Reinventing the flush door

The Maiman Co. , of Springfield, Mo., has developed a strong reputation as a provider of quality, custom stile-and-rail architectural doors. Meanwhile, the company has developed a name as an innovator, and was honored as the  1997 Innovator of the Year  by the  Woodworking Machinery Industry Association . So when owners Jane and Tim Bennett decided to expand Maiman's product line into commercial flush doors, they took a nontraditional approach.

The Bennetts originally looked at adding a traditional line to build flush doors. That process starts with a low-density core surrounded by an edge strip. Then a crossband is added to eliminate telegraphing, the core is calibrated in a widebelt sander and the final veneer is applied.

"We looked into it and we were going to spend $14 million on a core building system," says Tim. And the result is a veneer door that still has to be finished or painted. "We just thought there had to be a better way."

The Bennetts looked at the furniture industry, and saw the answer. Thermofused melamine makes a great vertical surface. With today's papers, it can match nearly any wood species to the untrained - or even trained - eye. So what if a door was produced from a solid slab of 1-3/4-inch melamine clad particleboard?

The hitch is the screw-holding ability of the particleboard core. Unlike cabinet doors, where the hinge goes into the back face, the hinge on flush doors is inserted into the edge, and the screw-holding ability of particleboard isn't great enough for that application.

It's magic

But that didn't stop the thought process. The team at Maiman came up with a solution, which is now a patented process, to increase that screw-holding ability. "It allows the doors to exceed extra heavy-duty ratings for screw withdrawal, hinge load and cycle slams," says Tim.

Maiman starts with a
1-3/4-inch-thick blank of 42-pound density thermofused melamine-clad particleboard. It is cut to size on an angular panel saw. It is then run though a line of two double-sided tenoner/edgebanders, a machine that applies the "Maiman magic" and a 46-axis CNC machine the routs the finished blank for hinges and lock hardware. A door comes off the line and is placed on a pallet ready for shrink-wrapping and shipment to the job site.

Removing steps

"We stumbled on a way to take many steps out of manufacturing a flush door and created a better product," says Tim. "It's not laminated, so it can't delaminate. It's a 42-pound density core rather than a 28-pound core. I'd like to see a college kid kick a hole in that door." It's also a door that requires no finishing and can be ordered in a broad range of patterns and colors. It is also at an attractive price point in the $110 to $150 range. "For the hotel, dormitory and hospital market, this is a natural," says Jane. "We can give them the look of a $400 door in an anigre veneer for less than half the price. The design possibilities are almost limitless."

As with most plans, coming up with the concept was one thing, executing it was another. Research into the idea started approximately three years ago, and the actual equipment was ordered in the summer of 2001. Maiman built a new 100,000-square-foot plant across the street from its 50,000-square-foot stile-and-rail door plant. The Bennetts say total investment in plant and equipment for the new line is in the $10 million range.

Finding suppliers

The first step in the process was finding a supplier for the thermofused melamine-clad board. The Bennetts talked to multiple vendors and settled on Uniboard. "It's not simple to just create a 1-3/4-inch thermofused panel," says Tim. Uniboard brought in Interprint to develop the papers. "Right now we have one pattern that is an exclusive face. We will end up with five or six exclusive patterns of designs that nobody could ever afford to do in wood."

Startup of the line has been slow, but relatively trouble free. The Bennetts attribute much of that to the complexity of installing a totally integrated line. "All the equipment talks to each other and is run off one central computer," says Tim. "The entire line runs with four or five people and has the capacity to produce 400 doors in an eight-hour shift."

Like any system of this complexity, there are glitches. In building the plant, Jane insisted on having many windows so there would be plenty of natural light. During startup, the line was shutting down many mornings at a certain time, then starting back up in 20 minutes without the operators finding a problem. Some days this happened, some it didn't. After a few days of head scratching someone figured out sunlight from a window was interfering with a bar-code reader. The reader was shaded, and the problem solved. "There have been a lot of glitches like that," says Jane. "With any line of this complexity, you have to start slow."

In the plant, the sheets of thermofused board are first cut to size on a Gabbiani beam saw. The door blanks are then stacked by job and moved to the beginning of the line where they are automatically fed into the first of two double-sided Stefani combinationtenoner/edgebanders.

