Casting Study: Control Boxes

The control boxes for Minn Kota electric motors went through several design phases before settling on zinc die casting as the material/process of choice. The boxes were originally sand cast aluminium and later die cast aluminium. Short tool life prompted engineers to investigate other materials/processes for the control box. Since the control box cover is produced as an ABS moulding, engineers first looked to that material. However, to maintain the same degree of structural strength, material thickness needed to be substantially increased. Another hurdle associated with plastic is its inability to adequately dissipate heat, which is a design consideration for the control box material. For this application, engineers determined that die cast zinc would outperform both molded plastic and die cast aluminium through close dimensional accuracy, low porosity, good heat dissipating characteristics, multiple finishing options, and extended tool life (estimated at 200 percent over the aluminium die cast tooling). After casting, the control boxes are powder coated for an attractive finish, which is also an important consideration in designing consumer products.