SYSTEMSINTEGRATION
SHOT SIZE REPEATABILITY IN
DIE CASTING SAVES MONEY
TROY TURNBULL
President
INDUSTRIAL INNOVATIONS
ARTICLE TAKEAWAYS:
Figure 1 Shot weight variations
IMPORTANCE OF LADLER DESIGN
Direct Drive Systems
The gearbox is either a ground helical
• Repeatable accuracy means lower cost of operation
gear set or a Cone Drive double• Robotic ladlers offer: servo motors & drives, heavy-duty support arms, LCD
enveloping gear set where the worm
operator stations, no dunking probes and die cast or ceramic ladle cups
is manufactured in an hourglass
configuration and wraps around the
worm wheel (see Figure 2). Either
Process consistency is the first step
Let’s say, however, the excess
provides low backlash and extremely
in achieving total quality. A reliable,
average is half of that or 3,000 lbs of
long life. The brushless servo motors
consistent process begins with reliable aluminum per week. The metal saving are directly coupled to the gearset
equipment.
difference is 2,700 lbs per week. At 50 reducing service drive train problems
weeks per year, that’s equal to 135,000 and improving mechanical response to
Quality ladlers play an important role
lbs of metal you’ve purchased,
the servo motors.
in the die casting process as having
inventoried, and melted unnecessarily!
an incorrectly sized biscuit can cause
The output shaft of the ladler linkage
And these figures are only for a 10
significant remelt costs. Robotic
arms is a large, one-piece shaft, which
pound casting!
ladling systems can achieve 99+%
goes completely through the gear box.
accuracy to consistently pour molten
What is this costing your company?
The positioning encoder, motor, and
metal from a furnace into the shot well One die caster stated that a biscuit
gearbox are giving direct drive without
of a die casting machine.
1” longer than needed (on a 2-1/2”
use of pulleys, belts, or cams.
diameter sleeve) costs about $50,000
IMPORTANCE OF REPEATABLE
Heavy Duty Support Arms
a year (per machine) in remelt costs.
ACCURACY
On larger models (more than 50
Repeatable accuracy means lower
99+% can be achieved by controlling
pounds of metal), the entire arm
cost of operation. Let’s compare a
the ladle cup spill off angle with a
assembly can be supported by a large
60-second cycle operation for 5 days,
servo motor and servo drive. One
housing with double opposed tapered
20 hours per day, using a 10-pound
revolution of the ladle cup is divided
roller bearings (see Figure 3).
nominal pour.
into almost 2 million parts (1,966,000
to be exact). What this means is
Ladlers with 10% repeatability for a
that the cup spill off angle can be
10-pound casting: 60 second shot x 20
controlled to 2 millionth of its rotation
hours x 5 days = 6,000 shots per week
and it’s this repeatability of the spill off
or 60,000 lbs of aluminum. The shot
angle that achieves the ladlers’ shot
weight variation would be from 60,000
size repeatability (see Figure 1).
lbs to 66,000 lbs (10% maximum
Figure 2
Figure 3
variation) or 6,000 lbs over.
Direct drive systems
Heavy duty support arms
• Quality ladlers can achieve 99+% repeatable accuracy
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This housing assembly supports the
total weight of the arm so there
is no load applied to the gear box
assembly, allowing very smooth arm
travel without torque interruptions.
Without the weight of the arm being
supported by the gearbox, the gear
box works for many years.
No Dunking
Industrial Innovations – Advance
Automation has developed
proprietary circuitry that prevents
dunking. The smart probe (see
Figure 4) remembers the furnace
metal position from its last pour
pickup. A back up probe is activated
if the primary probe fails. If both
probes fail, the ladler is programmed
to go no more than 1” lower than
the previous metal pickup point. If it
doesn’t sense the metal, it goes to
its home position and turns itself off.
The ladler doesn’t dunk, even if all
the probe wires are broken.
Our system consists of three probes:
standard, backup, and smart.
Should the standard probe fail, a
backup probe takes over to prevent
dunking of the arm into metal.
Warning lights flash on the Operator
Interface Station, signaling a probe
failure. Additionally, a smart probe
remembers the last metal level
detected and allows the probes to
advance only 1” below the last metal
level sensed. If the smart probe
doesn’t sense metal within 1”, the
ladler will dump all the metal in the
cup back into the dipwell and return
to the home position before shutting
itself off automatically.
Figure 4
Small probe-No dunking
Electronics and Operator Interface
Servo Ladler operator stations
are equipped with easy-to-read
color LCD (see Figure 5). Each
program should be easy to set up
and be menu prompted so even
operators with little or no previous
programming experience can
program the ladle. Typical units can
store up to 500 parts programs in
non-volatile random access memory
(NVRAM).
The Operator Interface Station
allows the operator to monitor the
status of the ladler and the metal
level in the furnace and control all
basic ladler functions. Warning lights
signal probe failures, low metal
levels, and aborted cycles. Indicators
signal the mechanism position and
ladle cup status. Controls can be
set to manual or auto by turning a
selector switch. A selector switch
increases or decreases the shot size.
Double insulated
wires for each probe.
Super high
temperature bearings
require no lubrication
or graphite powder.
The probe assembly
can be mounted on
either side of the arm.
Probe tips are
easily replaceable
and treated with
Advance’s exclusive
adwear treatment,
which resists
aluminum for months
and sometimes years.
The probes do not
require a coating.
LADLE CUPS
Die cast, direct mount - pinmounting design means no tools or
adapters needed for changing. Die
cast ladle cups are 1/4 to 5/16-inch
thick, heat-treated cast iron for long
life. The cups have non-wetting
surfaces that are resistant to thermal
shock and breakage. The cups
also insulate metal from heat loss
during the delivery cycle for uniform
product.
For long-lasting performance and
value, ceramic ladle cups are die
casting’s best kept secret. Made
from alumina-silica composition,
these cups are ideal for hightemperature applications such as
zinc and aluminum casting.
Understanding the importance of
repeatable accuracy in ladling is not
hard, and there are many automated
control systems available to make
it even easier that guarantee the
accuracy of your shot size.
Contact:
TROY TURNBULL
[email protected]
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