Overmoulding is a manufacturing process in which electronic components are encapsulated using a hotmelt material, for example Polyamides and Polyolefins. The low-pressure moulding process provides reliable protection from moisture, dust, and dirt as well as protecting against impact and vibration. A range of materials can be used to create durable, multi-functional products with improved protection, ergonomics, and design.
The materials used in low pressure overmoulding have a lower injection pressure and melting point which ensures that no delicate electrical components are damaged in the process, this also means that the material can be injected directly onto the PCB/connector/electronics. This technique is particularly popular in industries such as automotive, electronics, and medical.
At Overmould, we specialise in the gap between Potting and Conventional injection moulding: Low Pressure Injection Moulding.
What is Ovemoulding?
Overmoulding involves encapsulating electronics using hotmelt materials such as Polyamides. This technique is commonly used to improve product functionality, protection, or ergonomics. Overmoulding is particularly useful in applications requiring durable, protective enclosures for delicate components such as printed circuit boards (PCBs), connectors, wires, cables, or batteries.
The process of overmoulding typically involves injecting a specialised material–often suited for Low Pressure Moulding (LPM)–onto the base component. Materials like polyamides are commonly used due to their excellent flow properties and ability to create a watertight durable layer. For electronic components, the polyamide material is heated and delivered into a machined metal cavity tool using mechanisms such as air pressure, gear pumps, or piston pumps. This makes sure sensitive components, such as PCB, are completely encapsulated, providing mechanical protection and environmental sealing.
This process can be applied to various products ranging from medical devices to consumer products. This technique allows manufacturers to create innovative designs that meet specific user requirements.
How does overmoulding work?
Overmoulding works by injecting a polymer over an exposed substrate, whether this is a PCB, a power cable, or an electrical component, to create a durable seal and encapsulation to protect the part from dust, water ingress, moisture, vibration, and more.
Here’s the step-by-step for how this process works:
Step 1: Design Phase
Before the physical work starts, our team of specialist LPM designers create detailed specifications for both components–the rigid base & the overmoulded part as well as the mould tool. Often, this involves computer-aided design (CAD) software for precision.
Step 2: Material Selection
It’s important to choose the appropriate materials based on desired properties and the parts environment/usage. Some characteristics include, but are not limited to, UV stability, chemical resistance, temp resistance (high or low), shore hardness ratings, durability, adhesion, colour, flexibility, and many more.
Step 3: Tool Manufacture and Development
After the design of both the part and the mould tool is finalised and signed off, the development tooling is manufactured either in aluminium or steel (dependent on varying factors such as yearly volume, features, size & complexity of the moulded part): There are also options for a 3D printed tool for rapid prototyping of parts.
Once ready, the mould tool undergoes surface treatment, (if necessary e.g. cleaning or priming), to support the removal of the part. The metal tooling is then trialled on site and first-off samples are sent to the customer for approval.
Step 4: Overmoulding Process
The unmoulded part (PCB/connector/component) is placed into the mould cavity where the hotmelt Polyamide material is injected around it under low pressure. The material can be injected via air, a piston pump, a gear pump, or an extruder (this again depends on the material chosen and the spec of moulding equipment). The heat from the process acts as an adhesion promoter and helps the bond between the material and original part.
Step 5: Cooling & Ejection
After injecting the polyamide material into the mould cavity under pressure, cooling occurs (again under pressure) so that material sets & cools before being ejected from the mould. The curing/cooling process typically takes 15-60 seconds depending on the size & complexity of the part. After the 60 seconds curing time, you can hold a part in your hand.
Step 6: Quality Control
Each individual moulded part undergoes rigorous testing and quality checks to make sure they meet industry standards regarding strength, adhesion between layers, aesthetics, etc., before being packaged for distribution. We have various quality control measures in place.
What are the benefits of Overmoulding?
Overmoulding provides versatile solutions to manufacturing challenges by combining different materials to improve product durability, functionality, ergonomics, protection, and appearance. The advantages of overmoulding are numerous:
1. Protection from Industry Environments
One of the primary reasons for using overmoulding is to protect the delicate electronics from moisture, dirt, dust, impact, and vibration.
2. Improved Aesthetics
Overmoulding allows for creative design possibilities by combining different colours and textures in one product. This not only enhances visual appeal but also helps brands differentiate their products in competitive markets.
3. Two-Stage Moulding
Using two-stage LPM in your process can solve all your industry needs. The combination of materials in an overmoulded product often leads to increased durability. The inner layer (the Pre-mould) can protect component from moisture, dust, dirt, the vibration, impact etc. This fills the bulk of the part. The second layer (the overmould) can act as a more attractive cosmetic layer.
4. Cost-Effectiveness
The initial setup for overmoulding is generally much lower than traditional injection moulding methods, which means that it can lead to cost savings in the long run. Fewer assembly steps are required since multiple components are combined into one part during production.
What materials are used in overmoulding?
A range of materials can be used in overmoulding to achieve specific functions and properties, including:
- UV Stability
- A range of shore hardnesses
- Colour (the ability to colour a material using a masterbatch)
- High temp/low temperature resistance
- Alcohol & chemical resistance
- Adhesion
- Flexibility
- Up to IP68 standard
Which industries use overmoulding?
Overmoulding has applications across different industries. Here are some of the most common:
Aerospace & Defence: Overmoulding to meet complex specifications, rigorous production processes and the highest levels of compliance.
Automotive: Overmoulding of complex electric, electronic and non-electronic systems to deliver products with unwavering reliability.
Environmental: Overmoulding to create products that need to withstand a variety of harsh conditions in many different environments.
Electronics: Overmoulding of electronics to deliver effective IP rated packaging / enclosure, strain relief and cable sealing in one easy step.
Lighting & Entertainment: Overmoulding to ensure powerful, user-friendly, robust products that perform consistently and reliably.
Medical: Overmoulding to meet the highest quality standards and reliability using the correct medical-grade plastic.
Understanding what overmoulding is shows its significance in modern manufacturing processes across different industries. By injection a low-pressure moulding material in one shot through careful design considerations and precise execution steps—from initial concept through quality control—overmoulding stands out as an innovative solution tailored towards improving user experience while optimising production efficiency!
Whether you’re looking at ergonomic tools or electronic devices with improved functionality, contact us today to discuss low pressure moulding or product prototyping for your next project!
