Frequently Asked Questions

What is the purpose of low pressure molding?

Low pressure molding is used for overmolding or encapsulating delicate or sensitive electronic components. It is also suitable for molding cables, creating strain relief, and provide wire fixations. This application provides protection against moisture, chemicals, corrosion, electrical shorts, physical impact, etc.

What are the advantages of low pressure molding over traditional potting process?

Low pressure only requires 3 steps whereas potting typically require 8 to 9 steps. Low pressure molding offers extremely fast production cycles with minimal labour.

Does the low pressure molding require housings for the components?

Low pressure molding can be applied to components pre-inserted into an engineering plastic housing. However, a housing is not typically required.

What is the typical cycle time?

Depending on the size and the use of material, typical production cycle time range between 15 to 45 seconds.

What materials do you use for low pressure molding?

Polyamide (PA), a thermoplastic provided by Henkel, is the material we use for low pressure molding. Polyolefin can also be used in some rare cases.

What is the viscosity of low pressure molding materials?

The viscosity can range from 1,000 to 10,000 cps when molten, but most materials have a viscosity of 3,000 to 7,000 cps for typical applications.  

What is the typical operating temperature of molded components?

The operating temperature is typically between -40 ºC to 170 ºC, and sometimes can go up to 185°C of short-term exposure.

Is PA UV resistant?

Some PA materials are UV resistant. Please refer to their TDS.

Is PA food grade?

Some PA materials have food grade certification provided by the manufacturer, Henkel. FDA certification are not typically provided.

What colours of low pressure molding materials are available?

Henkel’s Technomelt polyamide offers black, amber, white, and clear. Color blending is available, but the addition of pigments might alter the adhesive properties.

Can low pressure molding be applied to components with LEDs?

We have done numerous projects with LEDs. If the LEDs are for meant illumination, we suggest exposing the top surface of the LED chip, and cover the rest with regular opaque PA materials. In the case of extreme waterproof requirement, the use of PA 668 clear, or sealing the LEDs with clear epoxy can be an option. If the LEDs are only for indication purpose, we suggest overmolding them with amber PA materials, since they are widely available.

What typical IP rating can low pressure molding accomplish?

The achievable IP rating highly depends on the overmold design, the exposed areas, and the geometry of the components. Performing plasma treatment on the components before overmolding can enhance PA adhesion. Waterproof property can be as high as IP67.

What are the chemical properties of polyamide?

Polyamide, commonly called nylon, is a semi-crystalline thermoplastic which is composed of linear aliphatic segments that are connected by amide linkages. Nylons are resistant to many chemicals, including ketones, fully halogenated hydrocarbons, esters, fuels, and brake fluids.

What material is used for production molds?

We typically use NAK80 steel for production molds. Lifespan of the mold is usually 200,000 to 800,000 cycles.

What is the typical injection temperature and pressure?

The injection temperature is typically between 190 °C to 230 °C. When reaching the cavity, the temperature will rapidly go down to 150 oC to 190 oC, and drops even lower during cooling stage. Sensitive components are typically unharmed with proper temperature settings. Injection pressure typically ranges between 20 to 500 psi.

Can regrind materials be thrown back into the melting tank for reuse?

Since PA is a thermoplastic, it can be re-melted for reuse. However, for applications where adhesive properties are critical, we recommend to keep the use of regrind materials at minimum. Regrind materials may be contaminated with mold release agent, and could compromise adhesion performance.

Can delicate sensors or batteries be overmolded without damaging them?

Yes, we have done numerous successful projects with delicate components in the past. Mold and cavity design are very critical. We suggest perform some testing with prototypes before mass production.

Who does the CAD design?

We typically request CAD drawings of the component to be molded from our clients. We do the overmold and the mold design according to the requirements.