Plastic injection mold assembly process specification

Plastic injection mold assembly constitutes one of the most important post-processes during injection mold manufacturing, since mold quality is closely related to assembly. Mold parts go through such processes as milling, drilling, grinding, CNC and EDM, and after passing inspection, emphasis is placed on the assembly process. The quality of assembly directly affects the quality of the mold and is thus one of the decisive factors of mold quality; a high-quality mold is not possible without high-quality mold parts; high quality injection molds can only be obtained through high-quality mold parts and high-quality mold assembly techniques. There are many control points in the process of injection mold assembly, covering a wide range of aspects, in which many problems are easy to occur. In addition, the molding cycle and cost are closely related to the mold assembly process. This Process Specification for Assembly of Plastic Injection Mold specifies the technical points that may occur in the injection mold assembly process that is comprised of subassembly and final assembly,

for which, the technical requirements are stated as follows:

  1. The appearance and installation dimensions of the assembled mold shall conform to the requirements specified in the assembly drawings.
  2. The planes of the top clamping plate and the bottom clamping plate shall be parallel, with the parallelism ≤ 0.02/300.
  3. The core and cavity sizes of the assembled mold should meet the requirements of the assembly drawings, with the overlapping degree of the core and cavity centers ≤ 0.02mm.
  4. The shape and size of the mold should meet the requirements of the assembly drawings, with the maximum dimensional error ≤ +0.05mm.
  5. The seaing surfaces of the assembled mold must be in close contact with one another, with the gap less than 50% of the overflow value of the plastic material, so as to avoid flashing caused by the leakage from each sealing surface. Ensure that there is clearance between sealing surfaces to guarantee smooth venting. 
  6. Every contacting and go-through parts of the assembled mold is well in place to avoid surface burns or flashing caused by melt.
  7. The sliding motion between all the guide pins and guide bushes of the injection mold is steady and smooth, without skew and blockage.
  8. All the sliders of the injection mold are able to slide steadily and smoothly, without skew and blockage, and return and localization are accurate and reliable, which meets the requirements specified in the assembly drawings. 
  9. The guiding and sliding motion of all the lifters is steady and smooth, without skew and blockage, with accurate return and localization.
  10. The mold gating system shall ensure that all the channels are smooth and free from blockage, and that the runner puller and the limit device movement shall be smooth and reliable, without skew and blockage, with an accurate limit stroke, which meets the requirements specified in the assembly drawings. 
  11. All the return pins, ejector plate, ejector sleeves and ejector pins of the mold ejection system are steady and smooth, without skew and blockage, while the limit and return are reliable. 
  12. the mold cooling system are smooth, with the coolant tightly sealed to ensure that there is no leakage.
  13. The various pre-reset mechanism are assembled according to the technical requirements specified in the drawings. The return mechanism is stable and reliable. The installation of oil / gas cylinders and electrical appliances meets the requirements specified in the assembly drawings, with sound safety protection measures in place.
  14. The various water pipes, gas pipes, support feet, and other accessories of the mold are assembled according to the technical requirements specified in the mold drawings, with clear labels to facilitate mold transportation, trial and production.