Know Your Product: Shrink Tape for Composites
Shrink Tape: Putting the Squeeze on Composties
Fabricating yards of Carbon fiber tubing for robotic machinery, patching large fiberglass chemical tanks, and building a high quality bicycle frame; what do all of these projects have in common? Quite a lot, actually.
First, each application requires the highest level of safety and performance from the parts involved. In order to accomplish this, many fabricators will use a technique known as vacuum bagging to fabricate their parts. The compression of the vacuum bagging process helps to maximize the properties of the materials, ultimately creating a better finished part.
However, this leads to a second thing these projects all have in common; all of them have the potential to have complex shapes, that can be large, cumbersome or unique enough that it might seem too labor intensive for the vacuum bagging process. So what is a fabricator to do?
Say hello to shrink tape
What is Shrink Tape?
Shrink tape is a polyester compaction film that can be easily wrapped around laminates to create mechanical pressure. Unlike vacuum bagging, this tape creates pressure by way of heat, rather than vacuum. When heated, let’s say with a heat gun for example, it shrinks up to twenty percent, squeezing the composite material within.
Like vacuum bagging, this eliminates excess air and resin, and gets composite parts closer to an ideal resin-to-reinforcement ratio. As a result, finished parts are improved physical properties. It is important to note that “shrink tape” is tape in name only. This is not an adhesive, its size makes it easy to handle and wrap, especially on a job site.
Using Shrink Tape for Composites
When wrapping a part, the tape should be applied reasonably tight. If the tape is wrapped too loosely, less shrink force is left for applying final pressure. For more pressure, multiple layers of shrink tape can be applied.
When taping, the start end of the tape can be locked by one or two overlaps. The finish end can be scured using heat-resistant flash tape. Ideal usage temperatures range from 175°F to 300°F. The tape will finish shrinking in about 20 minutes and has an easy removal process thanks to a release coating on the tape. After use, this tape should be thrown away.
Other questions? Let us know your thoughts in the comment section below. If you’d like to know more about Vacuuming bagging for composites, check out our blog post on Basic Vacuum Bagging Set-up, or head over to the Fibre Glast Learning Center and check out our white papers on Vacuum Bagging Techniques and Equipment. Be sure to check out our facebook, and follow us on twitter @Fibreglast for more information the composites industry.