Shopfloor Accuracy Is the Key

Measuring parts for leading-edge technology fuel systems used in diesel engines

Cummins uses the Surfcom 5000 advanced contour and surface measuring machine and the Rondcom 60 form measuring machine to measure tiny precision parts.

The situation

The XPI common rail fuel system is manufactured by Cummins-Scania XPI Manufacturing LLP, a 50-50 joint venture company located at the Cummins Fuel Systems facility in Columbus, Indiana, and at the Cummins plant in Juarez, Mexico.

“Our work in progress is reduced because we are able to measure in real-time and more frequently than we did in the past,” said Spencer Wilkison, XPI Quality Manager at Cummins. For Wilkison, the accuracy and frequency of the measurements is key to Cummins which designs and manufactures leading-edge fuel systems for diesel engines.

In the fall of 2006, Cummins was in the process of deciding which brand and machine to select for its measuring needs. Evaluation first started out in the lab to establish a baseline from past measurement practices and environment. After calibrations on products from selected providers, specific trials were conducted on artifacts. The machines had to pass the litmus test in production. "We had to be sure that there wasn’t any degradation due to changes in cleanliness and vibration," adds Wilkison. Based on the measurement results, service, support and some of the intangible support that Carl Zeiss offered, Cummins decided to purchase three Rondcom and five Surfcom machines. As part of its capacity expansion starting in the spring of 2008, the company phased in an additional five machines, including one GageMax coordinate measuring machine from Carl Zeiss.

Wilkison stressed the importance of the grinding process. "Precision grinding is required for our components. Multiple grind operations are necessary, which produce final print features or critical in-process features." After each operation, the operators perform all of their own measurements. After the measurement process, all of the data is sent to SPC to control processes and review monthly production capability.”

Significant Benefits

Running operations reinforced the companies decision for ZEISS systems:

  • Zero customer rejects related to any precision grinding features
  • Scrap has been reduced
  • Time required for the Pre-Production Approval Process (PPAP)

Automation makes the difference

“TIMS software is easy to use. It took our operators only a day to familiarize themselves with the software," explains Wilkison. “What we want to highlight is that you don’t have to be an expert to be able to measure a part. The software allows the operator to run an automated program, where they do nothing more than put on a part and press the start button. I believe our accuracy has improved with the automation, because it eliminates operator error during setup.”

Looking to the future

“In the short term, as capacity expands, we will duplicate what we’ve created with the existing equipment,” says Wilkison. He believes the first step towards improved quality assurance is to think “outside the box,” and not be content with past measurement practices.

The single best experience so far has been the reliability and robustness of the Carl Zeiss equipment. The machines run almost 24 hours a day over three shifts. This is important, since there are always those skeptical of such a big change and the risks involved with a program this large.

About the company

Cummins Inc., a global power leader, is a corporation of complementary business units that design, manufacture and distribute engines and related technologies, including fuel systems, controls, air handling, filtration, emission solutions and electrical power generation systems. Headquartered in Columbus, Indiana, USA, Cummins serves customers in approximately 190 countries and territories through a network of more than 500 company-owned and independent distributor locations and approximately 5,200 dealer locations.