December 2004

Wood Goes "High Tech"... Finally

Honeycomb panels offer performance, design flexibility and, most importantly, much lighter weight

By Gary Wernlund
Honeycomb panels are versatile, as illustrated in these two diverse applications for stairs and office furniture.

When I entered this industry in 1982, an older gentleman, kind of a fatherly influence in my life, called to tell me how excited he was about my career choice. He raved that woodworking was an "emerging industry" and that several innovative technologies were approaching. He said he saw me as a young man getting in on the ground floor of a great opportunity.



Through the years, his words have rung in my ears a number of times, but never as loudly as now. We are using computers to design our products, CNC equipment to fabricate them and automated handling devices to more efficiently move parts and material throughout our operations. Yet, when it comes to composite panels, most of us are still "thinking inside the box."



Enough, already. I think it is time that panels go high-tech!



One of the greatest examples of creative thinking and collaboration was in the movie "Apollo 13" when Mission Control had to instruct the crew of the crippled spacecraft how to build a breathing device. The crew's supplies were severely limited; they had to improvise using the simple materials that were available.



What Would You Do?



Suppose you were given the task of designing a new furniture-grade panel, one that was 50% or more lighter than those currently available and yet with the favorable characteristics of particleboard or MDF, including appearance, tight tolerances and strength. To make things even more challenging, what if you, like the crew of Apollo 13, faced limited material choices and needed to maintain material costs? How creative could you be with your panel's design? Would it occur to you that a honeycomb core might be the answer?



The advantages of lightweight panels are well understood in the aircraft, automobile and construction markets. It is time for the woodworking industry to start reaping the benefits with this same concept in wood panels. Whether it is residential and office furniture or store fixtures and displays, consumers want new looks sporting thicker panels - without the extra weight - making "the fields ripe for harvesting."



Honeycomb panels fit the bill. They are lightweight, strong, flat and offer added bonuses like easier handling for retail customers or commercial installers. In addition, the panels lower transportation costs and are more environmentally friendly.

In short, lightweight honeycomb panels offer woodworkers an opportunity to lead the market with an aircraft-grade material.



A few manufacturers are already taking advantage of honeycomb panels. A study of one furniture maker using panels 70% lighter than traditional composite products revealed several important advantages including reduced freight and packaging costs, less damage during transportation, improved ergonomics on the shop floor and lower production costs.


A honeycombed-paper core is the secret ingredient of aircraft-grade, lightweight panels.

How the Panels Are Made



The continuous, automated process for producing such an aircraft-grade wood panel involves using polyurethane reactive (PUR) hot-melt adhesives. The adhesive is combined with particleboard as a frame and a thin layer of high-density particleboard for the surfaces. Adding the secret ingredient, a honeycombed-paper core, produces an aircraft-grade wood composite panel.



One of the limitations with previous methods of manufacturing lightweight panels included high labor content/product cost associated with processing panels on a multi-opening press. In the past, lightweight panel production involved manual handling of stiles and rails, manual cutting of honeycomb and excessive labor in assembly of components. In addition, it was difficult to efficiently batch production to optimal levels on a multi-opening press, and the panels were susceptible to warping due to moisture being trapped during the hot-pressing process.



The development of PUR hotmelt adhesives helped cure a lot of these ills. Using PUR hotmelt adhesives eliminates the formation of moisture in the panel and allows for continuous production flow, automatic assembly of framework, automatic inlay of honeycomb core, and increased capacity and reduced labor.



There are two main methods for successfully applying PUR adhesives for lightweight panel production. The first is using slot nozzles that precislely dispense adhesives and allow for automatic width adjustment. New developments in roller application provide an alternative. These high-tech glue spreaders offer improved coating results and adhesive utilization for the hotmelts used in lightweight panels.



Automated assembly represents another key development for producing lightweight panels. A stile and cross rail magazine must be employed on high-capacity automated lines, as well as an automated alignment station on semi-automated lines. Recent technological developments also make it possible to automate cutting, preparation and insertion of the honeycomb material. These developments help generate significant time and labor savings.



Companies looking to produce honeycomb panels at a smaller output can consider investing in a less expensive, semi-automated system. For example, Torwegge offers an Optimat-type machine, where the price/value relationship is improved due to economies of scale with the production of multiple machines. This concept is "incrementally expandable" and allows for sections of automation, such as a feeder and stacker, to be added later. The process also allows manufacturers to become adept at the process elements, including application of the PUR adhesive and handling of the honeycomb material.



Newer Is Better



Compared to the conventional method of producing lightweight panels, the new panel process more than doubles production output by incorporating automated

Have something to say? Share your thoughts with us in the comments below.