Tooling Product News

Integrated Hot Runner Systems Improve Efficiencies And Reduce Costs

By: John Blundy of INCOE Corporation

“Optimum performance and less expensive. Quality, and faster delivery.” Sound familiar? You bet, if you’re in the mold manufacturing business. Mold deliveries continue to be reduced, and technology continues to advance, placing both demand as well as benefit to the mold manufacturers. Injection molders continue to look for improved efficiencies while they cut their operating costs; as they are continually required to reduce their prices of injection molded products.

For some time now, Hot Runner manufacturers have provided Injection Half (or Hot Half) systems to reduce the overall assembly time of a mold by selling the Hot Runner system as a completely self-contained unit. This also tended to reduce errors in wiring. An improvement of this concept are Unitized systems, which are complete drop-in, pre-assembled units, including electrical connections as well as either pneumatic or hydraulic plumbing required for valve gates systems. The Unitized systems provide all the advantages present in a complete injection half at a reduced cost.

With minor modification to the mold and using a Unitized Hot Runner design, Integrated Hot Runner Systems can be constructed providing these improvements:

Reduction of Hot Runner installation time
Elimination of errors associated with wiring
Reduction of cost as compared to conventional “Injection Halves”

The “heart” of the Integrated system lies in the Unitized manifold design. Nozzles are threaded directly into the manifold; therefore the necessity for a retainer plate is eliminated. Also, a uniform heat profile is ensured since the junction of nozzle and manifold is inside the manifold, thus eliminating any transitional heat loss usually found with conventional “bushing” type systems. “Bushing” type systems often require a separate heater band on the flange to provide heat to this area, thus increasing operational cost. Another area where the Integrated design reduces power consumed is due to the fact the manifold system has very little contact with the mold. This minimal contact reduces heat loss from the manifold and allows the mold to maintain a more consistent temperature level.
Threaded nozzles also eliminate the tendency for plastic leaks between the nozzles and manifold, which can occur during heat expansion of conventional “bushing” type system designs. Production is then interrupted in order to affect repair.

mold/Hot Runner system is also disassembled. Also, since the Unitized manifold system is fully functional before being installed in the mold, full testing of electrical and thermal functions can be performed at the factory before shipment.

The Integrated Hot Runner System further provides the injection molder the added benefits of:

Routine maintenance can be performed without removing the Hot Runner system from the molding machine. While conventional injection halves also allow some maintenance to be performed while in the molding machine, it is limited to only the very front of the nozzle area due to the retainer plate. Servicing beyond this point requires the Hot Runner manifold system to be removed from the machine in order to expose the manifold system.
Simple Hot Runner system/mold interchangeability. Inserts can easily be interchanged without mold removal.

Figure 1 - featured at the right: Integrated Hot Runner System. Nozzles are threaded into manifold and wiring is Unitized. The system becomes a self-contained assembly.

Since the Integrated system is based upon using the Unitized pre-wired design for installation in the mold, the chance for pinched or severed heater and thermocouple wires is eliminated during assembly. All wiring from heater to junction box is encased within a conduit specially designed for that purpose. This is always a benefit whenever the Valve gate operational plumbing can be serviced without disassembly.

Figure 2- featured at right: Integrated Hot Runner Valve Gate System. Valve Gate connections and plumbing are also attached to the manifold and become part of the self-contained assembly.

Incorporating the Integrated design involves preliminary review with the mold manufacturer to ensure proper operation. The Unitized Hot Runner manifold is mounted directly to the top plate of the mold. Also added to the cavity plate are straps that can be placed in two positions, first on the cavity side of the mold, and second placed so as to capture both the cavity and core side of the mold joined at the parting line.

Figure 3: The mold strap in the position shown will capture both the core and cavity plates as the moving platen is retracted.

The Integrated system in no way compromises the normal production function in injection molding. When normal routine maintenance is required, the following simple procedure is applied. Open the mold using the set-up mode of the molding machine. Remove the socket head screw used to fix the cavity plate to the top plate.

Figure 4: Remove the socket head screw used to
fix the cavity plate to the top plate.

Close the mold using the set-up mode of the molding machine. Move the strap from the cavity plate and place it over the parting line, so that the core and cavity plates are joined.

Figure 5: Integrated Hot Runner System is
fully exposed inside the press.

Slowly actuate the opening stroke, again using the set-up mode of the molding machine. This action will now pull both the mold core and cavity plate from the top plate and expose the entire Hot Runner system. Any of the following operations can now be performed without removing the Integrated system from the injection-molding machine:

Gate tip exchange
End cap exchange
Nozzle heater exchange
Nozzle thermocouple exchange
Manifold thermocouple exchange
Complete Hot Runner inspection

The Integrated design substantially reduces the downtime normally required when compared with a conventional Hot Runner design, from perhaps a full shift to only 1-2 hours since the entire Hot Runner system is now completely exposed and easily accessible.

In the event complete removal of the Hot Runner system is still required, a lifting hook can be placed on the top plate, then by removing the mold clamps the assembly can be moved to the workbench for further service.

Figure 6: If necessary, only the top plate and the Integrated
Hot Runner System need to be removed from the press.

The Unitized Hot Runner system can now be completely removed by unscrewing the socket head screws used to fix the system to the top plate.

Figure 7: Once outside the press, the Integrated Hot
Runner System is easily detached from the top plate.

As the Unitized system provides the ability for a complete drop-in functional assembly, the unit can now be completely refurbished when, and if, required at the factory and afterward simply re-installed for further production.

Figure 8 - featured above: Once outside the press,
the Integrated Hot Runner System can be completely
refurbished. When complete, the Integrated Hot Runner
System only needs to be re-installed for further production.

Integrated Hot Runner Systems provide considerable advantages in ease of installation and operation, and with reduced costs, thus meeting the demands of today’s extremely competitive market.

John Blundy is Vice President of Business Development for INCOE Corporation. He can be reached by calling 248-556-7816 or via e-mail at John.Blundy@INCOE.com.

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