Acrylic lens introduction and processing technology are simple
Acrylic lens, the material of the bottom plate is PMMA, refers to the general name of PMMA plate after electroplating. Acrylic lens instead of glass lens, with light weight, easy to break, convenient molding, easy coloring, etc., has become a lens production A new process.
1. Acrylic contains polar side methyl group, has obvious hygroscopicity, water absorption is generally 0.3%-0.4%, must be acrylic sheet before molding
Must be dried, drying conditions are 80 °C -85 °C drying 4-5h. The
2. Acrylic has significant non-Newtonian fluid properties in the molding processing temperature range. The melt viscosity decreases significantly with increasing shear rate, and the melt viscosity is also sensitive to temperature changes. Therefore, for the polymethyl methacrylate molding processing, increasing the molding pressure and temperature can significantly reduce the melt viscosity and achieve better fluidity. The
3. The temperature at which acrylic begins to flow is approximately 160°C. The temperature at which decomposition begins is greater than 270°C, with a wide processing temperature range. The
4. Acrylic melt has a high viscosity, and the cooling rate is fast. The products are prone to internal stress. Therefore, the control of the process conditions during the molding is strict, and post-processing is also required after molding. The
5. Acrylic is an amorphous polymer, shrinkage and its range of changes are small, generally about 0.5% -0.8%, is conducive to molding a high dimensional accuracy of the plastic parts. The
6. Acrylic cutting performance is very good, its profile can be easily machined to various sizes.
Acrylic can use casting, injection molding, extrusion, thermoforming, laser engraving, laser cutting and other processes.
1, casting molding
Casting molding is used to form plexiglass sheet, bar and other profiles, that is, the body bulk polymerization method profiles. Post-processing of the molded product is required. Post-treatment conditions are 2h at 60°C and 2h at 120°C.
2, injection molding
Injection molding uses pellets obtained by suspension polymerization and is molded on an ordinary plunger or screw type injection molding machine.
Thermoforming is a process in which a plexiglass plate or sheet is made into various shapes and shapes. A blank cut to a desired size is clamped on a mold frame, heated to soften it, and then pressed against the mold surface. The same shape as the profile is obtained, and the edge is trimmed after cooling to obtain the product. Pressurization can be done by vacuum drawing or by directly pressurizing a punch with a profile. Thermoforming temperature can refer to the recommended temperature range in Table 3. When rapid vacuum low draft forming products are used, a temperature close to the lower limit should be adopted. When deep forming products with complex shapes are formed, close to the upper limit temperature should be used, and the normal temperature is generally used.