Methods to Make a Roll Wrapped Carbon Fibre Tube

Glossy carbon fiber tube? Composite producers utilise the roll wrapping process to create high-strength carbon fibre tubes with either a basic raw look or a cosmetic polished appearance. Indeed, Easy Composites has one of the most comprehensive online inventories of roll wrapped carbon fibre tubes. However, there are situations when a carbon fibre tube with highly specific dimensions, fibre type/orientation, or look is required. Want to know carbon fiber tube price?

If the tube you want to build has parallel sides or a continuous taper, you can use the roll wrapping procedure to make your own bespoke carbon fibre tube without any special equipment other than a metal mandrel of the proper size and a large enough oven to cure it in.

1. Metal mandrel

The roll wrapping technique is wrapping prepreg carbon fibre around a metal mandrel, therefore the first step is to obtain a metal mandrel with the appropriate diameter for the tube size. Because the carbon fibre will be wrapped around the outside of the mandrel, the outer diameter of the mandrel must match the inside diameter of the carbon fibre tube you’ll be making. The quantity of reinforcement (the number of layers) you wrap around the mandrel will decide the exterior diameter of your carbon fibre tube.

We utilise an aluminium mandrel because aluminum’s high coefficient of thermal expansion (CTE) makes it ideal for the roll wrapping process. Steel or other metals can be used, however metals with a greater CTE are easier to work with.

You’ll almost certainly need to use a lathe to turn down a solid aluminium rod to create a tapered mandrel if you want to make a tapered carbon fibre tube.

Once you’ve found the right size mandrel, make sure it’s entirely clean and smooth to help in extraction. After that, a high-temperature chemical release agent, such as Easy-Lease, should be used to thoroughly prepare the mandrel.

2. Prepreg carbon fibre

Although various types of reinforcements, such as a dry fabric wetted out with epoxy glue, may be viable in theory, only prepreg carbon fibre provides the precision and simplicity of handling required for the roll wrapping process in fact.

On the inside of the tube, we utilise a layer of XPREG® XC110 210g woven prepreg, followed by numerous layers of XC130 300g unidirectional prepreg, and finally a final layer of the XC110 210g woven prepreg on the outside of the tube. These layers offer hoop strength to the tube by having fibres orientated in the 0° axis (along the length of the tube) and the 90° axis (around the circumference of the tube), making the tube less resistant to crush or burst forces and splintering. The tube’s longitudinal stiffness is provided by the bulk of the reinforcement in the 0° axis.

The performance of the tube can be precisely optimised for its specific usage by adjusting the layup to include more or less woven layers or by changing or alternating the orientation of the unidirectional plies. A tube for a prop-shaft, for example, will be subjected to mostly torsional forces, thus the unidirectional fibre can be positioned off-axis, at 45°, to handle these forces.

3. Composites shrink tape

After the prepreg carbon fibre reinforcement has been wrapped as firmly as possible around the mandrel, the reinforcement is tightly wrapped with composites shrink tape to offer additional consolidation.

It’s crucial to make sure there’s plenty of overlap while applying the shrink tape. Each wrap of the tape barely moves the tape along the tube a few millimetres. Although doing it by hand is labour consuming, having a lot of overlap will offer significantly greater consolidation pressure as the tape shrinks during the cure.

4. Oven cure

When considering the roll wrapping procedure outside of a complete production facility, having an oven to cure the tube is likely to be the most limiting element. The roll wrapping technique, unlike other prepreg processes, does not necessitate precise temperature control or the multi-step ‘ramp and soak’ cure cycles that are commonly required. The technique also doesn’t necessitate an active vacuum line into the oven. As a result, the only requirements for a roll wrapped tube oven are basic temperature control and enough space to accommodate the tube in. Anything from a household oven to a powder-coating oven might be used, depending on the size of the tube you wish to build.