1. Preparation and treatment of metal mandrels

The tube winding process involves winding carbon fiber prepreg onto a metal mandrel, so a mandrel of the appropriate size needs to be prepared in advance. Since the carbon fiber will be wound on the outside of the mandrel, the outer diameter of the mandrel itself needs to match the inner diameter of the carbon fiber tube you will be using. The outer diameter of the carbon fiber tube will be determined by the number and thickness of the carbon fiber prepreg layers wound on the mandrel.

     2. Apply release agent

Once you have the correct sized mandrel, ensure it is completely clean and as smooth as possible to facilitate product demolding. Then, apply a release agent evenly to the mandrel surface (to facilitate subsequent product demolding).

  3. Preparing Carbon Fiber Prepreg

Although alternative types of reinforcing materials, such as dry fabric impregnated with epoxy resin, can theoretically be used, only carbon fiber prepreg can provide the precision and ease of handling required for the roll packaging process.

  4.Tube rolling process

Remove the PE film and release paper from the prepreg, then place them in order, making sure to leave an overlap area (3-5mm is sufficient).

Place the metal mandrel parallel to the edge of the first layer of prepreg and apply even force to wind the mandrel forward. Alternatively, a plastic sheet can be placed on the metal mandrel for more even force distribution.

More prepreg can be wrapped around the end section, as the product is difficult to demold later, and this section can be used to remove the product.

5. Wrapping BOPP stretch film

Once the prepreg carbon fiber reinforcement is wound as tightly as possible onto the mandrel, it is then tightly wrapped with BOPP stretch film to provide further consolidation.When using BOPP stretch film, it is important to ensure ample overlap. Each turn of the tape is advanced only a few millimeters down the tube. While this is time-consuming by hand, the large overlaps in this manner provide greater consolidation stress as the tape shrinks during curing.

6. Oven curing

Aside from the mandrel, having an oven to cure the tubing is likely a major limiting factor when considering the coiling process outside of a full production environment. However, unlike other prepreg processes, coiling does not require precise temperature control or the often-necessary multi-step curing cycles. Vacuuming is also unnecessary. Therefore, the only requirements for oven-curing coiled tubing are basic temperature control and sufficient dimensions to fit the tubing. Depending on the desired tubing size, anything from a household oven to a powder-coating oven can be used.

7. Remove the product

Remove the BOPP wrapping film, then take out the product. If the appearance is desired, it can be sanded or painted.