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Composite Manufacturing Tips

Advice For Production Carbon Fiber and Fiberglass Manufacturing


Closed Molding Demo
Todd Johnson

If you have ever built something in your garage out of carbon fiber or fiberglass, you know the feeling of accomplishment one gets from making something from only a cloth and a liquid. The next thought that enters the head, "I could probably manufacture composites on a larger scale."

Composites manufacturing is great because one can scale up slowly from a concept, to the garage, to a small shop, all the way to a large factory. With sales and marketing being easier then ever with the internet, one can find a market for their hand made composite products. These could be aftermarket car or motorcycle parts or maybe a surfboard.

When moving to a production environment, below are a few simple, yet helpful tips which could greatly improve your products, cash flow, and work environment.

Keep Your Materials Fresh

Working with fresh resin and gel coat is extremely important. Although you might get a price break on purchasing materials in a larger quantity, it is best to keep raw material inventory low, for a couple of reasons. First, gel coats have an extremely short shelf life, generally 90 days for polyester gel coats. A rule of thumb is, for every 10 degrees F above the recommended storage temperature (usually 77F), the life of the gel coat will decrease by 50%.

For resins, promoted polyester and vinyl ester resins have a fairly short shelf life as well, often 180 days. Epoxies can last a few years, and un-promoted resins can last a year or longer. Once a resin begins to age, it becomes difficult to work with, the viscosity can change, and the gel time can drift.

The second reason to manage raw material inventory closely, is that as a small business, your cash flow is extremely important. By receiving your raw materials "Just In Time", you are better positioning yourself for success.

Manage climate

In many composite manufacturing shops, climate and temperature can change dramatically from day to day, or even from morning to afternoon. It could be 40 degrees F in the morning, and 95 degrees in the afternoon. Temperature of your resins, gel coats, and molds can have a tremendous impact on your ability to process quality composite parts.

Gel coat in particular, is very sensitive to humidity and temperature. It is an extremely good practice to monitor both by keeping a log prior to spraying. A simple "fix" is to keep your resins and gel coat drums on a pallet. This will keep the contents closer to ambient temperature, instead of the concrete sucking the heat out of the drum.

Keep A Log

If you are manufacturing composites, it is only a matter of time before you have a quality issue. Quality issues not only cost time in re-work and scrap, but opportunity cost in not making more parts.

By keeping a log on humidity, temperature, product batch number, it is much easier to deduce the problem and correct it quickly.

Separate Trimming and Sanding

It is good to have a clean shop environment, and this should not be too hard. However, trimming and sanding composites is one of the dirtiest parts of composite manufacturing. Carbon fiber and fiberglass dust is brutal, and makes for an itchy and uncomfortable work environment.

The first correction would be to isolate the sanding and trimming. Some composite manufacturers create sanding booths or sectioned off rooms. Vacuuming and collecting the dust pays in saving workers from constantly sweeping and cleaning dust. Plus, it is a healthier work environment.

Protect Your Workers

On that note, make personal protection mandatory. Many composite technicians believe they are invincible and do not need to protect themselves from the dust, noise, and fumes. However, all of these can create long term health concerns. If your key worker cannot hear you, or needs to take days off for health reasons, this will effect your bottom line.


Many of the composite manufacturing tips above might seem like "no-brainers," but they are some of the most commonly overlooked areas of composite manufacturing. If one follows these tips, they will be more likely to create quality parts, and ultimately, make more money.

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