Optimizing PMC operations.
We spoke to a few industry experts in the machine clothing arena, and asked for their ideas about what is essential for effective clothing management. Advice about careful decision-making and supplier-mill partnerships formed the core of each answer.
"A good clothing management program is like driving a car," said David Procter, PM2 production manager at the Stora Enso Port Hawkesbury mill. "One person in the mill should be 'driving' the program. Many people can feed information on performance, costs, and direction to that one person, but just as a committee cannot drive a car, a committee will not produce an effective clothing management program."
To further avoid confusion, Proctor recommends limiting the number of clothing suppliers to two or three for the entire machine. "A single supplier situation is too risky and multiple suppliers cloud the decision making process," he advised. "With only two clothing suppliers, they can truly be considered partners. Both partners should be part of joint target and goal setting meetings. There is a huge synergistic benefit in having two equal partners working together with the mill personnel, and everyone pulling (not pushing) in the same direction."
When partnering with fewer suppliers, mills must choose carefully. "It's the sharing of expertise that will gain success, which is more commonly known as teamwork," said Bill Jeffrey, communications manager, Voith Fabrics. He recommends the following:
* Select clothing suppliers who have a full-line of quality, innovative products and diagnostic service capabilities.
* It is important that the supplier is financially healthy.
* Both mill and supplier must have an understanding of mill management's paper machine operating objectives, and the mill's customers' needs.
"The mill and supplier who view the paper machine and clothing as a system, and harmonize it accordingly, will get the most from their program," Jeffrey noted.
Oliver Baumann, product manager, Wangner, agrees. "Our company's approach is that there is more to success than merely selecting the correct fabric for a particular paper machine," he said. "An effective supplier works closely with the customer to offer a reliable total solution for the specific machine being considered. This includes the extremely important aspects of delivery reliability and availability. There is no other way to achieve high paper machine efficiency."
Baumann lists quality, skill and reliability as the most essential elements of successful machine clothing management. "Ever wider and faster paper machines impose increasing demands on paper machine clothing performance, particularly when it comes to retention and drainage. The production process at the wire part must therefore be adjusted accordingly, and this can only be achieved by using state-of-the-art, high-quality, reliable products. Overall process performance is a pivotal factor in determining optimum paper machine efficiency, and the machine clothing is a major contributor in this regard."
According to Jeff Landry, marketing manager, Asten-Johnson, "it is critical that the paper machine clothing be managed to optimize water removal from the time it is installed until it is removed. In the wet end, current standard operating practice is to perform a water balance measurement at the former and press sections," he explained. "This can be done 'manually' using various measuring instruments or can be monitored on-line by measuring the various flows of water on the paper machine. The total water removal in each section can then be tracked and clothing performance can be accurately assessed and optimized." AstenJohnson's Ecoflo system is an example of the type of system that measures and records the flows in the wet end section.
"Insuring sound technical clothing management in your wet end will yield enormous returns. By optimizing clothing selection at a cost of pennies per ton, you can substantially improve your paper machine productivity by dollars per ton," Landry added.
"With paper machine clothing accounting for less than 2% of the total cost per ton of paper, the largest opportunities for impacting mill profitability are usually in energy, raw materials, and labor," said Steve Cole, director-value creation management, Weavexx Corporation. "The driving force for Weavexx as a machine clothing supplier is value creation--helping customers produce measurable benefits from paper machine clothing application through innovation in product technology." According to Cole, Weavexx developed its OpenDOOR product as the first "formal" program in the PMC industry for value creation and documentation.
"It is imperative that the supplier and paper mill team work together to match the proper product technology with the precise objectives of the mill," said Cole. "Even the best technology, when misapplied, can lead to inefficiencies, non value-added activities, and economic loss. Therefore there must be established guidelines for each project."
Stora Enso's Procter suggested that program goals should use a maximum one-to-two year time scale, with specific targets set within a much shorter time frame. "Some targets can be met (or not met) within minutes of start-up," he noted.
