Corrugated plants considering a new Flexo Folder Gluer, glue system, or glue station face a fundamental choice between contact and non-contact applications. However, the right answer is not universal. It depends on product mix, condition of the machine, order size, corrugated sheet quality, and the glue itself.
Contact methods are somewhat more established, but non-contact has not replaced them. Both technologies are still being installed in plants around the world today, and both have a permanent place in the corrugated manufacturing industry.
In making the decision, consider how each method works, where each one fits, and why both still have a place in modern manufacturing.
Contact Gluing
Contact gluing relies on an applicator head that touches the board as it travels underneath or over the head. Adhesive is extruded from the head directly onto the sheet as it passes. The Valco Melton BoardRunner is a contact platform built around this principle.
Where it Excels
Customers that choose contact often have other contact systems in the facility and benefit from a central glue pumping system that delivers pressurized adhesive to each Flexo. This means only two redundant glue pumps to maintain, and the glue system on each machine starts with a regulator.
That cost advantage extends to the rest of the glue system. The regulators, valves, and glue stations all handle lower pressures, which makes them simpler and less expensive than their non-contact equivalents. Each station uses a single valve, and inside or outside gluing can be achieved on one station by reversing the valve and guide on the BoardRunner.
Contact adhesive is also typically less expensive than what is needed for non-contact, and it can be specified at a lower quality grade because the application process is inherently less sensitive to glue properties. There is very little shearing action anywhere in the fluid handling equipment, which makes the system robust to a wide range of glue selections.
As each board passes a contact station, the wiping action keeps adhesive from building up on the applicator head, so clogging is rarely an issue in normal operation. Routine flushing and cleaning are still part of preventive maintenance, but the system does not require the active tip-sealing approach that a non-contact valve does.
Large-format machines, or plants that need to dispense multiple beads across wide tabs, benefit from the flexibility of contact stations. Applicator heads are available in a range of sizes and configurations up to 150mm wide (6") and can be swapped by snapping the old one out and a new one in.
The need to enter the machine to change heads favors longer runs with fewer order changes, although contact stations can be installed on both sides of the machine for faster changeover. Plants that run a large amount of inside glue in bottom-up format, and that do not want a second glue station on the opposite side of the machine, can achieve good application from the bottom with a minimum of expense. The BoardRunner platform, with its optional Auto-Gap features simplifies set up on contact stations and allows it to adapt the highest line speeds on the market.
Tradeoffs
On a contact station, each time board size or flute changes, a setup step is added because the gap and air pressure both need to be set correctly for the new flute and sheet size. The same gap and weight relief settings need to be correct to apply glue consistently on a sheet warped in the machine direction, which makes contact gluing somewhat more dependent on flat board. Automated gap adjustment options eliminate the changeover step on lines where changeovers are frequent.
On machines that currently generate a lot of scrap, contact
stations on the 4th panel side often perform better, since scrap can become
lodged between the applicator head and the lower guide.
Even with those considerations, the operating profile of a contact line is simple compared to what non-contact requires. Success with a contact station depends on consistent housekeeping, correct gap and weight relief settings, and valve maintenance every 200 million cycles. Contact does not demand that same level of ongoing discipline to perform reliably.
Where It Fits
Contact is the right answer on stable runs and in plants where cost and operating simplicity are the primary levers.
Non-Contact Gluing
Non-contact gluing dispenses adhesive from multiple valves mounted above the board, with no physical contact between the valve and the substrate; the Valco Melton 3NC and 3NCR series glue station are built specifically for this type of application.
Strengths
No need for contact with the board means warp and surface variation are not an issue. Beads land consistently regardless of board condition, which makes non-contact a natural fit for inconsistent or warped board.
Higher-performance electric valves run faster and are capable of stitching, which helps plants focused on adhesive consumption reductions. Pattern changes are made from the control with no head or nozzle change required. The valves use an engineered ceramic seat rated for more than 500 million cycles before maintenance, and an integrated tip sealer prevents clogging.
The tip sealer on the 3NC and 3NCR glue stations is a mechanical silicone pad that presses against the nozzle and cleans it as the nozzle depresses into the pad. Once the feeder indicates that sheets are being fed through the machine, the station opens and begins dispensing immediately.
The 3NCR is a reversible non-contact glue station for occasional outside glue applications. The valve and tip sealer are mounted on a common plate that is reversed on the station using quick-disconnect levers, and the mechanical tip sealer continues to function in both orientations. This eliminates the need for a second glue station on the 4th panel side and keeps the glue lines from drying out on the side that is infrequently used.
Another advantage of a non-contact system is the ability to program each valve independently. On boxes with a tapered tab, each pattern can be adjusted to ensure full coverage and a better seal. A tapered set of glue lines can be entered automatically, making the inner lines longer than the outer ones.
Weaknesses
Non-contact glue stations require a higher-quality, shear-thinning adhesive in the 500 to 900 mPas range. A warming hose can be used to keep viscosity and dispensed volume consistent. These adhesives are typically more expensive than the equivalent contact glue.
A central pumping system can still be used in the plant, but all machines would need to run the same adhesive, which requires an evaluation of whether to standardize on non-contact across the facility. Additional pumping capacity would also be needed at each machine to boost the pressure to non-contact levels for reliable application.
For large-format boxes, the 4NC/NCR and 8NC/NCR versions of the non-contact glue stations are available, although they carry a higher cost than their jumbo contact equivalents.
Both Still Have a Place
Modern corrugated plants run a wide range of line speeds, board grades, and box styles, and no single dispensing method covers all of them equally. Contact remains the strongest option for stable runs and for plants where adhesive cost and system simplicity are the priority. Non-contact is the better fit where speed, board variation, or stitching-driven adhesive savings are paramount.
Talk to Valco Melton
Whether you have already decided on a contact or non-contact gluing station, or you are still working through which is best for your facility, the experts at Valco Melton are here to help. Call us at 513-874-6550 or email [email protected] to discuss the benefits of our BoardRunner contact gluing stations or our 3NC non-contact gluing stations.
Categorized in: Corrugated