P.E.T material has characteristics 
                                of good chemical effect tolerance, nice transparency, 
                                and satisfied the food safety grade standard, 
                                which has been used in many products, such as 
                                mineral bottle, fruit juice bottle, carbonate 
                                drink bottle..., etc. If it is used for cosmetic 
                                containers, it is better to use P.E.T.G. material 
                                since P.E.T.G has even better chemical effect 
                                tolerance. unlike for acrylic container, which 
                                the internal must fix with PP material container. 
                              The biggest issue for P.E.T material is that 
                                it absorbs humidity from the air, therefore, one 
                                must dehumidify the material to be below 0.05%. 
                                Otherwise, the product will become easily destroyable 
                                with also crystal white finishing surface. Based 
                                on this issue, a P.E.T injection machine must 
                                come with a complete set of dehumidifier, which 
                                dries the air between -29 to -40 degree, and for 
                                dryer machine it's about 180°C. Furthermore, in 
                                order to prevent the mold gets sweaty, the mold 
                                must have dew preventing equipment, which normally 
                                uses cool air to blow, but sometimes using dry/hot 
                                air process system. The workshop should also include 
                                air condition and dehumidifier. 
                              In order to improve the production efficiency 
                                and to prevent the beat break up, it is better 
                                to design the machine using double loop controlling 
                                type. That is, the mold can be opened during screw 
                                charging action to shorten the cycle time. Also, 
                                the mold side should be warped and dewy. Then, 
                                it is important to design the injection screw 
                                compression rate (L/D rate) to prevent heat break 
                                up from strong friction heat. 
                              The process of making a the mold is also not 
                                a easy task, as it is difficult to make and expensive. 
                                Without skilled mold design and structure, many 
                                problem may occur. Therefore, one must purchase 
                                a full equipment set and complete setting and 
                                testing the mold to avoid trouble. Usually, a 
                                full set includes P.E.T injection molding machine, 
                                dehumidifier, hopper dryer, auto loader, water 
                                chiller, mold, conveyer belt transmission system 
                                and robotic arm..., etc. A blowing machine will 
                                be required on two step injection machine, but 
                                will not be required on P.E.T preform production; 
                                additional injection molding machine and bottle 
                                cap cutting machine will be required to produce 
                                bottle cap.  
                              There are two types for P.E.T injection machine: 
                                single step type and double step type. For the 
                                single step type, the mold rotates 180 degree 
                                and blow the P.E.T preform after injection, before 
                                cooling down to make the P.E.T bottle. As for 
                                the double step type, the P.E.T injection machine 
                                makes the P.E.T preform first. Then, it moves 
                                the P.E.T preform to the blowing machine to be 
                                heated up and blow to P.E.T bottle. So, the double 
                                step requires a blowing machine.  |