Hand-wrapped heat shrinkable tape is an important element in the manufacturing process for products ranging from sporting goods and automotive products to aerospace components and industrial parts.
Designed to apply shrink force during a curing process (such as in an autoclave or oven), hand-wrapped heat shrinkable tape begins to compress as the temperature rises — compacting layers of composite material and resin, also known as prepreg or layup. The result is a composite product with a variety of advantageous properties that include:
- The high strength and durability composite materials are known for
- Even lamination of material throughout the entirety of the part
- A clean, consistent, and resin-rich surface finish on the part
- Absence of air voids and other defects caused by poor compaction
In many production environments, this tape is hand-wrapped as opposed to being applied by an automated process (though that is common as well). Whether the tape is hand-wrapped or applied via equipment depends on your products and goals, but the ideal outcome should be easily attainable as long as certain factors are observed during the process. Today, we’ll review several of these and how our Hi-Shrink Tape line of products excels in applications where hand-wrapping is required.
1. Tape Shrink Percentage
Not all compaction films provide the amount of shrink needed to achieve success with a given material. Basic films like cellophane, nylon, or polypropylene are often wrapped under high tension before being put into a curing process. Unfortunately, these films will relax as the temperature increases — resulting in a lower-quality lamination. With Hi-Shrink Tape, you choose a shrink percentage from the start. We offer hand-wrapped heat shrinkable tape products with shrink percentages ranging from 0% to 20%. The higher the shrink percentage used, the greater the compressive force on the part.
Pro Tip: Our Hi-Shrink Tapes are numbered according to their thickness and shrink percentage. In our 220 Series, for example, the first digit (2) represents the thickness in thousandths of an inch. The second two digits (20) represent the shrink percentage.
2. Tape Thickness
The thickness of your hand-wrapped heat shrinkable tape also plays an important part in how much compressive force is applied to the material. Tapes with greater thicknesses will apply more force to the wrapped material as the curing temperature increases. Dunstone offers Hi-Shrink Tapes with thicknesses that include 0.001” (0.025 mm), 0.002” (0.050 mm), 0.003” (0.075 mm), and 0.005” (0.125 mm) — with a few unique options available.
Multiple Solutions: Explore our full line of Hi-Shrink Tape products and request a sample.
3. Taping Tension
Along with your choice of material, one of the most important factors in the performance of a hand-wrapped heat shrinkable tape is how much taping tension is applied when wrapping the part. This combined with the shrink percentage of the tape influences the amount of overall force (in pounds per inch of width) applied to the product. On average, most people using hand-taping composite materials are applying between five and eight pounds of force, but it’s essential that hand-wrapping is consistent from end to end.
Failing to maintain consistent taping tension when applying the tape will result in an uneven surface finish and even porosity in the composite layers themselves. This puts the overall product performance at risk. When hand-wrapping heat shrinkable tape, it’s important to keep the tape snug to the part surface and ensure there are no loose areas in the application. Get more tips on hand-taping in our FAQ section here.
4. Number of Layers and Overlap Percentage
Closely related to the above is the number of layers or overlap used when hand-wrapping the tape. While the number of layers will depend on your part and what you’re looking to achieve, multiple layers will provide greater compaction. Additionally, the amount of overlap will produce greater compaction as well. It’s important to be consistent with the amount of overlap as the tape is wound around the circumference of the part and down its length. It’s also critical to wrap each subsequent layer using the same overlap percentage.
With Dunstone Hi-Shrink Tape, a common approach is to test the compaction beginning with a 50% overlap. If more force is needed, the overlap can be increased to 75%. For less force, 25% overlap will ease up on the compaction applied to the part.
We’ve Got Answers: Check out our FAQ page to see common questions about tape application.
5. Part Diameter
Whereas smaller diameter parts will see easy compaction thanks to our hand-wrapped heat shrinkable tape products, those with larger diameters will generally require thicker tapes, higher overlap percentages, higher tension, and perhaps more layers of tape in order to achieve the desired compressive force. To support applications with these larger parts, we developed our 500 Series of Hi-Shrink Tapes. This product provides maximum compressive force thanks to its .005” thickness. As with our other Hi-Shrink Tapes, we can customize the amount of shrink percentage needed for your application.
Could You Benefit from Traverse Pack?
While hand-taping is required in many applications, consider whether your environment could benefit from the implementation of a traverse pack of shrink tape. These packs are traverse-wound on a core that is wider than the slit width, allowing for longer continuous lengths of shrink tape. The key advantages here are:
- Removing this manual task from your production team
- Not having to repeatedly switch to new spools
- Being able to order significant longer lengths of tape
- Maximum consistency in the tension/overlap of the tape
- Reduced material issues due to human error and inconsistency
- Precise application for the best possible results post-cure
Find the Right Hand-Wrapped Heat Shrinkable Tape Today
Dunstone has been manufacturing our shrink solutions for decades, and we’re ready to put those years of expertise to work for your next application. Simply reach out, let us know what material you’re working with and what you want to achieve, and we’ll provide you with a complimentary sample for testing.