Detailed Explanation of Vacuum Infusion Process for Automotive Carbon Fiber Parts

 

To help FRP novices understand the vacuum bag molding process, this article illustrates the simple process of vacuum resin induction for automotive carbon fiber accessories. I hope it will be of some help and reference to you.

 

 

Vacuuming FRP Mold

For most vacuum bagged FRP shells, there is actually not much difference in the requirements for vacuuming and hand lay-up molds. It’s just that the flange of the vacuuming mold is relatively larger (such as 15cm), which is to facilitate the bonding and sealing of the vacuum bag with butyl tape.

 

Vacuuming Pperation Steps

The first step: clean the surface of the FRP mold and apply the release agent; first stick the sealing tape to the edge of the mold flange. The considerations for this are: 1. The edge of the mold flange is large enough and does not hinder subsequent operations. 2. Prevent scattered carbon fiber debris from causing air leakage during sealing at the flange edge.

 

 

Apply Sealing Tape

Step 2: Cut Carbon Fiber Cloth

Don’t cut the carbon fiber cloth too small, and take into account the rough edges that will be cut off later. You can also cut the carbon fiber cloth in advance. If it is difficult to calculate, you can cut one sheet first, try to lay it out, and then cut it according to the size.

 

 

Cutting Carbon Fiber Cloth

Step 3: Laying Carbon Fiber Cloth

For laying out multiple layers of carbon fiber cloth, you can use a sizing spray to facilitate bonding and laying it out to fit the mold surface. Don’t spray too much, as it can easily lead to potential risks of poor bonding.

 

 

Try not to tear the texture of the first layer of carbon fiber cloth crooked. You know the principle of selling goods based on their appearance!

 

 

Laminated Carbon Fiber Cloth

Step 4: Lay the Release Cloth

The release cloth will not stick to the product. After the part is cured, it can be easily torn off and form a woven pattern similar to cloth on the back of the product.

 

 

Laying Down the Release Cloth

Step 5: Laying Down the Guide Net

The main function of the guide net is to promote the flow of resin and quickly and effectively disperse the epoxy resin in the entire part layer.

 

 

Laying the Guide Net

Step 6: Laying the Spiral Tube and Placing the Inlet and Outlet of the Glue

 

 

Resin Injection Seat

The spiral tube is the resin delivery and dispersion channel. Because it is spirally open, when the resin flows in one direction, it will quickly disperse into the guide net it flows through and into the entire carbon fiber cloth layer.

 

 

Arrange The Resin Guide Pipe

Step 7: Lay And Stick The Vacuum Bag Film

Since the structure of this component is simple and the epoxy resin gel time is long, there is no need to worry about the extra consideration of resin guide not being in place. Just find a symmetrical position and arrange a glue inlet and a glue outlet respectively. The vacuum bag should be cut larger and sealed carefully to prevent bridging and puncturing of the vacuum bag. Evacuate! Ensuring airtightness is the first priority.

 

 

Vacuum Bag Film Laying

Step 8: Vacuum Tube Connects Vacuum Pump and Resin Collector

 

 

When using a PVC hose to connect the vacuum equipment and the resin collector, you can cut it at a bevel angle to make it easier to push the hose into the vacuum nozzle in the vacuum bag and then seal it with butyl tape.

 

 

Resin Collector

Pay attention to these locations. It is easy to cause micro-leakage due to not squeezing the sealing tape hard.

 

 

Vacuum Pump

Step 9: Vacuum Leak Test

Fold the rubber inlet hose in half and test the overall vacuum tightness to determine whether the resin vacuuming requirements are met.

 

 

PVC Vacuum Tube

Carefully find the leaking point, correct it and reseal it. Once the vacuum degree reaches the part requirement, you can proceed with the subsequent operation.

 

 

Vacuum Test

Step 10: Weigh and Properly Mix Epoxy Resin and Curing Agent

 

 

Epoxy Resin Configuration

Note that the epoxy resin and curing agent must be accurately measured and evenly mixed, otherwise the product may become soft or the resin will remain sticky.

 

 

Vacuum Epoxy Resin

Step 11: Epoxy Resin Vacuum Infusion

Since the structure of this component is relatively simple, the vacuum epoxy resin infusion speed will be very fast. It is generally enough to complete the infusion of this small part in 15-20 minutes.

 

 

Introduce Vacuum Resin

Step 12: Wait For Epoxy Resin To Cure And Remove Auxiliary Materials

After the epoxy resin is guided, the inlet hose and outlet can be closed and the epoxy resin can be completely cured; usually, it can be cured for 3 hours at 60-80℃. Curing at room temperature requires more than 24 hours. After curing, demould and remove the vacuum auxiliary materials.

 

 

Demolding Of Carbon Fiber Parts

Step 13: Cutting Parts and Grinding and Polishing

After cutting carbon fiber parts, it is recommended to sandpaper and water grind and then polish; dry grinding is not recommended because the grinding dust is pressed into the pinholes on the surface, which will be difficult to clean.

 

 

Cutting The Carbon Fiber Shell

Step 14: Repairing Pinholes On The Surface of Carbon Fiber Parts

It is difficult to completely eliminate pinholes on the surface of epoxy resin parts because the carbon fiber cloth has weaving intersections. Twill cloth is relatively better than plain cloth.

 

 

Automotive Carbon Fiber

For the pinhole treatment on the surface of the parts, you can use epoxy resin glue to fill or spray 2K varnish to seal. Varnish will have a better UV resistance effect, but the strength is not as high as epoxy resin. Which one is more suitable for you? Weigh it according to the actual situation.

 

 

Carbon Fiber Shell

At this point, a simple carbon fiber shell for a car has been basically vacuumed and completed. Of course, not all vacuumed parts are operated in the same way, because the structure of the parts and the actual requirements are different, the specific operations are slightly different, but the basic routines are similar.