Few land-based environments are harsher than worksites. Agricultural and construction equipment (ACE) undergoes tremendous stress from weather, dirt, and hard use – if precautions aren’t taken, corrosion will set in quickly, reducing the equipment’s life span and putting its operators at risk. It’s no surprise, then, that ACE companies tend to have rigorous specifications for pretreatment. Certain ACE projects require mechanical surface preparation (i.e., blasting) before chemical pretreatment. Blasting is very effective for maximizing coating adhesion, particularly in outdoor environments, but some companies will consider the added cost too prohibitive.
Chemical pretreatment, on the other hand, is non-negotiable. The number of stages and types of chemicals may vary from project to project, but all ACE parts rely heavily on pretreatment to stave off corrosion and promote adhesion. There’s no way around it: you can’t guarantee good results for ACE parts if you’re not properly maintaining your pretreatment system.
Most pretreatment systems re-use chemicals. Keep an eye on the concentration and pH of your chemical stages, and add virgin chemical as needed when concentrations dip. Meanwhile, monitor your rinse stages for total dissolved solids (TDS) and pH – runoff carrying over from the chemical stages will eventually contaminate rinse water, rendering it useless.
Temperature is another key factor in pretreatment. If your basins are too hot, they’ll boil; if they’re too cold, cleaning suffers. Keep your temperatures in the warm sweet spot. Use the system’s downtime between shifts to check your nozzles, replacing any that are plugged, broken, or misaligned. The timing of your maintenance is as crucial as the maintenance itself. Stick to regular intervals (common practice is once at the start of a shift, and once halfway through the shift), and base the length of your intervals on how many parts you’re willing to risk reworking. The longer the interval, the more room for error.
No matter what, log everything you do, clearly and concisely: “8 AM: stage 3 concentration is low, adding X mL of virgin chemical.” If your records show persistent problems, it’s time to re-evaluate the whole process. Your chemical company will be a resource in these instances – the technical sales rep should be stopping by monthly to perform audits, review logs, and offer suggestions for improvement. Ask them to provide your technicians with cheat sheets or guides for chemistry adjustments.
Day-to-day maintenance will only carry you through for so long. From time to time, the line will need to be shut down, the tanks emptied and scrubbed, and all chemicals replaced. The frequency will depend upon the number of parts you’re processing daily. Ask your chemical company what they recommend for your shop. The more proactive you are with pretreatment maintenance, the less you’ll find yourself reacting to breakdowns and reworking parts.