One innovative manufacturing method for water cooled controller housing

Aluminum die casting alloys are lightweight and possess high dimensional stability for complex part geometries and thin walls. Aluminum withstands good corrosion resistance and mechanical properties as well as high thermal and electrical conductivity, making it a good alloy for die casting.

The casting process implements a steel mold often capable of producing tens of thousands of castings in rapid succession. The die must be made in at least two sections to permit removal of castings. The casting cycle begins with the two die halves are clamped tightly together by the die casting press. Molten aluminum is injected into the die cavity where it solidifies quickly. These sections are mounted securely in a machine and are arranged so that one is stationary while the other is moveable. The die halves are drawn apart and the casting is ejected. Die casting dies can be simple or complex, having moveable slides, cores, or other sections depending on the complexity of the casting. Most machines use mechanisms actuated by hydraulic cylinders to achieve locking. Others use direct acting hydraulic pressure. Die casting machines, large or small, very fundamentally only in the method used to inject molten metal into the die.

Due to die casting process’s characters, it can not be avoided that some typical defects occur. These typical defects include gas Porosity、Shrinkage Porosity、Inclusions、Cracks、Cold Shut、Network Cracks and others. And two risky results can be caused, one is leakage and another is poor thermal conductivity.

Large components like inverter or controller housing or chassis are always aluminum die casting parts. With more and more high power electrical components installed into housing, traditional air cooling device like heat sink is not sufficient to get parts working properly by cooling down temperature especially for some key electrical components like IC, IGBT. So water cooling device must be involved.

How to manufacture one aluminum die casting housing with water cooling chamber? M-stirling's engineers, co-worked with our casting partners invested vast knowledge and experience, succeeded in inventing the innovative manufacturing method for forming this great product housing.

Our process firstly is to create one separate cold plate. Use CNC machining to get internal desired channel, and seal one top cover on channel by vacuum brazing technique. Thus, one complete cold plate is finished. And all electrical components requiring heat transfer will be directly contact this cold plate tightly through installation. We can rely highly on cold plate with leakage free due to high quality consistent AA6061 or 6063 aluminum plate material. The second step is to cast the complete housing by including this ready made cold plate. After casting process, further processing like machining, surface finish can be implemented to get the final housing. Usually, die casing material is like ADC12 or A380.

Let’s see what the conductivity difference between die casting and 6063 aluminum plate.

AA6063 conductivity 201 W/mK

ADC12 conductivity 96 W/mK

Then we can get one extremely excellent thermal performance by introducing this kind of housing. We do not need to worry about leakage risk and poor thermal conductivity due to typical die casting defects.

In August of 2021, we have been approved of manufacturing patent for this method. And the patent number is CN202111006618.5.

Currently, there are at least 10 models of controller, inverter or communications housing which were already introduced this new advanced method. And positive feedbacks from customers are encouraging us to boom this technology.