Detailed explanation of resin vacuum introduction process

What is resin diversion?

First lay the reinforcement, that is, "dry" fabric (not mixed with any resin) on the mold, then lay the vacuum auxiliary materials (such as mold release cloth, diversion net, vacuum bag), and finally use the vacuum pump to vacuum

If the resin diversion process is operated correctly, FRP parts with satisfactory strength and appearance quality can be produced

Preparation-materials and equipment you need

The key factors for the success of resin diversion: the correct vacuum equipment and auxiliary materials need to be prepared in advance

Mould

The edge of the mold should have a large enough flange to fix the vacuum auxiliary material

equipment

Vacuum pump: up to 99.

Silicone nozzle: placed in a vacuum bag to connect the resin feed line and the vacuum line

Resin collector: If you only use the diversion process once or twice, you can also use air felt instead of the resin collector to collect a small amount of resin; but for long-term use, it is best to invest in a professional resin collector

Vacuum bag auxiliary material

• Vacuum bag film

  
  

• Vacuum sealing tape (ie, sealing tape or putty tape)

• Diversion net
  

• Release cloth
  

• Air felt (if you don't have a resin collector)
  

• Spiral tube
  

• PVC vacuum tube

• Paper tape or pressure sensitive tape
  

Material

• Release agent (release wax, PVA or chemical release agent)

• Reinforcement, such as diversion felt, chopped strand mat or glass fiber cloth

• Vacuum diversion resin

Step by step guide

01 Prepare the mold surface

Mold release agent should be used on the mold surface
.
Semi-permanent release agent is a very reliable high-gloss release agent, used correctly will get a high-quality surface
.
Application: Use a lint-free cloth to coat the surface of the mold with a chemical release agent
.
Wipe the release agent, wait for a moment to start to evaporate (1 minute, depending on the temperature and type of release agent), use a second piece of lint-free cloth, gently draw a circle to wipe off the excess release agent
.
Apply 6 layers on the surface of a new, unused mold, with a minimum interval of 15 minutes between each layer
.
The mold can be used at least 30 minutes after the last coat is applied
.

02 Cutting and laying reinforcements

According to the molding needs, cut the reinforcement of the appropriate size
.
If possible, use one layer of reinforcement as a template to cut out the remaining layers
.
Make sure that the fabric you cut is large enough to cover all the edges of the product, and consider the burrs that need to be cut later
.
Place the reinforcement into the mold (you can also place multiple layers at a time)
.
For complex molds, especially those with uneven or multi-contoured shapes, it is sometimes necessary to use styling glue to stick the fabric to the surface of the mold and the bonding between each layer
.

03 Add release cloth

The release cloth is used as the first layer of the craft material in the resin diversion suit.
After the product is finished, it can be torn off from the product, leaving a relatively consistent surface, and it can also be used as an ideal bonding surface
.
Usually, the release cloth is spread to one layer, covering the entire surface of the reinforcement
.
It is not necessary to overlap the release cloth on the edge of the reinforcement, but it does cover all, so usually the cut area is slightly larger than the reinforcement
.

04 Add diversion net

The diversion net (also called "diversion medium") is used to ensure that the resin can freely penetrate into the laminate from the resin diversion tube (and spiral tube)
.
The guide net of this shape means that even under full vacuum, there are still gaps for the resin to flow
.
The diversion net also needs to be laid on one layer (multiple layers can be overlapped if necessary, and it will not cause any impact)
.

05 Fixed spiral tube

A spiral tube is a spirally wound plastic tube used to improve the flow of resin from the feed tube to the laminate
.
The resin will be dispersed along the entire spiral tube, so the standard approach is to fix the spiral tube at the edge of one end (that is, the end where the resin feed tube is fixed), which means that the resin is quickly evenly distributed along the mold from one side to the other.
distribution
.
The spiral tube must be directly fixed on the diversion net
.
Ensure that the resin can more easily flow from the spiral pipe into the deflector
.

06 Fix the silicone nozzle of the resin feed end

The silicone connector is a black silicone connector
.
It has a channel at the bottom that can run from side to side
.
The spiral tube can pass through the channel to ensure that the resin can flow from the resin feed tube through the joint to the spiral tube
.
Fix the resin feed joint in the middle of the spiral pipe
.
Press the joint on top of the spiral tube so that the spiral tube can run on the bottom of the joint
.

07 Fix the silicone nozzle on the vacuum side

This is also a silicone connector
.
Fix the silicone nozzle on the diversion net (sometimes, in order not to reduce the risk of absorbing too much resin, fix the silicone nozzle on the release cloth), at the opposite end of the resin feeding spiral tube
.

08 Sealing tape

Sealing tape is like a very sticky rubber tape
.
This tape is widely used in all vacuum bag processes, and its soft characteristics can efficiently provide a sealed environment
.

