Aluminium Die casting draft angle is the taper or slope of the die casting in the vertical direction. The surface of the die casting that is perpendicular to the parting line of the mold needs to be drawn; so that the die casting parts can be easily released from the core or cavity.
Why is the draft angle of die castings important?
The shrinkage stress of die castings during the molding cooling and shrinkage ; will causes the castings to stick to the core; in order to reduce the resistance to release, make the cores easier to pull out ; prevent the surfaces of the castings from being scratched ; due to friction caused by the relative movement. In short; the die casting release draft angle must be the same on the side of the casting as the release direction.
How to design the mold draft angle?
1) Consider the problem of wall thickness, thicker part will bring influence on filling.
(2) consider the problem of mold release; this is very important in die-casting practice; there very easy have kind of problem; which is more annoying than injection molding mold release; so the setting of the mold draft angle need to pay attention to; general mold draft angle is 1 to 3 degrees; usually taking into account the smoothness of the mold release, the outer draft angle than the inner die draft angle to be smaller, the outer draft angle is only 1 degree, while the inner die draft angle minimum to be about 2 to 3 degrees.
(3) design taking into account the mold design; if there are multiple positions of the extraction center; as far as possible on both sides, preferably not in the lower extraction center; so that over time the lower extraction center will be prone to problems.
(4) some die casting appearance may have special requirements; such as oil spray; powder spray; etc., when it is necessary to avoid the structure of the important appearance of the location to facilitate the setting of the gate or slug.
(5) in the structure to avoid the complex structure of the mold; such as the use of multiple slider or spiral extraction, etc.
(6) for those parts need machining; that the parts need to be designed to enough machine allowance;no need too much; otherwise will expose the porosity inside, leaving the machine allowance is best not greater than 0.8 mm.
(7) Then Material choice, whether to use ADC12 or A380, depending on the specific requirements
(8) generally can not Run deep holes! better way is to make point hole on the mold building stage, and then run post-processing.