Machining Hm 2471

Glass-mat hard laminates ("hartmatte", UP GM) belong to the family of industrial laminates: glass-fibre mats are impregnated with a thermoset resin and pressed under heat and pressure into sheets or rods. In Hm 2471 (UP GM 203), the reinforcing material is a glass-fibre mat and the bonding resin is an unsaturated polyester resin (UP resin) – the NEMA equivalent GPO-3. The material combines high electrical insulation performance with good resistance to arc tracking and creepage (CTI 600) at a limiting temperature of 130 °C; the colour is characteristically white (natural). Within the glass-mat hard laminate family, Hm 2471 represents the standard grade – the mechanically upgraded grade Hm 2472 (UP GM 204) offers, on the same basic construction, higher strength values and a higher limiting temperature of 155 °C.

Hm 2471 (UP GM 203) machines well – sawing, milling, drilling and turning can be carried out cleanly and accurately with sharp, carbide-tipped tools. Because of the abrasive glass-fibre content we use wear-resistant tools and ensure adequate dust extraction. This allows us to reliably produce high-quality insulating and structural parts – from single items to series production.

Hm 2471 (UP GM 203) is worthwhile whenever a highly insulating, mechanically resilient structural material is needed for applications up to 130 °C – for example:

• Insulating and separating parts in low- and medium-voltage switchgear engineering
• Components requiring arc- and tracking-resistance (CTI 600)
• Support insulators and busbar holders
• Structural parts in electrical machine and transformer engineering
• General electrical insulating parts up to 130 °C continuous service temperature

Hm 2471 (UP GM 203) falls in the mid-price segment of technical insulating laminates. Component price is determined mainly by sheet thickness or rod diameter, dimensions, material utilisation (offcut), machining effort and batch size. We are happy to quote binding prices on request based on your drawing.

Equally important are the limits of the material:

• Direct food contact – Hm 2471 (UP GM 203) is not declared suitable for this
• Continuous use above approx. 130 °C – Hm 2472 (UP GM 204) with a limiting temperature of 155 °C is the better choice
• Applications with particularly high mechanical loading – Hm 2472 (UP GM 204) is also more suitable here
• Permanently damp/wet environments without additional protection
• Applications requiring non-machining forming or welding (thermoset)

An honest assessment – and how the disadvantages can be mitigated in practice: Advantages:

Disadvantages:

Practical tip: Hm 2471 (UP GM 203) is the right choice for electrical insulating and structural parts with high requirements for tracking and arc resistance up to 130 °C continuous service temperature. If a higher limiting temperature or higher mechanical strength is required, Hm 2472 (UP GM 204) is the better choice.

• High electrical insulation performance
• Good resistance to arc tracking and creepage (CTI 600)
• Thermoset, dimensionally stable
• Good machinability
• Self-extinguishing (UL 94 V-0)
• Not declared suitable for direct food contact
• Continuous use limited to approx. 130 °C
• Glass-fibre content is abrasive, increased tool wear
• Cannot be formed or welded (thermoset)
• Mechanically less resilient than Hm 2472 (UP GM 204)