Because the heat sink aluminum mould has many long and thin teeth and bear a high extrusion pressure, each tooth must be with high strength and toughness. If there is a big performance difference between the teeth, the teeth in poor strength or toughness are liable to fracture. Therefore, the quality of mould must be reliable. It is better to use H13 steel produced by a reliable manufacturer, or choose high-quality imported steel. The heat treatment of the mould is very important, to use vacuum heating quenching(High pressure pure nitrogen quenching is preferred), can ensure the performance of all parts of the mould uniform after quenching. After quenching to take three tempering, so that the mould hardness is in HRC48 ~ 52 in the premise of enough toughness. This is an important condition to prevent broken teeth of the mould.
Reasonable design and precision of the mould is the key to extrude the heat sink aluminum profile. The ingot should not be squeezed directly into the mould working belt. For the flat and wide heat sink aluminum profile, design a diversion mould, the metal flow to both sides, reduce the extrusion pressure of the mould work belt, and make its pressure distribution even. As a result of heat sink aluminum profile section wall thickness difference is big, the mould working belt should keep their difference correspondingly. The production of the mold should also be very fine, the blade must be maintained symmetry, processing error between the teeth to be less than 0.05mm, the processing error is easy to produce biased teeth which make the thickness of the heat sink is not even, or the phenomenon of broken teeth.
