American Technical Molding provides plastic injection molding using hot runner molds, a process that offers the lowest cost per part when a large number of plastic parts need to be manufactured quickly.
Primary advantages of hot runner molding 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 de-molding
- 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
Hot Runner Molding: Precise Computer-Controlled Accuracy and Advanced Processes
Hot runner molds are usually connected to needle valve nozzles, which are activated with precise computer-controlled timing for accurate reproduction of parts.
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: Weigh the Cons with the Pros
There are, however, a few disadvantages to hot runner systems that need to be considered:
- Hot runner molds are more complex and expensive to build than cold runner molds
- Higher initial start-up costs than 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
