A closed, slot-nozzle edgebanding system provides an innovative alternative for dispensing PUR hotmelts at Atlanta Sunbelt Products.

For nearly 20 years, Atlanta Sunbelt Products, a mid-sized manufacturer of restroom partitions and laminated case goods components, has maintained a reputation among its customers for combining excellent customer service with durable, quality products. John Busener, president of the 10-man, Winder, GA-based firm, says he believes the only way to maintain this long-standing reputation is to stay on top of the newest technologies in the manufacture and assembly of wood products.

“For me, it’s both a company and a personal goal to always look for ways to produce a better product,” Busener says. “I have confidence in the product we offer, and honestly believe it’s the best out there for the price. I credit that to taking some risks and leading the way in using new technologies, rather than following the curve.”

Atlanta Sunbelt Products was one of the first in the industry to dispense PUR hotmelts in edgebanding applications. In 1997 Busener started researching adhesives that could offer a stronger, better quality bond to non-porous substrates than the industry-standard EVA. Although EVAs are adequate — offering a heat resistance of 80C and cold resistance of -20C — Busener says he found that PURs offer much higher heat and cold resistance between 150C and -40C respectively.

       
 
Atlanta Sunbelt Products finds that using PUR adhesives in its edgebanding applications provides more durable end products over a wider range of temperatures.
 
       

“EVA materials are still used in about 90 percent of all industrial edgebanding applications but they don’t provide the best in temperature resistance,” he says. “EVA material can be reactivated with heat and can get very brittle in cold temperatures. My product is shipped and used in all sorts of climates, and I know I can rely on the PUR to hold up.”

Busener says he also knew that the same chemical properties that made PUR his choice for strength and performance, also posed challenges during material processing and application. He says he had a difficult time finding a machinery manufacturer to work with him because of the premature curing, charring and maintenance problems associated with PUR adhesive.

“There have been great strides on the part of material suppliers for making PUR adhesives easier to use. But, four years ago, a lot of machinery suppliers just didn’t want to deal with it; some wouldn’t even return my phone calls,” he says.

Up to the Challenge

Busener’s search for an answer led him to Nordson Corp., a manufacturer of adhesive dispensing equipment that had amassed experience in PUR material applications.

Since starting the relationship with Nordson nearly four years ago, Atlanta Sunbelt Products has succeeded in dispensing PUR material for applying edgebanding on wood-based parts. The initial edgebanding system at the company’s 24,000-square-foot facility was composed of a simple Nordson hotmelt adhesive applicator and a chemcoated pot hooked-up to the parent machine’s open glue roller. The system worked, but still presented complications because the PUR was dispensed from a pressurized pot.

Recently, however, Atlanta Sunbelt Products began running its edgebander with Nordson’s latest edgebanding technology, an adjustable, closed, extrusion slot-nozzle system using Nordson’s EB60V slot-nozzle gun. Busener says benefits of the system include “easy adjustability, controlled dispensing and minimal maintenance.”

Glue Pot Eliminated

The new closed edgebanding system, which replaces the roller and open glue pot with adjustable slot-nozzle technology, includes a Nordson MC Series applicator for PUR processing, an EB60V adjustable edgebanding slot gun for applying the material and a PLC interface to the company’s IDM Activa edgebander from SCM Group USA.

Unlike traditional edgebanders that incorporate open glue pots and rollers, the PUR glue supplied by Kleiberit Adhesives USA is metered, providing adhesive control through fixed pressure dispensing. Thus, coating widths can easily be adjusted to accommodate different board widths, without line stoppages.

Leading and trailing edge patterns are predetermined by the IDM Activa’s PLC. Panels are fed into the edgebander and the EB60V gun is triggered to start and stop dispensing at the preset points based on each panel’s length. The positive application pressure to the panel provides accurate and repeatable coating, with consistent coating weights that are substantially less than open roller systems. The system is used to apply both PVC and high-pressure laminate edging materials.

“You can assign a glue-line width and height to each specific panel without stopping to change a shim blade,” Busener says. “With our PLC interface, the predetermined starting and stopping points are infinitely variable and very precise. There’s also no corner build-up or excess glue on the panel. It’s a very clean, controllable process.”

Eliminating rollers and open glue pots also eliminates airborne contamination. As a result, the closed configuration reduces production costs associated with maintenance, cleaning and labor. In addition, the closed system has fewer moving parts to maintain and repair than a traditional pot system.

Busener adds that the closed system’s MC Series applicator provides even processing and constant adhesive viscosity for high bonding quality. The temperature control prevents adhesive charring and premature curing, eliminating adhesive waste.

Better Products

According to Busener, the Nordson system solves problems commonly associated with applying PUR adhesives with systems using glue rollers and open pots. He says his company is more productive because downtime for changing panel sizes and routine maintenance is drastically reduced. Busener also attributes a reduction in PUR adhesive consumption to the system’s controlled application process and the elimination of material waste when cleaning the glue pots.

“The bottom line for me is that I’m putting out a better product,” Busener explains. “I’m getting a better bond with the PUR and better appearance because there’s no excess adhesive being used.”

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