first consider using finishing processes such as straightening, polishing, extrusion, and shaping to repair them. If finishing processes cannot completely solve these problems, certain parts of the die casting should be machined. It is important to note that when machining, a smaller machining allowance should be selected, and the surface unaffected by the parting line and moving parts should be used as the blank reference surface as much as possible to avoid affecting machining accuracy.
Design Specifications for Draft Angles in Die Castings
When designing die castings, structural draft angles should be included in the structure. If there are no structural draft angles, process draft angles must be provided where necessary. The direction of the draft angle must be consistent with the demolding direction of the casting.
