Digital Magazine

Custom coating operation is a clean winner

Targeted toward industries with very strict standards, Rexam Custom's Netherlands plant sets its own high standards of quality.

Rexam Custom, a specialty supplier of custom coated and laminated products, operates six facilities in the United States, the United Kingdom, and the Netherlands. The newest of those sites is a state-of-the-art operation located in Kerkrade, Netherlands. With easy access to Germany, Switzerland, and Austria, the new facility is capable of producing specially coated products certified for use in all the markets served by Rexam Custom. These products will ultimately be shipped worldwide.

Because Rexam Custom operates in markets that demand absolute levels of quality, says production manager Steve Hughes, process control and validation are paramount to the company's operation. Quality systems and procedures are applied throughout the plant, from checking incoming raw materials through in-line monitoring using Computer Integrated Manufacturing (CIM), to final off-line quality checks. CIM facilities include infrared and beta-gauge thickness control and laser inspection 2,400 times a second. The facility is on its way toward achieving ISO-9001 certification for accountability, repeatability, and traceability of finished products throughout the production process.

A Silent but Valued Partner

Rexam Custom is a div. of Rexam Inc., which operates 53 manufacturing sites worldwide, primarily in North America. Rexam Custom, says plant manager Jonathan Haddock, delivers "high-value-added, high-cost-of-failure products" for imaging, flat panel displays, and advanced materials markets with applications in graphic arts, storage and retrieval, electronics, medical, and various other applications.

Customers rely on the company to supply "critical components" for their own end products, Haddock explains. "We want to be a high quality, highly valued partner to our customers. You don't see our name on any of these products, but we obviously are providing critical components to those products." (He adds that Rexam Custom's strict code of confidentiality does not allow the company to divulge customers' names.)

To achieve its high quality standards, Rexam has designed a facility that operates under stringent Class 1000 "clean-room" conditions. This dictates that the air must contain less than 1,000 dust particles/cu ft. The typical particle count in such a clean room is about 200, compared to 4,000 in a hospital operating room and 100,000 in a clean industrial plant. The need to eliminate dust particles during coating is critical to many applications where even the smallest speck of contamination will spoil the functionality of the final product, says Hughes.

To achieve these standards, Rexam Custom designed its Kerkrade facility around three distinct zones: "normal," "intermediate," and "clean." Receiving and shipping, which has the most contact with an outside environment, is designated as a "normal" area. This is where all "dust-generating" materials, such as cardboard shipping containers, are handled.

Raw materials, such as rollstock, are removed from these containers and moved to an "intermediate" storage area, where they are kept in black plastic wrap for protection and confidentiality. When the product is ready for use, an automatic guided vehicle enters on a track from the clean room, picks up the designated roll-stock, and returns to the intermediate area.

The Class 1000 clean room itself has a high-volume, low-velocity cross-flow air system that moves 45,000 cu ft of air per hour. As a result, the air inside the clean room is fully replaced every 1.5 minutes, enhancing product purity. To help assure maximum air quality in the Class 1000 clean room, air pressure in the plant varies, with the greatest pressure maintained in the clean room. This enhances an air-flow system that keeps particulates from the "normal" and "intermediate" areas from entering the clean room.

"One of the things that is critical to clean-room manufacturing is how you divide your plant into areas with separate air-handling systems," says Jan Lemmens, plant expansion project manager. "This is to prevent particle contamination in the manufacturing process. You don't want the air taken from one area and simply blown into another, so you have to design your air-handling units very carefully."

The Coating Operation

The centerpiece of the facility is a proprietary coating operation that is designed to produce a wide range of custom-coated products in varying run lengths. Rexam Custom can produce laminates from 6 to 750 microns thick and coatings from 1 to 180 microns on material up to 1.6 m wide. The company uses three coating methods - reverse roll, gravure, and slot die, and three coatings - solid, solvent, and water-based - on a wide range of films and metal foils.

The first of four machines planned for the Kerkrade facility, the coater now in use can produce up to 30 different products. It is designed for relatively quick changeover of rollstock and coating heads to accommodate shorter runs. (Each can be changed in less than one hour.) The coater is composed of unwind and rewind sections, two in-line tension controls, three web cleaners, one corona treater for enhanced laydown, and five ovens for precise drying. The system is capable of combining two web paths to convert a single product. An ultraviolet curing unit is located after a thickness gauge to ensure proper drying, and a portable IR drying unit is available for applications that are sensitive to air movement.

Each drying unit has a single exhaust fan leading to a main chamber that delivers solvent-laden air to a roof-top thermal oxidizer. To ensure proper destruction of contaminated air, the coater cannot operate until the oxidizer reaches a minimum of 730 deg C. Standard running temperature is approximately 860 deg C. The unit achieves an efficiency of more than 99% air purification.

The facility also houses a computer-controlled slitter that can deliver stock as narrow as 25 mm, although it is used mainly to cut large master rolls into smaller rolls of about 1 m.

In addition to the main equipment, the facility has two proprietary computerized mixing machines to deliver precise amounts of solvents and water-based coatings. The amount of bulk ingredients used in coatings is automatically measured and fed from central storage tanks and, when the mix is ready, the computerized dosing system automatically records the quantities blended. The mix is then transported to the production area.

To maintain safety and the quality of the product in process, employees are required to wear face masks. A roof-top tank contains 660,000 cubic liters of water - enough to douse the entire factory for four hours should a fire or massive spill occur. A separate tank is located beneath the plant floor to capture and contain the released water.

Black box "solvent sensors" are strategically located to automatically maintain acceptable solvent levels. Should solvent concentration rise to "Level 1," the sensors automatically increase air flow into the room. At "Level 2" the exhaust system is raised to maximum capacity. At "Level 3" electricity throughout the entire room is shut down to avoid health and safety problems.

"We did not just follow [safety] regulations," explains Lemmens. "We built in our own standards to exceed them and stay ahead of the game."

Jonathan Haddock sums up the operation: "It's a completely different approach than that of many other companies. We're putting a lot of emphasis on improving our product management so that we can offer better service and an even faster response time to our clients. We've got to do this to make our strategy in Europe and our strategy for this site successful."

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