Cambridgeshire, United Kingdom  ·  ISO 9001:2015 certified 01480 861 221  ·  info@cfcompositesltd.com
Home/Capabilities/Prepreg lay-up

Prepreg lay-up.

Carbon fibre with the resin already in it, cut to shape and laid by hand to the ply book.

MaterialPrepreg
LaidBy hand
RoomCleanroom
01When you need it
The resin is measured before it arrives.The plies are laid by hand, here.

Prepreg is the material behind most high-performance carbon parts. The fibre comes already impregnated with a measured amount of resin, so the ratio is fixed before it reaches us, rather than depending on how much resin is brushed on by hand.

It needs heat to cure, so it is laid up here and cured in the same building, in the autoclave or one of the two ovens.

How it is cured
02How it works

From the freezer to the bag.

Lay-up is manual work, and most of the quality of a finished part is decided here.

01

Out of the freezer

Prepreg begins to cure slowly at room temperature, so it is kept frozen until it is needed. It has to come up to room temperature before the pack is opened, otherwise moisture condenses on the material.

02

Cut the plies

Each layer is cut to its pattern, with the fibres running in the direction the design calls for. A ply laid at the wrong angle looks identical and behaves very differently.

03

Lay to the ply book

The ply book sets the order and orientation of every layer. Plies are laid by hand in the cleanroom, because anything trapped between two plies stays in the part.

04

Debulk and bag

As the lay-up builds, stacks of plies are compacted under vacuum to pull out air trapped between layers. The finished lay-up is sealed in a vacuum bag, ready for cure.

On the bench
A lay-up under vacuum, ready for cure
03Why prepreg

Measured resin, not brushed.

Wet lay-up still has its place. For a part that has to be light, stiff and repeatable, prepreg is the better material.

Wet lay-up

Resin added by hand
  • Resin is brushed or rolled onto dry fabric at the bench
  • How much goes on varies from part to part and from person to person
  • Excess resin adds weight without adding stiffness
  • More air is trapped between layers, and voids weaken a laminate
VS

Prepreg

Resin measured by the supplier
  • The fibre arrives with a fixed amount of resin already in it
  • Every ply carries the same ratio, so the second part matches the first
  • Less excess resin, so a lighter part for the same stiffness
  • Cured under heat and pressure on the same site, for fewer voids
04Equipment

The room and the material.

Material storage, lay-up and cure sit under one roof, so a lay-up goes from the cleanroom to cure without leaving the site.

Walk-in freezer2.4 × 2.4 m
CleanroomTemp controlled
Autoclave1.5 × 3.0 m
Ovens2 out-of-clave
05Who uses it

Where this comes up most.

Wherever a part has to be light and stiff at the same time.

Next door to the cleanroom

From the bag, into the autoclave.

06Next

Where this fits.

07FAQ

Common questions.

About prepreg lay-up specifically. The general ones are answered on the homepage.

Which prepreg materials do you use?

It depends on the part. Tell us what it has to do, and any material your specification calls for, and we will confirm what we would use.

Why does lay-up need a cleanroom?

Anything that settles on a ply ends up inside the laminate, where it can weaken the bond between layers. Our cleanroom is temperature controlled, which also keeps the material handling the same way through the day.

Can you lay up to our own ply book?

Yes. If your engineering team has already specified the laminate, we lay it to your ply book.

08 Enquiry

Tell us about the part.

A drawing, a photograph, or just a description. Whatever you have is enough to get a price, and we reply to most enquiries the same working day.

Nothing to attach? Leave it blank and describe the part above, or call us on 01480 861 221.

We reply to most enquiries the same working day.
Call us Request a quote