Machining Hm 2472

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 2472 (UP GM 204), the reinforcing material is a glass-fibre mat and the bonding resin is an unsaturated polyester resin (UP resin), NEMA equivalent GPO-3. Hm 2472 is the mechanically upgraded grade within the Hm 2471 (UP GM 203) material family: higher flexural and tensile strength as well as a limiting temperature 25 °C higher (155 °C, thermal class F) than the standard grade Hm 2471 (130 °C). The colour is characteristically white.

Hm 2472 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 2472 is worthwhile whenever a highly insulating, particularly resilient structural material is needed for elevated thermal requirements – for example:

• Insulating and separating parts with elevated continuous thermal load (up to 155 °C)
• More heavily loaded structural parts in electrical machine engineering
• Support insulators and busbar holders for elevated requirements
• Components requiring arc- and tracking-resistance (CTI 600)
• Applications where the standard grade Hm 2471 reaches its mechanical or thermal limits

Due to its upgraded mechanical and thermal properties, Hm 2472 falls in the upper price segment of the hartmatte series. Component price is determined mainly by sheet thickness or rod diameter, dimensions, material utilisation (offcut), machining effort and batch size. Hm 2472 is priced above the standard grade Hm 2471, since the upgraded properties require more manufacturing effort. 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 2472 is not declared suitable for this
• General applications without elevated thermal or mechanical requirements – the more economical Hm 2471 is sufficient here
• Permanently damp or wet environments without additional protection
• Applications requiring non-machining forming or welding – not possible as a thermoset

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

Disadvantages:

Practical tip: Hm 2472 is the right choice when the limiting temperature or mechanical resilience of the standard grade Hm 2471 is not sufficient. For general insulating and structural applications up to 130 °C, Hm 2471 is the more economical alternative.

• Higher limiting temperature (155 °C, thermal class F)
• Higher flexural and tensile strength than the standard grade
• High comparative tracking index (CTI 600)
• Thermoset, dimensionally stable
• Self-extinguishing (UL 94 V-0)
• Not declared suitable for direct food contact
• Higher price than the standard grade Hm 2471
• Glass-fibre content is abrasive, increased tool wear
• Cannot be formed or welded (thermoset)