Digital Magazine

Consider film cores when analyzing costs.

Film cores are rarely considered key components in a total system cost analysis, but using the wrong ones may cost you more than you realize.

As film markets become more competitive, producers, converters and suppliers are being forced to more closely scrutinize their costs. Every aspect of production - from raw materials to packaging - is being carefully weighed to ensure that all the costs involved in the manufacturing system are understood and are as low as possible.

The film core should be a key component in any examination of system costs. Traditionally, the film core has been treated as a commodity item, because it seemingly represents only a fraction of the value of the completed roll of film. While it is often overlooked, if the film core fails to perform properly during winding, transporting or unwinding, it can jeopardize thousands of dollars worth of product and "cost" the film manufacturer, as well as the converter, in overexpenditures throughout the total system.

Therefore, it is critical to understand the impact core selection has on total cost. For example, film yields can be increased, line set-up times reduced, film roll packaging materials consolidated, warehouse space eliminated and management time minimized through the selection of the proper core for a specific application.

When examining the core in a system costs analysis, converters should give attention to the core's surface, straightness, moisture content, strength and packaging.


Film yield losses can often be directly related to the film core's surface. For example, films such as polyester are very sensitive to surface imperfections. While end-use application is a major determinant in specifying the core's surface, it is a general rule that the thinner the film, the more defect-free the film core surface must be.

The two key surface variables are waviness and roughness. To better understand these, think of the core as a road surface. Waviness describes the road itself - whether it is flat or hilly; roughness describes the road's surface - smooth or bumpy.

Excessive waviness can result in uneven tensions, air entrapment and spiral marking of the film. Excessive roughness, such as that caused by a gritty spot on the core surface, can cause pimpling throughout the roll. Of the two, waviness is generally a greater concern than roughness for film manufacturers.

When considering core surface improvements, manufacturers must ask two questions to make the most cost-effective choice: 1. Will improvements in the film core surface positively affect film yields? 2. Is the improvement in yield greater than the increased price associated with an upgraded core?

For instance, a polyester film manufacturer recently upgraded to a core with improved surface characteristics. While the price of the core increased 40%, the manufacturer was able to save several hundred thousand dollars annually through yield improvements and market expansion.

Conversely, film manufacturers and converters must also be aware that core surface downgrades can affect yields and lead to cost savings. A commodity film manufacturer, for example, downgraded to a less sophisticated surface with higher roughness and waviness levels without negatively impacting yield. This change resulted in an annual savings of more than $100,000.


Generally, the wider the film web, the straighter the core needs to be. This is especially true with thinner gauge films. Cores that are warped and bowed - even if the imperfections are only slight and barely perceptible to the eye - can cause film to acquire machine-direction corrugations, negatively impact operating speeds and efficiencies and lead to breaks from uneven tension across the web. The core should be compatible with the manufacturing process.


There are two reasons why core strength is becoming an increasingly important variable in total system costs analysis:

* Film lines have grown wider and faster, and demands on core strength have increased. Concurrently, the amount of film being shipped per roll is increasing due to converter demands for fewer changeovers.

* Core design technology is advancing; leading core suppliers are investing in research and development to stay ahead of trends. Thus, film manufacturers should be regularly evaluating core requirements and working with suppliers to determine the optimum core to meet the requirement.

For example, one film manufacturer was using a 10-in.-inside-diameter core because a 6-in. core had historically not met its straightness and strength requirements. Advances in technology have allowed this manufacturer to convert to the less expensive 6-in. core. The manufacturer was also able to roll more film, because the redesigned core was strong enough to carry the heavier load.

Thus, system costs were lowered, and the level of customer satisfaction among converters increased.


An examination of the packaging methods currently used for incoming cores could also yield cost reductions. If core dimensions have changed, or if there has been some consolidation in the range of cores being purchased, it may be possible to change the way cores are currently packaged.

