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CNHi produces castable design for tension arm

CNH Industrial (CNHi) develops and manufactures machinery for the agricultural and construction sectors. The company strives for continuous improvement of its machinery and therefore wanted to optimise a component, namely the tension arm of a drive - an adjustment that needed to be made at short notice.

From welding to sand printing

The original piece consisted of a welded structure made up of three parts. The rigidity of the tension arm had to be increased to improve the alignment of the belt drive mechanism. CNHi consulted Sirris about this matter. A cast product was chosen for this application, and so Sirris chose sand printing as the manufacturing technique for the prototype moulds of the new design.

A new design was obtained by means of a topological optimisation. This optimisation involved consistently working on the basis of the requirements imposed on production by traditional techniques.

Feasible and affordable

If this software is given completely free rein, then it comes up with a very complex geometric design which, because of the numerous recesses and undercuts, is difficult to manufacture with conventional casting techniques. Another key requirement for the customer of course is that the end solution is affordable. By imposing a number of restrictions on the numerical model, a new geometry was obtained that could meet all these requirements.

Ready for conventional casting techniques

This geometry was checked in terms of castability: the ratios between the various sections, minimum wall thicknesses, and so on. The maximum torque of the final designis significantly lower than in the original model, and satisfies amply the predetermined requirements. The sand moulds for the prototypes were manufactured using sand printing technique with the aim to perform functional tests at the earliest possible opportunity.

The final design of the tension arm is ideal for manufacturing these components in a single production phase using traditional casting techniques.