Low-pressure injection molding provides custom over-molded cabling solutions using standard low-cost connector components. Today's competitive marketplace is forcing manufacturers to re-assess all aspects of production - from raw materials affecting manufacturing lead time, to capital equipment. Time-to-market, production flexibility and cost containment are all critical elements to be considered while ensuring you meet customers' performance requirements. Low-pressure injection molding with hot melts is one manufacturing method that can improve existing processes and meet the needs of today's ever-changing technology landscape.
Low-pressure molding is bringing injection-molding capability to applications previously unserved due to either cost or processing challenges. The low-pressure injection-molding process utilizes polyamide resins to allow low-pressure filling of molds. The combination of the process and material offers many benefits to manufacturing costs and finished product performance. Injection molding is no longer cost prohibitive or inflexible to product changeovers. And, sensitive electronic components can now experience the protection and security offered by over-molding.
Resins Used in Low Pressure Molding
Resins used for these applications in the electronics industries can be of various chemical types.
Epoxy resins have been widely used for many years – they are generally hard and tough and exhibit low shrinkage on cure. They are characterised by an excellent level of mechanical properties, good high temperature performance and good adhesion to a wide variety of substrates – chemical resistance is also good. The cross-linking or curing process generally takes place slowly especially where small volumes of resin are involved. Fast cure hardeners can be used but these generate much heat during curing, giving rise to a high exotherm which can damage electronic components and cause high mechanical stresses on both components and the circuit.
Polyurethane resins are elastomeric or rubbery in their cured state and are preferred where circuits to be potted contain delicate components such as ferrites or glass reed switches. It is much easier to tailor the cure speed with urethane systems and the usable life and gel time of these can be adjusted to suit customer requirements, leading to faster process times and less work in progress. Polyurethanes show lower exotherm during cure than epoxies – the heat generated is not usually a problem, even for fast cure systems.
Challenges Facing Injection Molding
Any production process today must be efficient while allowing for flexibility to meet changing customer needs. Injection molding offers manufacturers the opportunity to seal and protect components from the dangers of ingress and movement. However, starting or retooling an injection-molding process is typically an expensive endeavor. In addition to the expense of the actual injection-molding equipment, including heavy presses, there is the cost of extensive water-cooling systems and fabrication of costly steel molds.
Benefits of Low-Pressure Injection Molding
- Safe for electronic components
- Quick Turnaround on Tooling/Molds
- Cost effective for short runs because of low-cost aluminum molds
- No scrap; polyamides are nearly 100% reusable
The low-pressure molding process utilizes inexpensive mold designs and simple dispensing equipment. Low-pressure injection molding uses aluminum molds, which are quick to produce, relatively inexpensive to manufacture and easy to integrate into the production process. Due to the low injection pressures, large X-ton presses are not required for mold closure. The reduced production time and cost allow lead times to be shortened and give the manufacturer the flexibility to meet specialized customer needs. The aluminum molds' low costs and reduced set-up times make them ideal for injection molding of short-run, low-volume specialty parts.
Interested in Learning More About Low-Pressure Molding for Cable Assemblies and Electronics?
We at JEM Electronics stay on the cutting edge of new technologies to ensure our clients receive the highest quality products with on-time delivery. If you are interested in learning more about molded cable assemblies please contact us today to discuss your next project.