Case Study_ Die Casting Housing

A Brief Overview

Most of the components of LED lights are made with aluminum die casting as it offer great dimensional accuracy, besides being durable and sturdy. Thermal design is very important to ensure the lifespan of both the light and the fixture. More and more LED light fixture designs are now available that use aluminum die casting. The flexibility in graphic design and attractive price are the major reasons to make use of aluminum die casting to manufacture LED light fixtures.

Part Photo

Part Issue

The die casting housing has cold spots on fins during trial production, cannot meet the surface demand. Refer to below photo.

Issue analysis

This is a aluminum die casting housing with pins. The thin fins are located in the deep cavity of the part. Generally speaking, aluminum alloy liquid cannot fill the deep cavity directly in the front. The liquid flows from the bottom plane of the fin to the far end, and then flows back into the fin after collision from the far end, forming eddy currents in the fin. During die-casting process, it is difficult to fill the deep cavity smoothly, and the gas also difficult to exhaust in the deep cavity. The fins of part has defects such as cold spots, under-casting, porosity, etc.

Solution

• Raise the tooling temperature, increase the pouring temperature, as well increase the fluidity of aluminum alloy liquid.

• Speed up the injection, increase the thickness of the inner gate from 2mm to 2.4-2.6mm (increase the cross-sectional area of inner gate), in order to shorten the filling time and let the aluminum liquid fill the cavity before solidification.

• The upper of two overflow should be widened out, same as the wide of overflow groove. The thickness of overflow groove should be between 1.2 –1.5mm. The upper of wavy exhaust groove should have over 30mm width, in order to increase the exhaust effect of the mould.

• The cross gate of this part is too long, and has an curved bridge on it (refer to photo), which impacts on heat rejection, flow rate, and poor filing into the parts. 

• By changing the flow direction of the inner gate, let the aluminum alloy liquid to be sprayed into the deep cavity of the pins directly, this can only solve the cold spots/porosity which close with inner gate, but no effect on the pins which far from the inner gate.

Do not spray too much release agent on the cavity of pins, to avoid the release agent cannot be sent out quickly at the deep cavity.

• During the pins with release agent, the parts should be dry in the deep cavity by the direction of pins.

• The use of vacuum die casting will also facilitate the filling of alloy liquid, which can help eliminate the cold insulation defects of the cast.

How to send out the heat on pins?

A. For the die of the heat sink structure, it is recommended to adopt the splicing structure to form the cavity of the heat sink. In order to vent gas from the mating gap of the splice.

B. In order not to affect the structure and strength of the mold, it can also be shown (refer to below photo), at the back of the mold, that is, at the top of the heat sink splicing and inserting a piece, forming the top cavity of the heat sink, so that it can not only use the matching gap of splicing and inserting to exhaust, but also easily clean out the aluminum material of the adhesive mold after the adhesive mold.

C. For the top of the heat sink, a flat top rod or a small circular top rod (refer to below photo) should be set to push out the heat sink. This is not only conducive to the release of the heat sink, but also can use the gap between the top rod and the mold to discharge some gas.

Have a project in mind?

Wetron aluminum die casting services for lighting industrial parts are applied in several leading markets. We meet customers demands for high quality demands ranging from die cast housing, light cover, LED heat sink etc. We take great pride in our ability to optimize the tooling and manufacturing.

Contact us directly and find out more and also see how we can save you time and money on manufactured components.