Yes, hollow tubes can be produced using injection molding, though the process and technique differ from traditional solid part injection molding. Here are the primary methods used to create hollow parts, such as tubes, through injection molding:
1. Gas-Assisted Injection Molding
Overview
Gas-assisted injection molding involves injecting a gas (usually nitrogen) into the molten plastic during the injection process. The gas creates hollow sections within the part, which can be utilized to form hollow tubes.
Process
- Injection: Molten plastic is injected into the mold cavity.
- Gas Injection: Gas is injected into the molten plastic, creating a hollow section. The gas pressure pushes the molten plastic to the mold walls, forming the desired shape.
- Cooling: The part is cooled and solidified, and the gas is vented out.
- Ejection: The hollow part is ejected from the mold.
Advantages
- Material Savings: Reduces the amount of plastic used.
- Weight Reduction: Produces lighter parts.
- Improved Surface Finish: Can reduce sink marks and other surface defects.
- Structural Integrity: Provides good strength-to-weight ratio.
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2. Core-Back (Injection-Blow Molding) Technique
Overview
This technique is a hybrid process that combines injection molding and blow molding, suitable for creating hollow parts like tubes, bottles, and containers.
Process
- Injection: A preform (a smaller version of the final product) is injection molded.
- Blow Molding: The preform is transferred to a blow mold, where air is blown into it, expanding it to the final shape.
- Cooling and Ejection: The part is cooled and ejected from the mold.
Advantages
- Complex Shapes: Can produce complex hollow shapes with high precision.
- Consistency: Provides uniform wall thickness and consistent quality.
3. Insert Molding with Mandrels
Overview
Insert molding involves placing a pre-made insert (a mandrel) into the mold cavity, which shapes the internal hollow section of the molded part.
Process
- Insert Placement: A mandrel or core is placed into the mold cavity.
- Injection: Molten plastic is injected into the mold, forming around the mandrel.
- Cooling and Ejection: The part is cooled, and the mandrel is removed, leaving a hollow tube.
Advantages
- Precision: Allows for precise control of internal dimensions.
- Versatility: Suitable for various sizes and shapes of hollow sections.
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Considerations for Hollow Tube Injection Molding
1. Material Selection
- Thermoplastics: Common materials include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), and other thermoplastics with suitable flow characteristics.
- Reinforced Plastics: Glass-filled or other reinforced plastics can be used for added strength.
2. Mold Design
- Complexity: Molds must be designed to accommodate gas injection, blow molding, or mandrels.
- Cooling Channels: Efficient cooling is crucial to maintain part quality and reduce cycle times.
3. Process Parameters
- Pressure and Temperature: Precise control of injection pressure and temperature is essential to ensure the integrity of hollow sections.
- Cycle Time: Optimizing cycle time helps in reducing production costs while maintaining quality.
Related Conten: Plastic Parts Manufacturer
 DTG Mould Trade Process |
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| Quote: | According to sample, drawing and specific requirement. |
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| Discussion | Mold material, cavity number, price, runner, payment, etc. |
| S/C Signature | Approval for all the items. |
| Advance | Pay 50% by T/T |
| Product Design Checking | We check the product design. If some position is not perfect, or can not be done on the mould, we will send customer the report. |
| Mold Processing | Send report to customer once each week |
| Mold Testing | Send trial samples and try-out report to customer for confirmation |
| Mold Modification | According to customer’s feedback. |
| Balance Settlement | 50% by T/T after the customer approved the trial sample and mould quality. |
| Delivery | Delivery by sea or air. The forwarder can be designated by your side. |
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