Learn Cable Over-molding

Learn Cable Over-molding

Over-molding divide into inside molding and outside molding.

Cable/Wire harness over-molding mainly has the following functions:

1. Organization and fixation: Organize messy wires, cables, etc. into bundles so that they are arranged in an orderly manner for easy installation and maintenance.

2. Cable protection: Prevent the cable from being damaged by wear, pulling, etc., and extend the service life of the cable.

3. Improve safety: Reduce safety hazards such as short circuits and leakage caused by cluttered cables.

4. Improve appearance: Make the wiring inside the device or system neater and more beautiful.

5. Easy to identify and manage: Cables with different functions can be distinguished through specific molding methods to facilitate subsequent management and operation.

6. Enhance electromagnetic compatibility: Reasonable wire harness shaping helps reduce electromagnetic interference and improve system stability.

Here are some common over-molding methods:

1. Braiding: Use braiding material to braid the cables together to form a bundle.

2. Wrapping: Use tape or other materials to spirally wrap around the cable to fix it.

3. Sleeve: Pass the cable through a special sleeve to achieve shaping and protection.

4. Crimping: The cable is fixed and formed by crimping terminals and other methods.

5. Injection Molding: Put the cable into the mold and inject plastic and other materials to form it.

Injection molding is a common wire harness forming method.

First, the wire harness to be formed is placed in a specific mold, and the shape of the mold is designed according to the final shape of the required wire harness. The molten plastic material is then injected into the mold cavity. During the injection molding process, the plastic fully fills all parts of the mold, tightly wrapping the wire harness. As the plastic cools and solidifies, the wire harness is held in place, creating the finished wire harness in a specific shape.

The advantage of injection molding is that it can achieve highly precise and complex-shaped wire harness molding with good stability and consistency. It can provide better protection for the wiring harness from the influence of the external environment, such as wear, vibration, moisture, etc. At the same time, this method can also improve the overall aesthetics of the wiring harness.

However, injection molding also has some limitations, such as higher mold costs, potentially relatively long production cycles, and may not be economical for low-volume production. But for large-scale wire harness production, injection molding is still a very effective method.

Below is outside molding illustration:

Molds for injection molding can usually be made of the following materials

1. Steel: such as carbon structural steel, alloy structural steel, etc., with high strength, wear resistance and good thermal stability.

2. Cemented Carbide: High hardness and strong wear resistance, suitable for high-demand injection molding production.

3. Aluminum Alloy: Lighter in weight and better in thermal conductivity, it is often used in some molds that have weight requirements.

4. Copper Alloy: Has good thermal conductivity and corrosion resistance.

5. Mold steel: Specially treated mold steel has excellent comprehensive properties.

Here are some factors that affect injection molding quality:

1. Temperature: Including barrel temperature, nozzle temperature, mold temperature, etc. Temperature that is too high or too low will affect the melting, flow, cooling and solidification of plastic, thereby affecting the quality of the product.

2. Pressure: Injection pressure, holding pressure, etc. play an important role in filling and compacting the melt. Improper pressure may lead to problems such as insufficient filling and flash.

3. Injection speed: Too fast or too slow may cause defects such as bubbles and weld marks in the product.

4. Mold design: The structural rationality of the mold, cavity surface roughness, exhaust system, etc. will directly affect the dimensional accuracy, appearance and demoulding of the product.

5. Plastic material properties: Characteristics such as fluidity and shrinkage have a great impact on the molding quality.

6. Molding cycle: Unreasonable settings such as cooling time, mold opening and closing time, etc. will affect product quality and production efficiency.

7. Gate design: The location, size and shape of the gate play a key role in the flow of the melt and the quality of the product.

8. Screw speed: affects the plasticizing effect and uniformity of plastic.

9. Back Pressure: Appropriate back pressure helps improve melt quality and product performance.

10. Environmental factors: Such as humidity, cleanliness, etc. may also have a certain impact on the product.

Common defects during the injection molding process mainly include the following:

1. Undershot (short shot): The plastic fails to completely fill the cavity.

2. Flash (overflow): The plastic overflows the mold cavity to form excess parts.

3. Sink marks: Local depressions appear on the surface of the product.

4. Bubbles: Cavities formed inside the plastic.

5. Weld marks: Traces formed when two or more strands of melt merge.

6. Warp deformation: The shape of the product is distorted or bent.

7. Silver streak: Silver streaks appear on the surface of the product.

8. Poor surface gloss: The surface of the product is not bright enough.

9. Scorch: The plastic is partially carbonized due to overheating.

10. Dimensional deviation: The size of the product does not match the design requirements.

Here are some ways to fix sink mark defects in injection molding:

1. Adjust process parameters: Appropriately increase the injection pressure, extend the holding time, and increase the compaction of the melt.

2. Optimize mold design: Reasonably set the location and number of gates to ensure that the melt evenly fills the cavity; add cooling water channels to make cooling more uniform.

3. Raise the mold temperature: But be careful not to make it too high to avoid causing other problems.

4. Control plastic materials: Choose materials with smaller shrinkage to ensure stable material quality.

5. Adjust injection speed: Avoid injection speed that is too fast or too slow.

6. Increase the amount of shrinkage: When possible, add some extra plastic to compensate for shrinkage.

7. Improve product design: Try to make the wall thickness of the product uniform and avoid excessive thickness or thinness in local areas.

8. Polishing the mold: Improve the surface finish of the cavity and reduce the melt flow resistance.

9. Accurate control of material temperature: Ensure that the plastic is fully melted and the temperature is uniform.

10. Enhance post-processing of products: such as appropriate heat treatment, etc.