FAQs | Tarapath | Low Pressure Moulding

Frequently Asked Questions

How long is a typical injection cycle?

The molding cycle is dependent on the size and material section thickness of the component. Typical cycle time ranges from 15 to 60 seconds and that can be for single or multi-cavity mold-sets. Product handling may take additional time.


What are the best materials for the construction of the mould-sets?

Both tool steel and aluminium can be used for making low pressure moulding tools. There are pros and cons to both, so care should be taken when selecting the best material.

Aluminium has good heatsink properties, so can aid in dissipation of heat from the moulding cycle. It is also relatively easy to machine. It is however quite soft, so can be susceptible to scratching of the cavity surface. Tool steel overcomes this problem, but does not remove heat as well as aluminium. Cooling channels can be added to overcome this problem.

Whichever material is used, it is important to design the mould-sets specifically for the part, volume and material being used.


What is the minimum tolerance that the Technomelt materials can hold?

The Technomelt materials shrink 1 to 2% depending on the grade of material. This must be taken into account for critical applications. Tolerances of +/- 0.1mm can be met on smaller components. Packing of the cavities during injection can reduce shrinkage.


What is a typical injection temperature for these materials?

Melt reservoir temperature ranges from 180ºC to 230ºC. Depending on die-set design, this would typically correspond to cavity temperatures of 140ºC to 190ºC.


Can material regrind be used?

For applications where material mechanical and adhesive properties are critical, regrind should not be used. There can be some slight degradation of mechanical properties of the material from repeated re-melting.

For non-critical applications the runners can simply be thrown back into the melt reservoir without any regrinding. It is strongly recommended to confirm that component molded from “regrind” material meets the final component specifications.


Can the mold be plated to eliminate mould release?

The Technomelt materials are adhesives and tend to stick to most surfaces. It may be possible to use some coating for permanent mould release. Each application should be looked at individually, as clever part design, and tool design can eliminate the need for mould release completely.


How do these Technomelt materials compare to engineered resins economically?

Technomelt does not replace other plastic materials directly. If a component can be moulded successfully with PVC, there is no reason to consider Technomelt. If PVC moulding results in high scrap levels as result of high pressure, low pressure moulding may be more economical as result of reduced scrap, and lower tooling costs. More typically, the low pressure moulding operation replaces several manufacturing operations such as moulding of a plastic housing and potting with epoxy.


Can batteries be over-moulded without reducing their effectiveness?

Many types of batteries have been successfully over-moulded with Technomelt. However, a simple prototype overmould for a particular battery is recommended before starting full scale production.


Is there any distortion of the final component with this process?

No, not if normal design guidelines are followed. (Uneven encapsulation such as a very thick material section on one side of a PCB with a thin layer on the other could result in warping).


Who will prototype my parts?

Industrial Design, 3D CAD Modeling, Prototype Tooling, Prototype runs and Production Tooling is supplied by Tarapath, as well as prototype parts when necessary.


Does Tarapath provide start-up training on moulding equipment?

Yes. Start-up and training typically takes 4 to 6 hours depending on the number of operators and machine model.


Who will provide technical support for the materials?

Tarapath will supply both material and application specific support.


What is the delivery time for materials?

The OM product line is manufactured in Europe and warehoused in Melbourne. We generally keep significant quantities of each material above forecasted volumes. Accurate forecasts are critical as the lead time is 90 days for delivery from Europe to Australia.


What is the delivery time for machines?

12 weeks approximately.


What is the delivery time for mould-sets?

Typically 4 to 8 weeks.


What would be the price range for a typical production mould-set? Prototype mould-set?

There are many variables to take into account when considering the cost of tooling. We are often asked for ballpark figures. It is generally more useful to provide information about the project, part, application, volume etc. and receive an accurate quotation.

As a general rule, prototype tools are around 50% of the price of production tooling.


If mould-sets are provided by Tarapath, will a moulding profile be pre-determined prior to delivery?

Yes, any mould-set from Tarapath will be documented so that all moulding parameters can be entered directly. Some minor fine-tuning may be required as result of different ambient conditions, and in the situation that the customer’s machine type is not available for trialling.


What is the lowest pressure that parts can be molded at?

25 psi is typically the lowest practical pressure. For anything lower the runner and gate design become very critical.


What is the typical viscosity of the material?

Technomelt molding materials have a viscosity range of 3400-7000 centipoise at 210ºC. What can it be compared to in its molten state? In their fully molten state, Macromelt materials can be compared to maple syrup at room temperature.


How are air bubbles avoided in the final moulded part?

By ensuring that a mould-set is vented correctly and optimizing the injection profile. Densely populated circuit boards may require several steps in the injection profile to avoid any “shadow effects” behind components. In some cases two shots are required.


What is the maximum temperature that the materials can withstand during over-mould with a traditional resin?

This is very dependent on the components to be over-molded and the shape/size of the cavity. We cannot offer a clear rule of thumb.


What is the typical shrinkage of the material and will the part maintain dimensional stability after molding?

Shrinkage varies during injection and can usually be controlled by packing the mold with pressure. The shrinkage rate 24 hours after injection ranges from 1 to 2% for the different materials.


How are the materials packaged? Should they be dried prior to use?

Materials are shipped in metal 20kg bags. To retain best material properties, it is recommended to dry material prior to use.


Let us assess your product and see if Low Pressure Moulding is the solution you’ve been looking for.