Water Injection Technology offers Higher Quality and Shorter Cycle Times, TECHNYL® grades and technological support for Water Injection Technology (WIT) applications from Rhodia Engineering Plastics.

Rhodia Engineering Plastics is a global material supplier for PA 6 and PA66. The company is dedicated to develop materials that offer the properties to achieve high quality under-the-hood automotive applications with the highest requirements, such as in cooling systems of car engines.

A promising new technology in the production of such applications is Water Injection Technology (WIT), which just led to the first commercial applications. Rhodia visits K 2001 with a clear and competitive edge in WIT, that is set to win the company new business in a number of automotive markets. Rhodia sees highest demand for its WIT-moulded PA 6 and PA 66 materials in thin walled components and demanding under-the-hood automotive applications.

The automotive technical support team at Rhodia Engineering Plastics built its own WIT mould and injection unit and developed the new WIT materials specifications from first-hand manufacturing experience. The Rhodia WIT development team gave particular focus to the glycol resistance of the engineering thermoplastic, the thickness of the walls – (required to be constant) and the inner surface quality.

The Rhodia engineers used several moulding techniques in their research, such as pushback (see figure 2 below), side-cavity moulding and pre-filling.

Rhodia’s researches established a market for high quality automotive parts with hollow profiles; these cavities being needed, either for mechanical reasons or for the transit of fluids. Rhodia’s resulting WIT system gives automotive suppliers a way to mould these parts with greater precision, while adding the benefit of reduced shrinkage and warpage. The automotive market, in fact, gives Rhodia a number of WIT opportunities for many components; such as handles and pedals, ducts for heating and cooling and structural parts such as front-ends and roof-rails.

Even though WIT competes with Gas Injection Technology (GIT) for many applications, WIT outscores its rival in a number of ways. The main advantage of WIT is the cooling effect of the injected water, which can lead to a reduction in cycle time of up to 70 %. For any moulder, this leap in productivity is hard to ignore. In addition WIT offers a reduction in part-weight due to the thinner remaining wall-thickness. In ducts and pipes WIT further offers better internal surface characteristics and a naturally flow-optimised cross-section.

These last characteristics are particularly important when developing ducts for automotive heating and cooling systems.

To be able to use the advantages of this new technology, manufacturers can draw on Rhodia’s expertise in designing and establishing WIT-units, as well as injection machines that have the appropriate interfaces. The research by the Rhodia’s automotive support team has already led to some promising results. Apart from the ongoing research of existing TECHNYL grades for use in WIT produced mechanical or structural parts, a number of standard grades have already reached the market. A TECHNYL grade especially developed for WIT produced cooling circuit applications will be available in the near future.