Vacuum Bagging Video
Vacuum bagging is a process that requires unique materials and processes, but can be simple to operation in an ongoing basis.
There are many advantages to vacuum bag molding, a few of which include:
- Improved resin/glass ratio
- More consistency across the laminate and part -to -part as compared to open layup
- Containment of air emissions from the resins
As compared to hand layup and chop layup, there are a few disadvantages, including
- Higher consumable material cost
- Higher capital equipment cost
- Difficulty with superior surface finish
Some parts are more suitable for vacuum bag molding than others. It also depends upon which process it is being compared with.
Vacuum bag molding requires an extremely tight seal between the mold and the bag. Molds with multiple pieces or holes for inserts can be difficult to complete a seal.
Parts that are overly large and complex can present challenges with placing resin and reinforcement before the cure cycle starts. The bag must be completely sealed and under full vacuum before the curing cycle of the resin begins.
The basic premise of vacuum bag molding is that the air is removed from the bag, allowing the atmosphere (air on the outside of the bag) to push the bag onto the part on the mold, compressing the layers of resin and reinforcement. Many misinterpret the process as “sucking the extra resin out.” We are merely allowing the laminate to be compressed by the weight of the air above us in the atmosphere to consolidate it before cure. The excess resin is usually absorbed by extra layers of sacrificial material inside the bag.
Environmentally Friendly Composites
Many experts argue that composites already are very environmentally friendly based upon their long life span and their good strength-to-weight ratio that saves energy. Many composites structures have long made use of end-grain balsa wood as a core material. This is a renewable resource that is favorable to the carbon footprint.
The strikes against fiberglass composites as being environmentally friendly point out that most of the resin systems are derived from oil and natural gas feedstocks. Most of these feedstocks come from the extra byproducts of making diesel and gasoline. Fiberglass reinforcements consume lots of energy in their manufacturing process.
Resin and reinforcement companies have been working to “green” composites materials. BioResins have been successfully made and used in products that see the real world. These resins use soybean and corn feedstocks to replace the oil and natural gas derivatives to make them from a renewable source. Much work has been accomplished with reinforcements to move towards natural materials. Hemp has proven very useful in this application. Recycled thermoplastics have also been applied to composites products as a reinforcement.
Further research and development, along with identifying appropriate real-world applications will allow composites to flourish as a true sustainable material. It has already proven to be a great material for lightweighting vehicles and structures to result in great energy and material savings. The long life and durability of composites keeps it from landfills to minimize environmental impact.
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