Celanese Hostaform® C 9021 GV3/30
An In-Depth Analysis of a High-Performance, Low-Warpage POM Copolymer
1.0 Product Overview
Hostaform® C 9021 GV3/30 is a high-performance engineering thermoplastic developed by Celanese, belonging to the polyoxymethylene (POM) copolymer family. Formulated for injection molding, this grade is renowned for its highly crystalline structure that imparts an exceptional balance of mechanical, thermal, and chemical properties.
The designation "GV3/30" signifies a critical modification: the material is reinforced with approximately 30% by weight of glass spheres. This specific reinforcement is chosen to produce molded parts with exceptionally low warpage and high dimensional stability, making it a specialized material for precision components where maintaining tight tolerances is a primary design requirement.
Key Performance Attributes:
- Exceptional Dimensional Stability & Low Warpage: Isotropic glass sphere reinforcement minimizes differential shrinkage, ensuring parts hold their intended shape with high fidelity.
- High Rigidity and Hardness: Increased modulus and surface hardness for structural components that must resist deflection and indentation.
- Broad Chemical Resistance: Excellent resistance to solvents, fuels, oils, and strong alkalis, ideal for aggressive automotive and industrial environments.
- High Resistance to Thermal & Oxidative Degradation: Inherent property of the acetal copolymer backbone ensures long-term stability at elevated temperatures.
2.0 The Core Advantage: Dimensional Stability
The primary value of Hostaform® C 9021 GV3/30 lies in its solution to warpage, a common challenge in reinforced thermoplastics. The key is the use of isotropic (symmetrical) glass spheres instead of anisotropic glass fibers.
Chart illustrates the near-uniform shrinkage of Hostaform® C 9021 GV3/30 compared to the significant differential shrinkage typical in glass fiber-reinforced materials, which leads to warpage.
The molding shrinkage data provides quantitative validation. The shrinkage values in the parallel (1.7%) and normal (1.4%) directions are very close, with a differential of only 0.3%. This near-uniform shrinkage is the physical mechanism behind the material's advertised "low-warpage" and "dimensionally stable" nature.
Furthermore, its Coefficient of Linear Thermal Expansion (CLTE) is identical in both parallel and normal directions, ensuring parts expand and contract uniformly with temperature changes, minimizing internal stresses in precision assemblies.
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3.0 Mechanical Performance
The 30% glass sphere reinforcement provides a substantial increase in stiffness and creep resistance compared to unfilled POM, making it ideal for load-bearing applications.
Comparison of key mechanical properties between glass-sphere reinforced C 9021 GV3/30 and its unfilled counterpart (C 9021).
| Property | Value (SI) | Test Method |
|---|---|---|
| Tensile Modulus | 3900 MPa | ISO 527-1/-2 |
| Tensile Stress at Yield | 38 MPa | ISO 527-1/-2 |
| Nominal Strain at Break | 12 % | ISO 527-1/-2 |
| Flexural Modulus (23°C) | 3500 MPa | ISO 178 |
| Charpy Notched Impact (23°C) | 3.0 kJ/m² | ISO 179/1eA |
| Ball Indentation Hardness | 167 MPa | ISO 2039-1 |
4.0 Industry Applications
Automotive Components
Ideal for structural housings (window lift plates, gear housings), fuel system components (pump housings, filler components), and mechanical parts (gears, levers) due to its chemical resistance and stability.
Precision & Industrial Engineering
Serves as a metal replacement for bearings, bushings, rollers, pump impellers, and valve bodies, offering weight reduction, noise damping, and corrosion resistance.
Electrical & Consumer Electronics
Excellent electrical insulation (CTI of 600) makes it valuable for connectors, bobbins, and insulators. Its stability is key for small gears and chassis components in printers and appliances.
5.0 Injection Molding Guide
Proper processing is essential. While pre-drying is not normally required, the following parameters are a recommended baseline for optimization. A "gentle" approach with slow injection speeds and low back pressure is advised to maintain material integrity.
| Parameter | Recommended Range |
|---|---|
| Melt Temperature | 190 - 210 °C |
| Mold Surface Temperature | 80 - 120 °C |
| Injection Pressure | 600 - 1200 bar |
| Holding Pressure | 600 - 1200 bar |
| Back Pressure | 0 - 20 bar |
| Injection Speed | Slow |