Increase profit by centerlining your corrugator: by controlling your corrugator's operating parameters, centerlining gives your plant new roads to consistent quality and performance.

Editor's note: A much more detailed article on the centerlining process is available at TAPPI's website Visit www.tappi.org, click on the Solutions! link, then click on Online Exclusives.

Centerlining is a process that offers consistency of product and performance. It uses operating parameters established by trial runs on each board grade the plant produces. This establishes maximum speed and board quality when the raw materials are fully within normal specifications. You will need the right tools to test your containerboard and starch to be 100% sure your suppliers meet expectations. These machine conditions should then be adopted as standards--by all shifts at all times.

Centerlining is an on-going process designed to help your plant identify opportunities for improvement, and help management focus on making these changes. It requires continuous effort and diligence to improve this process. Results of the plant's combined efforts will include:

* Reduced operating costs, waste, downtime, and warp 

* Improved board quality

* Increased throughput

* Increased profit

GETTING STARTED

The beginning stage of centerlining your corrugator consists of data collection to determine the stability of your process variables. These variables include materials management, starch, heat, gaps, gauges, level, and alignment. Mills must also make certain that the entire corrugator is within original equipment manufacturer (OEM) specifications. Maintenance integrity and calibration of all machine gauges is essential, both to the development of "best run settings" and to process repeatability once centerlining is completed.

After the variables are in firm control, the plant is ready to move into the next phase: minimum quality expectations. Each variable noted above has a different set of required factors that the plant must address to achieve minimum quality expectations. For example, some required factors for material management are:

* Incoming sampling inspection--to insure consistent quality of all raw materials and machine parts.

* A plant-wide documented complaint procedure to recover losses due to defective material (liner, medium, starch, ink, glue lap, etc.)

* Roll damage report procedure--to recover losses due to improper loading and blocking of liner and medium during shipment.

* Establish specifications and expectations on liner and medium with your containerboard suppliers.

Required factors for minimum quality expectations for other variables will include target measurements, procedure guidelines, testing methods, and suggestions for working with suppliers.

PROJECT RESPONSIBILITIES

Before your team establishes a centerlining program using best run settings, the plant must bring the corrugator up to a sound mechanical condition. Once maintenance has made the corrections, the plant needs to begin a simple planned maintenance program.

Management is responsible for organizing the speed trials and best run settings, and the crews on all shifts must commit to the expected speeds. Then, the production manager must review results daily. Plant personnel should seek solutions for all causes of slowdowns in future runs.

Finally, management must train all crews under the new procedures. At the end of the training, operators and mechanics should have as clear an understanding and sense of ownership of the centerlining process as management.

FINAL NOTES

The key to success is this simple mantra: "doing it the same way every time." Developing, maintaining, and controlling information about best run settings can become a logistic nightmare, depending on the approach plants take to manage this process. Box plants can have 20 to 30 board-grade variations; keeping current settings posted can be very time consuming. Evaluate which settings are the most frequent, then post the data for the crews to else daily. Once posted, implement follow-up activities to monitor current best run settings by examining any changes. Corrugator centerlining requires continuous effort, but it will pay off.

The author wishes to thank Technical and Logistical Consultants for their assistance and support.

About the author: Rick Croker is director, technical services, for Georgia-Pacific Corporation. Reach him by email at: [e-mail]