Although the dispensing equipment you select is of the utmost importance, to ensure a quality adhesive pattern is applied precisely and without error, box makers often overlook the importance of preventative maintenance. Let’s be honest, it’s usually an afterthought. We have seen time and time again, problems relating to adhesive dispensing equipment that could have been avoided if the box maker would have just followed a few simple steps, every so often, to make sure their glue machinery was running at 100% efficiency. To help you avoid this unwanted downtime and make sure your glue patterns are always at their best, here are seven preventative maintenance procedures for better box manufacturing.
1 – Overtime, particles and coagulated glue can build up on filter screens causing restricted adhesive flow and excessive stress on the adhesive. Cold glue filters should be checked once per week after installation or after a change in the type or brand of adhesive. Depending on the amount of build-up, adjust the frequency to accommodate your dispensing equipment. Remember, opening the filter housing allows air into the system, so make sure you have the proper purge valve set up before you begin.
2 – Make sure glue pressure follows machine speeds. For box makers, the glue regulator is the most important adhesive delivery component in determining how much glue volume is applied at a given machine speed. If you experience too much glue on the joint when the machine slows down, or there is not enough glue when the machine speeds up, it could be the regulator. To test fluid regulators without an electronic pressure control, use the T-handle on old-style regulators and the Auto/Manual switch on the new style regulators to manually check the function. If pressure does not increase or decrease, a simple repair is in order. Valco Melton regulator repair kits for corrugated box manufacturers provide a quick and inexpensive solution.
3 – Applicator heads and nozzles must be kept clean. Buildup over long periods of time and a lack of cleaning after the machine is down can cause added downtime. Likewise, worn applicator heads can cause poor pattern quality (ticking at the end of the pattern, buildup on the leading edge or even missing glue lines). Applicator heads are wear items, subject to the abrasiveness of paper and are susceptible to some chemical corrosion after prolonged exposure. Quick-disconnect fittings are another critical component to achieving quality adhesive patterns. Loose applicator heads are prone to leaking. To avoid issues, inspect the fittings to verify that the applicator head is properly secured to the valve. Replace quick-disconnect fittings as required.
4 – Check to see if the Electronic Pressure Control (EPC) speed-tracking curve is accurately set up. Doing so will help you to achieve optimum pattern volume at all machine speeds. If the EPC is not working properly, you are relying 100% on operator skill to monitor adhesive output. This requires constant adjustments in order to maintain proper adhesive volume. Without a functioning EPC, the amount of wasted adhesive can quickly become a costly problem.
5 – A slipping encoder can cause intermittent pattern length variations, which can mean a troubleshooting nightmare for maintenance departments. Encoders should be regularly inspected for smooth rotation, good wheel or timing belt condition, and secure mounting. Box makers should also pay close attention to common problem areas such as incorrect belt tension, damaged encoder cables or loose cable connections. By adding simple encoder maintenance to your schedule you can prevent extended downtime and hassle.
6 – Glue hose lines back to the regulator should be inspected for kinks and flushed periodically to check for clogged sections. An inexpensive section of tubing can become a costly problem for corrugated box manufacturers if it causes a flow restriction, as this results in poor glue volume at high machine speeds. Don’t overlook the pump suction line. A damaged suction line could cause air pockets to get into the glue line. This results in skips in the glue pattern or no glue pattern at all. Signs of leakage are not always obvious; plan now to avoid problems later.
7 – Ensure there are no false triggers from tab scrap. Corrugated box manufacturers operating with tab-side installations are often plagued by flying tabs from the slotter. False triggers from tab scrap can be the result of broken or dull knives. Replacing worn-out knives along with routine maintenance is recommended to combat false triggers from tab scrap. Additionally, a dual scanner setup using two photo eyes, along with control settings can help block false triggers.
