Parting surface design
Whether the design of parting surface is reasonable or not has great influence on the difficulty of process operation, the sticking of mold and the quality of parts. In general, according to the characteristics of the prototype, the location and shape of the parting surface should be as simple as possible on the premise of ensuring the smooth demoulding of the prototype and the installation accuracy of the upper and lower parts of the mold. Therefore, it is necessary to correctly and reasonably select the location of parting surface and gate, and it is forbidden to tilt the reverse drawing die to avoid demoulding. The prototype is fixed with smooth wooden boards along the parting surface, so that the upper and lower molds can be pasted separately. When coating the release agent on the prototype and parting surface, it must be uniform and thoughtful, and it must be coated for 2 ~ 3 times. After the last release agent is dried, it can be applied again.
Brush gel coat
After the release agent is completely dried, brush the special gel coat for the mold twice with a brush, evenly, and brush the second layer after the first layer is initially set. The gel coat is black, and the total thickness of the gel coat layer should be controlled at about 016 mm. It should be noted that the gel coat should not be painted too thick to prevent the surface from cracking and wrinkling.
Preparation of resin glue solution
According to the viscosity of normal temperature resin, it can be preheated appropriately. Then, mix 100 parts of wsp610/epoxy resin and 8- 10 parts (by mass) of acetone (or propylene oxide butyl ether) in a clean container, and after stirring evenly, add 20-25 parts of curing agent (the amount of curing agent should be increased or decreased according to the site temperature)
Glass fiber is pasted layer by layer
When the gel coat is initially set and feels soft and non-sticky, the prepared epoxy resin glue solution is coated on the gel coat, and then a layer of chopped felt is laid, and the cloth layer is compacted with a brush to make the glue content uniform and discharge bubbles. In some cases, it is necessary to use sharp objects to pick up bubbles. The laying of the second layer of chopped felt must be carried out after the first layer of resin glue is solidified. After that, it can be made into the form of a cloth and a felt by pasting layer by layer. After pasting 2-3 layers each time, the next layer can be pasted after the exothermic reaction of resin curing reaches the peak (that is, when the resin glue is sticky, it is usually about 60min) until the required thickness is reached. When pasting, the glass fiber cloth must be laid flat, and the seams between the glass fiber cloth should be staggered, and try not to overlap at the corners. It is necessary to strictly control the amount of resin glue in each layer so that the fiber can be fully infiltrated, but not too much. High glue content, difficult elimination of bubbles, large curing heat release and large shrinkage. Low glue content and easy delamination. After the first mold is cured, the excess flash is cut off, and the impurities on the surface of the mold and the other half prototype are cleaned, so that the release agent can be removed, the gel coat layer can be made, the injection hole and the exhaust hole can be placed, and the second mold can be pasted. After the second mold is cured, the redundant burrs are cut off. To ensure that the mold has sufficient strength and avoid mold deformation. Some brackets, fasteners, locating pins, etc. Can be properly bonded to improve the mold structure.
De-glazing and finishing
The mold pasted at normal temperature (about 20℃) can be basically solidified and formed in 48 hours, that is, it can be demoulded. When demoulding, it is forbidden to strike the mold with hard objects, and try to blow intermittently with compressed air to make the mold and the master mold gradually separate. After demoulding, according to the use requirements of the mold, some mechanical processing such as drilling can be done on the mold, especially in the dead corner where the material is not easy to fill during pouring or injection molding, some air holes must be drilled and no air holes are reserved. Then the post-treatment of the mold is carried out. Generally, the mold surface is polished by 400 # ~ 1200 # water sandpaper in turn, and the mold surface is polished by a polishing machine. After all processes are completed, the mold can be delivered for use. There are several points to pay attention to: first, the master mold should be smooth; Second, the release agent should be uniform; Third, there should be no bubbles when making the first layer; Fourth, it should be carefully polished. Of course, there are many details in the middle, so it is impossible to list them one by one.