Technology

Characteristics of plastic molds and methods to increase service life

Characteristics of plastic molds and methods to increase service life
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Basic Features

  • (1) High precision is required. A pair of molds is generally composed of a concave mold, a convex mold and a mold frame, and some of the molds may be multi-piece split molds. Therefore, the combination of the upper and lower molds, the combination of inserts and cavities, and the assembly of the modules all place high demands on the machining accuracy. The dimensional accuracy of precision molds often reaches μm level.
  • (2) Complex shapes and surfaces Some products, such as automobile covers, aircraft parts, toys and household appliances, have a shape surface composed of multiple curved surfaces. Therefore, the mold cavity surface is more complicated. Some surfaces must be mathematically processed.
  • (3) Small batch mold production is not mass production. In many cases, only one payment is made.
  • (4) Multi-process die processing, often using milling, boring, drilling, reaming, tapping and other processes.
  • (5) The service life of repeated production molds. When the use of a pair of molds exceeds its service life, a new mold must be replaced, so the production of molds is often repeated.
  • (6) There are sometimes no drawings or data in the production of profiling molds, and the profiling process should be carried out in kind. This requires high simulation accuracy and no deformation.
  • (7) The mold material is excellent. The main material of the high-hardness mold is mostly high-quality alloy steel, especially the high-life mold. Cry2 and CrWMn are commonly used. These steels have strict requirements from rough forging, processing to heat treatment. Therefore, the preparation of processing technology cannot be ignored, and heat treatment deformation is also a problem that needs to be taken seriously during processing.

According to the above characteristics, the machine tool should meet the processing requirements as much as possible. For example, the function of the CNC system must be powerful, and the machine tool must have high precision, good rigidity, good thermal stability, and contour functions.
How to increase the service life of the mold
For users, increasing the service life of the mold can greatly reduce the stamping cost. The factors that affect the service life of the mold are as follows:

  • (1) Material type and thickness;
  • (2) Whether to choose a reasonable mold gap;
  • (3) The structural form of the mold;
  • (4) Whether the material has good lubrication during stamping;
  • (5) Whether the mold has undergone special surface treatment;
  • (6) Such as titanium plating, titanium carbonitride;
  • (7) Align the upper and lower turrets;
  • (8) Reasonable use of adjusting shims;
  • (9) Whether the diagonal blade mold is used correctly;
  • (10) Whether the mold base of the machine tool is worn;

Process flow arrangement

  • (1) Bottom surface processing with guaranteed processing volume;
  • (2) Casting blank benchmarking, two-dimensional and three-dimensional profile surface check;
  • (3) Rough machining of two-dimensional and three-dimensional profiles, non-installation surface, non-working surface processing (including safety platform surface, bumper installation surface, pressure plate surface, side reference surface);
  • (4) Before semi-finishing, the alignment of the lateral reference plane should ensure accuracy;
  • (5) Semi-finished two-dimensional and three-dimensional profiles, finishing various installation working surfaces (including stopper installation surface and contact surface, insert installation surface and backrest, punch installation surface, chip cutter installation surface and supporting back surface, spring Mounting surface and contact surface, various stroke-limiting working surfaces, inclined wedge mounting surface and back surface), various guide surfaces, guide holes, remaining reference holes, semi-finished products of finished height reference surfaces, and record data;
  • (6) Inspection and evaluation of processing accuracy;
  • (7) Inlay process of fitter;
  • (8) Before finishing, align the reference surface of the technical reference hole and check the remaining amount of the insert;
  • (9) Finishing profile 2D, 3D, side punching profile and hole position, finishing reference hole and height reference, guide surface and guide hole;

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