Leading car and truck designers are achieving significant weight and cost savings by building leaf springs in composites, and gaining performance advantages from the material. Composite leaf springs weigh up to 60% less than their steel counterparts. These weight savings save costs by providing the driver or operator with a greater loading capacity and/or reduced fuel consumption.
 
The mechanical properties of composites are another advantage over traditional materials. The energy absorption and fatigue resistant characteristics of Prepregs are outstanding. Composite leaf springs absorb energy more readily than steel, giving driver and passengers a more comfortable and quieter journey. The fatigue resistance is greater than with steel, and it is reassuring that in the unlikely event of a fracture with composites, the failure would be gradual and identifiable, avoiding the sudden catastrophic failure of metal parts.
 
Composite leafsprings can withstand the harshest environmental conditions to which vehicle suspension systems are subjected. They are non-corrosive and resistant to salt damage in winter climates as well as oil, petrol and battery acid. Unlike metal, it is unnecessary to coat them with protective anti-corrosion paint.
 
Composite leaf springs are moulded into shape in a single operation. The Prepreg process enables leaf springs designers to incorporate contoured shapes, as a single part, providing the best solution for any specific axle unit. The reduced part count and volume processing of composite leaf springs can provide added cost-saving benefits for the manufacturer.
 
M9 and M10 Prepregs

Prepregs are fibre-reinforced resin systems, which are cured at temperature and under pressure to produce exceptionally stiff yet lightweight structural components.
 
M9 and M10 are Hexcel’s recommended Prepregs for leaf springs, supplied with a unidirectional glass fibre reinforcement. Prepregs are supplied in roll form, and are cut to shape before being placed into a mould tool. The resin systems are versatile, curing temperatures from 85°C to 150°C/185°F to 300°F.
 
Different levels of tack are available throughout the range. M9 is a high tack resin, M10 provides medium tack and M10.2 is low tack, The Prepregs provide a good surface finish and are cured under a range of pressures from 0.3 to 5 bar.
 
M9 and M10 have a shelf life of 60 days at room temperature, making them easier to store than many other systems. They are clean and safeto use.
 
The use of resins in Prepreg form allows for consistent high fibre volume ratios and precise resin placement. The products are rigorously tested by Hexcel’s quality control department.