SL materials produce demanding prototypes

Valla specialises in rapid tooling and prototype manufacture, primarily in the white goods, medical and automotive markets, and uses ProtoFunctional material technologies for stereolithography.

Valla, based in Villeurbanne near Lyon in France, specialises in rapid tooling and prototype manufacture, primarily in the white goods, medical prosthesis and automotive markets.

With over 40 years of experience, Valla capitalises on its vast knowhow to offer advanced product development and tooling solutions, in part based on ProtoFunctional material technologies for stereolithography by DSM Somos.

Valla provides a complete service to its clients - design validation and models for photography, testing of design concepts with fully functional prototypes, and low volume production tooling.

In 1995, the company purchased an SLA250 machine, adding stereolithography (SL) to its rapid prototyping (RP) service offering.

Valla initially switched the SL material originally installed in its SLA250 to Somos 8110 resins in 1998, and soon after graduated to Somos 9110 resins, which provided Valla with a competitive edge in the demanding RP market.

Patrick Valla, President Director General of Valla, commented: "We could see great benefits in migrating to increasingly sophisticated materials for our SL applications".

"The flexibility offered by Somos 9110 resins made handling and finishing of SL parts far easier, as well as enabling us to offer fully functional models to our customers".

Continuing with the policy of offering high grade ProtoFunctional materials to its customers, Valla began offering Somos WaterShed in 2003 for the transparency and ABS like physical properties it provided.

Patrick Valla explained: "This material is perfect for us, it looks and behaves much like ABS".

"Its clarity is ideal for many of our white goods prototypes".

To continue this progress, Valla was looking for a premium grade white resin.

The company worked closely with DSM Somos engineers in Europe and the USA to specify the properties the new material required, and invested in an SLA5000 machine for the testing and development of the new resin.

This collaborative effort resulted in the creation of Somos White, with Valla being the first European company to work with it.

The reaction of Valla's customers was excellent.

"They particularly liked the look and feel of Somos White, which accurately simulates the texture of the finished product".

"We used the new material, in combination with Somos WaterShed, to construct the prototype for an electric iron for Calor, part of the SEB Group, which we exhibited at Euromold in Frankfurt", said Valla.

A further benefit highlighted by him is that Somos White has excellent machinability, opening up further opportunities for he or his customers to process on high speed machining centres parts made in the material.

Valla has proprietary technology which, combined with the ProtoFunctional capabilities of Somos materials, allows it to supply its customers with fully functional prototypes which can withstand high temperatures - up to 250C - at a fraction of the cost involved in traditional methods.

Normally this would require machining a prototype directly from high temperature grade plastic, or producing an aluminium mould which is then injected with suitable temperature resistant plastic - both very costly methods.

Valla first uses its SLA machine to create a detailed and accurate model using Somos ProtoFunctional resins.

This model is then duplicated in Valla's own high temperature resin, providing significant cost savings and enabling it to produce five complete parts in just 10 days, a difficult task for such a demanding application.

In addition to traditional manufacturing techniques, Valla also carries out production of low volume parts directly in ProtoFunctional SL resins.

Somos White has proved invaluable as an ABS simulant, particularly for applications where the parts are exposed to liquids or high humidity or when snap fit functions are part of the specification.

Valla added: "We have manufactured sets of elevator control buttons for people with special needs directly in Somos White; it is ideal for small batches of detailed parts".

He concluded: "We have definitely reaped the rewards of incorporating advanced Somos materials into all levels of our business, enabling us to offer technically superior and cost effective solutions to our customers".

Somos White and WaterShed are part of the Somos ProtoFunctional family of stereolithography resins.

In addition to mechanical properties which allow the resins to be used as an ABS simulant, the materials' specific chemistries produce exceptionally high photospeeds and minimise the "overcure" necessary when building parts.

These advantages allow maximum drawing speeds from the stereolithography machine, while drawing upon only a fraction of normal milliwatt usage (less than 100mW for an SLA5000 machine, and less than 70mW for an SLA3500 machine).

The potential for significant increase of the laser's lifetime can furthermore correspond to interesting cost reductions for the stereolithography machine owner.

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