The design of die-casting parts must take into account the wall thickness of die-casting parts, casting fillet and demoulding slope of die-casting parts, ribs, casting holes and hole-to-edge minimum distances on die-casting parts, rectangular holes and grooves on die-casting parts, die-casting There are seven aspects of the machining allowance of inserts and die castings in the piece .
Casting fillet design specification
Usually, the parts of the die-casting part should have rounded corners (except at the parting surface), which makes the flow smooth when the metal is filled, the gas is easier to discharge, and the crack due to the acute angle can be avoided. For die-cast parts that require plating and finishing, the fillets can be evenly coated to prevent build-up of paint at sharp corners. The fillet radius R of the die-casting part is generally not less than 1 mm, and the minimum fillet radius is 0.5 mm.
Specification for insert design in die castings
Firstly, the number of inserts on the die-casting part should not be too much; secondly, the connection between the insert and the die-casting part must be firm, and at the same time, it is required to groove, bulge, etc. on the insert; again, the insert must avoid sharp corners. To facilitate the placement and prevent stress concentration of the casting, if there is serious galvanic corrosion between the casting and the insert, the surface of the insert needs to be protected by plating; finally, the casting with inserts should avoid heat treatment to avoid the phase of the two metals. It causes a volume change that causes the insert to loosen.
Design specification for wall thickness of die castings
Thin-walled thick-walled die-casting parts have higher strength and better compactness. In view of this, the design of die-casting parts should follow the principle that the wall thickness should be reduced as much as possible while ensuring that the castings have sufficient strength and rigidity. And keep the wall thickness uniform. Practice has proved that the wall thickness of die-casting parts is generally designed to be 2.5-4mm, and the parts with wall thickness exceeding 6mm should not be produced by die-casting. The effect of the wall of the die-casting part is too thick and the wall is too thin on the quality of the casting: if the wall of the casting is too thin, the metal will not be welded well, which will directly affect the strength of the casting, and will cause difficulties in forming; the wall is too thick or severely uneven. At the same time, shrinkage and cracks are likely to occur. On the other hand, as the wall thickness increases, defects such as porosity and shrinkage inside the casting increase, which also reduces the strength of the casting and affects the quality of the casting.
Design specification for machining allowance of die casting
Under normal circumstances, due to the limitations of the die-casting process, some dimensional accuracy, surface roughness or geometrical tolerance of die-casting parts cannot meet the requirements of product drawings. Enterprises should first consider the use of such as correction, light-drawing, extrusion, Refining and other methods of finishing to repair, when the finishing can not completely solve these problems, it should be machined some parts of the die casting, here it should be noted that the mechanical processing should consider the selection The small machining allowance, as far as possible, the surface that is not affected by the parting surface and the movable forming is the blank reference surface, so as not to affect the machining accuracy.
Design specification for the draft of the die casting
When designing a die-casting part, the structural slope should be left on the structure. When there is no structural inclination, the process slope of the demoulding must be available where necessary. The direction of the slope must be consistent with the direction of demolding of the casting.
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