How One Company Meets Their Need for Speed
More, better, faster, is the mantra of every
manufacturer, especially as it applies to inspection. Howmet Inc.
(Cleveland,OH) thinks it has found the solution to more, better faster
inspection.
Howmet, a division of Alcoa (Cleveland, OH)
who manufactures compressor and turbine blades for aircraft jet
engines, thinks it has found the solution to the "more, faster, better"
inspection dilemma.
The company has implemented a new first-article inspection process that
combines a GOM white-light scanner from Capture 3D (Costa Mesa, CA)
with computer-aided-inspection software from Raindrop Geomagic
(Research Triangle Park, NC).
"The combination gives us the ability to perform our inspections on a
greater number of parts in a shorter amount of time," says Steve
Vanderkooi, an engineering support manager who has been involved with
inspection at Howmet for 32 years.
Howmet performs a 100-percent dimensional inspection for each new part.
The process involves verifying every feature on the part and comparing
it to a customer-supplied part print or a 3D CAD model. First-article
inspections are done prior to full production release, often while a
part is in development.Analyzing More in Less Time
The new process at Howmet replaces a coordinate-measuring machine (CMM)
system with GOM's ATOS II scanner, which can capture and calculate
precise 3D coordinates for up to 1.3 million points in about seven
seconds.
"The CMM's that we used previously captured only a few points in the
time that the ATOS II scanner can capture hundreds of thousands,"
Vanderkooi says, "So we're now able to do a more thorough inspection in
less time. The ease-of-use of both the scanner and Geomagic Qualify
software also play a key role in speeding inspection and making results
easier to analyze."
The ATOS II system digitizes a physical part by projecting patterns
from a white-light projector onto the object's surface. Two cameras at
either side of the sensor head capture the patterns. As the object is
scanned, the areas in which measurements have been recorded are
displayed on the computer screen. The system monitors its calibration
and the effects of the environment to ensure reliable measurement in
rough industrial conditions. Measure-ments from the scanner are
automatically transformed into a common object coordinate system.
Howmet saves the complete 3D data set of the scanned blade as an STL
file and brings it into Geomagic Qualify, where it is compared to the
CAD model of the object.Unique Turbine Blade Challenges
Turbine blade inspection poses some unique challenges, such as
analyzing the twist of a newly manufactured blade compared to the CAD
model. This is difficult using a CMM system, which depends on the
operator to accurately capture the points that will show whether the
blade is twisted within the allowable tolerance. Often, there is not
enough point data to make an accurate comparison.
Howmet uses a feature in Geomagic Qualify to automate twist analysis.
The software allows Howmet to align a cross section of the scanned
model to reference data, and to automatically generate statistics on
the twist of the blade. Constraints can be placed on maximum rotation
and twist tolerance. The software also provides graphical inspection
for turbine blade properties such as mean camber line; maximum
thickness; leading-edge and trailing-edge radii; thickness at offsets
from the blade ends; and chord length.
"Geomagic worked with us to add new functionality to Qualify and answer
any questions that we had while we were testing the product," says
Vanderkooi. "That made us comfortable in choosing it for current and
future first-article inspection."<
GD&T Automation
In addition to specific turbine analysis functionality, Howmet is
benefiting from new automation for geometric dimensioning and tolerance
(GD&T). Much of what used to take special in-house codes and
expertise can now be done in a few simple steps within Geomagic
Qualify, according to Vanderkooi.
With the new process, a GD&T callout can be created on the 3D model
with a click of a mouse. The model with callouts can be manipulated
interactively, and a single view can have multiple callouts, all of
which can be edited. A one-button command performs evaluation of
callouts on the test data, creating views, annotations, and tables of
the results. Results can be displayed as a simple pass/fail (green/red)
display, or as a detailed color map showing different levels of
variance. All test data are automatically recorded in a graphical
report that can be output in HTML, PDF, Microsoft Word, or Excel
formats.Faster Analysis of Multiple Parts
The new capabilities provided by computer-aided inspection have not
come a moment too soon for Howmet. Increasingly, the company is facing
the demand for more quality inspection results in less time.
"Customers are moving quickly to statistically based inspections in
which the qualification is based not on a single piece, but on a
sampling of parts," says Vanderkooi. "New part inspection would take
much longer to complete if we had not implemented automation to
minimize inspection time."
Traditionally, studies based on a sampling of parts are done using CMM
to generate metrics on dimensions for each part. This is a
time-consuming process, since each part must be measured individually.
Data are then typically transferred to an analytic program, evaluated,
and then published.
Vanderkooi is replacing the CMM-based process with automated trend
analysis within Geomagic Qualify. Once a part is scanned and a report
is saved, the software automatically generates capability studies
defined by Howmet. Batch processing enables nontechnical users to
collect data and generate reports on a large number of parts.
Statistical analysis tools within the software allow Howmet to compare
parts for predefined factors such as repeatability, changes over time,
and variations from part to part.
"The ability to create one inspection routine and automatically apply
that routine to additional parts is critical to our business," says
Vanderkooi. In the near future, Vanderkooi believes that the
combination of the ATOS II scanner and Geomagic Qualify software will
have a positive impact on every aspect of Howmet's inspection
processes, but for now speed is the key. "Speed of inspection is our
main challenge," says Vanderkooi. "Everyone wants the results
yesterday. Our new process is helping us deliver more complete results
much quicker."
For more information, please contact Bob Cramblitt, head
of Cramblitt & Company (Charlotte, NC) at (919) 481-4599.
