Design Guidelines CAVITY DESIGN To maximize the integrity and life of the gate area, various factors must be considered: Recessed Gate Areas When designing gates into recessed areas such as dimples, a generous radius should be incorporated to avoid extended thin sections of plate steel (see figure at right). Nozzle Seal Off Diameter Nozzle Seal Off Diameter To provide a durable nozzle seal diameter surface in the gate bubble, a surface hardness range between 49 - 53 Rc is recommended (see figure at right).
Design Guidelines Optimized Gate Cooling (Key Elements) 1) Minimize the distance from the cooling channel to the gate detail The maximum recommended distance between the cooling channel and the gate detail is 3 times the cooling channel diameter. 2) Cooling should surround the insert. The cooling water should reach flow speeds that cause effective mixing of the fluid. For most inserts, a flow rate of about 6.8 - 8.3 liters (1.8 - 2.2 gallons) per minute is sufficient.
Design Guidelines Gate Inserts Gate Insert Gate inserts provide an effective method of cooling the gate area, since the entire circumference is cooled. Cooling circuits for the gate insert should be independent from the plate cooling circuit to provide better control. The gate insert is a replaceable wear item. Gate Cooling Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining. 2006.
Design Guidelines Cavity Plate Interface Bolts Cavity plate interface bolts are used to fasten the cavity plate to the hot runner. The interface bolts should be installed from the clamp (moving) side of the cavity plate, to enable separation of the cavity plate while the mold is still secured within the machine press.
Design Guidelines MACHINE INTERFACE Machine Nozzle Requirements To prevent pressure loss, dead spots, and to provide a leak-free seal, the mating surfaces and orifice diameters of the machine nozzle and sprue bushing must match. To optimize hot runner performance, the sprue bushing orifice should be the same diameter as the primary sprue bushing flow channel.
Design Guidelines HOT RUNNER PLATE DESIGN GUIDELINES Stainless steel is the preferred material for plate manufacture. Suitable steel types are listed below: Type AISI 4140 AISI P20 AISI 420 DIN 1.2316 Hardness (Rc) 30 - 35 Rc 30 - 35 Rc 30 - 35 Rc 30 - 35 Rc Manifold Pocket / Pillar Support Husky recommends that a pocket be machined into the manifold plate for the manifold. The manifold pocket: • • Allows close positioning of the plate bolts to the nozzle components, minimizing plate deflection.
Design Guidelines Plate Bolting To maintain constant seal-off and minimize plate deflection, bolts should be positioned around each nozzle drop and along the outside plate perimeter. Bolt Size M8 (5/16 UNC) M10 (3/8 UNC) M12 (1/2 UNC) M16 (5/8 UNC) M20 (3/4 UNC) Ultra 250 1.0 (All Pitch) 0.75 (Small Pitch) 1.0 (Large Pitch) 0.5 (Small Pitch) 0.75 (Large Pitch) N/A N/A Recommended Quantity Per Drop Ultra 500 Ultra 750 Ultra 1000 1.0 (All Pitch) N/A N/A 0.75 (Small Pitch) N/A N/A 1.0 (Large Pitch) 0.
Design Guidelines PLATE COOLING Plate cooling circuits maintain a uniform mold plate temperature and match thermal expansion of the mold plates. To design a uniformly cooled mold, consideration must be given to the cooling circuit layout, number of channels, lengths, and diameters. Typical cooling circuit layouts for 2, 4, 6, and 8 drop systems are provided below.
Design Guidelines WIRE GROOVES Wire Grooves Power and thermocouple wires are typically routed to the electrical connectors within wire grooves. Wire grooves: • Protect the machine operator from live wires. • Provide orderly routing of hot runner wires. • Prevent potential wire damage. Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining. 2006.
Design Guidelines TOP OPERATOR AIR A hot runner requires a number of service connections such as electrical for heaters, water for plate cooling and air for valve gate operation. Locations for these connections are flexible, however based on experience the schematic indicates recommended positions.
Design Guidelines VALVE GATING DESIGN CONSIDERATIONS To ensure optimum gate quality, valve stems must respond quickly to the open/close signals. To avoid sluggish valve stem movement, the following should be considered prior to installation: • Air supply should be clean and dry at a pressure between 550-830 kPa (80-120 psi). For thin wall parts and engineering resins the pressure should be between 100-120 psi. • A four way solenoid valve is required to activate valve stems.
Design Guidelines CONTROLLER INTERFACE Voltage Supply To determine the correct manifold heater wattage, the available voltage supply must be specified. This practice is necessary since a significant wattage reduction can occur if the lower voltage is not compensated for. For a given heater the power output at 208V is only 75% of that at 240V. Voltage Supply 240 V 208 V Wattage 2,880 W 2,160 W Amperage Limitations The amperage limit for each zone of the temperature controller needs to be identified.
Design Guidelines Husky Standard Electrical Connector Requirements Establishing an electrical wiring and connector standard will allow future interchangeability of hot runners and temperature controllers. The following Husky standards have been developed around typical controller capabilities for systems ranging from 2 to 16 drops. The departure from the standards may be required if space is not available or if the current requirements exceed the connectors limitations.
