Frequently asked questions about mould sets
Are the gates on the mould much different than those used in traditional engineered plastics?
Typical gates are 2mm (0.080”) diameter and 0.5 mm (0.020”) long. A tapered design is normally recommended to ensure the gate brakes consistently from the component without any cutting.
Will a moulding profile be pre-determined for mould-sets provided by Overmould Ltd?
Yes, any mould-set from Overmould Ltd will be documented so that all moulding parameters can be entered directly. Some minor fine-tuning may be required as a result of different ambient conditions.
Are multi-cavity moulds practical considering the single station machine only has 1 ton clamping force and the shuttle and rotary machines only has a maximum of 5 ton clamping force?
Multi cavity moulds are normally used for all production moulding. 1 ton of clamping force may sound limiting, but with packing pressures rarely exceeding 10 bar (145 psig) this will normally allow for cavity cross sectional area of at least 80 square centimeters (12 square inches).
What is the delivery time for mould-sets?
Typically between 2-4 weeks.
What kind of mould release is recommended?
After extensive testing of a wide range of mould release agents, one product has shown superior performance. Mono-Coat E-255 from Chem-Trend Incorporated. We do not recommend the use of Silicone based release agents when over-moulding electronic components. Silicone can migrate over time resulting in partial electrical insulation and non-functional components.
Can the mould be plated to eliminate mould release?
The Technomelt® (Formerly Macromelt®) materials have strong adhesive properties and tend to stick to most surfaces. It may be possible to use some coating for permanent mould release, but we cannot recommend any specific coating systems at this time.
What are the best materials for the construction of the moulds?
7075 Aluminum is well suited for mould-set manufacturing. Aluminum offers excellent heat transfer (i.e. short cycle times). Aluminum 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 this area of the cavity. This is generally required when moulding connectors. Mould-set 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.