Cold / hot runner injection molds

One of the most diversified and reliable manufacturing processes available today to produce a plastic parts is injection molding . Half of all possible types of equipment for plastic processing is injection equipment. It is also the most massive and technological.

Professor Christian Schonbein (Sweden), inventor Alexander Parkes (England) and entrepreneur John Wesley Haight, are considered as inventors of cellulosic plastics. It was them who gave a go to everything what is happening in the industry today.
Cold runner or hot runner injection system ?
Various types of molds are used for injection molding plastics. And the first thing the client encounters when ordering is the choice:
What type of injection mold do I need?
Traditional cold runner or more progressive hot runner injection mold?

Cold runner molds by Sumar Tools

The main difference from the hot runner mold is that the runner is not heated up in the cold runner mold system; accordingly, after the injection cycle sprue, runner and gate are cooled with molded parts. The main advantages:

  • low cost,
  • high reliability,
  • easy maintenance,
  • less skills required for set up and operation,
  • change of material and color of injection molded part is easy.

But cooling the sprue provides a larger mass of plastic, which goes into waste. If the workshop has a crusher for slabs and smaller waste, then the resulting crushed crumb can be recycled ( for exaple ,added to plastic granulate)
It must be kept in mind that if the products have a small mass, then the sprue’s weight may even exceed it. This fact negatively affects not only the efficiency of use of the material, but also the productivity of the injection molding machine, since the cooling time of the castings increases.
That is why during the design of cold runner injection systems in Sumar Tools factory, we pay a lot of attention to the balance of parameters of equation. This is what allows us to get acceptable installation performance.

Hot runner injection molds by Sumar Tools

Hot runner injection molds by Sumar Tools
Hot runner molds which considered as a more progressive, are favorably distinguished by:

the absence or minimal amount of waste (sprue/runners/gate), faster production cycle times, a stable technological process and less defects, requests less manual labor.

  • the absence or minimal amount of waste (sprue/runners/gate),
  • faster production cycle times,
  • a stable technological process and less defects,
  • requests less manual labor.

The Sumar Tools hot runner system transfers injection pressure to the mold area with minimal loss. And despite the fact that hot runners often come with a higher upfront cost and require some additional maintenance, their more efficient design can often easily provide a valuable return on this investment. Hot runners significantly overcome the inefficiencies of its cold runner counterpart.
With all the advantages, hot-run molds are not recommended for processing some non-heat-resistant plastics, for example, hard PVC compositions.
It is also necessary to take into account the high cost, energy costs of production, difficulty in maintenance, require facility with a powerful cooling system.

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