Scorching during Injection: Preventing Premature Vulcanization.

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.