Challenge

To print 760 cable guides for ALSTOM to be used in American and European trains within a very short lead time, while improving the resistance of the cables to vibrations and avoiding damage through abrasion.

Objective

These parts must have fire safety certification (EN 45545 standard) and also meet the standard specific to the railway industry, namely level 2 of the 3-level “R1-HL2” fire hazard scale.

Production stages

I. The 3D design was carried out using Catia by an engineer of ALSTOM’s design department in order to create the new part and a 2D plan established from the 3D design submitted to Kimya.

II. Definition by Kimya of the appropriate material and printing profile:

The filament was exceptionally produced from granules normally used only in the injection process in order to speed up the overall process in this case. The filament is made of polycarbonate (PC) loaded with flame retardant additives.
Two months of iteration were required to achieve the dimensional and geometric tolerances and to meet the requirements of the particular standard:Numerous tests were performed on high-temperature machines to find the perfect temperature combination (nozzle and plate) in order to overcome the issues faced during extrusion and printing, due to the type of granules being used and the crystallization speed.
Compensatory measures have also been established to offset shrinkage of the part on cooling. The dimensions of the 3D part were increased during experimental iteration to allow for the reactions of the part after printing.
Manual post-treatment was carried out in two critical areas in order to minimize roughness.

Gains for ALSTOM

The parts were ready for delivery in just two months – twice as fast as with the classic injection process. Despite the higher cost of the part, the production savings associated with the absence of injection molding makes additive manufacturing more attractive for ALSTOM. This production process will therefore become standard for this part from now on.