Resin Infusion Research

https://media.easycomposites.co.uk/datasheets/EC-TDS-Guide-to-Resin-Infusion.pdf 

Vacuum Bagging Materials  

Resin Infusion Procedure

Step 1 - Preparing the mold

1. Ensure that the mold has at least 10 cm of extra space around the perimeter

2. Add mold release agent

3. Line the perimeter of the mold with tacky tape

Step 2 - Laying the reinforcement

1. Cut the carbon fiber, leaving an extra 10 cm of space around the perimeter

2. Position first layer of carbon fiber in the mold and spray with adhesive (this will be the surface layer)

3. Position next layers and repeat

Step 3 - Laying the consumables

1. Position peel ply on top of the last layer of carbon fiber and spray with adhesive

2. Lay polypropylene infusion mesh and stick to the perimeter with duct tape

Step 4 - Placing the tubes

1. Position the resin inlet and vacuum on opposite ends of the mold

2. Use spiral tubes to line a U-shape around the mold with the open end  of the U facing the vacuum

3. Keep the flow distance from the spirals to less than 50 cm

4. Cut away the mesh in front of the vacuum and place the vacuum directly onto the peel ply (this slows the resin flow, maintaining the vacuum for longer)

Step 5 - Vacuum bagging

1. Seal the bag to the tacky tape on the flange of the mold; use tacky tape to create pleats all around the mold

2. Cut the resin hose at a 45° angle, puncture the bag over the inlet fitting, and insert the tube

3. Wrap a small amount of sealant tape around the joint

4. Clamp resin feed tube and connect in to the catchpot

5. Connect the catchpot to the pump with a silicone hose

6. Listen for any hissing sounds; these indicate a leak

7. Perform a drop test: clamp the line between the vacuum bag and the catchpot and wait 20 minutes, then switch off the pump and unclamp the line. If pressure drops when the clamp is removed, there is a leak

Step 6 - Running the infusion

1. Mix the resin: weight of mesh and peel ply + (weight of fabric)/1.5 + 100 g (extra for bucket and hose). Make sure to use a slow hardener and ensure that the temperature is between 18-25°C

2. Secure the resin feed line to the resin bucket

3. Gradually unclamp the feed line. When the resin reaches the feed line, fully unclamp

4. Once you see resin in the vacuum line, clamp the vacuum line and switch off the vacuum pump

5. Resin will continue to flow through even after the pump is turned off. Allow this resin to flow for another 1-5 minutes

6. Firmly clamp the resin inlet and allow the part to cure for 24 hours

Step 7 - Demolding the Part

1. If the resin in the field line cracks sharply when flexed, the part is ready to be demolded

2. Tear the vacuum bag and remove the peel ply and mesh layers

3. Use a gentle level to pop out the part

Required Materials

• Peel ply

• Spray adhesive

• Epoxy infusion resin (must be specific to infusion)

• Infusion mesh

• Infusion spirals

• Silicon connectors (for inlet and vacuum connection)

• Vacuum bag

• Feed vacuum hose

• Vacuum pump capable of <5 mbar (99.5% vacuum)

• Catch pot

• Line clamps

Notes: 

• Most important thing is that mold and bagging is leak tight

• In vacuum infusion- vacuum pressure is used to drive resin into a laminate. Dry materials are laid into the mold and the vacuum is applied before resin is introduced

• When testing keep track of resin flow rates

• Benefits of vacuum infusion: 1. Better fiber to resin ratio (strengthens part by having less excess resin which is brittle) 2. Less wasted resin 3. Very consistent resin usage 4. Unlimited set-up time 5. Cleaner

Drawbacks

• Complicated set up, easy to ruin a part, trial and error

Tips:

• Prepare everything in advance- once the resin has been mixed with the hardener no time to fix mistakes