09 Lay and stick the vacuum bag

Now it's time to wrap everything in a vacuum bag
.
The high-quality vacuum bag film is not only strong (not easy to be pierced) but also has proper stretchability
.
From the overall point of view, accidental damage to products caused by inferior vacuum bags is a greater waste
.
When using a vacuum bag, it is very important to ensure that the shape and contour of the mold are adequately wrapped in a vacuum bag
.
Incorrect placement of the vacuum bag so that there is any "bridging" at the corners of the mold will cause excessive resin in the final product, reducing strength and quality
.

Cut out a large enough vacuum bag film that is 50% larger than the mold area
.
Starting from the corner, tear off the paper on the back of the sealing tape, press the vacuum bag film, and stick it to the exposed sealing tape
.
Move along the edge of the mold, tear off the paper on the back of the tape and stick it to the vacuum bag film, tearing and sticking
.

Just as you glue the film to the tape, be as careful as possible so that the vacuum bag does not have any wrinkles or creases
.
Press down firmly with your fingers, and rub while pressing to make the vacuum bag film and sealing tape stick together to create a sealed environment
.
If you have completed the vacuum bag sealing, but there is a leak (we will do a leak test later), then it may be caused by the wrinkles or folds of the vacuum bag
.

10 Connect and seal the vacuum tube (also called draft tube) at the resin feed end

After the vacuum bag is bonded, you can make a hole on the vacuum bag to connect the resin flow tube
.
Use a pair of scissors or a knife to make a cut in the vacuum bag directly above the resin feed silicone joint
.
Cut a section of PVC vacuum tube from the position where the feed tank is placed to the feed joint on the vacuum bag
.
When you cut the PVC hose, make a bevel (approximately 45°) so that the hose does not accidentally seal at the bottom
.
Pass the beveled end of the hose through the small hole on the vacuum bag and press it into the hole of the feed connector
.
Make sure that the hose is actually connected to the feed connector
.
Seal the hose to the vacuum bag by wrapping a ring of sealing tape around the hose
.
Press firmly to ensure that the sealing tape creates a sealed environment
.

11 Connect and seal the vacuum tube on the vacuum side

Repeat the previous step, this time using another PVC pipe to connect the resin collector and the vacuum nozzle
.
Cut the hose at an angle, cut a small hole in the vacuum bag, push the hose into the vacuum nozzle in the vacuum bag, and then seal it with sealing tape
.

12 Resin feed tank

The resin feed tank should be firmly positioned near the mold
.
It is very important that the resin feed tank cannot fall over during the diversion period
.
The draft tube can be connected to the bottom of the feed tank from beginning to end, and if necessary, a paperclip or something can be used to keep the hose fixed
.

13 Connect the vacuum pump and the resin collector

Connect the other end of the vacuum tube to the resin collector, then cut a piece of PVC hose and connect the vacuum pump to the tree finger collector
.

14 Clamp the draft tube at the resin feed end

Place a pipe clamp on the feed pipe at one end of the resin feed tank to ensure that a sealed environment is created
.

15 Turn on the vacuum pump

Everything is ready, now we turn on the vacuum pump
.

16 Vacuum, adjust the vacuum bag

When the air is evacuated from the vacuum bag, you will see the vacuum bag close to the mold surface
.
In this case, you should move and adjust the vacuum bag.
Some complex areas on the mold require more vacuum bags
.
All vacuum bag processes (resin diversion process, vacuum bag pressing process and even prepreg process), this process is essential, so pay great attention to this step
.

As the bag begins to tighten gradually (of course, it is not all evacuated, and the vacuum bag will not be compressed), temporarily turn off the vacuum pump
.
At this time, you can move and reposition, make some folds where needed, and make sure that the vacuum bag is not bridging
.

In your first few projects, you may underestimate the amount of vacuum bag film used
.
If this happens, you will find that at this stage, because the vacuum bag will bridge a certain part of the mold, there is no extra vacuum bag to adjust
.
Once this happens, unfortunately, you have to stop, tear off the bag (and sealing tape), and do it again with a large enough vacuum bag
.
If you continue to use such a small vacuum bag, the quality of the product will be greatly reduced
.

17 Vacuum leak test

Turn on the vacuum pump and draw a vacuum
.
You will see the needle of the vacuum gauge start to rise
.
There is no need to turn off the vacuum pump and wait until the pointer is close to full vacuum
.
If necessary, adjust the vacuum bag film to ensure that there is no bridging
.

After a few minutes, the vacuum gauge's reading was close to 100%
.
Due to the changing atmospheric pressure and the calibrated meter, even if the full vacuum has been reached, the pointer may not accurately point to 100% vacuum
.
The most practical way to know when the perfect vacuum is reached is to look at the vacuum pump and see if any vacuum pump oil evaporates from the pump
.
When fully sealed, the sound of the pump will slightly change, and the vapor of the vacuum pump oil will stop evaporating from the vacuum pump
.

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After demolding, the product should have a perfect surface quality without any bubbles or pores; at the same time, the product is very strong and light, and can cut the excess edges of the product or modify the product by drilling and so on
.
If it is a high-end carbon fiber product that needs to withstand more direct sunlight, friction or other abrasion in future use, it is recommended to use 2K varnish for protection
.