Making the Case for Quality

               Cummins Six Sigma Project Results in a
               Smoother Ride for Dod...
Why the DMAIC Approach to Six Sigma?

     With their traditional before and after measurements, DMAIC
     projects are w...
“The first hurdle was to determine how to measure engine vibration                                                        ...
Big Results in a Short Time Frame                                        Using Six Sigma to Maintain a Smooth Ride Into
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Cummins Six Sigma Project Results In A Smoother Ride For Dodge Ram Pickup


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Cummins Six Sigma Project Results In A Smoother Ride For Dodge Ram Pickup

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Cummins Six Sigma Project Results In A Smoother Ride For Dodge Ram Pickup

  1. 1. 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. crankshaft counterweight radius, vibrations were To date, Cummins has: significantly reduced. • 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. The American Society for Quality ■ Page 1 of 4
  2. 2. 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 Company.” 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. Measure Performance 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 5 3500 4.5 3000 4 2500 3.5 Acceleration (m/s/s) SW data 3 2000 Engine RPM 2.5 RPM 1500 2 1.5 1000 1 500 0.5 0 0 100151 100153 100154 100156 100157 100159 100160 100161 100163 100167 100169 100232 100264 100265 WOW SGK BOB (SGK) in WOW WOW With New Engine & Package 100168 100270 100271 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. The American Society for Quality ■ Page 2 of 4
  3. 3. “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. 16% 14% Figure 3 Daimler Chrysler Vehicle Tungsten Crank Results 12% Percent Reduction 6 10% Baseline 96 mm CW 5 8% 100 mm Tungsten 6% 6% 4 6% 102 mm Tungsten 3 4% 110 mm <3% Tungsten 2 2% 1% <1% <1% <1% 1 0% t t t l) ess on n igh igh igh mm tio tica ati kn We We We ria ari 02 ore hic Va @1 et 765.193 1000 2000 3000 3484.39 rV on in he od P bly t s (t lat R Pis o ius ect ton dp sem rad Inj Pis CW 168 Crankshaft Tungsten Weights – Engine Mount Y Be As 12 2x W kC This chart shows a direct correlation between the size of the crankshaft counterweight ran Opportunity 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. The American Society for Quality ■ Page 3 of 4
  4. 4. Big Results in a Short Time Frame Using Six Sigma to Maintain a Smooth Ride Into the Future 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 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 • 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. The American Society for Quality ■ Page 4 of 4