Vacuum infusion provides a number of improvements over traditionally vacuum bagged parts. These benefits include:
Better fiber-to-resin ratio
Less wasted resin
Very consistent resin usage
Unlimited set-up time
VIP offers a better fiber-to-resin ratio than vacuum bagging. A typical hand lay-up usually results in excess of 100% fabric weight by resin. Resin alone is very brittle, so any excess will actually weaken the part. Vacuum bagging can reduce this number significantly; however, it is still not ideal and can lead to additional problems.
While vacuum bagging certainly improves on the hand lay-up, there is still a hand lay-up involved. Because of this, the laminate will always begin in an oversaturated state. Vacuum pressure will remove much of the excess resin, but the amount removed still depends on the variety of variables. This includes reinforcement material, resin, time factors, as well as others.
Vacuum infusion takes a different approach, in that a vacuum is drawn while the materials are still dry. From that point, resin is infused using vacuum pressure. Rather than starting with excess and drawing resin out, VIP starts with none and pushes resin in. Ideally, any excess resin that is introduced will eventually be sucked out into the vacuum line. As a result, only the minimum amount of resin is introduced. This lowers weight, increases strength, and maximizes the properties of fiber and resin. Parts constructed using VIP can approach prepreg levels of resin content.
Due to the nature of VIP, resin usage becomes very predictable. While a standard lay-up varies in resin content due to the human variable, VIP is remarkably consistent. Even when creating a large product, resin usage will be predictably similar upon repeated attempts. This results in less wasted resin, and more importantly, less wasted money.
Vacuum infusion provides another valuable benefit: time. A frequent problem that can arise in vacuum bagging is the time factor.