Mould sets for low pressure overmoulding are normally manufactured from aluminium and precision-machined to form the features of the desired part. Aluminium is well suited for mold-set manufacturing due to its excellent heat transfer properties (i.e. short cycle times) and is economical from a cost and time perspective.
Aluminium mould-sets are relatively soft and care must be taken not to damage the cavity surface. If the component to be over-moulded has steel or hard glass filled components, it is recommended to have steel inserts in the mould cavity to reduce any wear on key tool components. This is generally required when molding connectors. Mould-sets can also be manufactured from tool steel such as P-20. It may be required to cross drill steel mould-sets to ensure sufficient cavity cooling.
When using non-abrasive Polyamide molding materials such as Technomelt from Henkel, combined with the low injection pressure, there is negligible wear on the mould-set resulting in a long and cost-effective operational life manufacturing tens to hundreds of thousands of parts.
Multi cavity moulds are normally used for all production moulding. With 1 ton of clamping force and packing pressures rarely exceeding 10 bar (145 psig) this will normally allow for cavity cross sectional area of at least 80 square cm (12 square inches).
Most production mold sets utilise ejector systems. Guide-pins and ejector-pins are sandwiched in between a base plate and a retainer plate. This sandwiched arrangement slides on shoulder bolts with return springs. Typical ejector stroke ranges from 3 to 10 mm depending on the application.
Release agent may sometimes be required for mould sets. A new mold set may require application of this release agent several times daily. Considerable research has gone into selecting the optimum release agent for this technology. After extensive testing of a wide range of mould release agents, here at Overmould we have concluded that one particular product demonstrates superior performance: Mono-Coat E-255 from Chem-Trend Incorporated. We do not recommend the use of Silicone based release agents when over-molding electronic components. Silicone can migrate over time resulting in partial electrical insulation degradation and non-functional components.
Low pressure moulding machines from Overmould are specifically designed to accommodate various mould tool sizes, and a typical tool change only takes a matter of minutes.
The HB500 Docking mold set offers cost effective interchangeable tooling, so only one dock is required and you can have limitless numbers of inserts for multiple applications.
Any mould-set from us will be documented including a pre-determined moulding profile so that all molding parameters can be entered directly. Some minor fine-tuning may be required as a result of different ambient conditions.
Delivery time for mould-sets is typically 15 – 20 working days.