Materials Moulds for reinforced plastics made lighter, cheaper

Editor: Eric Culp

A metal coating can create moulds for carbon- and fibreglass-reinforced plastics from a range of substrates, according to its supplier.

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Spray-on metal can create thin surfaces on moulds for fibre-reinforced plastics. Here, the process has been used to make a mould for a motorboat hull.
Spray-on metal can create thin surfaces on moulds for fibre-reinforced plastics. Here, the process has been used to make a mould for a motorboat hull.
(Source: VeroMetal)

VeroMetal said the company's FormProtect coatings are being used successfully for manufacturing moulds for fibre-reinforced components (CFRP, GFRP-components). The process seamlessly applies metal to almost any surface via cold spraying or with the application of a putty-type product.

Creating a metal surface on nearly any substrate

The coatings can be used to treat almost any substrate, the supplier claimed. The first step of the process is to apply the material, which can be done with a conventional paint spray gun. Once an item is coated with the material, the treated surface is said to take on all the characteristics of high-grade metals concerning impact resistance and abrasion. When compared to the conventional plastic coating systems, the product reportedly has much better edge strength and abrasion resistance. Treated moulds are claimed to have superior service life compared to conventional moulds coated strictly with plastics. When compared with galvanic coatings, the layered metal coatings are much less expensive, according to the supplier.

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The adhesion between the VeroMetal FormProtect topcoat and the laminated layers underneath is said to be excellent for both heated as well as non-heated moulds. Heat resistance is quoted at up to ca. 150C, and the company said the coating creates moulds with uniform temperature distribution.

The good spraying properties of VeroMetal allow for very homogenous and thin topcoats, the supplier noted. These topcoats have shown less vulnerability to micro-cracks, which can occur from tension between the different layers. Such tension can be created by the different thermal expansion coefficients of CFRP moulds and topcoats.

Superiority said to cost just a tad more money

The FormProtect layer systems with metal reinforcement are said to be "clearly technically superior" to plastic coating systems, but they are only marginally more expensive, according to the supplier. Applying the material by spraying requires no significant procedural changes in the process of building moulds or master forms, the company noted.

VeroMetal said development of the product was supported by Professor Herbert Funke from the Dortmund University of Applied Sciences and Arts and Jens Brandes from fibretech composites GmbH. Both are said to have many years of experience in the development of moulds and have been working together with VeroMetal on the concept.

The company said the products offer metal coating thicknesses ranging from 100µ up to 800µ. Along with spraying, the material can also be applied in-mould and with a roller. Once the surface has been added to the substrate, it is said to offer high resistance to abrasion and pull-off.

Another advantage of the metal coating is its ability to extend the life of moulds, the company said. In addition, the product enables easier manufacturing at a lower cost because it enables the creation of lightweight tooling. This allows for the replacement of expensive galvanic and heavy aluminium moulds.

VeroMetal's Dieter Lehwald told ETMM that the company's product is currently being used by a firm that manufactures rotors for windmills in the power generation industry and another which makes 12m masts for sailboats.