Husky HRDC-DESIGN-GUIDELINES-060814 User Manual
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
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). If softer
materials are used (e.g. BeCu), these should be hard
chrome plated to increase hardness.
Gate Steel
Hardened tool steels such as 49 - 51 Rc AISI H13/DIN 1.2344 provide a good combination of strength and ductility.
Nozzle Seal Off Diameter
Thin Section
EDM Process
It is not recommended to EDM (electro-discharge machine) the gate area. A hardened surface layer resulting from the
EDM procedure makes the steel increasingly brittle, potentially leading to premature gate failure . It is also g ood pr actice to
machine the gate hole after hardening to avoid brittleness, caused by rapid quenching.
Gate Cooling
Gate area cooling is required to remove excess heat generate d
by the system. Sufficient cooling provides many benefits
including:
• Consistent gate quality
• Consistent gate vestige
• Greater control over material stringing
• Greater control over resin drool
• Greater control of gate blushing
• Faster cycles
Gate Cooling
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Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
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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
3) The gate insert material affects heat dissip ation and longevity.
Insert materials such as H13 (material of choice) and 420 SS are
7x less heat conductive than BeCu Alloys. The trade-off with
conductivity is hardness and gate life. Material choice will
depend upon the number of projected cycles and the cycle time
goals,
Independent Circuits
The cavity plate cooling circuit should be independent of the
manifold plate cooling circuit. This prevents coolant from leaking
onto the hot runner components whenever the plates are
separated.
2-3X
X
min 1-1.5X
Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
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Design Guidelines
Gate Inserts
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 Insert
Gate Cooling
2006.08
Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
157
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.
Latching
Nozzle tips, nozzle thermocouples, nozzle heaters, and nozzles
are replaceable while the hot runner remains in the press,
minimizing downtime when performing main te na nc e.
Cavity Plate
Interface Bolts
Design Guidelines
Hot Half
Cavity Plate
Latch
Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
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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.
Shut Off Nozzle
Resin decompression within the hot runner melt channels is re qu ire d for each molding cycle. Resin decompression is
essential for controlling gate vestige and minimizing material stringing.
Husky recommends that a shut-off nozzle be incorporated onto the machine injection unit. The shut off nozzle:
• Allows screw recovery after decompression without re-pressurizing the melt within the hot runner system.
• Enables screw recovery during mold open, which may lead to reduced cycle times.
Melt Filters
Melt filters are used to screen out any contaminants that may be present within the melt. However, melt filters increase
pressure loss, and can prevent material decompression. Melt filters ar e not recommend ed when mold ing small p art s, since
decompression is essential for producing consistent small gate vestige.
Restricted
Size
Optimal Size
(preferred)
Sprue
Bushing
2006.08
Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
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Design Guidelines
HOT RUNNER PLATE DESIGN GUIDELINES
Stainless steel is the preferred material for plate manufacture. Suitable steel types are listed below:
Type Hardness (Rc)
AISI 4140 30 - 35 Rc
AISI P20 30 - 35 Rc
AISI 420 30 - 35 Rc
DIN 1.2316 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.
• Provides superior structural support for the mold
and cavities.
An air gap should be maintained between the manifold
and manifold pocket to thermally insulate the manifold
from the surrounding plates.
The structural rigidity of the design is increased with
the incorporation of pillar supports. Pillar supports:
• Resist manifold plate deflection, by absorbing
machine clamping pressure.
• Pillars allow additional fastening of the manifold
plate to the backing plate within the manifold
pocket.
Manifold
Manifold
Pocket
Plate Bolt
(see chart
following page)
Manifold
Plate
Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
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Design Guidelines
Plate Bolting
To maintain constant sea l-o ff and minimize plate deflection, bolts should be position ed ar ound e ach n ozzle dr op and a l ong
the outside plate perimeter.
Recommended Quantity Per Drop
Bolt Size
M8 (5/16 UNC) 1.0 (All Pitch) 1.0 (All Pitch) N/A N/A N/A
M10 (3/8 UNC)
M12 (1/2 UNC)
M16 (5/8 UNC) N/A N/A 3 (All Pitch) 3 (All Pitch) 3 (All Pitch)
M20 (3/4 UNC) N/A N/A 3 (All Pitch) 3 (All Pitch) 3 (All Pitch)
The quantity and size of bolts assigned to each drop location is depend ent upon the nozzle series an d the number of drop s
(see table above). For systems greater than 12 drops, it is acceptable for drop locations to share drop bolts.
Ultra 250 Ultra 500 Ultra 750 Ultra 1000 1250 Series
0.75 (Small Pitch)
1.0 (Large Pitch)
0.5 (Small Pitch)
0.75 (Large Pitch)
0.75 (Small Pitch)
1.0 (Large Pitch)
0.5 (Small Pitch)
0.75 (Large Pitch)
N/A N/A N/A
3 (All Pitch) 3 (All Pitch) 3 (All Pitch)
2006.08
Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
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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.
2 Drop 4 Drop 6 Drop 8 Drop
The cooling circuit should be routed around areas
of high heat transfer, while maintaining a minimum
material thickness of 5,0 mm (0.20") between the
cooling line and other features.
Thermal Gate Valve Gate
5,0
(0.20")
5,0
(0.20")
Backing Plate Cooling
Manifold Plate Cooling
5,0
(0.20")
3,0
(0.12")
NOTE:
5,0
(0.20")
5,0
(0.20")
Avoid routing water lines in a manner that would result in uneven cooling of the nozzles and cavities.
Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
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Design Guidelines
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.
Wire Grooves
2006.08
Please confirm all dimensions and nozzle/gating suitability with Husky prior to machining.
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