"In-line" system adds finishing touch at Andersen windows.

Finishing system provides continuous flow to the manufacture of Frenchwood patio doors, a popular Andersen product.

Now in its 92nd year, Andersen Corp. is an industry leader in the manufacture of wood windows, patio doors and accessories. The company employs 3,600 people at its 65-acre facility in Bayport, Minn.

Within manufacturing, every operation has been engineered to foster high product quality, optimum use of resources and good economics. The company is implementing ISO 9001/9002 standards throughout its manufacturing department and operates using a "pull-through" just-in-time production scheduling system for maximum control of inventory.

Take, for example, the manufacture of Andersen's Frenchwood patio doors, which are among the most popular for both new construction and retrofit applications.

Andersen uses pine and some LVL (laminated veneer lumber) in its construction of Frenchwood patio doors. Andersen's construction method precisely "balances" the pine pieces to prevent moisture migration. The door parts are then sanded by a single head platen machine which provides a quality finish and a smooth surface.

Because product appearance and durability dramatically influence the customer's decision to buy, as well as his long-term satisfaction, much attention is given to preserving, priming and topcoating the wood that is used for all Andersen products, said engineering manager Dick Fowler. The pre-treating and finishing lines are provided by the Technical Products Div. of George Koch Sons.

Two 16-stage conveyorized flatlines apply wood treatment, prime and topcoating consecutively and automatically. The systems are flexible both in the size of components they can accommodate and in the ease with which changes can be made between the three colors Andersen applies - white, gray and brown. The latter is especially important because 10 to 15 color changes are often made within a single shift.

The finish lines

The Koch flatline systems are "in-line" and arranged in two mirror-image "horseshoes." Parts enter the system on an outer leg and exit at an inner leg. A series of precise 90 [degrees] transfers conserve floor space and allow parts to be coated in lineal fashion - end to end - and dried lengthwise, in dense configuration. Door parts are automatically conveyed through the drying systems on ribbon belt transport conveyors, also manufactured by George Koch Sons.

The finishing sequence begins with manual or automatic feed of the millwork. Parts are immersed "on the fly" in a wood preservative that incorporates a fungicide/mildewcide and water repellent. The immersion cycle, which is adjustable, is set at 20 seconds.

A steam-heated convection dryer flashes the solvent; parts are then transferred 90 [degrees] to a denibber before entering the primer booth.

Primer and topcoat are applied in downdraft booths which accommodate parts up to 96 inches long by 8 1/2 inches wide. This system allows operations which had been performed at several stations throughout the plant to be consolidated - with a significant reduction in material handling, says Fowler.

Application of a PPG polyurea primer using HVLP spray guns is followed by a second 90 [degrees] transfer, then a cure in a convection oven. This low-temperature, high humidity system is designed for fast, even curing of this primer formulation in seven minutes.

The third 90 [degrees] cross-transfer positions parts for denibbing and cleaning following the priming operation. Andersen uses a Koch 12/2 denibbing station with a 3M Scotchbrite abrasive wheel.

Then parts enter a second spray booth, where PPG's Flexacron polyurethane topcoat is applied. The high-efficiency downdraft booth achieves good control over the physics of paint application, according to Fowler.

The fourth and final 90 [degrees] cross-transfer directs parts to an enclosed, forced air ambient flash tunnel. The forced flash is followed by high-velocity convection drying using a dual-zone Koch convention oven. An infrared oven completes the thermal cure of the polyurethane topcoat. The final finishing stage is ambient forced air cooling.

The Koch/TPD finishing systems allow maximum day-to-day flexibility says Fowler. Loading and unloading, for example, can be manual or automatic. In either case, the finishing sequence is PLC-controlled and "hands-free" from the moment parts enter the system until the paint cure is complete. The result is significant labor savings, better systems ergonomics and lessened risk of product damage, according to Fowler.

Furthermore, the system is fully abated. VOCs are reduced through Anguil catalytic oxidation systems and spray booth use only dry filtration.

Better control

Process controls offer detailed tracking and status information at a glance. The system paints "selectively" with coating material applied exclusively to its target - the exterior surface - and nowhere else. The latter is in contrast to the overhead electrostatic system formerly used to finish door parts at Andersen. In the past, specially shaped masks were used to protect "no paint" areas from coating, and required chemical stripping for clean-up.

As with many facets of the system, spray equipment is "fully Andersenized," says Dick Fowler. "The high pressure, low-volume spray guns, which have the advantage of easy setup and adjustments, were modified to increase transfer efficiency."

The finishing systems work in concert with Andersen Corp.'s continuous flow philosophy, says Fowler. Operations are lean and linear. Millwork progresses through manufacturing, finishing and assembly, and into shipping cartons with minimal stockpiling.