Autumn Gluing Tips
In the early autumn, gluing conditions are close to ideal. This is also a good time to perform maintenance on machinery. Our semi-annual list of maintenance items includes:
• Storage
This is a good time to check the condition of bulk storage tanks and to remove any build up or sediment that might have accumulated over time. Make sure to check your inventory to make sure you don't have any old pails, drums, bulkdrums or totes hidden from view.
• Ripsaws
Good maintenance of ripsaws involves more than just changing saw blades. When was the last time alignment of parts, or the condition of arbor bearings was checked?
• Mixing Equipment
The mix ratio of two-part Multibond adhesives is important for good radio frequency gluing and for the development of proper water resistance. It has probably been a while since this ratio was checked.
• Glue Spreaders
Repair or replace any loose flights on conveyors. Remove any glue build up around the spreaders. Check the condition of the applicator rolls. Lubricate parts as necessary.
• Clamp Carriers
Clean and lubricate each clamp. This is also a good time to replace the thrust washer located behind the tightening nut on each clamp. Check each clamp to ensure that proper pressure is being applied. Make sure that the drive chains are in good condition. Replace any broken air or hydraulic gauges.
• Radio Frequency Presses
Most machines have several hydraulic pressure cylinders. Make sure that all of them are working. Check fluid level in pumps and make sure that all gauges are functioning. The beryllium copper strip along the front edge of the machine and other ground straps are frequently damaged or disconnected. The retard system in continuous flow machine needs to be cleaned and checked for wear.
The following two problems relate to PVA products, and are normally thought of as "winter problems," but can actually be more of a problem when the temperature drops suddenly and the building heat has hot been turned on. Fortunately, these problems can be reduced if the heat is turned on slightly before rather than slightly after the factory temperature drops too far.
- Early morning fog is a problem in many areas in late autumn. These cool and damp conditions frequently result in under-cured joints because most water-based glues cure more slowly under these conditions. If you are experiencing an increase in panel failures or delaminations, allow the panels to remain clamped an extra 10-15 minutes. If you are using radio frequency equipment, try increasing the cure cycle by five-10 seconds.
- Glue Line Chalking. Most glues dry clear or slightly opaque - a chalked glue line is abnormally light. A milky or chalky white glue squeeze out means that plant and wood are too cold for the adhesive being used. The "minimum use temperature" is noted on our data sheets as a guide. Try keeping the wood and plant temperatures at least a few degrees above this value for safety.
Unlike PVAs, PUR Hot Melts tend to set more quickly in cooler weather. This is normally not a problem, but if the open time or set time of a hot melt becomes too short, please consult your Franklin representative.