Low-Pressure Molding

Custom Molding

Add Value, Protection, and Professional Appearance to Your Product


Low-pressure molding is a fast and efficient direct part, or over-molding process, using hot melt polyamide and polyolifin plastics. It achieves exceptional sealing and protection of mechanical, electrical, and telecommunications components with higher productivity compared to those materials widely used in current sealing processes: e.g., two-component casting/potting resins or silicones. This notable process is environmentally responsible and contributes to total cost reduction due to improved productivity and reduced waste.

There are a number of areas where the low-pressure process is advantageous over standard high-pressure molding with PVC, PE, ABS, or other materials, such as:

  • Product and component sealing/encapsulation
  • IP-rated grommets and strain reliefs
  • Easier molding on open barrel components
  • Reduced part or component damage due to low temp/pressure
  • Faster support for prototype/low-volume market testing
  • Reduced overall tool cost and lead time; 3-4 vs. 8-12 weeks

Enjoy total adjacency support to your low-pressure over-molding needs with our other core capabilities.

  • Cable/harness design and manufacture
  • Prototype and production box build
  • Low-pressure over-molding and potting
  • Expert new design and NPI services
  • Cradle-to-grave product value stream service
  • Cost reduction specialists
  • Re-shoring and near-shoring proficiency
  • Quick-turn support
  • Kanban program management

Protect your products against dust, moisture, strain, vibration, impact, and damage. Fourstar can quickly help you custom-design, build, and mold your designs using the latest in 3D-CAD, modeling, and tool development. Our technical staff has over 30 years of direct experience with over-molding, design, and development.

Low-pressure molding allows for more precise molding on unsealed connectors and open and exposed components. Fourstar is one of the few in the region offering this service to complement high-pressure molding.


At Fourstar, getting great molding results is easy and fast!
Customer Idea
Fourstar Manufacturability
Fourstar Over-Mold Tool Design
Final Product

Quick Turn, Low-Pressure, Excellent Results

Benefits to You

  • Time to market: cost-effective and quick turnaround for low volumes and prototype
  • Low volumes accepted: a bridge between prototype and production tooling
  • Reduced tooling costs: aluminum molds are quick and less expensive
  • Low-pressure process: allows for easier open-barrel connector over-molding
  • IP-rated protection: guards better than high-pressure molding against dust and water intrusion/immersion
  • Design flexibility: for custom connector angles: right angle, low profile, lanyards, inserts
  • Custom configurations: binding two or more connectors into a single connector pack

Low-Pressure Molding Product Groups

Component Encapsulation
The low pressure applied during the molding process prevents damage to sensitive electrical and telecommunications components. The molding compound protects the components from external influences (moisture, mechanical stressing, etc.), and is also capable of serving as a housing.

Connector potting
Hot melts are used for sealing connectors; also for adding sealed cable strain reliefs.

Grommet Molded in Place
The molding process can be used to mold grommets in place, which greatly supports IP-rated designs and allows adding sealed grommets.

Working Specs

  • Standard mold base size: L: 150mm x W:200mm x H: 112mm
  • Working mold design envelope: L: 100mm x W: 150mm x H: 80mm
  • Materials: polyamides
    • Harder, more rigid than copolyesters, providing excellent product protection
    • A desirable material for molded strain reliefs and encapsulation of electronics and PCBs
    • Viscosity between 2,000 and 7,000 CPS; flows very easily around large and small parts
    • RoHS compliant; REACH reports available; conflict minerals compliant


  • Machine: 1.5-ton, low-pressure Mold-Man molding machine
  • Can run low- to high-volume production quantities
  • Precisely meter shot sizes
  • Accurate control flow rates
  • Exact pressure control


Fourstar uses TECHNOMELT® to deliver customers an advanced and environmentally sustainable solution to component protection, using compliant, natural material and producing minimal waste.

Equipment Benefits Passed on to You

  • Low pressure, high-speed molding with adhesives for fragile and delicate components
  • Short cycle times and simple single-step process
  • Encapsulation of components provides complete sealing and subsequent environmental resistance

Types of Low-Pressure Molding Materials


Bring Your Idea to Us—We’ll Make it a Reality

Fourstar’s Customized Solutions
Fourstar collaborates with you to provide total and partial product solutions that include:

  • Design services and consultation for box builds, cabling, harnessing, and molding
  • Planning, cost reduction, supply chain management
  • New product design and introduction (NPI), design for manufacturing (DFM)
  • Quick-turn prototyping and production
  • Assembly and molding; domestic and volume manufacturing
  • Product reshoring services

Fourstar Connections partners with leading companies to “find a better way” for time to market, new product introduction, and design for manufacturing initiatives. How can we find a better way for you? Contact us to find out how.

Contact Us Now!