PMMA plastic injection molding process About
In recent years, with the improvement of living standard, car into the home, the increased demand for plastics, VCD 's popularity, DVD 's coming, growing demand for transparent plastic, PMMA, as a transparent plastic, high transmittance, is widely used in high-precision telescope lens, eyepiece, objective lens, but the injection molding process has been difficult to break, technologies have been Japan's monopoly of domestic enterprises and scientific research, but still could not break though, especially in precision injection molding process.
PMMA of injection molding is indeed very difficult, there are many experiences, there are many mold factory in the next that dies when they think that is very simple, on a sheet, in fact not so simple! Many such molds to create, from the beginning design to production should pay attention to:
1. According to the product size and thickness, and glue plastic machine shot to determine the number of cavities, usually to open a two-point mode, or four points, too more and no good, keys can open a little more.
2. Design do first mold flow analysis, it is very important, especially rectangular lens, the gel-point into the corner of the long side of Kao 15MM Department is the best, if just a touch of perforated products here, or by plastic bit on the better production is easy to transfer gas lines and melt marks.
3. Exhaust the locations of the lens is generally transparent and deprive the thimble marks, auxiliary channel must be opened to help top up, the flow from the exhaust on the role of general adhere to the principle that corner over where there should be exhaust.
4. Flow channel and into the rubber mount design, trapezoidal open channel, into the open mouth plastic fan, flow should be polished very bright.
5. Steel selection, the yield in less than one hundred thousand, can be produced in Japan is NAK80 can, if big production, we must use high-S136 or the law of domestic SMV3W mirror heat treatment of steel, heat treatment to HRC52, and then after finishing polishing, very good results, their PMMA have some corrosion of steel with heat treatment can eliminate mold, after a period of time table noodle pitting phenomenon, of course, got to be in the original Gangcai procurement, many are domestic or completely fake in the S136, has totally failed to this effect, if the plan cheaper to buy this material, and everything good, that is, the surface polishing is not on, how are gray cast steel texture, regrets are too late, S136 directly in a Sheng-Lung Kee hundred or purchase, they are responsible for heat treatment, SMV3W only Lung Kee agents , the use effect is almost the same S136.
6. Die when the fuel injection temperature, 120 degrees heat, mold manufacture die must install a special thermometer in the mold.
7. Plastic machine to use a small screw type A, or smaller than the A-type screw the PC , PMMA special screw, speed is high, this is good or bad shape the basic guarantee of quality, there is a whole of this production motor precision injection molding machine, molding good effect, and now all of the plastic machine factory has developed such a dedicated machine.
8. There are some transparent pieces of thin, can increase nitrogen high-pressure injection, which is dedicated machines, there are still some way with the injection pressure molding, first shot and then high-pressure plastic mold forming.
[ Author: simon] [ Date: 4/1/2010 ] [ Hits: ]
