At present, current development features of the whole industrial production are various categories, rapid updating and drastic market competition. To meet customers' requirements for mold manufacturing with short date of delivery, high precision and low cost, plastic mold must have following development tendencies:
1. Mold design is developed from empirical design to theoretical calculation and computer-aided design. CAD, CAM and CAE are widely applied in mold manufacturing, making mold structure more rational and highly improving precision of mold. it also reduces processing cycle of mold design and development time of products.
2. Mold design is developed from high precision large size to high precision ultra small dimension. Ten years ago, the precision of precise mold generally is 5μm. Now, the precision has reached 2-3μm. Precise mold with precision of 1μm will come out soon. With requirements for microminiaturization and precision improving, the precision of some molds should be within 1μm. So, superfinish is required to be developed which can reduce manual operating quantity such as bench worker.
3. Multi-functional composite mold will be developed further. Plastic mold with multi colors or materials will be developed more quickly. The mold can decrease production cycle and assembly cycle of products. The mold will be developed and applied in different fields in the future.
4. With hot runner technology developing, proportion of hot runner mold in plastic mold is increasing gradually. The mold using hot runner aluminum alloy panel technology can improve productivity and quality of workpieces, saving raw materials of workpieces significantly. Therefore, hot runner is developed quickly abroad and it is quite popular.
5. The application of mold standard parts is increasingly wider. Mold standardization and application of mold standard parts have great influence on manufacturing cycle of mold. Using mold standard parts cannot only reduce manufacturing cycle of mold, but also can improve quality of mold and decrease cost. Therefore, the application of mold standard parts will be wider and wider. For example, plastic, stamping mold, centre, ejector sleeve, screw and spring can form standard parts.
6. Rapid economic mold has wide prospect. Nowadays is a period of multi-categories small-lot production. In 21st century, proportion of mode of production will account for more than 75% of industrial production. On the one hand, products have short service cycle, on the other hand, categories change frequently, which requests that mold having shorter production cycle is better. So, developing rapid economic mold attracts more and more attentions from people. For example, develop superplastic material to be used for making mold. Use epoxy, polyester, filler metal, glass or other reinforces to make simple mold. The features of simple mold are that have simple manufacturing techniques, manageable precision, low shrinkage and price, higher service life. Cement and plastic also can be used for mold of auto covering parts. The mold has been widely applied in the U.S. and Japan. However, it still needs to be improved, expanding its application. Rapid economic mold including medium or low melting point alloy mold, spray forming mold, electroformed mold, refined casting mold, stack mold, ceramic plastic sucking mold and epoxy mold will be developed further. Besides, quick die change device and rapid test device controlled by calculator and operated by manipulator will also be developed and improved.
7. With plastic forming technology constantly improving and developing, gas injection mold and mold adapting to high pressure injection molding are also developed. The precision of plastic parts is classified into dimensional accuracy, geometric accuracy and appearance accuracy (gloss and hue). To realize these accuracies, research on high pressure injection technology and mold, plastic injection compression technology and mold will continue being carried out. In plastic injection molding
, molding shrinkage is the largest factor having impact on molding precision. High pressure plastic injection molding can reduce shrinkage of resin and increase stability of plastic dimension. Mold should have good rigidity and high proof pressure. Especially cavity of precision mold should be quenched, having good sprue sealing. Mold temperature should be controlled correctly. Gas-assisted molding technology has already been ripe. It cannot improve internal and exterior quality of plastic parts, having low injection pressure, few deformation of products and easily forming products having largely different wall thickness, bur also it can save raw materials and improve productivity of products, reducing cost significantly further. Gas injection mold has already appeared in China, having received good results.