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A tale of two tenoners.

Still mostly associated with mortise and tenon joints, today's tenoners can be divided into two distinct product categories: those for processing solid wood components and those for processing composite panels.

In Conover, N.C., the Broyhill plant takes ash, maple, gum and hackberry blanks and puts them on a tenoner to produce about 3,500 chair tenon joints a day. According to plant manager Raeford F. Black, the machine cuts compound miters and straight tenons, producing chair stretchers, chair back ladders and vertical back slats for the company's line of dining room chairs.

In Northridge, Calif., 2,400 miles away, Harman Speaker Manufacturing uses its tenoner during all three shifts to shape and sand MDF and particleboard profiles. According to production manager Fred Garcia, the machine has to perfectly square panels that vary in width from 4 inches to 4 feet and will be used in the company's manufacture of 4,500 audio speakers a day.

Wait a minute. Two woodworking machines performing entirely different operations, yet both are still called tenoners? If it sounds confusing, it can be. With the advent of machinery engineered for processing panels, tenoners cover a very broad variety of responsibilities that range from simple and complex tenons to precision panel squaring. By being able to identify both types of tenoners and their capabilities, woodworking operations can find a tenoner that has the features that will allow their operations to increase productivity and produce high-quality goods.

What's the difference?

Panel tenoners have been designed to perform a variety of operations, and their roots go back to Europe and the 32mm system. The 32mm system is unforgiving if panels are not perfectly square. If a panel saw's blade is slightly out of alignment, it can lead to off-center boring. With their panel squaring abilities, panel tenoners can eliminate this problem.

"Many of today's panel tenoners are being purchased by office furniture manufacturers, kitchen cabinet manufacturers, door manufacturers and some hardwood flooring companies," said Phil Herzog, Homag product manager with Stiles Machinery Inc. "They can be used to perfectly square sheets of high-pressure laminate better than a panel saw because panel tenoners won't cause a fracture along the laminate line. Panel tenoners can also be used to cut a clean edge for proper edge-banding adhesion or cut tongue-and-groove joints for hardwood floors."

Differing from panel tenoners, conventional solid wood tenoners are being designed and engineered with better hopper placement and other features to quickly produce a strong joint with a clean, tight fit. Because the mortise and tenon joint has such a large wood to wood surface contact, it makes an excellent joint choice for furniture manufacturers.

Some similarities

Regardless of the type of tenoner, customers require shorter set-up times, increased feed speeds and the ability to produce a quality cut first time, every time. "Designing tenoners today relies on working with the customer to find out what the machine's application will be, what the customer's needs will be and the number of operations the machine will need to perform," said Bruce Rosenthal, general manager of Jenkins Div. of Kohler General Corp. "Designing and building double-end machining centers allows you to start with a blank sheet of paper."

Regarding set-up times, machinery manufacturers have responded to woodworkers' concerns that money can't be made when a machine is sitting idle. As a result, machinery manufacturers are designing tenoners that are cutting an hour or more from former set-up times. "When it came time for a changeover, it used to take us about an hour," said Fred Schneider, vice president and general manager of Visco Mfg., a manufacturer of pine and oak furniture based in Carson, Calif. "But now our changeover times run between five to ten minutes."

One reason for these reduced set-up times has been the addition of CNC programming. CNC tenoners have the ability to store numerous different profiles in their memories and can also make automatic adjustments for perfect alignment when switching profiles. "We use more than 20 different tenon profiles, and when we were going to buy a CNC tenoner, we took our top nine profiles and had them programmed into the machines," said Schneider. "It's been great for helping us reduce our changeover time which helped us control our work in progress."

Not only have CNC tenoners helped woodworkers control on-line production, but for some companies, CNC tenoners have helped them schedule future production runs. "Our CNC tenoner can help us plan our production runs for next week," said Ronnie Harper, director of manufacturing at Tell City Chair, Tell City, Ind.

Designing a tenoning system that can produce a smooth, quality tenon or edge are goals of machinery manufacturers. Their tenoners now reduce tear-out and provide a tight fit or smooth edge. High horsepower cutterheads alone will not necessarily reduce tear-out, according to some surveyed woodworkers, but cutterhead technology has helped produce higher quality cuts. "High horsepower isn't the key, but it is important," said Harper. "Sometimes speeding up the machine will also cause tear-out. Just when you think you know everything about wood, Mother Nature will prove you wrong."

Many companies have switched to using insert tooling in place of traditional cutterheads because they can be economical in the long run and they better maintain their diameter over a longer time span, which is especially important when using CNC tenoners. "It takes more money up front to purchase insert tooling," said Broyhill's Black. "But the overall cost of insert knives are chicken feed when it comes to the cost of rebuilding a new cutterhead." Black added that some tenoner insert knives feature a small spur on the knife to score the tenon before cutting to reduce the possibility of tear-out.

Many panel tenoners are also using polycrystalline diamond (PCD) knives because of their long life between sharpenings. "But some companies are using carbide-tipped bits because foreign materials in particleboard and MDF will cause the PCD bits to shatter," said Herzog.

Because feed speeds operate on a time principle, they are an important feature to woodworkers because feed speeds are the key to controlling productivity. Machinery manufacturers have been able to tailor feed speeds on their tenoners that allow plants to operate at maximum efficiency. "Our feed speed rate used to be 800 chair pieces an hour," said Harper. "Now our new tenoner is capable of producing 2,000 chair pieces an hour. We think that's the maximum speed the machine needs to operate at for our plant."

Ease in operation

Computer software for both types of tenoners is becoming a major attraction to machinery manufacturers because manufacturers are developing programs that can offer high accuracy as well as user-friendliness. Training operators on these user-friendly tenoners can result in training periods as short as three days.

"These tenoners feature touch screens and have more intricate designs that are forcing programs to be designed with graphics instead of numbers," said Rosenthal. "The result is a machine that's easier for operators to grasp, which results in shorter training. These machines are production friendly and allow manufacturing to respond quickly to market needs."

Adding on capabilities

The future of tenoners seems to be pointing toward adding more capabilities on both types of machines. Long available on the market are combination machines that can edgeband after squaring and tenoners that can perform sanding operations after tenoning. Additional operations like boring, sawing and routing are on the horizon, making the concept of designing entire machining centers that much closer to becoming reality.

"I'm constantly amazed when I walk into woodworking plants and see what customers are producing on their double-end machining centers as far as technology is concerned," said Rosenthal. "Operations are being done today on tenoners that were unthinkable a few years ago. All kinds of operations can be done on a tenoner, from complex miter cutting to jump grooving and milling. As far as the future of tenoners is concerned, it's a whole new ball game because of reasonably priced CNC controls."
COPYRIGHT 1992 Vance Publishing Corp.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1992, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
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Author:derning, Sean
Publication:Wood & Wood Products
Date:Nov 1, 1992
Words:1326
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