Laminating equipment manufacturers take stock in good bonds.
Manufacturers of laminating equipment are gearing systems toward increasing production rates, reducing the number of rejects and offering superior laminate finishes. However, the most expensive machinery on the market will still produce poor finishes, decrease productivity and increase waste if operators fail to understand the laminating system's capabilities and proper substrate preparation techniques are not followed.
Ask laminating equipment manufacturers what they think the most important point their customers are concerned with when purchasing laminating equipment and the overwhelming majority answer "price". Although price is always an important factor, equipment manufacturers are quick to point out other advantages that go beyond a machine's price tag. "Companies that buy laminating equipment should also be concerned with cost savings, controlling their production schedule and inventory," said John Williamson, national sales manager for Monco of Orlando.
The speed at which a laminating line operates is very important to laminating manufacturers. "It enables them to increase their productivity and lowers their unit cost," said Art Woodman, executive vice president for Hymmen International. "But speed isn't everything. Our customers desire to produce a continuous quality product and most are able to obtain their productivity and quality objectives by running their laminating lines at 70 to 100 feet per minute."
Choices and more choices
Whether choosing a hot or cold press system or opting for a continuous roll system, those interviewed by WOOD & WOOD PRODUCTS said it is important to remember that each laminating method has trade-offs when regarding factors like price, productivity, operating costs and machine capabilities. Careful attention must be paid to what kind of laminating will be performed. If tabletops and flat surfaces are to be laminated using low- or high-pressure laminates, hot and cold press options should be explored. If papers, vinyls or foils need to be laminated on various size pieces, dry or wet continuous roll machines should be used, according to Williamson.
PVA glues are often used with cold presses because of its easy-to-clean, easy-to-handle characteristics when pressing at room temperature, according to a guide published by Black Bros. Co. Inc. The guide also notes that cold presses can allow a company to get into a laminating operation at the lowest possible cost and expand the operation as required for future production needs.
But cold presses also have some drawbacks. "Some cold presses may be less expensive," said Mark Joel, vice president of Allwood Machinery Inc. "But they're also less productive."
Operating at temperatures of 180 to 200 F and above, hot presses use heated platens to cure the adhesive. "Hot presses in the U.S. use more pressure for more flexibility in production," said Joel. "And they also offer quick cycle times and require less labor." Some problems with hot presses include the inability to press shapes other than the size of the platen. Also, the adhesive used is usually urea formaldehyde, and the future of UF adhesives could change if any regulations are passed by OSHA or the EPA.
"Continuous roll laminating is a more flexible laminating system and there is no limit to the length of the piece to be laminated," said Lee Mullen, national sales manager for Therm O Web.
The differences between the wet and dry systems are great. "With the dry system, a hot oil roller bonds the hotmelt film to the laminate and the substrate," said Williamson. "A dry system costs less, is less complex by requiring only two people with minimum training to operate it and has about a one percent rejection rate. It's not difficult to produce 10,000 square feet an hour." Williamson added that the system is capable of laminating only papers and foils.
Wet continuous roll systems cost more than dry systems and the adhesive is applied with a glue spreader. "These systems need four well-trained people to operate, have rejection rates from three to four percent and do vinyls and papers," said Williamson. As far as production is concerned, Williamson said it is possible to surface 1 million square feet a month.
Although capable of higher productivity, roll type systems do cost more, said Don Jones, senior sales engineer at Black Bros. Co. Inc. "The cost of producing laminates on roll-type systems is less per square foot, but the machines cost more."
Laminating is undergoing a change toward greater automation and microprocessors are ever more common. Laminators are demanding increased production from their presses. But for laminating equipment manufacturers, productivity can have different meanings.
"There's a difference between American laminating needs and European needs," said Joel. "Most Americans are looking for flexibility in production so that they can produce a variety of laminate surfaces that include veneers, high-pressure laminates, papers and decorative foils. Europeans are interested in more capacity and their technology in regards to warm and hot presses is very advanced."
Platen technology is also taking steps to move beyond the solid steel, aluminum covered platens. "The aluminum honey-comb variety platen is good for quick heat up and even heating, but it's not good for high pressure laminating," said Joel. "Steel platens are good for high pressure, but they take time to get up to proper operating temperatures. Microprocessors now use timers to eliminate the waiting so that presses are ready go when employees show up for work."
Without exception, the machine manufacturers interviewed said they thought the quality of substrate and laminate technology is keeping up with the demands of today's high production laminating machines. A smooth surface and a low thickness variation in particleboard and MDF are important for good laminating. David Bailey, technical sales manager with Dieffenbacher North America Inc. said, "Press manufacturers are making presses that can process resin impregnated papers with curing times as little as 15 seconds."
