Extrusion Coating Line Audit Can Bring Big Benefits

Auditing your extrusion coating lines can be one of the more profitable resolutions you can make for 2001. This process will help your plant gain credibility with upper management by increasing production and reducing waste caused by weaknesses in procedures and equipment that could result in the following:

  • Variation in product properties
  • Excess operating waste
  • Surplus start-up time or waste
  • Poor reliability or significant downtime
  • Additional safety problems
This formal examination will allow accurate improvement recommendations for a specific plant or piece of equipment for enhanced safety, quality, and/or productivity. It also gives a plant the ability to make unbiased decisions on how and what to change.

The purpose of conducting these audits is to improve the areas that the audit is directed toward—not to point out shortcomings to higher authorities. By determining areas for improvement, a company can analyze how to enhance current practices in order to save and recoup lost profits.

There is a specific methodology that should serve as the overall framework of an extrusion coating line audit. Steps in the process include establishing the audit team, setting objectives, and establishing audit parameters.

The Audit Team
The first step in putting together an audit is to select your audit team. The most difficult part of doing this is making sure you have the right people. Team members must not only be the best in their respective fields but also be able to spend the necessary time required to complete the audit, which is typically one week per machine.

The team's make-up often depends on the particular audit areas and may be specific to one objective. Ideally, the team members will possess knowledge of corporate procedures that help them identify opportunities for improvement, obstacles to those efforts, and actions that can be taken to overcome those obstacles.

It is recommended that an audit team comprise an accounting manager, two department supervisors, two engineers (one process and one maintenance person), and a facilitator (either a group engineer or an external consultant). All team members should be from similar plants and understand company policies and procedures to make the most educated decisions possible.

Typically, these are not people that operate the specific line and are not located at the same facility. Therefore, they are more likely to keep results confidential and enable auditors to have a more objective viewpoint during their analysis. Any audit team member may come from outside the company; however, audit results should be kept internal, if possible. (A company with only one plant may be forced to use outside auditors.)

Another contributing factor to an audit's success is the use of an impartial facilitator that can guide the project through completion. The facilitator makes sure that audit procedures are followed, target areas are addressed, and proper reporting is accomplished. This role can be filled by a professional audit facilitator from outside the organization or by a senior manager within the plant.

The accounting team member ideally will do his or her audit prior to the rest of the team and provide a chart of plant waste or product cost to allow the main audit team to concentrate on areas that have a more profitable return.

Other audit team members should have expertise in the areas to be audited. For example, the engineers should understand the process and the equipment, while the department heads need to understand the products produced and the process variables. These are the key members that will make recommendations for the equipment, process, and procedural changes that should be considered.

Setting Objectives
Once an audit team has been selected, you need to determine the audit areas. Based on the results of earlier accounting findings, the focus should be on areas that offer the greatest opportunity for positively affecting the plant or department performance.

The first things to consider are the controlling variables that affect the extrusion and web handling process. Whether it is extrusion coating or film, the main controllable variables are pressure, temperature, and tension (P.T.T.). As the various sections of the line or lines are audited, the areas that can affect P.T.T. must be monitored continually.

Quality Control
To start the audit and to make sure the requirements of the various customers are understood, specification sheets and quality requirements should be reviewed. The requirements for the major product must then be determined in order to move onto the extruder resin feed system. This part of the extruder system often is overlooked, but it can and does have a major impact on the product's cost and quality. With more converters going to coextrusion, the accuracy of the blend system can affect the performance of the film or lamination. Many older lines (or mono lines) also have volumetric feed systems, while more modern, sophisticated lines may have gravimetric feed systems.

The main component of an extrusion system is the extruder, a major-effort component for a line audit. The purpose of the extruder is to melt, mix, and deliver a molten homogeneous polymer at a constant pressure and temperature. The audit team members must determine if the operator and supervisor have a solid working knowledge of the extrusion process and the variables involved. They also must know how the variables affect the process and determine their window of flexibility in changing those parameters.

One of the major areas for the audit team to examine is the thermocouple. Often a forgotten item of the entire system, the thermocouple is the feedback link that controls the system. In addition, the thermocouple serves as the communicator system and should be thoroughly examined.

The die and adapter are the next audit area on the components line. As every line is different, it is difficult to draw a universal check sheet that will fill every need. However, the audit team should endeavor to develop check sheets based on the piece of equipment or plant it will be auditing.

At the line section of the equipment, the audit team will need some basic tools to measure. Prior to auditing the winder and unwinds, the line element needs to be examined. When dealing with web handling, it's critical that the rolls be both level and aligned. The level and alignment are extremely important because offset rolls will cause uneven tension and force the web to shift sideways and wrinkle.

The unwinds on an extrusion coating/lamination line also should be reviewed closely by the audit team, since improperly inspected unwinds can lead to waste and quality problems. As there are many types of unwinds with various types of auxiliary equipment, there are general areas to check. Each audit team also will need to address specifics, however, depending on the unwind type. It is difficult to outline a general audit guideline for the winder due to the many different types and varying complexities.

Reporting the Results
Audits should be kept confidential and discussed only with those affected by the results. Most plants that conduct audits do not distribute the results externally. The fact that audit results will not be distributed outside of those being audited makes the audited plant or department more willing to share items and less likely to try and hide information. In an audit followup, when items of importance have not been corrected, additional actions may be justified. In most audits, the results are shared once problems are corrected.

Regular audits should become an integral part of any converting operation, because they ensure maximum uptime and efficiency and serve as a means to educate operators. Typically, the best time to conduct an audit is during a slack time in production. It is recommended that a follow-up audit be conducted every two years, but it may need to be conducted more frequently as machines get older.

There's no better time than the present to begin improving safety, quality, and productivity at your plant. This formal examination will allow the correct recommendations to be made for a specific plant or piece of equipment. The result will be an increase in production as well as a reduction in waste that was caused by previous weaknesses in procedures and equipment.

Give your plant the power to make unbiased decisions on how and what to change with an audit of your extrusion coating line.

Jan Ivey is a senior process consultant for Black Clawson Machinery, Fulton, NY. He has been with Black Clawson since 1996. Prior to joining Black Clawson, Ivey spent more than 30 years in the flexible packaging industry with Crown Zellerback, James River, and Printpack. He can be reached at 865/458-6183.

The views and opinions expressed in Technical Reports are those of the author(s), not those of the editors of . Please address comments to author(s).


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