Design Guidelines 2-8 Drop HR System Alternative (DME Standard) An alternative approach, is to employ one 25 pin connector for power and one 24 pin connector for thermocouples. 25 Pin (Power) 24 Pin (Thermocouple) Standard connector pin mapping for 24 pin connectors shown on previous page. Standard connector pin mapping for 25 pin connectors.This connector is used for power. Pins are rated to 10A.
Design Guidelines 12-16 Drop HR System Applications between 12 to 16 drops use the following connector types. Figure 1-4: 12-16 Drop System Connector Configuration 6 Pin (Power) 16 Pin (Thermocouple) 32 Pin (Power) 32 Pin (Thermocouple) Standard connector pin mapping for 6 pin connectors. Pins for zone control are rated to 30A. Pin Sprue Heater 1 2 Manifold Zone #1 3 4 Manifold Zone #2 5 6 Standard connector pin mapping for 16 pin connectors.
Design Guidelines STACK HOT RUNNER Machine Tie Bars HUSKY offers 2 level and 4 level stack hot runners in Ultra 250, Ultra 500, Ultra 750, Ultra 1000 and 1250 series nozzles. A 2 level stack mold will nearly double the output per machine of a single face mold; using a 4 level stack mold, productivity gains increase to nearly four times.
Design Guidelines MACHINE REQUIREMENTS FOR STACK MOLD OPERATION In order to successfully run a stack mold; a molding machine must meet several criteria: Injection unit The injection unit must be able to provide double the shot weight, plasticizing ability, and injection rate than would be required for a comparable single face mold. Sprue Break Capability The machine must feature sprue break capability.
Design Guidelines THERMAL GATE CONSIDERATION Ultra 250, Ultra 500, Ultra 750, Ultra 1000 and 1250 Series For all thermal gating methods, the nozzles can be positioned back to back. Clamp Side Injection Side Leak Proof UltraSeal Technology Back-toBack Nozzles Sprue Bar Anti-Drool Bushing Sprue Bar Heat Shield *Ultra 750 HT stack shown Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining. 172 2006.
Design Guidelines VALVE GATE CONSIDERATION Ultra 500, Ultra 750, Ultra 1000 and 1250 Series In order to accommodate customer requirements Ultra VG nozzles can be positioned offset or back to back. These designs provide ease of assembly and service access to the cylinders provided via air plates.
Design Guidelines SPRUE BAR The purpose of the sprue bar is to transfer the molten resin from the machine injection unit to the center section. When the mold is in the closed position, the machine nozzle seats against the sprue bar. When the mold opens the sprue bar moves with the center section and disengages from the machine nozzle. Sprue Bar Guide • Husky calculates the correct sprue bar length based on the mold shut height and the required mold opening stroke.
Design Guidelines OFFSET SPRUE BAR When the sprue bar can not be positioned at the mold centerline, an offset sprue bar can be used. Using an offset sprue bar requires additional mold shut height to accommodate the transfer manifold attached to the stationary platen. The sprue bar can be positioned at any side of the mold. Transfer Manifold Offset Sprue Bar Sprue Nozzle Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining. 2006.
Design Guidelines CENTER SECTION SUPPORT TYPES The center section of a stack mold is supported by the tie bars of the injection molding machine using one of three methods. • Horizontal Support • Vertical Support • Machine Mounted Carrier For all three methods, it is essential that the machine be level to avoid unnecessary wear on the mold and machine components caused by misalignment.
Design Guidelines The vertical support uses an hourglass shaped outrider that is fastened to the operator and non-operator sides of the center section. The weight of the hot runner is evenly distributed over a wide area of the lower machine tie bars by half shoes. The mold must be between 10,0mm (0.39") and 85,0mm (3.35") narrower than the horizontal tie bar spacing. The upper tie bars provide guidance and stability to the center section during operation.
Design Guidelines CONTROLLED CENTER SECTION MOVEMENT Controlled movement of the center section is critical to ensure that as the mold opens, the hot runner always remains centered between the clamp and injection sides of the mold. The recommended methods of controlling center section movement include: • Rack and Pinion Mechanism (Single and Multiple Gear) • Harmonic Linkage Mechanism (available only with Husky machines) The method employed for a given application is customer specified.
Design Guidelines Harmonic Linkage The Harmonic Linkage mechanism is only available for use in a Husky machine. With the harmonic linkage mechanism, a propeller and harmonic arm mechanism is fastened to the center section. The harmonic linkage mechanism is used for molds that have a short ejection stroke and a machine stroke less than 305mm (12.01").
Plate Length Vertical Tie Bar Spacing TOP Plate Width Customer Specified Water Fittings Type & Location Horizontal Tiebar Spacing Customer Specified Electrical Connector Type 180 Customer Features X & Y Location Customer Mold Drop Number X & Y Location OPERATOR SIDE Customer Mold Interface Tap X & Y Location Clamp Slot X & Y Location (Width, Length, Depth) Latch Tap Guide Pin X & Y Location Type & Diameter Machine Type Tiebar Diameter Maximum Hot Runner Thickness Guide Pin Protrusion Measured
Design Guidelines CUSTOMER DRAWING REQUIREMENTS (MANIFOLD SYSTEMS) Before Husky can begin engineering, the customer features indicated in the figure below must be defined by the customer when submitting the Mold Layout drawings along with the Design Information Form.
