GB/T 23641-2018 in English
VALIDFiber reinforced unsaturated polyester moulding compounds(SMC and BMC)for electrical purposes
- Issued on:2018-06-07
- Implemented on:2019-01-01
- File Format:PDF
- Delivery:Via email within 5 business days
$301.00
《GB/T 23641-2018电气用纤维增强不饱和聚酯模塑料（SMC/BMC）》由TC51（全国绝缘材料标准化技术委员会）归口，TC51SC1（全国绝缘材料标准化技术委员会电工用热固性模塑料分会）执行，主管部门为中国电器工业协会。
Introduction
Analysis of the core content of the standard
This standard specifies the technical requirements for glass fiber reinforced sheet molding compound (SMC) and bulk molding compound (BMC) based on unsaturated polyester resin (UP) and epoxy vinyl ester resin (VE), which are applicable to the field of electrical insulation. Compared with the 2009 version, the new version mainly adjusts the product classification system, performance index requirements and test methods.
Comparison of Material Classification Systems
| Classification Dimensions | 2009 Edition | 2018 Edition | Main Changes |
|---|---|---|---|
| Model Composition | Resin Type+GF Content+Characteristic Code | Resin English Abbreviation+Shape Code+Fiber Content+Formula Serial Number | Added a new formula serial number system and cancelled the characteristic code |
| SMC Model | 16 types | 13 types | Integrated some models with similar functions |
| BMC models | 10 types | 10 types | Maintain the number but adjust the performance indicators |
Key performance indicator analysis
1. Mechanical performance requirements
Typical SMC materials (UP-SMC-25a) have a flexural strength ≥ 180MPa and impact strength ≥ 75kJ/m²; BMC materials (UP-BMC-20a) have a compression strength ≥ 120MPa. Continuous fiber reinforced models (such as UP-SMC-35a) have a longitudinal tensile strength of more than 200MPa.
2. Improved electrical performance
- All modelsArc resistance time ≥ 180s
- Flame retardant materialsPTI index ≥ 600V
- Volume resistivity is generally required to be ≥1.0×1012Ω·m
3. Thermal performance specifications
UP-based materialsload deformation temperature ≥ 240℃, VE-based materialstemperature index ≥ 155, and the linear thermal expansion coefficient is controlled at ≤30×10-6/K.
Innovation of the test method
| Test items | Method improvement | Instrument requirements |
|---|---|---|
| Specimen preparation | Newly added profiling engraving process, requiring sampling from 300mm×300mm molded plate | CNC milling machine (4-edge flat-bottom milling cutter) |
| Compression performance | Adopt GB/T 1448 to replace the original method, speed 2mm/min | Universal material testing machine |
| Coefficient of thermal expansion | Specify the test range of 23℃~55℃, sample size 50×12.5×4mm | Quartz dilatometer |
Implementation suggestions
1. Material selection guide
- High-voltage insulation parts: VE-SMC-50b (temperature resistance 155℃) is preferred
- Structural support parts: UP-SMC-35a (continuous fiber reinforcement) is selected
- Scenario for flame retardancy requirements: Select a model with an oxygen index ≥31
2. Production process control
Compression molding recommended parameters: temperature 130-170℃, pressure 8-10MPa, curing time calculated as 20-60s/mm. Injection molding needs to control the injection rate 50-150mm/s.
3. Key points of quality control
- Glass fiber content deviation is controlled within ±2.5%
- Factory inspection items include 6 items such as bending strength and impact strength
- Storage temperature ≤25℃, valid for 3 months
Transition plan between old and new standards
It is recommended to refer to the model comparison table in Appendix B for product upgrades, with focus on:
- Original UP-SMC, GF25, Q, LS, E3 correspond to the new model UP-SMC-25a
- Electrical tracking resistance is no longer a general requirement
- New semi-conductive models (UP-SMC-30c/UP-BMC-25c)
Enterprises should update the sample preparation process in accordance with clause 7.1.4 to ensure the comparability of test data.
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