LTM? 350 CF Prepreg Tooling Material Enables Fast Curing (3 hrs), Energy & Cost Savings (43 %) for Structural Composites used in Hyper & Supercar BEVs

By Graham Parry, David Hulme, Edward Walker, Mark Steele, Brian Baleno

Solvay Materials

High performance battery electric (BEV) sport cars and supercars are entering the market and one of the key ways to achieve superior performance is to utilize carbon fiber structural composites. Lightweight, performance, and increased range are synonymous with the use of composites. Some examples of carbon fiber composites on a BEV sports or supercars may include structural battery packs, hoods, roof, subframe, and spoiler.

One obstacle to overcome with small volume production is the cost of tooling to produce structural composite parts. Using composite based production tooling is more economical than aluminum or steel tooling. Another driver is the lead-times required to manufacture carbon fiber composite tooling. One of ways to reduce the total cost of carbon fiber parts is to address the processing costs. Two key areas where savings can be gained are the reduction of time for lay-up and the cure and post cure cycles.

The use of master models with high coefficients of thermal expansion limit the temperature at which highly accurate carbon tooling can be cured which results in the long cure times currently used within the industry. The desire to reduce the overall time to manufacture a composite tool led to the development of LTM? 350. LTM? 350 is a carbon fiber epoxy prepreg specifically designed as a tooling material with the aim of reducing lay up and cure time, saving energy, and thereby? to provide economic savings.

Most carbon fiber epoxy prepreg used for tooling have a cure time in the range of 8 to 12 hours at 50 to 60 ℃. LTM? 350 has the capability to be cured in 3 hours at 60 ℃. Figure 1 below reveals the overall reduction in cycle time, autoclave clave time, and curing time benefits of LTM? 350 vs. Standard Tooling Prepreg.

Figure 1: Cure & Post Cure Comparison of LTM? 350 vs. Standard Tooling Prepreg

An example of an application that utilized LTM? 350 tooling is the inner car door shown below in Figure 2 below).

LTM? 350 tooling uses a heavier weight bulking ply than traditional tooling systems allowing tool thickness to be built up more rapidly. The tooling was designed for a composite structure of a 1-5-1 lay-up (surface to bulk plies ratio). A traditional approach for this tooling would use a 1-8-1 lay-up. Beyond reducing the curing time, optimized manufacturing processes for the surface and bulk plies of LTM? 350 tooling also allows for best in class tack and drape so assisting ease of lay up .The 1-5-1 lay up tool construction yielded a 25% time savings compared to traditional lay-ups.

LTM? 350 tooling offers the potential to save money on both material and process cost. The amount of saving depends on the tool size and master model construction. An example of potential savings is highlighted below in Figure 3.

Figure 3: Potential Cost Savings of LTM? 350

In summary, LTM? 350 tooling was developed to provide best-in class small volume carbon fiber composite production tooling with the fastest turn around cycle. The tooling allows for time savings by reducing lay-up time which is the result of using less bulk plies (1-5-1 vs. 1-8-1). Faster and shorter cure and post cures significantly reduces the energy use and therefore cost thereby providing a more sustainable and economic solution.?

>Read the press release “Solvay launches LTM? 350 low-temperature prepreg for unprecedented fast tooling”

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