How to design PET preform mould Private2 weeks ago - Real estate - Baltimore - 4 views
Since many factors enter into the design of plastics PET preform moulds, and into the design of products to be pet bottle mould, it is well for product designers, tool designers, and tool makers to have a common understanding of plastics PET preform moulds and PET preform moulding in order to cooperate to the fullest extent in making possible PET preform moulded products of high standards of quality and economy.
Requirements for PET preform mould Designing
To design plastics preform bottle mould, a plastics engineer should have an intimate knowledge of a proper design procedure which is based upon a knowledge of the characteristics of materials; of the technique of PET preform mould building; of the economics of each production schedule; of the tooling cost both to purchaser and to the PET preform mould manufacturers; of PET preform moulding equipment operation; of the special mould steels and alloys; and of the moulding and finishing facilities of his own plant.
In Integrated Two Stage approach the performs were made by more conventional injection moulding routes (with the number of cavities optimized to match the required output) and then, while still hot, were carried to a separate blowing machine with the optimized number of blow moulds to suit the required output. This was the first ‘integrated ‘approach to PET bottle making. Equipment developers took the ‘single-stage’ approach. Here the equipment had the same number of injection cavities as PET blowing mould. This was a more compact approach and proved ideal for small batch output with excellent glossy surfaces.
This chapter discusses the general blow molding process. Blow molding is a fairly straightforward process that includes melting, homogenizing, extruding, molding (blowing), cooling, and ejection. Different manufacturing plants can employ additional processes such as additional cooling or heating cycles and additives and colorants compounding. These additional processes depend on the design and intended application of the final product.
Plastic Resin Feeding or Charging: The first step in the blow molding process is plastic feeding. This is done by conveying the plastic pellets into the extruder hopper. Vacuum pumps draw pellets from big bags or bulk containers and transfer them into the raw material silos or hoppers. A rotary feeder at the bottom of the silo controls the rate of feeding into the plastifier or extruder. Compressed air is then used to convey the stored pellets to the extruder hopper. In other systems, plastic pellets from big bags or bins can be vacuum conveyed directly to the extruder hopper without the need for a separate conveying air system.
Plasticizing or Melting: As the plastic resin enters and goes through the extrusion machine, it is melted by continuous kneading and heating. Electric heating elements or heating bands are wrapped around the extruder barrel to provide heat for melting the polymer. The extruder screw has different sections that serve a specific purpose. These are feeding, compressing, and metering. The extruder screw is designed to provide sufficient shearing and compression to homogenize and extrude the plastic.