Dip Moulding Process

The following explanation  breaks the process down into its various stages and although much simplified remains the basic principle regardless of tool and finished component complexity.

The tool(s) also referred to as moulds or formers are mounted on a jig or plate with sufficient drop to avoid dipping the tool and part of the jig into the plastisol.

The tool is then preheated in an oven temperature set and timed for a suitable period dictated by the tool quantity, tool wall thickness and required wall thickness of the moulding.

After preheating the tool is placed over a tank of plastisol for for dipping. Speed is dependent on the tool shape and may be variable over the length- fast for straight runs and slow for hollows, undercuts and flats.

The dip stops at a pre determined point and the tool allowed to dwell for a sufficient period as the material gels (builds up) around the tool to achieve the required wall thickness.

After the dwell time is up the tooling is withdrawn at a constant or variable speed again determined by the tool shape and placed into a second lower temperature oven to fully cure the material.

After curing the tool is quenched in water to cool the moulding so as it can be stripped from the tool. Full cooling is not desirable as retained heat will allow for easier stripping over complex shapes.

At this point the moulding is stripped from the tool by hand usually with the aid of compressed air. Stripping can also be aided by the use of a release agent.

The above is a basic outline of the process and there may well be additional operations that are carried out during the cycle such as a double dipping and cutting on the tool prior to stripping and post moulding operations such as hole punching, cut outs, slicing and printing.

The completed moulding will have faithfully reproduced all the tool surface details internally and this can be used to advantage. A reverse stamped part number or wording on the tooling will be reproduced perfectly as will a pattern such as knurling. In the case of the pattern the moulding can be turned inside out immediately after stripping, the inside then becoming the outside of the moulding displaying the perfectly reproduced pattern.

The process is perfect for small to medium batch sizes with a moderate amount of tooling but equally capable of high volume production. The major advantage here is that even with high volume tooling for large production runs the tool cost will still be a fraction of the cost of other moulding processes.