What is Injection mould design?

 

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What is Injection mould design?

As to how to judge the quality of the mould, its 85% depends on the plastic mould design. And the quality of mould design involves a very wide of factors, like the theoretical knowledge, practical experience, and the design ideas are equally important. Design ideas include the following aspects:

  • Understand the plastic parts structure: whether they could be subjected to injection moulded, such as enough ejection draft, no shrinkage and deformation risk after release from the mould, reasonable structure of de-moulding, etc..
  • Plastic materials: there are a wide variety of plastic materials, choose the right plastic to determine the shrinkage, the gate and runner design. Understand the corrosion risk of plastic in order to determine the choice of mould steel.
  • Mould steel: according to different plastic and product requirements, make the correct choice of mould steel in order to achieve the quality and running life of the mould, which requires the designer to have a sufficient understanding of plastic and steel.
  • The injection moulding machine specifications: understand the injection machine clamping force, injection machine capacity, mould opening stroke, locating ring size, nozzle radius, screw position.
  • The cavity and its arrangement: they are decided by the projection area, the shape of the product, the accuracy, output and earning. They will affect each other to determine the mould base and standard parts choosing.
  • The runner: hot runner or cold runner? Is a direct feeding (2 plates plastic mould) or indirect feeding (3 plates plastic mould)?
  • The gate: the gate design are different according to the needs, it must consider the demands of the appearance requirements of the product, plastic flow, weld marks, venting and other factors, and gate size should be sufficient to fill the whole cavity .
  • The parting line: the parting surface selection is an important part of plastic mould design, it shall be taken into account for the factors such as product appearance, ejection ways, mould machining…
  • Forming parts design: forming parts design must consider appearance, processing methods, strength of the mould, ejection ways, cooling ways, flowing and the venting problem….
  • The side core pulling mechanism design: this mechanism changes mostly, so the most complex structure of the mould will be.
  • Ejection way: it is in a variety of ways, and it should pay much attention to the balance of ejection force, plastic mould strength, appearance, function and cooling effect.
  • Venting, it is very important to ensure product quality, the various forms of venting could be used, pay attention to prevent mould plates stick for vacuum problems.
  • Cooling: cooling impact moulding production so much and its design work is complicated, it is not only necessary to consider the cooling effect and cooling consistency, but also take into account of the effect of cooling system on the overall structure of the mould.
  • Processing:  all plastic mould designs should consider the feasibility of mould processing and only such designs have practical value to build a good plastic mould.
  • Drawing: according to the above design consideration, the drawing contains assembly diagram, parts diagram, ejection pins location diagram, wire cutting diagram and processing related purposes. In the drawing process, it should further improve the structure of the mould.
  • Check and audit: once mould design is completed, designer must be in conjunction with the clients and staff related to check the overall structure and the feasibility of processing.