There are many ways to make carbon fiber parts and each has their own pluses and minus.  Usually the factors are cost, time, and quality.  We are going to talk about some of the many techniques that are available but will concentrate on the infusion technique.  Epoxy infusion is in many ways a happy medium achieving the best results for all three factors of cost, time, and quality.

The three techniques we will discuss in this article are pre-preg, wet layup, and of course epoxy infusion.  The first method, pre-preg, will result in the highest quality parts but it is also the most expensive requiring the purchase of very expensive pre-impregnated carbon fiber cloth.  This cloth has the precise amount of resin impregnated into the fabric for the best results.  It also requires the use of vacuum bagging and expensive ovens to cure the part.  This is the technique used by race car and spacecraft manufacturers.  Its the best but very expensive.  So among our three factors, this method has high cost, high quality, and average time required to make each part.

The other common method for making carbon fiber is the wet layup technique.  In this method layers of carbon fiber fabric are put down on a mold and wetted with freshly mixed resin by hand.  Each layer is allowed to setup until tacky but not hard and another layer is laid on top until the desired thickness is achieved.  There is no vacuum bagging and no ovens required and it utilizes inexpensive dry carbon fiber fabric so this method is very inexpensive.  It does take some time as each layer has to setup for an hour or two so it high on the time factor.  And while you can make a high quality part with this technique, its very easy to add too much or too little resin to the fabric and therefore hurt the quality of the final part.   So its cheap, the quality can be good, but it takes some time.

So lets talk about epoxy infusion.  In many ways, this method has the best of the worlds of pre-preg and wet lay up and can make some very high quality parts.  To use the technique, you start with a mold just like the other two and you layer all your fabric on top of the mold.  The fabric is always try and therefor inexpensive and can include carbon fiber, fiberglass, and other speciality fabrics.  All the layers you will need are applied at one time with no resin.  The next step is to use vacuum bagging to remove all the air.  Atmospheric air pressure presses the layers of fabric tight against the mold ensuring a tight fit you cannot get with wet lay up.  Now comes the interesting part.  Using an air tight connector inserted in the plastic that makes up the vacuum bag a plastic hose is attached.  Through this hose passes resin into the fabric.  The vacuum of the bag literally sucks the resin into the fabric and mold and does so in a measured way.  Because air pressure is forcing the fabric and bag down to the mold, excessive resin cannot pool on the part.  Instead any excessive resin gets pulled to the sides of the part.  This method can make high quality parts because the resin fabric ratio is tightly controlled like pre-preg.  Also since all the desired layers are applied at once, the time it takes to make a part is rather low.  It also uses dry fabric and needs no oven so the cost is low as well.  You only need the vacuum bagging equipment and it does add cost to the method but the costs are not excessive.

So that is a quick overview of the three most popular methods for making carbon fiber parts.  Infusion comes out as a very attractive technique due to its high quality, lower cost, and fast construction times.  It does require the use of a vacuum pump and the related hoses and coupling but when compared to pre-preg, the costs are much lower and the quality is comparable.