shaping the future of metrology - Brown & Sharpe

measurement work took us a minimum
of four hours to as much as several days,”
Mason said.
With the PC-DMIS software in place,
technicians electronically transfer the
CAD model of the tooling into PC-DMIS
through IGES conversion. After the inspection
program is run, the measurement
data files are converted into visual
SPC and part dimension reports in just
minutes with the software’s report module.
This module lets Aeronautical Systems’
quality technicians print or plot a visual
report showing either measured values
or statistics from report values selected
from a CAD file.
Aeronautical Systems uses the PC-
DMIS Curves and Surfaces module to
import free-form 3D models from the
CATIA system and automatically extract
mathematical surface nominals and direction
vectors.When the operator clicks
on the surface to be inspected, Curves
and Surfaces drives the CMM along the
orthogonal surface vectors and collects
measurement data.That data is compared
to the CAD nominals and the “fit” of the
surface is accurately determined regardless
of its complexity.
Curves and Surfaces provides the
nominal and actual point deviation.The
program also automatically displays the
nominal tolerance band over the actual
data curve, providing clarity of the conformance
of a surface to its nominal model.
Although the company has just begun using
the new software, Mason said he expects
that the post-measurement work
could be reduced to about one hour, even
for complex tooling assemblies.
Automated
Shop Floor Inspection
In another, highly automated inspection
operation, Aeronautical Systems is
using a Brown & Sharpe Process
Control Robot (PCR ® ) as an
integral part of a White-
Sundstrand Flexible
Manufacturing System
(FMS).The fully integrated
manufacturing
and inspection system is
used in the production of
aluminum aircraft structural
components.
The PCR is an automated flexible
gage designed for production use on the
shop floor. It can measure parts of virtu-
Dimensional data collected with a Process Control
Robot is used by Lockheed Martin Aeronautical
Systems to monitor the operations of a White-
Sundstrand FMS. The PCR is an integral part of this
automated manufacturing system.
…we’re
seeing only 1 1 ⁄ 2
thousandths band
width error
in 100"
ally any configuration and complexity
without the need for dedicated fixtures.
At Aeronautical Systems, the raw material
for the airframe structural components,
already held in machining fixtures,
is loaded onto an Automated Guided Vehicle
(AGV) and delivered to the FMS. After
machining operations are complete, the
parts are conveyed to a wash station and
then to a load/unload station where they
are removed from the AGV and placed on
the PCR’s granite table for inspection.The
part is inspected in the same fixture in
which it is machined.
The FMS operator also operates
the PCR.To start the inspection
routine, he simply enters the
part number into the PCR’s
computer.The computer
then downloads the correct
inspection routine and
performs the inspection automatically.
Parts are inspected
for thickness, parallelism,
flatness, and hole location.
The PCR can accommodate parts that
range in size up to 36" high and 52" to
54" wide. A part of average size and complexity
requires 400-500 hits during an
inspection, requiring 18-20 minutes per
part. Dimensional data gathered during
the inspection operation is used to control
the machining process in the FMS.
“Dimensional data is stored and then
downloaded for SPC analysis,” said Frank
Denny, CMM Programming Group
Leader. “By looking at the trend analysis,
we know at all times exactly what is happening
to the part during machining. If
we begin moving out of control limits,
we’ll change a cutter or make whatever
process correction is necessary.”
Real-time process control is also possible
with the PCR.The machine is
equipped with red and blue lights. If the
red light comes on during the inspection
process, it indicates that the inspection
program has failed in some way—the
probe has run into the part, for example.
If the blue light comes on, it means that
the machine has found an out-of-tolerance
condition.
“When an operator sees a blue light,
At 125'
long, this
Brown & Sharpe
DEA gantry CMM at
Lockheed Martin is the
largest dual drive measuring
machine in the world. Some of the
components measured on the machine
have more than 19,000 features to be
checked per side. Inset: The F-22 Raptor.
he examines the inspection results
immediately after the machine finishes
the routine and corrects the process right
away,” Denny said.
Big Capacity
For Big Parts
The dimensions of extremely large airframe
components and tooling are inspected
at Aeronautical Systems on the world’s
largest dual drive gantry coordinate measuring
machine.The gantry CMM, installed
some 11 years ago by Brown & Sharpe
DEA, is 125' long and features nine granite
surface tables inside the machine rails.
“Most of the parts inspected here are
at least 120" long and we’ve had some
over 600" long,” said David Caudill,
Quality Technician and Assistant Manager
of the gantry machine. According to
Caudill, most of the workpieces inspected
on the machine are two sided,
meaning that dimensions have to be
checked to assure that feature relationships
exist between forward and aft, or
inboard and outboard sides.
“Even if we don’t have features we
can reach that are common to both sides
when we align the part on the machine,
we measure features from one side and
then verify those same features to the
other side of the workpiece,” Caudill said.
The majority
of parts
being inspected on
the machine now are
for the F-22 fighter and
the C-130. Inspection routines
run anywhere from 30
minutes to four hours, with
some of the larger components having
19,000 features to check per side.
For all of its size, the gantry CMM is
very accurate and repeatable.The machine
is equipped with a thermal compensation
system that includes sensors that monitor
the temperature status of the machine’s
scales and the workpiece, and apply correction
factors to measurement results.
“We’ve had the machine checked by
our own calibration people, and we’re
seeing only 1 1 ⁄ 2 thousandths band width
error in 100". That’s very good for a machine
this size,” Caudill said.
Flexible Measurement
Saves Time
For smaller aluminum airframe parts,
Aeronautical Systems uses a Brown &
Sharpe Xcel ® flexible, automatic coordinate
measuring machine. The Xcel is
located
in an environmentallycontrolled
room in the machine
shop.
In the past, many of these parts were
checked using hand tools, and in some
cases, fixed gages. But, as components
become more complex, the use of hand
tools to measure their dimensions becomes
more difficult.
“The Xcel saves us a lot of time measuring
parts that would be difficult to
inspect using hand tools,” said Darrell
Waddell, Quality Technician. “Some of
the parts, because of their configuration,
would be almost impossible to check
without a computer-controlled machine.”
Throughout its manufacturing operations,
Lockheed Martin Aeronautical Systems
uses a variety of quality and process
control tools to assure the integrity of
airframe components. Coordinate measuring
machines play a critical role in
those operations. o
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