"Benchmarking with other mills is a must. Nowadays there are many avenues to obtain benchmark information and they must all be used," continued Procter. "There has been so much happening in the last ten years in clothing design that it is very easy for a mill to be left behind."
Bob Mclntyre, diagnostic services team leader, AstenJohnson, noted that, in addition to choosing the correct fabric design for the grade of paper, proper machine maintenance is important to optimal performance. "Fabric conditioning must be properly designed and maintained, including lubrication and cleaning shower placement, orientation, nozzle type, rate of application and chemical addition as necessary. Guide and stretch mechanisms must be positioned, controlled and maintained to keep fabrics running straight and true. Machine elements must be checked periodically for condition and operation to avoid premature wear from contact (abrasion), thermal decay, and irregular compaction (vibration.) And finally, overall machine alignment must be maintained."
Success relies on experience and knowledge, noted Voith Fabric's Jeffrey. "Technical know-how is needed to efficiently manufacture paper to compete in world markets. Both the mill and supplier must be committed to investing their resources into achieving the established mill, end-use goals. Neither party can, nor should be expected to, provide this technical support unilaterally. There must be a return on investment for the mill and supplier."
Added Procter, "failed clothing trials can be extremely expensive for both the mill and the supplier. The cost of failure can be very high, but risks can be minimized by close liaisons and associations with the suppliers (partners) and other similar mills. The fear of failure should not override the fear of taking a risk," he emphasized. "Without risk there is no progress."
Mills and machine clothing suppliers can apply the concept of continuous improvement to the designing, testing, and implementation of new clothing machine programs. The keys are measurability and cooperation.
"It is crucial that improvements be measurable; both in the fabric itself and in the papermakers' production processes," said Baumann. "Wangner modifies and improves fabric designs that have already been successfully applied elsewhere to individually suit the largest possible number of paper machine positions. Wanger's development methodology is dynamic and relies on highly advanced measurement techniques to validate performance improvements."
As a case in point, he points to Wangner Surface Analysis (WSA), a nanotechnology-based opto-electronic scanning profilometer, developed to measure surface properties. "We can precisely examine and optimize all topographic values for most suitable material combinations and fabric structures," said Baumann. "Measured data can be reviewed in two or three dimensions by analyzing graphic displays generated by the accompanying software. By using this verifiable, repeatable process, we can demonstrate to a customer the improvement potential of a very specific fabric solution before it is actually applied on the machine."
According to Cole of Weavexx, several key principles must be managed for mills trying to improve and optimize a paper machine clothing program, and the company's Open-DOOR platform is an example of a vehicle for managing these principles. "What is the overall business environment--order backlog, inventories, profitability, competition?" asked Cole. "Also, what are the critical issues for the machine and mill in terms of quality, production, and efficiency? Objectives change, so it is imperative that we know what the current local targets are."
Other principles include machine clothing product technology and design reviews, to confirm critical issues, trail performance status and opportunities for improvement by position; service and support requirements; inventory management ("excessive inventory can sometimes impede the rapid adoption of new technology in the trail management process," added Cole); and contractual/account management issues. "Are both parties in compliance? Are the right supplier resources assigned? Is the account being managed to the customer's satisfaction? Again, it's all about value, and managing a process that maximizes it," he said.
"The essence of providing mill management with improved paper machine efficiency and sheet quality is clothing performance," said Bill Jeffrey. "Voith Paper Technology participates in the paper manufacturing process from stock preparation to roll wrapping. This integration of papermaking knowledge helps us produce better clothing."
Additionally, Voith Fabrics has access to five pilot paper machines that help accelerate the development curve for new products, said Jeffrey. "These advanced designs have proven to enhance machine performance and sheet characteristics."
