Short Shots: Diagnosing Incomplete Mold Filling in Complex Parts
Problem Statement
Incomplete mold filling, or short shots, occurs during injection molding of complex rubber parts. This issue compromises part integrity, especially in high-precision applications like EV battery seals or AI server gaskets. Root causes include improper material flow, inadequate mold design, or suboptimal processing parameters.
Material Science Analysis
Short shots often result from high viscosity polymers or insufficient curing time. FKM (Fluorocarbon Rubber) excels in high-temperature applications due to its fluorine content, which reduces viscosity at elevated temperatures. EPDM, while cost-effective, struggles in high-pressure cycles due to its lower tensile strength. HNBR offers a balance of chemical resistance and flowability but requires precise temperature control.
Technical Specs
- FKM: Shore A Hardness 70-90, Tensile Strength 15-20 MPa, Elongation at Break 150-250%, Temperature Range -20°C to 200°C.
- EPDM: Shore A Hardness 50-90, Tensile Strength 10-15 MPa, Elongation at Break 200-400%, Temperature Range -50°C to 150°C.
- HNBR: Shore A Hardness 70-90, Tensile Strength 20-25 MPa, Elongation at Break 100-300%, Temperature Range -40°C to 180°C.
Technical Comparison
| Parameter | FKM | EPDM | HNBR |
|---|---|---|---|
| Shore A Hardness | 70-90 | 50-90 | 70-90 |
| Tensile Strength (MPa) | 15-20 | 10-15 | 20-25 |
| Elongation at Break (%) | 150-250 | 200-400 | 100-300 |
| Temperature Range (°C) | -20 to 200 | -50 to 150 | -40 to 180 |
| Compression Set (%) | 15-25 | 20-30 | 10-20 |
| Chemical Resistance | Excellent | Good | Very Good |
Standard Compliance
RubberQ adheres to IATF 16949 standards, ensuring batch-to-batch consistency in material properties. Our in-house compounding process controls polymer ratios, fillers, and curing agents to meet ASTM D2000 and ISO 3601 specifications. This eliminates variability in viscosity and curing behavior, reducing the risk of short shots.
CTA
For custom material compound development or IATF 16949 documentation, consult RubberQ’s engineering department.
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