Staying away from junk bonds
Applying the correct adhesive, having a clean work substrate and paying careful attention to platen/roller temperatures can be the difference between creating a successful or unsuccessful bond. "A key to proper bonding is experimentation with adhesives," said Frank Bean, sales manager with Sorbilite. "One of the most important steps is finding the right adhesive for the job." Four main types of adhesives used in laminating are PVA (polyvinyl acetate), UF (urea formaldehyde), solvent and water-based contact cements, and hotmelts.
While all adhesives have their limitations, recent advances in adhesive technology has resulted in improved bonds and higher performance from the adhesives. "PVA glue technology has introduced catalysts or cross-linking agents to improve their temperature and moisture resistance. It's a good glue because it is user-friendly, sets quickly (usually in 30 minutes), works well on cold presses and cleans up easily," said Jones.
The main drawbacks to PVA glues are that they are water soluble and can cause surface bubbles if hot presses become too hot and vaporise the water in the adhesive. Also, PVA requires more drying time and better process control than contact adhesives, according to Walter Rohrback, president of Edgetech Inc.
Urea formaldehyde also has its special properties. "UF is widely used because it is the cheapest adhesive per square foot," said Mullen. UF is popular for hot press use because laminators like its resistance to bubbling because of the lack of water content, its water resistance and it is permanently cured. Drawbacks include shorter pot life and the UF healthy controversy. "Many adhesive manufacturers have lowered formaldehyde contents of their adhesives voluntarily in case OSHA or the EPA passes restrictions on its use," said Jones.
Contact adhesives are either solvent base or water base and are supplied ready for use and require no mixing, according to Black Bros. The adhesive also has very flexible production requirements. But solvent base contact cements are flammable and the fumes are drawing the attention of the EPA. According to Mullen, "A new trend that is developing is legislation regarding solvent base contact adhesives and the damage they may have on employee health and the environment."
Hotmelts, or ethylene vinyl acetates, are a dry laminating adhesive used on hot oil roller systems on which the roller must be heated to 400 F to activate the adhesive, according to Williamson. Advantages of hotmelts are that they are good for short production runs and quick changeovers. But because of the hot roller temperatures required to melt the adhesive, time must be allowed for the system to warm up.
Even before the adhesive is applied, preparation of the substrate is necessary to produce a clean surface for bonding. "Another key to proper lamination is a properly prepared surface," said Jones. "Dirt and dust have to be removed from the substrate before a uniform and correct amount of adhesive are applied." Particleboard is subject to contamination because contamination because small bits of wood generated during sawing operations will lead to telegraphing through the laminate.
Other areas in the laminating process can make or break proper bonds and finishes. Platen and roller temperatures play an important role. "The relationship of the caul plate temperature and the pressureless contact time of the paper on the plate is important in preventing pre-cure of the resins, which alters the sheen of the finished board," said Bailey. Exposing the laminate to heat above 370 F while post-forming can cause high-pressure laminates to yellow and may also allow the bond between the laminate and core to loosen on the flat surface next to the radius, according to Rohrbach. And if there is excessive moisture in the substrate or water-based glue, the excessive heat can also vaporize the water in the glue or substrate to produce bubbles under the laminate.
Guide to laminating equipment
WOOD & WOOD PRODUCTS contacted a number of laminating equipment manufacturers in researching this article. The following are some of the equipment manufacturers and distributors available. For more information, circle the corresponding number on the Reader's Service Card. Another valuable source for laminating equipment manufacturers and distributors is chapter 2 of the Red Book Buyer's Specification Guide.
Allwood Machinery Inc. represents three lines of laminating equipment including Barberan profile laminators, continuous laminators and laminator postformers, Sergiani multi-daylight presses and Orma Macchine feed through press lines, membrane presses, bending presses and hot and cold presses.
Offering cold presses that feature precision ground platens, Black Bros. Co. presses also have zone control for pressing different sizes, feed through conveyor tracks and motorized adjustable opening mechanism operation that is said to provide the operator with a more user-friendly machine.
Dieffenbacher North America Inc. says its laminating machinery offers quick changing of laminating foils and caul plates. Loading and unloading is performed by a Synchro-Quick system, and different lengths, widths and thicknesses of board formats are also easily changeable, according to the company.
The PF-100 manual postformer from Edgetech Inc. allows edging of pieces before and after postforming and the company says geometric shapes can be laminated on the machine. A rotating heat surface rotates around the postformed edge and a cooling surface holds and cools the surface after the forming process.
Functioning like a membrane press but working without the membrane for thermo-forming of a vinyl overlay to a substrate, the European Woodworking Machinery Multiform press by Buerkle is said to use less heat and pressure and can be used to thermofuse vinyl on fragile substrates. The company also says sharper corners are easier to achieve than on traditional presses.
