Web Coating Blog

The Importance of Coating Process Support Systems

                             The Importance of Coating Process Support Systems
                                            Edward Cohen

Ongoing technical projects are needed to improve the quality, cost & productivity of a coating line in order to remain competitive and rapidly develop new products. There are several important considerations when developing and identifying coater needs and deciding on the most effective programs too work on. These are:

One Thing to Optimize Process

A question that is often asked about the Web Coating Process is “ What are the one or two most critical areas of the process that I should concentrate on to obtain a coated product with high quality and low cost?”. A possible basis for this question can be found in an interchange in the 1991 movie “City Slickers”, between Billy Crystal and Jack Palance

NEW YEAR ANNOUNCEMENT

NEW BI-MONTHLY POSTINGS WILL FOCUS ON THE DRYING PROCESS

Daniel Bemi Megtec Systems, is joining the Web Coating Blog as a contributing author. His focus will be on new bimonthly postings on all aspects of the Drying Process.

Drying and curing of coatings, along with other drying and annealing applications, are often a critical component of the coating and laminating process. While there are several good texts available on drying theory, there is a shortage of written materials focusing on application “know-how” and real world drying challenges. As such, AIMCAL will be introducing a bi-monthly posting of dryer-related technical articles beginning in January 2007. These postings will be aimed at bridging the gap between drying theory and application-based, process knowledge.

If you have a topic of interest that you would like to see addressed by our experts, please send your suggestions to Ed Cohen email cohened146@aol.com

Consider Modernizing an Existing Coater to obtain Improved Performance

As a coater ages, often it cannot meet current productivity, quality and cost needs. When this occurs, consideration should be given to modernizing the coater to meet these current and future needs.

Some of the problems that can lead to the poor performance are:

• Increased sales resulting in insufficient manufacturing capacity to meet sales demand.
• The current quality requirements cannot be met by the existing coater.
• New theology is required to manufacture products.
• Cannot meet the requirements for new products being developed.
• Product costs are increasing and are not competitive.
• Increasing yield losses.
• Equipment is wearing out and design conditions can not be achieved and maintained.
• Coater is becoming hard to run consistently.
• Downtime in the coater is increasing.

Summary of AIMCAL Fall Meeting

The October AIMCAL Fall Technical Meeting provided a forum for the exchange of Information between technical personnel in the web coating Industry. 60 papers were presented in three sessions as follows:

• Web Coating & Laminating
• Vacuum Web Coating
• Emerging technologies

In addition there were table to exhibits, which also provide an opportunity for additional technical discussions.

I found all of the presentations were outstanding and provided me with useful technology about the web coating process.

Defect Characterization Techniques: Microscopy

The ability to characterize a defect and to determine why it is different from the surrounding acceptable material is essential to determining the proper corrective action to eliminate it. There are a wide variety of analytical techniques that are in routine use to characterize defects and to help determine its physical and chemical characteristics. In this article the use of three microscopic techniques to determine these properties will be discussed.

The microscope is an instrument that produces magnified images of small objects that are too small to be seen with the naked eye.  An optical microscope uses visible light and combination of lenses to produce magnified images of small objects. Microscopes can also use other types of radiation infrared, electrons  and X-ray to  produce the magnified images.

More Than Defect Detection – The Real Value of Web Inspection

Brian W. Heil, Vice President – Sales
ISRA Surface Vision
4357 Park Drive Suite J, Norcross, GA USA
www.isravision.com

This article explores opportunities to maximize the value of automated on-line film inspection. Examples are presented of implemented inspection systems that provide critical real time process and converting information to maximize yield, improve raw material quality, and strengthen customer relationships. A solution for automated re-wind control for defect removal that increases converting throughput is discussed. The implementation of this technology offers its users a variety of methods to achieve value. The user realizes the maximum value when all of the possible methods are implemented.

INTRODUCTION
Implementation…this is the difference between success and failure of any plan. The best plans, ideas, technologies, strategies, directives, and mandates are useless unless they are implemented. The top performing companies are top performers because they spend much effort on new ideas and technologies and much more effort in implementing these ideas and technologies. This comes from the top of the organization and sets an example of follow through. We can all think about a capital project that was a failure, a piece of equipment that “never worked” or the “person left the company” that had the project, or the “operators never used it”. Occasionally this can be the result of a bad idea, but in an overwhelming majority of cases, good ideas and technology failed because they were never implemented.

This stated, we arrive at the topic of this paper – The Real Value of Web Inspection. We will explore how web inspection systems can be implemented to achieve maximum value. When defects occur in an extrusion process they can be just a nuisance and have no cost ramifications or they can be catastrophic in terms of causing product performance or aesthetic issues. An example of nuisance defects would be small gels and carbon specks in plastic grocery sacks. If your process only creates nuisance defects you are fortunate in this respect, however, these products usually are high volume, low margin commodity products that are purchased primarily on price and involve high customer turnover. <

Of greater concern and cost are defects that affect the aesthetics and/or the functionality of the extruded product. Examples would be carbon specks that affect the appearance and holes that affect the function of flexible food packaging. Functional defects are always catastrophic by causing the product to fail its intended use or required specification. Aesthetic defects can sometimes be catastrophic by prompting customers to return the product or change vendors. When aesthetic and functional defects are not controlled, returns occur, customers are lost, yields shrink, manufacturing costs rise, and the ability to compete in the market place is compromised. The cost of identifying and removing defective product from finished rolls is significant. The cost of failing to accomplish this is also significant. Inspection or lack thereof carries a high cost. Various opportunities exist to turn this cost into a profitable investment.

LIMITATIONS OF STATISTICAL SAMPLING
Controlling extrusion related defect occurrences is sometimes attempted by statistical sampling. A small piece of the film from the end of each roll is analyzed in the lab and the roll is considered to be acceptable or unacceptable. This strategy has many limitations. The occasional catastrophic defect cannot be controlled and real time process improvement is not possible as many rolls can be produced before the lab results are analyzed. In addition, rapidly changing process variations are missed, as the lab sample represents only a snapshot in time equating to as little as 0.001 percent of the produced product.

Figure I shows the variation of gel counts for a single roll of blown film. The data was collected with an on-line ISRA SURFACE INSPECTION SYSTEM that classifies, maps, and trends defect counts. The system counts gel, speck, and gels containing specks per square foot of inspected film. The trend graph in Figure I shows defect counts for each size class and type of defect per square foot of film. Within a five minute interval the total gel counts range from 2.5 to 20 gels per square foot of film and every ten minutes the counts are similar. In this case, statistical sampling, in terms of analyzing the gel count of a piece of film from the end of this roll, would provide erroneous results that would initiate the wrong process control action.

By itself, statistical sampling may provide a low cost alternative to inspection, but its limitations result in higher risks with regards to missed catastrophic defects and higher costs due to reduced process efficiency.

Figure I – Trend graph of defect counts per square foot of inspected film showing short term variation of gel counts

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