Hot Runner Molding: 100% Virgin Resins, No Regrind Material, Large Volume Production, Thermoplastic Injection Molded Plastic Parts, Automated Production

DONGGUAN SINCERE TECH CO.LTD(SINCERE TECH) provides plastic injection molding solutions to industries of all types and sizes. We use a wide variety of state-of-the-art thermo-plastic injection mold processing and finishing equipment.

This means that we have the right size machines for your project, large or small, enabling us to provide you with the most economical production options available. For a full list of our processing equipment, read Production Facility and Equipment.

Our advanced manufacturing facilities include a wide range of thermoplastic injection molding solutions for many types of plastic parts, including processes for Hot Runner Systems and Cold Runner Systems.

Hot Runner Molding: Efficient High Production

Each runner system offers advantages and disadvantages. Choosing the system to employ depends on the requirements of the part to be produced. A few of the considerations include:

  • Part complexity
  • Color requirements
  • Physical characteristics of material
  • Type of material to use – virgin or “regrind”
  • Color changes during production run
  • Single or multiple design production

The primary difference between the two systems is that hot runner eliminates the excess material retained in the feed channels of a cold runner mold. This feature reduces the number of production stepsrequired, and saves in material and energy costs.

Furthermore, hot runners use only 100% virgin resins; no reprocessed or “re-grind” material is added. This is an important feature for specific applications where regrinding can cause material to yellow, or detracts from the material properties, such as clarity in light pipe or lens production, where long-lasting transparency is a specific requirement.

Hot runner systems shoot melted material directly into individual cavities. Hot runner is a more expensive process than cold runner systems, almost always used for large volume production of thermoplastic injection molded parts, or multiple part production using multi-cavity molds and stack-molding technology.

Hot Runner Molding: Applications & Possibilities

Hot-runner systems are almost always used when large runs have to be manufactured in highly automated production. Additionally, technological advances enable us to build molds with gates positioned to yield the best quality molded parts.

Hot runner molds are usually connected to needle valve nozzles, which are activated with precise computer-controlled timing. This allows for a number of advanced processes, including:

  • Multi-Cavity Molds – cavities with different geometries and/or volumes
    • Parts that belong together produced in one mold
    • Injection valve opening and closing can be adjusted to the conditions of each individual cavity
    • Injection pressure and holding pressure may be adjusted  independently of each other
  • Controlled Volume Balancing – a weld line can be shifted into a non-critical area of the molded part
  • Stack Molding – multiple parting lines for additional cavities in a given area

Hot-Runner Systems: The Pros and Cons

Primary advantages of hot runner systems include:

  • Materials cost savings – no runner to regrind or reprocess
  • Least expensive cost / piece
  • Reduction of energy costs
  • Shorter, faster cycle times – no runners to cool
  • Smaller machines – reduced shot volume into runners
  • Automated processing – runners do not need demolding
  • Gates at the best position for economical design
  • Elimination of runners means
    • No runners to remove or regrind
    • Reduces the possibility of contamination
    • Lower injection pressures
    • Lower clamping pressure
    • Consistent heat within the cavity
    • Shorter cooling time
    • Shot size reduced
    • Cleaner molding process
    • Eliminates nozzle freeze

There are, however, a few disadvantages to hot runner systemsthat need to be considered:

  • Hot runner molds are more complex and expensiveto build than cold runner molds
  • Higher initial start-up costs than for cold runner systems
  • Complex initial setup prior to running the mold
  • Higher maintenance costs – more susceptible to:
    • Breakdowns
    • Leakage
    • Heating element failure
    • Wear caused by filled materials
  • Risk of thermal damage to sensitive materials
  • Elaborate temperature control required