Cummins Six Sigma Project Results In A Smoother Ride For Dodge Ram Pickup
Making the Case for Quality
Cummins Six Sigma Project Results in a
Smoother Ride for Dodge Ram Pickup
by Janet Jacobsen
At a Glance . . .
It was less than nine months before Daimler Chrysler
• During an executive test
drive just months before launched its new 2006 Dodge Ram Mega Cab 4x4 pickup
product launch, Daimler when top company executives tested vehicle prototypes
Chrysler officials declared during a semi-annual executive ride-and-drive session.
a no-launch decision During the test drives, the automaker's executives deter-
because of excessive mined that excessive engine vibrations felt in the cab
vehicle vibration for the created a no-launch situation.
company's newly designed
Dodge Ram Mega Cab The company then turned to Cummins Inc., supplier of
4x4 pickup. the vehicle's 5.9-liter turbo-diesel engine, looking to Cummins Inc. deployed a Six Sigma team to reduce engine
• Cummins Inc., dramatically reduce the vibration levels—and quickly! vibration just six months prior to the September 2005 launch
manufacturer of the truck's of the new Dodge Ram Mega Cab 4x4 pickup.
Cummins, which already had a successful companywide
diesel engine, immediately Six Sigma program in place, immediately launched a Six
chartered a Six Sigma Sigma project to tackle the vibration problem.
team and employed the
DMAIC problem-solving About Cummins Inc.
process to diagnose and
correct the factors leading Established in 1919, Cummins is a global power leader that designs, manufactures, sells, and services
to the high vibration levels. diesel engines and related technology. Cummins serves its customers through a network of 550
• Through extensive testing, the company-owned and independent distributor facilities and 5,000 dealer locations in more than 160
Six Sigma team determined countries and territories. Due in part to its far-reaching Six Sigma program, Cummins enjoyed its most
that by increasing the
profitable year in 2005, earning $550 million on sales of nearly $10 billion.
radius, vibrations were To date, Cummins has:
• The Cummins' team • 3,700 employees who have completed Six Sigma training,
completed the DMAIC • 500 Black Belts, and
project in an extraordinary • 65 Master Black Belts.
time frame — just over four
months — resulting in a This cadre of “belts,” as they are referred to at Cummins, are assigned to one of three “versions” of Six
16% reduction in vibration
Sigma utilized by the company:
levels and a 100% increase
in sales of the truck in the • Technology Development for Six Sigma,
first year compared to sales • DMAIC (Define, Measure, Analyze, Improve, and Control), and
projections. • Design for Six Sigma.
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Why the DMAIC Approach to Six Sigma?
With their traditional before and after measurements, DMAIC
projects are well suited for customers, Cummins had learned,
because the customer can easily see the delivered improvement.
Cummins decided to deploy
this approach for the vibra-
tion issue in the Dodge
heavy-duty pickup model.
For an overview of Six Sigma at Cummins, With the vehicle launch date
see the case study “Six Sigma Saves close at hand, project buy-in
Nearly $1 Billion, Key Customers, and a
was immediate, both from
Cummins and Daimler
Chrysler executives. Members of the Cummins Vibration Reduction Six Sigma project team are pictured from
left to right: Ryan Pivonka, Cummins mid-range engine plant product engineering; Kerk
Define the Improvement Opportunity McKeon, Cummins mid-range engine plant launch team leader; Ian Package, structural
analysis; Dan Showalter, Black Belt; Chris Sanger, structural analysis; Matt Meek, Master
Black Belt; Joe Keil, crankshaft sourcing manager; Dennis Hurst, sponsor; Luke Marsh,
The opportunity for improvement was well defined after the exec- Daimler Chrysler representative; Paul Hayes, noise, vibration, and harshness; and Ilya
utive drive and ride event. “It was a no-launch situation and they Piraner, dynamic analysis. Not pictured: Carlos Da Silva, John Kupferer, and Rick Mason.
said this vibration has to come down,” explains Dan Showalter,
the Cummins Six Sigma Black Belt assigned to the project.
