Vacuum Resin Infusion Auckland

Vacuum resin infusion is an efficient process suitable for most thermoset composite materials, including polyester, vinyl-ester and epoxy.





At infusion, thermosetting resin undergoes a chemical crosslinking reaction that changes from liquid state to gelled and then glassy solid state, providing enough material for impregnation of preform. During this phase, resin must penetrate and fill each space within its surroundings as effectively as possible.

What is Vacuum Infusion?

Vacuum infusion is a composite fabrication method that sits between pre-preg and hand layup on the one end, and vacuum infusion on the other. It has slowly begun taking away from both processes as fabricators look for ways to build complex or thick parts more economically and quickly.

Selecting the appropriate resin for vacuum infusion is crucial, and an excellent resin supplier should be able to offer guidance in selecting suitable products, from catalyst to gel time. Without adequate gel time, resin may outgas in your bag and slow infusion processes down significantly.

Infusion can be performed using most thermoset resins such as polyester, vinyl-esters or epoxy; for optimal results use warm epoxy (or even hot!), as it has the lowest viscosity. As more heat is applied to it, its viscosity decreases; typically for every 10 degrees C above room temperature it halves! Such resins tend to tolerate heat application better than cold mold and autoclave-dependent ones while still curing with excellent quality and consistency over time.

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Vacuum resin infusion offers numerous advantages over other methods of composite production. It produces strong laminates with minimal void content that are lighter and stiffer than autoclave cured prepreg or hand layup in open molds.

Vacuum infusion does not rely on heated tooling or ovens for manufacturing composite parts; rather, it utilizes a bagged system which prevents laminators from coming in contact with resin and thus decreases exposure to VOC fumes and allergies significantly, providing a safer, more sustainable, and cost-effective method of making composite parts than open mold or hand layup methods.

Bagged reinforcement material handling also reduces VOC emissions and employee exposure to hazardous chemicals, making VIP suitable for more applications than open molded or hand layup and opening up a variety of resin options for use.

Technicians attach a vacuum bag and resin line to a mold, then use the vacuum to infuse resin into fiber laminate and trap any excess resin in an infusion trap. After curing for the desired length of time in the bag until hard, the vacuum is turned off. Infusion is faster, cheaper and more accurate than open molding or wet layup and makes incorporation of core materials much simpler.

Variations

There are various methods of vacuum resin infusion, but they all share common elements - differential pressure, dry-stack permeability, resin viscosity, flow distance and cross-sectional area are key variables to consider for an optimal infusion experience. Darcy's Law illustrates their relationships - finding an equilibrium is essential to successful resin infusion.

Ideal Infusion Conditions include infusing resin at higher pressure - slightly above atmospheric. This differential between ambient pressure and infuser pressure drives resin into a dry stack. You also want your resins warm - more than room temperature but even hot for some resins; this allows them to release excess air faster, speeding up their running times and decreasing gel time.

Reinforcing fabrics play a critical role in infusion: for optimal results, unidirectional or biaxial non-wovens offer natural pathways for resin to flow without needing to use stitched ply-stitch techniques. Woven fabrics may be less ideal due to their threads crossing over one another creating "crimp," making the fabric tougher but decreasing flow distance and creating air pockets within it that may reduce damage tolerance but create havens of trapped air.

Selection of catalyst is also key - for infusion processes, consider MEKP or DCPD resins which contain low hydrogen peroxide levels; these resins are easier to process than ortho or general purpose polyesters and have excellent moisture intrusion resistance properties.