Low-pressure molding is a superior method of encapsulating sensitive components. The different types of plastics used in low pressure molding are very important because they affect not only the strength but also the durability and thickness of the final product. PA is the material commonly used now in low pressure molding system. The reason is that the PA has higher mechanical properties and melting points. When you’re making a decision about your low pressure molding materials for your overmolding electronic design needs, you may find yourself facing a bewildering array of choices. Well, let us be your guide as we go through some basics for choosing a material for your electronics.
Overview of Low Pressure Molding
Low pressure molding is a process where plastic is injected into a mold under low pressure by low pressure molding machines. The injected plastic forms an overmold around the electronic component, protecting it from damage and providing strain relief. Because it requires less force to push the plastic into the mold, it's also more efficient than conventional overmolding methods.
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Watch More : Low Pressure Molding Process
Common Materials for Low Pressure Molding
The plastic that is used for this process should have characteristics such as, strength, strong fluidity, thermal stability and resistance to corrosion. The polymerization of the resin will take place in the molding machine where it is at a temperature of between 180°C and 240°C. The plastic must be able to flow around an object without blocking up any of the channels which are necessary for removing air from the mold during injection.
There are many different types of plastics that can be used for low pressure molding. Most commonly, the plastics PA is the polyamide synthetic polymer used in low pressure molding. The reason for this is that PA and PA alloy have higher mechanical properties and melting points. At the same time, a non-polar methylene structure is embedded between the amide groups of the PA molecular chain, and its structure can coexist in crystalline or amorphous regions, polar and non-polar structures, making PA macroscopically tough. In particular, the wire rod that uses PA material, with good friction and wear resistance, self-lubrication and fatigue resistance, has become one of the important reasons for its wide use as an engineering plastic.
The main PA material used for Low pressure plastic injection machine include :
- KY88** series (Kane New Material)
- Model BOSTIK (Bostik Findlay) TRL S.A. series
- TECHNOMELT (Henkel)® PA 668PA 2384
- And more
Bio-based Polyamide (Biopolyamides) is another material that is available for our low-pressure injection molding machines. It is a new class of bioplastics that are derived from renewable resources such as natural fats and oils.
All these low pressure molding materials are suitable for electronics related product applications for UV light resistance, thermal stability, solvent resistance and chemical resistance.
Tips to Select the Right Low Pressure Molding Materials
Low pressure materials can withstand higher temperatures than regular silicone rubber (SIL), so this makes them particularly useful for making electrical components such as heat sinks or connectors. They’re also ideal for making flexible parts like cables or wires because they don't require any post-curing time at elevated temperatures that would damage sensitive circuitry inside the device! Here are some tips for you to select the right materials for different applications.
-
Automotive electronic parts
: Because the ambient temperature is high, it is recommended that you choose high temperature resistant materials. -
Outdoor electronics
: These applications include wearable devices, bicycle components, devices for underwater use, or some sensors, which may require higher viscosity materials.
Versatile Low Pressure Injection Molding Machines
Most of the PA materials are suitable for King's low-pressure injection molding machines, especially modified PA materials or PA alloy materials, which are with improved strength, modulus, hardness, stiffness, and wear resistance. To meet the requirements of electronic devices, King’s Solution Corp put in tremendous efforts in R&D on low pressure molding injection machines. We continue to improve and enhance several functionalities in component sealing, moist-proof, water-proof, and dust-proof based on different characteristics of resins.
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Critical Steps in Understanding How to Process Them Correctly for Low Pressure Overmolding
In order to understand the characteristics of plastics, simple physical property inspections are generally performed before processing in factories, such as impact resistance, MI melting, softening point Ts, deflection temperature or thermal deformation temperature, tensile strain, and Young's Modulus etc.
In mechanical processing, there is especially a need to use screw shear mixing L/D ratio to inject, extrude, and mix color compounds, considering material applicability, matching mold design, and peripheral mold temperature machine temperature control.
In low-pressure plastic professional models with plastic flow characteristics, King’s technical team chose non-screw design and reflow, and back pressure controller.
The PA material is a polyamide synthetic polymer. The presence of the amide group shows water absorption. The amide in the amide is bonded, and the polymer is easy to crystallize. The higher crystallized polymers are, the lower the water absorption is. Therefore, dimensional stability and mold fit should be considered when using highly crystallized polymers. Consequently, it is very important to remove related and affective factors. Usually, lowering the moisture content is required. It is recommended to dry at 80°C for more than 4 hours. For products with higher softened temperature, then using a higher temperature and a longer drying time will help avoiding air bubbles or poor shape after forming.
Low Pressure Molding Machine Manufacturer
We hope that this article has helped you understand what materials are used in low pressure molding. Remember that it is important to choose the right type of material for your electronic overmolding project because they have different characteristics. The type of material will also determine how well it can withstand wear and tear over time, which affects its performance as well as longevity of use.
For more information about injection molding machines, please refer to Low Pressure Injection Molding Turn-Key Solution or contact us today.
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