Assembling a top-notch vibration reduction Six Sigma project
To measure engine vibration levels, Cummins sent 17 of its pre-
team was crucial to executing a swift turnaround time for the
production engines to Daimler Chrysler where the engines were
project. Showalter, experts from Cummins diesel engine busi-
installed in vehicles for testing in early March 2005. Figure 1
ness, as well as representatives from Daimler Chrysler and
shows that three of the engines exceeded the acceptable level of
ThyssenKrupp Metallurgical Camp Limpo, a Brazilian supplier
vibration. This initial test confirmed that vibration was indeed an
of engine crankshafts, held daily team meetings to complete this
issue to tackle with the Six Sigma project.
Six Sigma project.
Figure 1 First 17 Vehicles Measured for Vibration at Daimler Chrysler
Peak Steering Wheel Y Acceleration
Above 2600 RPM
With Measured Engine Vibration at 3000 RPM
BOB (SGK) in WOW
WOW With New Engine & Package
WOW With New Engine
Cummins sent 17 pre-production engines to Daimler Chrysler where they were installed
for testing. Three of the 17 engines (depicted in the first 17 bars) exceeded an accept-
able level of vibration. The final five bars depict further testing using the worst of the
worst (WOW) and the best of the best (BOB) engines. This testing confirmed the need for
a Six Sigma project to reduce engine vibration.
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“The first hurdle was to determine how to measure engine vibration For Daimler Chrysler to complete a crankshaft swap for testing
without the engine mounting affecting the vibration level,” Showalter they would have to pull out the engine, install a new crankshaft,
recalls. With rigid mounts on its side, the engine wouldn't shake like and then reinstall the engine in the vehicle, which required
it would under normal driving conditions. Showalter's team came up removing the body from the frame, Showalter explains. Doing
with a system that allowed the engine to hang freely by bungee cords this would likely introduce more noise and variation than what
so that it could move in any direction during the testing process with the team was attempting to measure.
accelerometers mounted on each engine to measure vibrations.
The team needed a way to easily check the effect of the counter-
Analyze to Determine the Root Cause weight radius without introducing additional variation, says
Showalter. One team member suggested creating a crankshaft with
bolt-on tungsten counterweights to simulate the different radii that
By May 2005 the team was ready for the analyze phase of the
were under consideration. With this system Daimler Chrysler
DMAIC problem-solving process. Without a readily apparent
could simply drop the oil pan, swap the tungsten counterweights,
cause for the excessive engine vibration, the Cummins team set
and rebolt the oil pan without disturbing the vehicle body.
out to test various possible root causes. Showalter says a multi-
variable study included the following evaluation items:
Figure 3 shows the results of the bolt-on tungsten counterweight
tests where four counterweight radii were tested. Showalter
• The existent “as forged” crankshaft counterweight radius capability
points out that the 110 mm radius was for testing purposes only
• An increase to the counterweight radius
as it would exceed the space available within the engine. These
• An increase of the counterweight from 8 to 12
Daimler Chrysler test data show that by increasing the counter-
• The impact of the bedplate thickness
weight radius, the vibration is reduced. “We didn't want to be
• The capability of the piston rod weights
right against the production limit of 102 mm, so we backed off
• The impact of the piston pin weight
slightly to 101.5 mm to give us a little margin for error in pro-
• The impact of assembly variation
duction variation,” remarks Showalter.
• The impact of injector variation
Cummins and Daimler Chrysler officials agreed on this improve-
Improve by Attacking the Root Cause
ment. The crankshaft counterweight radius was increased by
ThyssenKrupp Metallurgical and Cummins was able to supply
Results of the multivariable study showed the greatest reduction in
the modified diesel engines with the new crankshafts to Daimler
engine vibration could be gained by increasing the crankshaft coun-
Chrysler in time for the fall 2005 product launch.
terweight radius to the full limit of 102 mm for the 5.9-liter engine
(see Figure 2). Showalter reports that modeling experts on the team
Control the Improved Process to Maintain the Gain
produced models forecasting a potential 26% decrease in vibration
just by increasing the counterweight radius. “But, at this point, it
The final step in the DMAIC process is control, which for this
was all theoretical,” Showalter recalls. “Our next problem was mak-
project was completed in early July 2005. Cummins' control plan
ing sure that the vehicle would see the same reduction in vibration.”
identified the counterweight radius and tolerance as a major
characteristic, meaning that sampling is done within each batch
Figure 2 Vibration Reduction Summary
of crankshafts produced by ThyssenKrupp Metallurgical to
16% ensure that the new 101.5 mm radius is consistent.