The Model 5800 double-sided continuous paper laminator from Evans Machinery is intended for use in high-volume, high-speed applications where simultaneous lamination of both sides of a substrate is desired. Features include: 9-in. steel rollers and rubber rollers, wed tension controls that maintain even and constant paper tension, and top and bottom 10-in. glue line heaters. Operating speed ranges from 5 to 75 fpm.
Holzma-U.S. Inc. says the Friz membrane presses can apply decorative papers and PVC to shaped or contoured fiberboard and particleboard substrates. The press is said to offer the depth and visual appeal of a solid wood surface while offering the stability and economy of a laminated panel.
The double belt laminator from Hymen International features feed speeds of 30 to 40 meters per minute, utilizes low press temperature technology, has quick foil changes and uses cost-effective UF glue, the company says. Thickness and width settings are centrally controlled or program controlled.
Profile wrapping machines from Duespohl Woodworking Machinery can be used for wrapping papers, foils, veneers and other materials. According to the company, new features on the machines include production increases as well as new glue technology.
Midwest Automation's fully automatic spray system offers high-speed panel cleaning, adhesive application and infrared drying of solvent or water base contact adhesives when combined with powerized material flow. All the system's functions are PLC controlled to minimize overspray, the company says.
Monco of Orlando's Model TB-60 double-sided thermo-laminating system is capable of laminating hotmelt coated papers and foils to both sides of a substrate simultaneously at speeds up to 75 fpm. Hydraulic pressure is over 600 psi, with air pressure of 100 psi required. No assembly is required.
Iberpress membrane presses from Veneer Systems Inc. are reported to have minimum press cycles of three minutes, safety and emergency stop systems from any side of the machine and need only electric power and compressed air to operate.
Siempelkamp Corp. offers laminating presses of 60 psi and can press boards ranging from 2 ft by x 2 ft to 8 ft x 60 ft.
Sorbilite Inc.'s Pioneer membrane press is reported to bond thermo-forming laminates and thermo-setting laminates in one minute or less while using up to 50 bars of pressure. Punctured membranes are said to be eliminated while laminating temperatures to 275 [degrees] are possible, the company says.
Brandt postformers from Stiles Machinery Inc. apply direct heat to the laminate rather than radiation heating to allow for uniform heating for the full duration of the forming cycle. Features include a double swivelling heated forming bar, adjustable timer with stop settings and selectable pressure zones.
Therm O Web Inc.'s B-50 Compact can produce between five and 40 boards a day, while the B-50 Classic can laminate between 40 and 100 boards a day. Both machines can lay up plastic laminate and other materials on different substrates.
Unique Machine and Tool Co. offers a 60-in. pinch roller that is designed for extensive laminating of countertops and related pieces. Available to take 4 1/2-in. stock material, the machine also features four internal pressure cylinders for more clamping pressure.
Offering a machine that applies laminates to pre-profiled substrates in a single work cycle, Wemhoner America says its machine doesn't need workpiece specified tooling and eliminates the need for resetting the machine.
Woodworkers Equipment and Machinery Co. says that it designs laminating systems for all production ranges and combines new and used equipment to match production and expansion needs.
PHOTO : Hymmen International's double belt laminator features feed speeds of 30 to 40 meters per minute.
PHOTO : Brandt postformers from Stiles Machinery Inc. use direct heat to allow for uniform heating during the forming cycle.
PHOTO : Edgetech Inc.'s PF-100 manual postformer allows edging of pieces before and after postforming. Geometric shapes can also be laminated.
PHOTO : Friz membrane presses from Holzma U.S. Inc. can apply decorative papers and PVC to fiberboard and particleboard.
PHOTO : Sorbilite's Pioneer membrane press bonds thermo-forming and thermo-setting laminates in one minute or less.
PHOTO : The 60-in. pinch roller from Unique Machine and Tool Co. is designed for extensive laminating of countertops and other pieces.
PHOTO : Cold presses from Black Bros. Co. feature precision ground platens.
PHOTO : Midwest Automation's fully automation spray system cleans panels, applies adhesives and uses infrared drying.
PHOTO : Evans 5800 double-sided laminator is for high speed, high volume operations.
PHOTO : Iberpress membrane presses from Veneer Systems have minimum press cycles for 3 min.
PHOTO : Therm O Web's B-50 Compact and B-50 Classic can handle all types of laminating loads.
PHOTO : Workpiece specified tooling is not needed on Wemhoner's machines, eliminating resetting.
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|Title Annotation:||includes directory; advice to laminating equipment users|
|Publication:||Wood & Wood Products|
|Date:||Aug 1, 1991|
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