Tips & Tricks - machine bracket redesign
In this tip, we take a look at redesigning machine brackets to reduce the manufacturing cost. This can be done a number of ways, including changing the material, method of manufacture, and changing the load path.
Most machine brackets are either cast iron or welded steel. A quick comparison of material properties shows that for equal strength, steel sections can be 25% of the size of cast iron sections. For equal stiffness, steel sections can generally be 50% of the thickness of cast iron sections.
As weld metal is expensive, welded bracket designs push ahead of cast designs only when the amount of welding can be kept to a minimum, and high-speed downhand fillet welds are utilised. In many cases, components can be profiled or sheared from relatively thin sheet and bent to shape to reduce parts and weight. Thickness can easily be added where needed. Casting limitations on thicknesses and draft angles can often result in heavier components than their welded counterparts.
Comparative Bracket Analysis
As with any design, it is not a one-rule-fits-all situation. Depending on the production numbers involved, aesthetics, amount of welding, weight, part complexity and the dimensional accuracy required, both cast and welded brackets have their place.
The example opposite shows the improvements made in redesigning a simple cast bracket as a welded bracket. To ensure that the modified bracket performs to the same level or better than the original, a comparative analysis was run. Follow the link opposite to see the results.