Composite Material LRTM Molding Process Production Operation Instructions

1. Mold Preparation:

Operation Content

1. Use compressed air to blow away the dust on the surface of the mold, and then wipe the mold cavity and negative pressure belt with a clean towel. The new mold needs to be waxed with release wax PMR or 770 for 5 times, and then waxed once for each product produced, until 6-8 products are produced, and then it is transferred to normal maintenance.
2. Waxing requirements: Fold a clean cotton cloth of appropriate size in half 4-6 layers, and the waxing direction must move in the same direction. One person waxes in front and another wipes afterwards. Be careful not to miss it. Wipe off the traces of wax, and require that no obvious traces can be seen under side light.

3..After the mold has been used to produce 6-8 products, the negative pressure belt is no longer waxed. The mold cavity must be waxed once for 3-5 products. Waxing requires uniformity and no omissions.

Precautions

1. It is strictly forbidden to scratch the mold surface
2. Use qualified materials as required
3. No personal injury or environmental pollution

 

2. Gel Coat Spraying:

Operation Content

1. Clean the mold before spraying the gel coat. No dust, dirt or other foreign matter is allowed.
2. Gel coat cannot be applied to the part outside 5-10mm along the edge of the mold cavity.
3. When the temperature is 25-30℃, the curing agent ratio is 1.0-1.5%. The gel coat and curing agent must be mixed evenly. The gel coat must be stirred evenly before use.
4. Prepare the brush (spray gun). The brush (spray gun) is required to move horizontally and then vertically. The spraying should be uniform and the thickness should be controlled at 0.5-0.6mm.
5. After the gel coat is applied, check whether the coating is uniform on the mold. There must be no missing coating or too thick gel coat that affects the mold closing.

 

Precautions

1. Wear work clothes, protective glasses, gloves and other labor protection products
2. Minimize the impact of atomized gas on the environment when spraying gel coat
3. Keep a record of gel coat usage

 

3. Reinforced Fabric Laying:

Operation Content

1. First layer: 300g powder chopped mat, all laid in the mold cavity, required to be laid flat, compacted corners, and not shifted.
2. Second layer: closed mold mat 300\180\300, only laid in the mold cavity, no flange, required to be laid flat, compacted corners, and not shifted.
3. Third layer: 600 fabric, all laid in the mold cavity, required to be laid flat, compacted corners, and not shifted.
4. Fourth layer: 600 fabric, all laid in the mold cavity, required to be laid flat, compacted corners, and not shifted.
5. Fifth layer: 600 fabric, all laid in the mold cavity, required to be laid flat, compacted corners, and not shifted.
6. The flange flipped over part can be fixed with spray glue, and there should be no looseness to avoid product defects or difficulty in mold closing. After the front cover is laid, you can prepare to close the mold and measure the negative pressure.
7. (Back cover) The sixth layer: demoulding cloth, which is fully laid in the mold cavity. It is required to be laid flat, compact the corners, and not shift.
8. The seventh layer: the guide net. In principle, all layers cannot overlap when the glass fiber is coated, and the joint parts must be dislocated by 5-8 cm; the flange can be fixed with spray glue, and there must be no looseness to avoid product defects or difficulty in mold closing.
9. The eighth layer: The vacuum bag film is pre-placed with a certain margin compared to the mold area to prevent the formation of dead corners at the turns. The vacuum bag film is bonded and sealed with the sealing strip, and it must be ensured that there is no pressure release.

Back cover operation steps: 1. First, stick a circle of sealing tape on the edge of the flange. 2. Then lay the resin guide tube (spiral tube) on the edge of the flange to ensure that the strength of the guide tube is not too weak. 3. The requirements of the demoulding cloth are fully covered in the mold cavity. 4 The guide net is also fully covered in the mold cavity like the demoulding cloth. 5. Paste the vacuum bag film along the sealing tape, and fold it every 300mm. The actual use area of ​​the vacuum bag film must be larger than the actual area of ​​the mold cavity, and there must be no leakage.

Precautions

1. Wear protective work clothes
2. Pay attention to the protection of the mold
3. Collect the cut fabric scraps in a special bucket and do not throw them away to avoid affecting hygiene.
4. Ensure that the vacuum bag film is intact and not damaged.

 

4. Mould Closing to Measure Negative Pressure:

Operation Content

1. Mold closing, the negative pressure belt must be clean and free of foreign matter, and the glass fiber fabric cannot be pressed on the negative pressure belt or placed in the negative pressure bag. Then connect the vacuum line as required, and use a vacuum pump to pump negative pressure. If the pressure reaches -0.1MPa (see Figure ①) (see Figure ②), there is no air leakage. Otherwise, check whether there is air leakage, and check whether the fabric is too thick or other reasons, and take corresponding measures to eliminate the air leakage until the pressure is -0.1MPa and stable.
2. Pipeline connection instructions: The mold glue inlet is connected to a DN16 plastic pipe for about 1m; the negative pressure bag suction port is connected to an interface of the resin collector with a DN12 orange plastic pipe for about 2m, and a resin collection pot is installed on the mold cavity outlet. The collection pot pipeline interface is connected to the vacuum collector with a DN10 transparent plastic pipe, and the white spiral tube on the collector is connected to the vacuum pump.
3. After all inspections are completed and meet the vacuum requirements, you can proceed to the next step of glue injection.

Notes

1. Wear protective work clothes
2. Be proficient in vacuum pump operation
3. Pay attention to electrical safety precautions

5. Resin Injection:

Operation Content

1. Check the negative pressure bag pressure is -0.1MPa, the pressure at one end of the collector is -0.06MPa, and start the next operation. Otherwise, check the cause and meet the requirements before continuing to the next operation.
2. The glue inlet is stuck, install the resin collector at the exhaust port, connect the pipeline to the vacuum pump at the outlet, and adjust the regulating valve to start vacuuming the mold cavity until the pressure is -0.06-0.08MPa, otherwise check the cause and meet the requirements before continuing to the next operation.
3. Adjust the ratio of resin to curing agent in the injection equipment (generally 100:1.5–2), connect the equipment outlet and the mold feed port, and start injecting glue. During this process, pay attention to the stability of the resin injection equipment. The resin pressure is generally 1 kg.
4. When resin appears in the collection pot, stop pouring when no bubbles appear, close the glue inlet hose and wait for the gel to solidify, and release the negative pressure with the negative pressure belt after solidification.

Notes

1. Wear work clothes, protective glasses, gloves and other labor protection supplies
2. Operate the RTM machine and equipment maintenance as required