Overmolded cable assemblies power everything from rugged industrial robots to life-saving medical devices. But how exactly are these ultra-durable cables made? In this guide, we’ll break down the step-by-step manufacturing process, material choices, and quality standards that ensure reliability in harsh environments.
What Are Overmolded Cable Assemblies?
Overmolded cable assemblies are wires and connectors encapsulated in a protective layer of molded thermoplastic or rubber. This process:
Seals out moisture, dust, and chemicals.
Reinforces stress points to prevent fraying.
Customizes shapes and colors for easy installation.
Step-by-Step Manufacturing Process
1. Design & Prototyping
CAD Modeling: Engineers design the connector layout and mold shape.
Material Selection: Choose between TPE, silicone, or PVC based on application needs.
Prototyping: 3D-printed molds validate fit and function before mass production.
2. Wire Preparation
Cutting/Stripping: Wires are cut to length and stripped for termination.
Termination: Connectors (e.g., Molex, JST) are crimped or soldered.
Testing: Continuity and resistance checks ensure no defects.
3. Mold Creation
CNC Machining: Steel or aluminum molds are precision-cut for high-volume runs.
3D-Printed Molds: Used for low-volume prototypes (e.g., 50–100 units).
Mold Type
Material
Cost
Lifespan
Steel
Hardened steel
High
500,000+ cycles
Aluminum
Aerospace-grade
Medium
50,000–100,000 cycles
3D-Printed
Resin
Low
100–500 cycles
4. Overmolding Process
Mold Setup: Wires are clamped into the mold cavity.
Injection: Molten material is injected at 200–400°C (depending on material).
Cooling: The assembly cools for 30–120 seconds before ejection.
5. Finishing & Testing
Trimming: Excess material (flash) is removed.
Labeling: Laser etching or color-coding for identification.
Quality Tests:
Pull Testing: Ensures wires withstand 50+ lbs of force.
Hi-Pot Testing: Checks insulation integrity at high voltages.
IP Rating Validation: Submersion in water for 30 minutes (IP67/IP68).
Material Choices and Their Impact
Material
Temperature Range
Flexibility
Cost
Best For
TPE
-40°C to 90°C
High
$$
Consumer electronics
Silicone
-60°C to 200°C
Moderate
$$$
Medical, aerospace
PVC
-20°C to 80°C
Low
$
Indoor appliances
Overmolding vs. Other Sealing Methods
Method
Durability
Waterproofing
Flexibility
Cost
Overmolding
High
IP67/IP68
High
$$$
Potting
Moderate
IP54
Low
$$
Heat Shrink
Low
IP40
Moderate
$
Key Equipment in Overmolding
Injection Molding Machines: 100–500 tons of clamping force.
Robotic Arms: Precisely position wires in the mold.
Automated Testers: Perform continuity, resistance, and hi-pot checks.
Common Challenges & Solutions
Material Adhesion Failure:
Cause: Poor bonding between wires and overmold.
Fix: Plasma treatment or chemical primers for better adhesion.
Air Traps/Voids:
Cause: Inadequate venting in the mold.
Fix: Redesign mold with micro-vents or vacuum-assisted injection.
Inconsistent Wall Thickness:
Cause: Uneven cooling.
Fix: Adjust injection speed or mold temperature.
Quality Control Standards
IP67/IP68: Submersion tested at 1m (IP67) or 3m (IP68) for 30 minutes.
UL Certification: Complies with UL 2238 for safety.
MIL-STD-810G: Vibration and shock resistance for military use.
Real-World Applications
Industrial Robots: Overmolded power cables survive 100,000+ flex cycles.
EV Chargers: Withstand rain, UV exposure, and temperature swings.
Portable Medical Devices: Biocompatible silicone seals survive repeated sterilization.
FAQs
Q: How long does it take to create a custom mold? A: 2–4 weeks for CNC-machined steel molds; 3–5 days for 3D-printed prototypes.
Q: Can you overmold existing cables? A: Yes—if connectors are compatible with molding temperatures.
Conclusion
Overmolding transforms fragile cables into rugged, long-lasting solutions. By combining precise engineering with rigorous testing, this process ensures reliability in the most demanding environments.
Ready to design a custom overmolded assembly? [Contact us] for a free consultation—prototyping available in 10 days.
LDZY electronics is a China manufacturer of connectors and custom cable assemblies (flat ribbon cable assemblies, discrete-wire cable assemblies, overmolded cable assemblies)