Figure 3 Daimler Chrysler Vehicle Tungsten Crank
96 mm CW
6% 6% 4
<1% <1% <1%
t t t
ess on n
igh igh igh
kn We We We ria
@1 et 765.193 1000 2000 3000 3484.39
rV on in
he od P bly
lat R Pis
ius ect ton
rad Inj Pis
CW 168 Crankshaft Tungsten Weights – Engine Mount Y
kC This chart shows a direct correlation between the size of the crankshaft counterweight
C radius and the levels of engine vibration that were recorded during the bolt-on tungsten
The crankshaft counterweight radius was chosen for the improvement project as it counterweight testing. The 110 mm radius was for testing purposes only. Ultimately, a
showed the greatest potential for reducing engine vibration. radius of 101.5 mm was selected.
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Big Results in a Short Time Frame Using Six Sigma to Maintain a Smooth Ride Into
Just five months after the executive ride and drive, this project
was officially closed on July 15, 2005. It was ultimately respon- With the success of this Six Sigma project, Cummins has
sible for lowering engine vibration by 16%, which, of course, increased the counterweight radius in all crankshafts used in
was good news to Daimler Chrysler. Luke Marsh, who at the diesel engines supplied to Daimler Chrysler, including those that
time of the project was an NVH (noise, vibration, and harshness) will become part of the 2007 model of the Dodge Ram Mega
engineer for Daimler Chrysler and a member of the Six Sigma Cab. The company will continue to designate this as a major
project team, said, “I was surprised that they (Cummins) were characteristic so that regular testing is conducted to ensure the
able to reduce the engine vibration that much. It was pretty consistency of the counterweight radius into the future.
impressive that they were willing to do what they did for us.”
Showalter says what he and other Cummins employees involved
Marsh credits the projects' swift time frame to the good relation- with Six Sigma like about this quality methodology is that Six
ship that his company has with Cummins and notes a mutual trust Sigma lays out a road map of steps to follow. “We've followed
between the two organizations. “This was the best Six Sigma those steps and it kind of led us along the yellow brick road,” he
project that I've ever seen. I was very happy with it,” he said. reflects.
For More Information
The truck found a receptive audience from the automotive press
as it received the following awards:
• Learn more about Cummins' Six Sigma project on the Dodge
• Truckin' magazine's Truck of the Year Ram Mega Cab 4x4 by contacting Black Belt Dan Showalter
• Best Overall Value of the Year for full-size pickup class from via e-mail at d.g.showalter@Cummins.com.
IntelliChoice, Inc.® • For more information about Cummins Inc., visit the com-
• Autobytel's Editor's Choice for Best New Large Pickup pany's Web site at www.cummins.com.
• 4 Wheel & Off-Road magazine's 4x4 of the Year • Read the companion case studies to this piece:
• Six Sigma Saves Nearly $1 Billion, Key Customers, and a
And, James Healey wrote in his September 30, 2005, USA Today Company
review of the truck, “ . . . perhaps the easiest of all pickup diesels • Cummins Capitalizes on Six Sigma to Minimize Long-
to live with because it is quiet and smooth.” Consumers have pur- Term Interest Rate Risk
chased it in numbers that continue to beat sales estimates, which
Contributing to This Article
in turn, creates higher sales for Cummins' diesel engines.
Showalter says that when the project closed in July 2005 it was Daniel Showalter is a technical advisor in the current product
estimated that 9,000 trucks would be sold in 2005, but 18,811 electronics support area at Cummins. He also served as a Six
were actually purchased—more than double sales projections. Sigma Black Belt at Cummins for two years. Showalter earned a
He explains that Chrysler estimated that a loss of 10% of sales bachelor's degree in electronic technology from Purdue
would occur without implementing this fix. “Ten percent of our University and his master's degree in management from Ashland
gross profit would have been gone without this Six Sigma proj- University. Showalter joined Cummins in 1993 as a principal
ect,” Showalter reports. He goes on to say that sales estimates for engineer.
2005-06 were pegged at 19,000 trucks, but revised estimates
About the Author
through June 2006 boost that number to 39,752 vehicles—more
than a 100% increase.
Janet Jacobsen is a freelance writer specializing in quality and
compliance topics. A graduate of Drake University, she resides
in Cedar Rapids, Iowa.
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