External thread can be cast out, due to the need of casting and mold structure, adopt two types of thread type ring, with 0.2 ~ 0.3 mm machining allowance. Cast out the minimum pitch of 0.75 mm, the minimum thread diameter 6 mm, maximum thread length of the pitch 8 times. Internal thread while it is possible to cast out, but by using a mechanical device to turn the core in the die-casting mould, make the mould structure is more complex, and increase the cost. So generally cast out of the bottom hole, first by machining again into internal thread. Alloy CNC machining parts die casting on every wall and connection, regardless of right Angle, acute or obtuse, the root of the blind holes and grooves, should be designed with rounded corners, only when is expected to determine the parting surface position, do not use the rounded connection, the rest parts generally must be rounded, rounded shoulds not be too big or too small, too small alloy die castings are prone to crack, caused by excessive loose shrinkage cavity, alloy die casting round generally take: 1/2 wall thickness R or less wall thickness or less.
Alloy die casting can die casting the minimal size and depth of the hole, hole formed by the core distribution location in the cavity. Fine core is easy to bend or break when pulled, so the smallest size and depth of the hole. The depth should be a certain Angle, so that the core pulling. Self tapping screw for alloy die casting in bottom hole, bottom hole diameter is recommended for the cast hole to the edge of the minimum distance In order to ensure the casting has good forming conditions, the cast hole to the edge of the casting should maintain a certain wall thickness character, symbol, design, cast in die casting, should be raised. Rib height more than 0.3 m, so as to adapt to the characteristics of mould manufacturing. USES now began to popular new technology: "transfer of color film," color can be text, logo, design, color alloy die casting film heat transfer to the surface of alloy die casting. After casting die casting, play the text with laser on the casting surface, symbol, design, can play only a very slight. Shrinkage is often referred to as shrinking. It refers to the alloy by the solidification of solid, liquid and cool to room temperature were smaller percentage of available under type said: the structure characteristics of shrinkage rate and the size of the alloy die casting, wall thickness, alloy chemical composition and process factors and so on. Alloy line shrinkage is commonly: free shrinkage 0.6% ~ 0.8%, hindered contraction in 0.3% ~ 0.6%. Table 5 as a core of different metal alloy die casting wall thickness in line shrinkage rate reference value.
Alloy die casting die casting hole cast hole size and depth of the die casting alloy die casting size and hole deep, low requirements for hole can be directly out of specification: in terms of depth in the table refers to the fixed mold core, the activities of a single core can be appropriately increased its depth. For larger aperture, the accuracy is not high, the depth of the hole can be die cast light housing beyond the scope. Casting hole should be cast out as far as possible, this not only can make the wall thickness uniformity, reduce the hot section, saving metal, but also save the machining time.