Case study 1.
Fabrication becomes a casting.

The problem

One of DGI’s largest customers, a commercial vehicle manufacturer in the Midlands, had a problem with a long standing fabricated part, used on the vehicle suspension. Due to the rugged nature of the vehicle and frequent off road use, the part in question, a Damper Bracket, comes under severe loads which has resulted in a number of failures, where the bracket has bent or in some cases broken completely.

The resultant failure can leave the vehicle stranded, often in remote areas and a very costly warranty claim from the dissatisfied end user.

Evaluation of problem

The original bracket had passed FEA testing but the requirements of the bracket have now changed. To overcome the issue, the bracket would need to be redesigned to incorporate greater strength; unfortunately this involved thicker sections and strengthening ribs and the positioning of the bracket in relation to the steering mechanism, meant this was extremely difficult to accomplish with a fabrication.

Options

One aspect of the service that DGI provide is an evaluation of specific engineering problems and free and impartial advice on potential solutions, from their range of processes including investment casting, commercial grade investment casting, sand casting and die casting.

To achieve the relatively complex shape of the bracket and to reduce any commercial impact, the commercial grade investment casting option was agreed upon. Because the process enables complex tooling to be produced and a variety of sections to be cast, the required mechanical properties were achieved and comparisons made using DGI’s Cosmos stress analysis program, to show the old fabrication Vs the new cast version.

Added benefits

We at the Dean Group are always looking for opportunities to add value to parts, be they investment cast or otherwise. By adding value, we can reduce subsequent machining operations, improve aesthetics, add part numbers or company logo’s or in this case, incorporate a second item into the same casting. As you can see from the photo, there is a second part to the assembly which is clamped in place, shown painted red. Our solution incorporates the two items, reducing overall costs, inventory and actually producing a stronger component.

To view the edrw of the new part, please download the free eDrawing Viewer from the website link below.

Logistics

Having chosen a suitable material, a 3D CAD model was produced by DGI from 2D information supplied by customer. Bespoke casting simulation software is used to confirm sound cast integrity. The existing part was benchmarked using Cosmos stress analysis, to enable us to identify the weak sections of the fabrication and to enable us to compare our cast alternative.

DGI’s design was submitted to customer in both 2 and 3D formats complete with stress analysis comparison for approval; at this point a prototype part is an option but was not deemed necessary in this case.

Tooling orders are then placed and sample parts produced for formal approval and fit and function testing before production begins.

The outcome

A solution to a potentially expensive problem was achieved, producing a casting that is stronger, more aesthetically pleasing, lighter and cheaper than its fabricated predecessor. The resultant casting requires less post machining and has the added benefit of incorporating another part into the design.

This is a win win situation and one that could not have been achieved by simply producing a stronger fabrication.

> to top of page