Thompson Composite moulding

TCM are a dedicated team with decades of carbon fibre and glass fibre production experience. We are very interested in taking on unusual projects from design to production.

What are the manufacturing methods?

There are two ways to create a fibre reinforced laminate; "wet" layup and pre-impregnated fibre layup.

The "wet" layup process has been used since the advent of composites to create moulded shapes from glass or carbon fibre and resin.

It is the easiest and least labour intensive method available for moulding composites parts and is now utilised primarily by do-it-yourselfers to create products without large capital investment.

The primary disadvantage of the wet laminate is the lack of resin control.

Dry fiber (glass, carbon, etc.) is laid into the mould and resin is poured and brushed over the cloth in a relatively uncontrolled fashion. Layer upon layer are added in this manner until the desired thickness is met. With this uncontrolled resin impregnation, the laminate can be made too resin rich - adding excess weight and reducing overall strength and stiffness. Additionally, without proper attention, areas of the laminate can end up without enough resin, thus creating a high content of voids and subsequently decreasing mechanical properties.

The pre-impregnated (pre-preg) fibre method has been developed over the past two decades to create stiffer, stronger laminates with controllable, predictable results. In this case the fibre is pre-impregnated with resin at a production facility, rolled on spools, and frozen to prevent the resin from curing prematurely.

This material is cut and hand laid into a mould to the proper thickness and cured by one of two methods described below. The resulting laminate has a precisely controlled resin volume (+/- 2%) and will be 20-30% stiffer and stronger than an equivalent-thickness wet laminate.

The first method of curing a pre-preg laminate is to put it under vacuum bag compaction and place it in an oven for the prescribed amount of time until the resin "glasses", flows and hardens in the shape of the parent mould.

The second method for curing the pre-preg laminate employs the same vacuum bag compaction as the first, but adds the extra force of the autoclave to "pressure cook" the laminate. In both instances, the cure temperature will also be the maximum allowable temperature of the cured laminate with a continuous service temperature slightly lower.

In the case of the many car hoods/bonnets we have built, the laminate consists of a lightweight closed-cell core sandwiched by two pre-preg skins.

• We have our own autoclave for pre-preg development
• Our own purpose-built spray-booth for finishing
• In house 3-axis CNC milling to develop products and prototypes.
• In house wood templating skills to develop frameworks & prototypes

In reality, it is necessary for the user to match his/her up-front equipment investment with an appropriate budget for maintenance and repair. This includes both time (education and frequent inspection of components) as well as expense (the cost of engaging a skilled mechanic or the replacement cost of damaged components).

For example, the reliability and cost of maintaining a high-end £100,000 super-car is not the same as a mass produced £25,000 sports car. In the same way, a £500,000 yacht has a different maintenance requirement vs. a £5000 dingy. It’s up to the consumer to consider needs vs. resources and accept the hidden costs of ultra high-performance components.

Twenty years ago, composites were already well established in aviation and sporting goods industries, and current composite general-consumer components benefit from a further 20 years development of materials and manufacturing. Most of today’s products are “high tech” far beyond of the technology of 20 years ago, although some are even more advanced, benefiting from recent developments in composite materials and design. They demonstrate exceptional strength, durability, and light weight that older technologies can’t approach.

Carbon fiber components can be extremely resistant to heavy use and abuse. Notice skis, white water kayaks, tennis racquets, dragster driveshafts, racing wheels, sail board booms, and hockey sticks, all made of carbon fiber.

At first glance, the material seems softer and easier to damage than aluminum. But the outside layer of fibers is often a 3D weave placed exclusively to resist damage (impacts, scratches, etc.). The fibers that do the principal load bearing are safely encased within. So, cosmetic harm to the outside layer is often not as serious as one might assume.

The dark, varied appearance of carbon components doesn’t show abuse as easily as aluminum. Sure, a ding is disappointing, but years down the road, carbon components often don’t look as beat up as their aluminum counterparts. But as a result, a user can’t always easily identify damaged parts that need replacement. Impacts and hairline cracks are hard to spot.

For small, superficial scratches to the surface clear-coat, an easy cosmetic repair is available. Simply clean the mark and brush on clear nail polish. For a nearly undetectable result, orient the chip facing up. Lay a drop of polish in the recess with a toothpick. When it fully dries, lay in another drop. Eventually, the chip is filled up to its original level. Very light polishing with something like Simichrome can make the damage disappear.