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Tooling Considerations

The types of moulds used in the rotational moulding process are as follows. Rota Design balances the advantages, disadvantages and product design parameters in preparation of its recommendations.

Cast Aluminium

Cast aluminium moulds are predominant in many applications since it is relatively easy to replicate products with complex shapes and intricate detail. Textures and finishes may be imparted to the finished component by shot blasting, peening or simply polishing the mould surface. A pattern is required to define the basic mould shape and allowances for shrinkage during cooling of the casting have to be considered.

NC Machined

Rota Design take the 3D CAD design data and feed it into an NC machining centre to create a mould from a block of solid aluminium. This is a fast way of producing a mould in a cost effective manner, and with excellent accuracy.

Accuracy is important in the case of multiple moulds in order to minimise parting lines, especially where the product aesthetics are critical. The surface of the mould may be acid etched to provide texture or features.

Fabrications

Moulds fabricated from bright mild steel plate, stainless steel or aluminium are commonly used. Rota Design provide the plate development data for curves and complex shapes in a format ready for input into the laser cutting machine.

Large moulds may be fabricated using MIG welding, polished and sometimes coated with a smooth Teflon type finish. This surface finish assists in releasing the product from the mould and provides a resilient surface to the mould thus extending its life.

Surface texture is difficult to achieve using fabricated moulds but inset embossed patterns for company logos etc may be included.

Resin and non-metallic

Polyester and epoxy resins in liquid form may be used to produce moulds, however, their relative life is short and thus are normally restricted to prototyping and short production runs, of say, 100 components.

Rota Design provide advice based upon experience and the best balance for any given product design and application.