Scorching during Injection: Preventing Premature Vulcanization
Problem Statement
Premature vulcanization, or scorching, occurs during injection molding when rubber compounds cure before fully filling the mold cavity. This results in incomplete parts, surface defects, and compromised mechanical properties. Scorching is particularly problematic in high-temperature applications (>150°C) and with fast-curing compounds.
Material Science Analysis
Scorching arises from excessive heat generation during shear mixing or prolonged exposure to elevated temperatures. FKM (Fluorocarbon Rubber) exhibits superior resistance to scorching due to its high fluorine content (66-70%), which stabilizes the polymer backbone against thermal degradation. In contrast, NBR (Nitrile Rubber) and EPDM (Ethylene Propylene Diene Monomer) are more prone to scorching due to their lower thermal stability.
Technical Specs
- Material: FKM (Grade: Viton® GF-600S)
- Shore A Hardness: 75 ± 5
- Tensile Strength: 15 MPa
- Elongation at Break: 200%
- Temperature Range: -20°C to 200°C
- Compression Set (22h @ 200°C): 25%
- Chemical Resistance: Excellent against oils, fuels, and acids.
Technical Comparison
| Parameter | FKM | NBR | EPDM |
|---|---|---|---|
| Scorching Resistance | High | Low | Moderate |
| Temperature Range (°C) | -20 to 200 | -40 to 120 | -50 to 150 |
| Compression Set (%) | 25 | 40 | 30 |
| Chemical Resistance | Excellent | Good | Moderate |
Standard Compliance
RubberQ adheres to IATF 16949 standards to ensure batch-to-batch consistency. Our in-house compounding process controls polymer ratios, fillers, and curing agents to meet ASTM D2000 and ISO 3601 specifications. This eliminates variability and prevents premature vulcanization.
CTA
For custom material compound development or IATF 16949 documentation, consult RubberQ’s engineering department.
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