Manufacturing of Die Cast Trucks

The Manufacturing of Die-Cast Trucks

Despite their specialized purpose, die-cast trucks are designed and manufactured in much the same way as die-cast components used for industrial and home applications. From die design through the die-casting and finishing processes, die-cast trucks follow a straightforward path on the road to retail sale.

Designing Die-Cast Trucks for Manufacturability

The first step in the manufacturing process is to design the die for the truck parts. Each part has to be designed for manufacturability so that each part can be properly cast, removed from the die, and has the proper strength to maintain its shape when assembled and handled. Next, a metal alloy must be chosen for the truck parts. Zinc alloys are commonly used because parts can be made with close tolerances with minimal shrinkage after the metal has cooled. Zinc is often alloyed with aluminum to improve the metal’s strength and hardness. Zinc alloys can handle the hot chamber process, resulting in faster manufacturing and cooling times.

The Hot Chamber Die-Casting Process

The die-casting process begins by assembling the die. The die may have multiple cavities for multiples of the same part, or one die may contain different cavities for different parts. The die is assembled with inserts as required and the sprue pin is inserted in the sprue hole in the die. The die is then clamped together to minimize the amount of flash that extrudes out of the seams of the die.

The injection mechanism of the hot-chamber casting machine sits in the molten metal of a holding furnace. The furnace is attached to the die assembly by a gooseneck. The injection cylinder plunger is pulled up, and a port in the injection cylinder opens, allowing molten metal to enter the cylinder. When it is time to cast the part, the plunger is pushed downward, forcing molten metal through the gooseneck and nozzle into the die cavity. The metal flows through the nozzle, around the sprue pin, through the runners and gates into the die cavities. A die may have an overflow cavity to ensure that the main cavities fill completely. The die-cast part is then allowed to cool in the die. The die may also contain a waterline to speed up the cooling process. After the metal has solidified in the die cavity, the plunger is pulled back, and the die can be opened and the casting can be ejected.

Die-Cast Part Finishing

After a die-cast part has been removed from the die, it needs to be finished before it can be assembled into the final product. First, any excess material, such as flash or sprue, is removed from the part. The die-casting process generally produces a good surface finish, so not much post-casting machining is required. After the excess material has been removed and the seams cleaned up, the part can be plated or painted, depending on the function of the part. At this point, the part can be included in the assembly of the truck.

Sources

Engineering Fundamentals - http://www.efunda.com
North American Die Casting Association web site - http://www.diecasting.org/