Are firefighting products suitable for injection machines?

Whether fire-fighting rubber products are suitable for molding with rubber injection molding machines needs to be comprehensively judged based on their specific needs, material properties and production processes. The following are key analysis points:

1. Features of rubber injection molding machines**

- **Advantages**:

- **High precision**: Suitable for complex structures (such as sealing grooves, special-shaped parts), ensuring dimensional stability (tolerance within ±0.1mm).

- **High efficiency**: Automated production (cycle time can be shortened by 30-50%), suitable for large batches (such as monthly production of more than 100,000 pieces).

- **Material utilization rate**: Reduce flash, and material waste can be controlled below 5%.

- **Limitations**:

- **Equipment cost**: The initial investment is relatively high (about RMB 500,000-2 million, depending on the model).

- **Material limitations**: Rubber with good fluidity is required (such as EPDM Mooney viscosity <60, silicone fluidity >150mm/s).

Compression molding

2. Typical requirements for fire-fighting rubber products**

- **Common products**: sealing rings (O-rings, flange gaskets), hoses (pressure resistance ≥1MPa), diaphragms, protective covers, rubber boots, masks, gloves, etc.

- **Performance requirements**:

- **Temperature resistance**: -50°C to 300°C (such as silicone rubber fire-fighting gaskets need to withstand more than 200°C).

- **Media resistance**: oil resistance (ASTM D471 test volume change rate <20%), acid and alkali resistance.

- **Flame retardancy**: in line with UL94 V-0 or GB/T 2408 standards. Generally, it is molded with brominated butyl rubber materials.

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3. Material and process compatibility**

- **Applicable materials**:

- **EPDM**: ozone resistant, aging resistant, suitable for injection with a Mooney viscosity range of 40-80.

- **Silicone rubber (VMQ)**: High temperature resistance, requires a dedicated hot runner system (barrel temperature 120-180°C).

- **Fluororubber (FKM)**: High chemical resistance, but poor fluidity (requires high pressure injection, such as 150-200MPa).

- **Not applicable**:

- **Thick-walled products** (such as shock absorbers with a thickness of >20mm), molding is more economical (vulcanization time is shortened by 50%).

- **Highly filled rubber** (such as carbon black content >40%) may cause excessive injection pressure.

**Brominated butyl rubber is corrosion-resistant, wear-resistant, fire-resistant, oil-resistant, etc.

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4. Comparison with other processes**

- ****:

- **Low cost**: Equipment investment is about 100,000-500,000 yuan, suitable for small batches.

- **Limitations**: Long cycle (5-15 minutes/piece), many edge burrs (subsequent trimming costs increase by 15%).

- **Calendering**:

- **Suitable for sheet materials** (such as fire blankets), but not for three-dimensional complex parts.

5. Decision-making recommendations**

- **Prioritize rubber injection molding**:

- The product is a precision seal (such as fire valve O-ring, requiring a sealing pressure > 10MPa).

- Monthly production exceeds 50,000 pieces, and fast delivery is required.

- The material is EPDM or silicone, and the formula is suitable for rubber injection molding.

- **Choose molding/other processes**:

- The product has a simple structure (such as a flat gasket), thick wall or super-large parts (such as fire water tank sealing strips).

- The material has poor fluidity (such as high hardness NBR) or contains a fiber reinforcement layer.

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6. Implementation steps**

1. **Material testing**: Verify the flow curve of the rubber in the injection molding machine (such as using a capillary rheometer).

2. **Mold sample**: Develop a multi-cavity mold (such as 1 out of 8) and optimize the gate position (to avoid weld lines affecting sealing).

3. **Process parameter optimization**: injection pressure (80-200MPa), vulcanization time (adjusted according to the rubber compound T90).

4. **Certification compliance**: Ensure that the finished product passes fire certification (such as UL, CE, CCCF).

If the product meets the requirements of high precision, complex structure and mass production, the rubber injection machine is an efficient and reliable solution, but the matching of materials and processes needs to be strictly verified. It is recommended to cooperate with professional rubber equipment

 suppliers to carry out samples (such as using T0 molds for 3-5 times) to reduce risks.