Impact Extrusions versus Other Processes

The impact extrusion process is a far superior process over the deep drawing process when the part design requires: (a) the base to be thicker than the side walls; and (b) when the shell length is more than twice the diameter. Deep-drawn parts are typically limited to a 1:1 wall/bottom ratio and a length width ratio of 2:1. The impact extrusion process typically has a wall/bottom ratio of 1:2 and is typically limited to a length/width ratio in aluminum of 8:1 and a 4:1 ratio in steel in a single operation. Further processing can triple these ratios. Cost savings are realized through the elimination of excess handling, lower tooling costs, and reduced labor costs. Additionally, material yields are much greater when using the impact extrusion process. Material yields typically are greater than 90% when using the impact extrusion process versus 80% or less using the deep draw process.

Impact Extrusion versus Forging

When the design of a part requires that it be strong, lightweight with minimal draft angles and the need to maintain close tolerances is necessary, the impact extrusion process is a better choice over a forging. Impacted parts have a surface area/mass volume ratio of 16:1 versus 6:1 for forgings. This allows impacts to have a much thinner wall section than a forging, resulting in a lighter weight part that exceeds or is comparable in strength to a forging. Another advantage of the impact extrusion process is its capability to consistently maintain tolerances in the 0.005” range versus 0.060” for forgings. The close tolerance capability of impacting in many cases eliminates the need for costly secondary machining operations.

Impact Extrusion vs. Casting

When the design of a part requires it to be light in weight yet strong with smooth surfaces, the impact extrusion process may be preferable to casting. In addition, thin wall parts may be produced using the impact extrusion process which would be difficult or impossible to cast. Parts produced from the impact extrusion process are 3% more dense for aluminum and 8% more dense for steel over the casting process. Often times the need to perform secondary machining operations are not necessary since the impact extrusion process has the capability to maintain closer tolerances over casting.

The raw material cost for the parts manufactured using the impact extrusion process is generally two to three more than material used in the casting process. This additional cost is attributed to the cost of additional labor to convert bars into slugs. However, the higher raw material costs are offset by savings in the tooling costs. Impact extrusion tooling generally costs between $5,000 and $10,000 per die set. Typical tooling costs for sand castings are $20,000 and up to $150,000 for a set of tools when using the die casting process.

Impact Extrusion vs. Stamping

The impact extrusion process offers significant advantages versus the metal stamping process by providing the capability of increased geometry, multiple wall thickness, and the elimination of sub-assemblies versus the stamping process. Impacting offers more complex geometry than is possible with deep drawn parts. Due to the limitations of the stamping process to produce parts with complex geometry, assembly operations often are required to produce a final part.

Impact Extrusions vs. Sub Assemblies

The impact extrusion process when used to consolidate or eliminate subassemblies offers significant cost savings and product improvements over the use of sub-assemblies. Cost savings are recognized by the conversion of many components into a single component and are often less costly to produce than individual components. Having a single component reduces the supplier base needed to support multiple components and lowers inventory costs.

The products performance is enhanced by the elimination of costly welds or other costly joining techniques. In most cases the need for costly inspections of joints is eliminated. Since the product is a single component it is much stronger than a sub-assembly and the potential for leaks is eliminated.