Also, progressive core manufacturers are working to develop reusable core packaging systems that eliminate corrugated materials and improve product protection. These systems save money by reducing core unpacking time at the film manufacturer's plant and eliminating corrugated disposal costs. Often these packaging systems can be directly integrated into the manufacturer's process.


By taking the time to properly match core attributes to film requirements, and by aligning with a supplier that can provide the technical expertise and capabilities to foresee and solve problems, manufacturers can reduce total system costs.

Additionally, an increased awareness among converters and core specifiers on how to look at cores from a cost-savings approach allows them to help film producers make the most cost-effective core-purchasing decisions. This ensures the receipt of full film value and translates to a win-win situation for all involved.

In 1994 AlliedSignal's Specialty Films plant in Pottsville, PA, improved its bottom line by 15%, with total system cost reductions contributing significantly to the increase. This substantial savings was not an accident, since the company aims for all its suppliers to reduce costs by 6% a year.

Over the past few years AlliedSignal's Specialty Films business, a nylon and polyvinyl chloride film extruder for a wide range of industries, has examined its purchasing and manufacturing processes to find ways to reduce total system costs and improve productivity. One key element of this cost-reduction process has been the development of teams, made up of representatives for AlliedSignal and its suppliers, that examine all areas associated with cost.

One such team, which includes Sonoco Products Co., is responsible for a $70,000 cost reduction at the company's Pottsville facility. Overall, this team's efforts resulted in a 15% total cost reduction at the facility.

"Our most successful teams are those with proactive supplier representatives," says Tim Berndt, materials management process leader, AlliedSignal-Pottsville. "Our productivity improvements would not have been possible without the help of suppliers like Sonoco."

While the teams explore ways to reduce the company's costs, product cost reduction is not considered the only method to achieve this savings. sonoco, AlliedSignal's sole core supplier, also looked at its customer's manufacturing process for ways to help reduce total system costs. "I've seen our Sonoco representative spending full days here on the production floor with our operators in order to help us save money down the road," says Berndt. "We've already seen results; Sonoco has saved this facility money in more ways than one."

After Sonoco studied AlliedSignal's current core specifications and applications, it proposed switching to a thinner wall core, which would lower costs without sacrificing quality. Sonoco all examined the length of AlliedSignal's cores and recommended moving to a shorter core to reduce waste and further reduce costs.

"Before Sonoco simply switched to a thinner wall core, they performed a number of tests to make sure the core would fulfill our manufacturing needs and quality standards," says Berndt. "We have had a zero-defect role, absolutely no core-related issues since the switched."

Core specification is only one area in which Sonoco has provided advice and cost savings. AlliedSignal has also looked to Sonoco for counsel on what to look for when ordering new machinery, and when AlliedSignal reported problems with its core-cutting machinery, Sonoco analyzed the problem and recommended switching to a different blade. "As a direct result of Sonoco's recommendation, we now have a superior quality cutting blade, with a lower cost than the one we were using before," says Berndt.

Scrap recover is another issue Sonoco is investigating for the Pottsville facility. Presently, Sonoco takes back scrap, processes it and reuses it in its cores. According to Berndt, Sonoco is also working to incorporate the plant's corrugated scrap into its recovery program. "They've even offered to put a baler on-site."

"Our relationship with Sonoco is the perfect model of how our teams were designed to work," concludes Berndt. "They've made a commitment to understanding our business, and that is what helps them to help us. Sonoco is constantly proving that we made the right decision to go with them as our sole film core supplier, and I don't expect that decision to change."

Robert W. Kearns is marketing manager, film industry, at Sonoco Products Co. He has authored a number of papers and spoken on such subjects as customer-supplier partnerships, customer satisfaction and film core specification. He has held various marketing and planning positions at the company for 17 years, including director of corporate planning and development.

James H. Munroe, market specialist, film cores, has spent the last five years specializing in the manufacture, development, sales and marketing of sophisticated film cores used by the polyester film industry. He has consulted for and visited film core manufacturers throughout the US, Europe and Japan.

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