"At this point the system recognizes the stacks and the quantity of doors within the stack," explains David San Paolo, Maiman's operations manager. After the first combination machine - which trims the door to final height, preheats the edge, glues the edge, applies the band, trims top and bottom of the band, trims the end of the band and adds a final chamfer - a bar code is applied to the top of the door. "This is where the door gets its identity," says San Paolo. "Every subsequent piece of equipment knows this is a specific door for a specific order for a specific opening in a specific building. Everything on this line is made to order, but at a high-production level."

San Paolo says that even in a large job, there is much variation on size from door to door, on locksets and on handing. The line can easily machine combinations of left- and right-handed doors, different locksets and different sizes. On a large job, production is generally scheduled by floor of a building, so when doors come off the line they are stacked in pallets for each floor. San Paolo points to a label, "When the doors get to the job site, the contractor will look at the label and see this is door 315. That means it's for the 15th opening on the third floor and it matches the numbering in the architectural plans."

One-pass machining

After the label is applied, the doors make a 90-degree turn and move to the second Stefani combination machine. It trims for width and applies the edgbanding on the outside edges. When the door blanks leave the two combination machines, they are totally sized, laminated, edgebanded and ready for final machining for hinges and locksets.

Maiman is using PUR adhesive to apply the edgebanding. San Paolo says there is extra work and investment, but the results are worth it. "The PUR hotmelts make a far superior bond," he says. "We've used them for laminating in the stile-and-rail plant for about three years, so PUR wasn't new to us."

The combination machines are equipped with the Nordson slot die system for application of the PUR adhesive. San Paolo says support from both the machinery and PUR adhesive suppliers has been excellent. Maiman has worked with Jowat, Kleibert and Swift on the adhesive. CanPlast supplies the PVC edgebanding.

From the combination machine the blanks pass through a custom station and then to a custom Lehbrink door milling machine. San Paolo says the machine can have as many as five heads working simultaneously on the door blank. It routs for hinge plates, drills pilot holes and routs for door hardware.

Expandable line

"This machine even comes in with a chisel and squares the corners on the hinge rout," says San Paolo. The Lehbrink machine is the constraint in the line, or the slowest machine. San Paolo says the system is designed so doors can be put into buffers in front of the machine automatically. The line is also designed so a second door-milling machine could be added, effectively doubling the line's output.

"This machine is state-of-the-art for door preparation," says San Paolo. "It has 46 different axes." He says it is more complex than a CNC router in that it has five stations that work on the door simultaneously. Four stations can be machining the edges for hinges while the fifth is routing for door hardware. The machine even predrills the pilot holes for hinge attachment.

"When the contractor gets it, all he has to do is put the lockset in and hinge the door," says San Paolo.

Ready to ship

When the door leaves the machine, it is ready for packaging. A turntable can turn the doors, so all tops are stacked in the same direction for shipping. All the line's material handling equipment was supplied by Mahros. SCM Group was responsible for making sure everything from both Italian and German sources communicated smoothly. "SCM did a very good job on integration," says Tim. "Installing this goes way beyond just installing an edgebander." He says all the manufacturers involved in the line worked together to ensure communication between the lines. The entire line is run from one PC that controls it.

Integration old hat

That level of integration wasn't new for Maiman. In the stile-and-rail plant, special lines were developed to create the custom stile-and-rail doors on a build-to-order basis. An example is a line made up of a Weinig moulder and Koch boring and doweling machine that produces fully machined stiles and rails ready for assembly. "Weinig and Koch had to collaborate closely on that line, so we had some experience in putting together these complex lines, and that helps," says San Paolo.

Now that the plant is in production, the Bennetts, Ally Dorrance and Steve Hubert who are in charge of sales for the flush door line, are facing the task of selling a new and different product.

"We really have to go out and sell this product," says Jane "Today 80 percent of the flush doors sold are either red oak or birch, because those species fit the budget. Now we are offering the look of figured anigre or mahogany at that same price. We have to explain the product and the price. Once the customer understands it, we get overwhelmingly positive response."


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About the author
Bruce Plantz

Bruce Plantz was an editor and contributor to CabinetMaker, FDM, and CabinetMakerFDM for many years. He is currently vice president, director of content and innovation at WATT Global Media.