How to Use Resin Infusion Process to Form Products
Step 1: Prepare Materials
Before using the vacuum infusion molding process, we first prepare the required auxiliary materials. If we prepare them during the production process, it will be very troublesome. After all the materials are prepared, we can start the operation.
Step 2: Mold Preparation
This step is critical. When preparing the mold, many factors need to be considered, such as the air tightness of the mold, surface finish, cleanliness, defects, width of the mold flange, etc. The mold I chose is an epoxy system mold. Because the infusion molding process is cured at room temperature, it does not need to be cured at high temperature. This mold can withstand temperatures of 50°~60°
We need to apply 4-6 times of release agent to a new mold. I chose Easycomposites’ Easy-lease chemical release agent. This release agent has a very good release effect and is semi-permanent, which means that you don’t need to wipe the release agent again next time you make a product.
Step 3, Bonding Sealing Tape
After the release agent is wiped off, we can glue the sealing tape on the flange edge of the mold. Since it is cured at room temperature, the sealing tape can be selected as low-temperature sealing tape. Another advantage of gluing the sealing tape in advance is to avoid the fiber bundle being pressed under the sealing tape during the subsequent layering process. If the fiber bundle is pressed under, it will cause the airtightness inside the vacuum bag and fail to form a vacuum state.
Step 4, Layering
In this step, you can lay the layers according to the process requirements (carbon fiber cloth, glass fiber cloth, layer thickness). When laying all the reinforcement materials, cut off the part that exceeds the sealing tape with special scissors to avoid affecting the bonding of the vacuum bag and the wrinkling of the product area under the vacuum. After cutting to size, you can use paper tape or pressure-sensitive tape to fix the fiber material, but the premise is that the reinforcement material must be completely attached to every part of the product area to avoid bridging when vacuuming.
Step 5, laying Auxiliary Materials
After the reinforcement material is laid, the release cloth can be laid. The release cloth is the auxiliary material of the first isolation product. It is easy to tear off after curing and forming, and the original weaving pattern of the release cloth is formed. The release cloth should be laid larger than the reinforcement material, because it will be easier to tear off the product after curing. After covering the entire product, fix it with paper tape.
The next step is to lay the guide mesh. Choose the appropriate guide mesh according to the complexity of the mold surface. If the surface is more complex, you can choose a woven guide mesh. This guide mesh is softer and easy to lay on complex areas of the mold. Because this mold is not that complicated, I chose a medium-speed guide mesh.
Arrangement of the guide spiral tube and the resin guide silicone seat
When guiding the resin, the spiral tube can make the resin flow quickly along the spiral tube and quickly infiltrate into the fiber layer through the guide net. After the arrangement is completed, it is fixed with paper tape. Here, special attention should be paid to the arrangement of the silicone base. Do not lay the guide spiral tube under the silicone seat of the discharge port. Only the spiral tube is arranged at the feed port.
Step 6, Bonding the Vacuum Bag
This step is particularly important. We need to cut the vacuum bag large enough because we need to reserve space for pleating according to the mold surface. These pleats can make the vacuum bag press down along the mold contour when vacuuming to avoid bridging.
Step 7: Connect the Vacuum Pipeline
After the vacuum bag is bonded, we can connect the vacuum pipeline. There are two silicone seats on the mold that need to be connected by PVC guide tubes, and one is connected to the resin inlet. We can use a blade to cut the silicone seat outlet, insert the guide tube into the silicone seat and seal it with sealing tape, and finally lock it with a pipe clamp.
The discharge port is connected to the resin collector. An inner tank should be placed in the resin collector to collect excess resin. Each connection port must be sealed to ensure no air leakage.
Once the resin collector is connected, the vacuum pump can be connected. We insert the guide tube into the barbed connector of the vacuum pump.
Step 8: Vacuuming
When the pipeline is connected, you can draw the vacuum. We must ensure that there is enough vacuum film in every corner of the mold surface, and that every area of the mold surface can fit the mold surface. No bridging should occur. If there is bridging, turn off the vacuum pump, open the pipe clamp of the resin feed port, relax the vacuum film, and then handle the bridging area until all places are completely fitted to the mold.
When the pointer of the vacuum gauge reaches -1 air pressure and the sound of the vacuum pump changes, it means that the inner cavity of the vacuum bag is already in a vacuum state. At this time, we can turn off the vacuum pump and clamp the guide tube of the resin outlet with a pipe clamp.
Now we can perform a vacuum leakage test. We wait for 15 minutes and always observe the pointer of the vacuum gauge on the resin collector. If there is a leak, the pointer will change. At this time, you need to check all possible leaks, such as (the bonding of the sealing tape, whether there are pinholes in the vacuum film, whether each connection port is tightly sealed, and the airtightness of the mold), etc., and test again until the vacuum state is completely reached.
Step 9, Guide Resin
It is very important to choose a resin suitable for infusion, because you need to consider many factors, such as the resin’s wettability, viscosity, activation time, curing time, fluidity, etc.
I chose Easycomposites’ special infusion resin, which has low viscosity and can quickly infiltrate the entire reinforcement. The mechanical properties of this resin are also particularly excellent. At the same time, this resin matches two fast and slow curing agents, and the operating time is wide, so there is no need to worry about insufficient operating time. We turned on the vacuum pump again to ensure that there was no leakage.
The ratio of this resin is 100:30 (100 parts of resin to 30 parts of curing agent). You can use fast or slow curing agent, or half fast and half slow, but you must mix the ratio accurately and stir it thoroughly. Since there will be bubbles in the resin when stirring, it needs to be left for about 5 minutes to degas.
At this time, we can put the guide tube of the resin feed port into the prepared resin barrel, and remove the tube clamp on the tube, so that the resin can enter the mold cavity with the vacuum pressure.
We can see that the resin quickly infiltrates into the reinforcement along the spiral tube and the guide net. The bubbles in the resin will also be gradually drawn out of the mold cavity by the vacuum pump as the vacuum pressure increases. When the resin is completely infiltrated into the product, we can use a pipe clamp to block the feed port.
When the resin is completely infiltrated, the excess resin is collected into the resin collector through the work of the vacuum pump. When there is no excess resin on the silicone base at the resin feed port, the resin outlet can be clamped with a pipe clamp, that is, the pipe connected to the resin collector. At this time, the diversion has been completed, and the curing time is 24 hours at room temperature @25°, and then it can be demoulded.
Step 10, Demoulding
Tear off the vacuum film and the silicone base can be reused.
When tearing off the release cloth, be sure to wear protective gloves to avoid the resin fibers cutting your skin.
When demoulding, you will find that it is easy to remove the product from the mold after wiping the Easy-lease chemical release agent.
After demoulding, you can proceed with the subsequent processing, cut according to the product line, polish the edges, and a complete guide product is completed.
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