The fiberglass mold technology is a necessary condition for producing a large number of fiberglass products. In order to improve the quality of FRP products, it is necessary to have good molds, which can not only meet the dimensional accuracy of the products, but also meet their structural mechanics and mechanical properties according to the properties of the products. In terms of appearance, it is necessary to have good smoothness, smoothness, and average thickness. In order to produce high-quality molds and in response to the current technological level and quality status of domestic mold manufacturing, the mold manufacturing process is described below for reference by technical colleagues.

1. Mold manufacturing conditions

1。 environment condition

Temperature: During the entire manufacturing process of male and female molds, the same ambient temperature should be maintained, which is 21-28 ℃.

Humidity: Humidity has a significant impact on the curing of gel coats and resins. The ideal humidity range is 40-60. When manufacturing molds, if the relative humidity exceeds 65 degrees, suitable production conditions should be waited for after construction, especially in northern and coastal areas with high humidity, and more caution should be exercised.

2。 Clean workshop

It is impossible to produce high-quality molds in a dirty environment. The Yin Yang mold manufacturing area should be highly clean, and the maintenance and management standards should be higher than the product production area. Therefore, at the beginning of mold manufacturing, dust removal and cleaning work in the mold manufacturing area should be done in advance.

III. Clean compressed air

Clean and dry air supply is another factor in manufacturing high-quality molds. If the air inside the air duct contains a small amount of water or oil, there will be a large number of pinholes and pits on the surface of the adhesive layer of the mold, which requires a lot of labor to repair. Therefore, the quality of the mold will be greatly affected. The air compressor needs to be placed in a good environment and equipped with an effective air dryer and oil-water separator.

Four. Choosing high-quality auxiliary materials and selecting high-quality raw materials are important conditions for manufacturing high-quality molds. The cost of raw and auxiliary materials used for manufacturing molds only accounts for a small portion of the total cost. It is not allowed to use product resin or expired materials and inferior materials to try to save.

5. Developing a reasonable mold manufacturing plan is one of the factors in making a good mold. Whether it is traditional laying methods or new low shrinkage systems, the required time is determined by the chemical properties of these raw and auxiliary materials. Any attempt to take shortcuts or accelerate the process will have a negative impact on the quality of the mold.

2. The operation process of mold coating is a key link in mold manufacturing. It can even be imagined that the mold coating is the entire mold. All back layers and structural frames are used for surface coating of the mold.

Molded gel coats require higher usage and curing conditions than general product gel coats. High quality mold surfaces require very precise operations and the mixing process of mold gel coats.

One. Spraying equipment is an important part of the mold manufacturing process. Appropriate jet pressure plays an important role in avoiding porosity, flow, and color separation phenomena.

The currently used 871 spray gun is mixed with the curing agent by hand in the spray gun tank to ensure accurate proportions. However, the distribution of the fan-shaped mixture produced by the spray gun produces a good atomization effect, the injection speed is slower than that of the pumping system, and its working time is limited by the time of raw material gel.

2。 Inspection of rubber sleeves for molds

The storage life of the mold rubber sleeve is a very strict indicator, and according to the recommendations of the rubber sleeve supplier, this is very important. In most cases, manufacturers can guarantee the quality of rubber sleeves from packaging to a specific time. Therefore, production inspectors should regularly check the production date or date number of each barrel of gel coat to confirm whether the gel coat is within its effective service life.

(1) After use, use a pneumatic mixer to thoroughly mix each bucket of mold gel coat and ensure that all materials in the bucket are completely mixed. Then, let the gel coat stay for a few minutes to restore its own viscosity, and then use it.

(2) Temperature

Confirm that the temperature of the gel coat is between 21~28 ℃, which is the appropriate temperature required by the molding process. Gel time per barrel

Defined by the supplier. After entering the factory, the quality inspection department must check the gelation time, i.e

A. The sample should reach the standard test temperature of 25 ℃;

B. Add the specified amount of curing agent and stir evenly;

C. Record the time from curing to adding gelatin.

(4) Viscosity

It is necessary to use a Brookfield viscometer to test the viscosity of the gel coat. The temperature of the gel coat sample is 25 ℃.

a. Select a suitable rotor to place in the sample;

b. Low speed and high speed rotational viscometers;

C. Record the reading and convert it into a viscosity index.

The quality inspection of mold materials is an important aspect that mold production enterprises often overlook.

III. The mold should be treated with release wax and release agent

Release wax or release agent treatment.

(1) After polishing the fiberglass mold with water, clean it thoroughly and wipe it dry with a towel. After completely drying, wrap 3-4 layers of clean gauze with an appropriate amount of demolding wax (American marine brand r333), evenly apply it to the surface of the mold using the curling method, wait for 3-5 minutes, wipe with a clean white towel until the mirror effect is achieved, and leave for about 2 hours. Repeat the above operation 4 times. The fifth surgery lasted for more than 6 hours.

After applying wax on anti slip surfaces and complex shapes, it is recommended to use release agents multiple times.

(2) A. Clean new or old molds with appropriate solvents (such as acetone), and the surface impurities and wax scale should be cleaned and dried.