According to Dave McCann, vice president and regional business leader, AstenJohnson, the best way to apply continuous improvement to paper machine clothing programs is for mills and suppliers to work together on all trial applications. "By collaborating on key trials, and carefully following the trial and gathering key production information before, during and after removal, major improvements can result. Critical are the thorough gathering of pertinent machine data and a clear outline of realistic expectations before undertaking any trial of clothing," he said. "The final stage of continuous improvement is garnering the value provided, quantifying it in dollars, and applying what was learned for more improvement.
Through this joint, mutually beneficial and mutually reliant approach, great gains can become the standard expectation."
WHAT YOU WILL LEARN:
* Factors in effective machine clothing management.
* Innovations designed to enhance clothing performance.
* "Machine clothing strategies keep wraps on cost," Solutions!, August 2004. Product code: 04AUGS026.
* "Machine clothing: how do the best mills operate?", Solutions!, January 2004. Product code: 04JANSO70.
RELATED ARTICLE: NEW OPTIMIZING TOOLS CAN MAKE A DIFFERENCE FOR PAPER AND BOARD MAKERS
By Bernard Festor, technical director, Albany International Europe-Forming; and Sabri Mourad, project leader, Research and Development-Forming
Papermakers have used several optimization methods to improve the wet end performance of a paper or board machine. In the past, actions were usually taken step-by-step, adjusting parameters one by one; variable factors included slice opening, vacuum, fabric tension, and consistency.
New optimization tools allow changes in three or four parameters (factors) at the same time. With this approach it is possible to discover interactions between different parameters.
The Expert system from Albany International is an example of the multiple-parameter approach. Expert is based on design of experiment (DOE). This statistical method has been helpful in the optimization and improvement of many industries. An opportunity exists to use this method for paper machine optimization.
With the Expert method, technicians make purposeful changes to input factors (tuning parameters) of the wet end process, and track the effects on the output (formation, dryness, smoothness etc.) A set of trials is defined and run on the paper machine. The mill analyzes the trial results, and uses the results to determine the impact of different variables on the industrial process with a minimum number of runs and the highest accuracy.
Each project is divided into six critical stages:
* Define the process improvement targets.
* Define the method for measuring the evolution of the target properties; also, define values about the accuracy of the measurement.
* Define both the fixed and variable trial parameters.
* Define the minimum and maximum of each variable parameter. In some cases, intermediate values should also be defined.
* Establish the trial procedure.
* Gather and analyze all trial results.
CASE STUDY: OPTIMIZING PAPER FORMATION AND PRINTABILITY
Figure 1 shows a gap former installed on a wide, high-speed SC machine. The project goal was to improve formation (as measured by Ambertec). The specificity of this case is the strong relationship between printability and formation. The project identified the best parameters to improve paper printability of both sides of the paper sheet (measured by Heliotest).
[FIGURE 1 OMITTED]
Mill technicians studied eight different factors of the wet end and stock preparation processes during this project, including slice opening, headbox angle, wire/jet ratio and dilution water ratio in the headbox. Each of the eight parameters was divided into several subgroups. The expertise accumulated in DOE allowed the mill to design a trial plan including 26 trials to study the effect of all these factors. Technicians collected a large quantity of data during these trials, and performed in-line and lab analysis on collected paper samples. The analysis using the DOE statistical method allowed them to discover which factors significantly influenced the formation and Heliotest values.
The key factor to improved formation was the lip opening of the head-box (Fig. 2). The influence of this factor was amplified by studying the detected interactions. On the other hand, the Heliotest was modified due to the tuning of the vacuum level on both the forming roll and the forming shoe. The optimization of both the formation index and the printability level provided a significant improvement in paper quality.
[FIGURE 2 OMITTED]
Editor's Note: Expert is a tradename of Albany International Corp., Albany, New York, USA. Ambertec is a tradename of Ambertec Oy.
EDITED BY JANICE BOTTIGLIERI, SENIOR EDITOR
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|Title Annotation:||Machine Clothing|
|Publication:||Solutions - for People, Processes and Paper|
|Date:||Oct 1, 2004|
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