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Frequently asked questions
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Protect Electronics with Macromelt
Marcomelt is a versatile low temperature thermoplastic similar to the hot melt plastics widely used for glue guns. With its improved formulation, Macromelt is a consistent engineering plastic that has guaranteed mechanical and electrical properties suitable for the exacting standards of the electrical and electronic industries .
Marcomelt’s low temperature and pressure profile makes it especially useful for electrical and electronic applications. Its tensile strength makes it suitable for strain relief, for example, needing above 45kg/cm2 to yield. Electrically, it’s an excellent insulator–just 1cm of Macromelt withstands
200kV. At around 200 degrees it flows like maple syrup enabling it to be applied to electronic components and soldering at low injection pressure while achieving a mould definition suitable for a wide range of applications. Macromelt is a class of moulding between open pouring and high pressure injection moulding.
Protection
Light, insects, rain and dust are a few possible contaminants that affect function or long term reliability of electronic components. Encapsulation is a good strategy: low cost Macromelt makes it easy.
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A typical component for which environmental protection is desirable. This multi-turn potentiometer is fitted to equipment that has
potential for both water and dust pollution. Without Macromelt, the designer would need to provide a housing with fixings increasing cost, build time and design effort. |
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This is the multi-turn potentiometer encapsulated with Macromelt. It is fully sealed against moisture and dust and its reliability has been increased. Encapsulation requires little skill and throughput is fast enough for production processes.
If desired, identification marks or characters can be impressed in the mould tool and additional holes or fixings can be incorporated. |
Strengthening
Low cost mould tools for Macromelt can create components that add strength to vulnerable assemblies.
Strain relief
A popular application for wiring. Macromelt has adhesive properties enabling it to bond to wire casing. By placing the wire (or cable or bundle) in the mould tool, a strong plastic feature with holes or lugs etc. can be fixed to the wiring. Exposed joints can be enclosed.
Identity
Although quantity is required to make coloured Macromelt as economic as black or neutral, red, blue and other colours can be obtained for cosmetics or identity. But identity can be shown by letters, numbers or symbols and these can be engraved on the wall of the mould tool. Black Macromelt shows characters with good detail.
Blanking components, etc.
Sometimes a chassis part needs a shaped bung, or a cavity needs a cover. Perhaps a sharp metal feature need a plastic boot. When the component cannot be sourced from a catalogue, Marcomelt and low cost mould tooling can provide a solution. The applications are numerous and diverse. Think Macromelt!
Prototyping
Macromelt is a versatile plastic and will serve to make prototype casework and components from low cost tooling. Being a low pressure system, surface detail is below that possible with injection moulding but basic shapes and structures are excellent.
Insulation
At 10^13 ohms per cm^3, Macromelt’s insulation properties together with its physical strength make it suitable for mains protection and shrouding of high voltage. It ruptures above
200kV per cm. Its high volume resistivity means that it cannot disturb most electronic circuits.
Tamper proofing
Some assemblies must not be touched. If the assembly can be encapsulated, Macromelt is a good solution.
Pre-injection overmould
Integrating electronics into moulded structures gives designers ways to improve functionality and reliability. But injection moulding flow rates can be aggressive and assembly positioning can be a problem.
Fine wire structures, for instance, can be damaged within the stream of melt and
sensitive components can be thermally shocked.
Macromelt can provide a solution by pre-encapsulating vulnerable features at a low temperature and pressure and then presenting the protected assembly to the injection moulder for the final mould. This can also assist in positioning the assembly in the injection over-mould tool. By using Macromelt, reliability goes up.
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A simple low cost aluminium mould tool with basic shapes is all that is needed to encapsulate an assembly: and advantage of low pressure moulding. Here the spindle and wiring locate the component, the main cavity being a little larger than the body diameter. The mould halves locate on tooling pins.
Low cost and speed of production is a major benefit of Macromelt moulding. |
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Mould tools are made to suit the target machine so that registration and clamping are accurate and efficient. Here the gate for Macromelt entry can be seen at the top on the mould split line. The hole at the front is clearance for the potentiometer spindle.
Engineering Solutions can design and manufacture mould tools for your applications. If the application is non-critical, Engineering Solutions can work from sketches. Exacting requirements need engineering drawings. |
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After low pressure injection, the mould is released after a short cool down period. The component is then pushed out and allowed to cool fully.
The mould is then reassembled for another component. |
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