Home >> R & D project into DMLS technology and conformal cooling

A research & development project (ANTIOPE) has demonstrated the importance of a new technology like DMLS for the tool making industry. Led by a French technical centre specialising in plastic injection moulding, Pôle Européen de Plasturgie (PEP), the project manager was Bruno Le Razer, who is now working in the DMLS team at 3T RPD Ltd.

One of the aims of the ANTIOPE project was to improve the DMLS technology in order to reduce the cost and leadtime of the production of inserts whilst maintaining or increasing the overall quality of the inserts.

French company LEGRAND, a leading manufacturer of electric fittings and wiring accessories, was keen to test the improved DMLS technology to produce more efficient inserts in a shorter time. One of the products chosen for the project was a wall socket in ABS (see Fig 1.) with a very high volume production (> 1 million parts a year). Two inserts; core and cavity; (Fig 2.) were designed around that part as shown.

In order to optimise the design of the cooling channel, the first step was to analyse the performance of the existing mould in terms of thermal performance. The simulation showed an uneven mould temperature distribution with a fairly high hot spot (around 75°C), which means that the quality of the part will not be optimum. (see Fig 3.)

The second step was to redesign the cooling channel to get a more uniform mould temperature distribution. With the inserts being produced layer by layer, there is nearly no limitation in the cooling channel design (see Fig 4.).

A new thermal simulation has shown that this time the mould temperature was more uniform and that the hot spot was lower (around 53°C), which will lead to a shorter cycle time and a better part quality due to a more uniform part temperature (see Fig 5).

A fully instrumented mould was produced using the DMLS inserts. A first set of inserts was built on an EOS M270 machine using the EOS DSH20 steel powder in 70h and fitted in the bolster in around 50h. (A second set of inserts was built recently using the new MS1 tool steel powder in 35h). The cost and leadtime of the mould were reduced by about 30%. Finally, during the injection moulding trial, the simulation results were confirmed in terms of mould temperature and cycle time.

This study has shown that by using the DMLS technology it is possible to significantly reduce the cost and the leadtime of a plastic injection moulding tool (results dependent of part geometry). The introduction of conformal cooling will lead to higher productivity and better part quality.

Finally, it is very important to do a full thermal simulation with various conformal cooling configurations to guaranty the optimum results in terms of productivity.

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