B. Chemleans PMR is soaked with clean gauze and applied to the mold.

C. After application, evenly apply all parts of the surface with a dry cloth before the chemlease PMR dries and solidifies.

D. When using this product for the first time, it must be repeated 4-5 times, with an interval of approximately 10-20 minutes. If the mold area is large, continuous coating can be applied after each coating. After the final coating, the mold must be polished with a dry cloth and allowed to stand for more than one hour.

E. During one use, the gel coat may be difficult to apply, which is the reason for the poor demolding effect. A small amount of demolding wax can be applied, and there is no need to use it afterwards.

F. If demolding is difficult, use chemleans PMR 1-2 times to save costs and ensure quality.

Four. Spray gel coating

Spray gel coating after the mold is coated with mold release wax (agent). It is recommended that the thickness of the mold adhesive layer be 1mm. The adhesive layer is divided into two layers and sprayed twice, with a thickness of 0.5mm. Each layer is sprayed three times, with a thickness of 0.15mm~0.17mm. The thickness of the mold adhesive layer needs to be strictly controlled, and it is required to accurately measure the adhesive layer thickness at multiple locations on the mold surface using an adhesive layer ruler after each spraying.

The correct painting method is:

Spray the first layer with a thickness of 0.15mm~0.17mm.

(2) Spray the second layer perpendicular to the first layer, with a thickness of 0.15 mm~0.17 mm.

(3) Spray the final coat of paint in the direction of the first coat, so that the thickness of the first coat is 0.5mm.

(4) To avoid cracking or wrinkling, spray another layer of adhesive coat after the first layer has solidified. The curing time at room temperature is 90 minutes.

3. After spraying paint

Lay the mold layer within 1-3 hours. After the coating is cured and the surface is not sticky, lay the mold layer. At present, we basically use the traditional multi-step paving method.

One. raw material:

A. Mold resin

The mold resin has a high heat deformation temperature and low shrinkage rate, and is basically made of meta benzene resin and vinyl resin.

B. Glass fiber reinforced material

Short cut strand felt is a very good mold reinforcement material that can minimize the printing of fiber threads. Compared to knitted fiber felt and fiber woven fabrics, short cut felt has more advantages.

C. Quality inspection

To ensure that the mold resin meets the usage requirements, quality inspection should also be conducted on the mold adhesive layer. Including material storage period, mixing test of each batch and gel time and viscosity test.

2。 first floor

The mold layer starts from the first layer. The quality requirements for the first layer are very high. It is necessary to avoid reconditioning or damaging the gel coating after the completion of all moulds. According to the complexity of the mold shape, when pasting the first layer, a surface felt of 30 gm2 should be selected, and a short cut felt of 300 gm2450 gm2 should be selected. When laying the layer, it is necessary to carefully roll it with an iron roller to ensure that all bubbles are removed and the reasonable ratio of resin and fibers is ensured. After the first layer of maintenance, the road surface should be carefully and comprehensively inspected, including all corners, surfaces, and other areas where problems may occur. If bubbles and other defects are found, please carefully remove the bubbles and repair the wound.

III. The general thickness of the thick layer is M450 × 4~5+Rx × n. The thickness of the small mold is about 8mm, and the thickness of the large mold is about 15mm. Manufacturers must strictly implement the stacking process and schedule.

Four. A good way to develop a laying plan is to observe changes in the hardness of the layer. When the hardness of the layer reaches 80% to 90% of the fully cured hardness, the next layer can be laid. When using a hardness tester to measure layer hardness, it is necessary to record multiple readings and calculate the average value as the hardness value. This method can eliminate data errors caused by different curing times, and is usually faster than laying layers according to the paving schedule.

4. Internal structure of the mold

After the mold is laid, the next step is to make the internal reinforcement structure of the mold. The purpose of strengthening the structure is to evenly transmit external forces to the surface of the mold and prevent deformation of the mold surface.

The fundamental cause of rubber sleeve cracking is mold deformation. Therefore, the design of a rigid mold structure will greatly prevent the rubber sleeve from drying and cracking.

Both steel frame structures and sandwich box structures should be suspended 14 feet above the formwork surface. If the structural framework is directly connected to the surface of the mold, different heat conduction will cause indentation on the surface of the mold. In addition, foam or laminate or other insulating materials shall not be placed between the structural layer and the surface. Glass fiber should be used for bonding between structures and laminates, but cannot be embossed with woven fabric.

5. Demolding

After the frame structure is fully cured, it can be demolded. The first step is to cut the edges of the mold in sequence, then evenly insert multiple release wedges between the male and female molds, apply force evenly (do not apply force separately to avoid damaging the mold), use a rubber hammer to hit each stress concentration area (do not use a hammer), and finally completely demould.

6. After mold treatment

After demolding, carefully inspect all parts of the mold, and if surface defects are found, they should be noted and marked. In an ideal state, the mold does not need to be polished on the surface, only the mold surface needs to be polished. In general, molds cannot reach their ideal state and must be polished using traditional methods.