Pretreatment Maintenance

Posted on Tuesday, January 24, 2023

By Ted Bunton and Donnie Glueck

There are several items that need to be addressed and maintained when operating a multi-stage pretreatment washer. While it can be overwhelming if you’re unfamiliar with the process, it is the lifeblood of a paint shop. Educate yourself, utilize your vendors, and be diligent in maintaining this process.

No More Excuses
There are myriad excuses regularly used to avoid preventive maintenance (PM), none of which are acceptable. Is your favorite excuse on the list?

Time—no one ever seems to have the time for PM programs but can always find the time to repair once a piece of equipment fails. Devote the necessary time to PM and it will pay dividends at the end of the day.

Production—having equipment down for PM will interfere with production for sure. However, having equipment broken down will have a larger impact.

Cost—dumping chemistry down the drain when it was working perfectly fine the day before seems like a waste of money. A pretreatment failure will far exceed the cost of dumping the tank(s). Chemistry defects are not always visible to operators and will typically require parts to be stripped down to the substrate for repair. Some chemistry failures may go unnoticed until the parts have reached the end user, which results in a dissatisfied customer and loss of good will.

What and When to PM 
Use equipment manuals, vendor information, and a record of history to determine ‘what and when’ in establishing a PM program. Equipment manuals will give you a baseline for maintenance. Using your vendors’ knowledge will allow one to fine tune a timeline as well as what needs to be done for the maintenance. Keep track of past failures and defects to accelerate the PM schedules when needed.

While the above points are key to developing a good PM program, few people have the perspective of how a company benefits from a solid PM program. These include:

  • Adjusting production schedules around predicted downtime.
  • Lower failure cost and defect rate.
  • Elimination of the attitude of ‘this company runs everything into the ground’.
  • Higher employee morale.

Routine tank maintenance can consist of several items.

  • Follow a regular schedule of draining your rinse tanks. Rinse tanks are equally as important as chemical tanks.
  • Remove sludge or contaminants while draining the tanks.
  • Check flame rods on the burner(s).
  • Observe the scale on the burner tube or take a picture for future comparison.
  • Fill with water.
  • Add the appropriate amount of chemical.

Daily & weekly checks:

  • Titrate all chemical tanks.
  • Check conductivity of rinse tanks.
  • Record ALL data using software or process control documentation.
  • Observe nozzles for misalignment or plugging.
  • Confirm accurate temperature readings of heated tanks.
  • Listen for possible bearing failures on washer pumps or belts falling off the exhaust blowers.

Maintaining a recirculating washer is like raising a kid. Every one is different and each have their own areas that need support. Maybe your washer is always having clogged nozzles due to your incoming soil load on the parts. In this case, having extra nozzles would be extremely beneficial as it will decrease downtime. Drop the clogged nozzles in a properly marked bucket or tank of descaler or nozzle cleaner. This way when you need to replace a nozzle during break, there are plenty available for use. Keeping a few extra risers on hand is equally as beneficial, especially if you have the quick disconnect risers in addition to the nozzles.

Is There a Crystal Ball?
Are there ways to measure or predict a breakdown? Possibly. How does one go about predicting these types of issues? First, you need to find a way to measure how hard the line is working. Does your line operate one shift, two shifts, or three? Measuring line footage, hour meters, tons of steel, and square footage are all good possibilities to gauge your paint line. While you may not utilize all these components, relying upon two or three of these is preferred. Once these factors are determined, they can be compared to your resources. Factors include water, gas, and chemical usage.

All these components can and will assist in determining your tank life and PM schedule, which in turn can aid in planning production. Communicating this to your team members is priceless. They can plan accordingly to make sure they have everything on hand for the job. Chemically descaling your washer once or twice a year, depending upon your water, is highly recommended. Every 1/8 inch of scale on a heating tube equates to an increase of 15-20% in your energy costs. The scale essentially acts as insulation. Taking the time to complete this task will certainly pay for itself. Compare the pictures that you take of the burner tubes each time the tanks are drained. This way you will have factual evidence of when a chemical descale is due.

The bottom line is one must collect data, record it, and use it. Rely upon your equipment manuals and your vendors. Vendors get into several different plants and get to work with some incredible people and processes. They are a great resource that should be utilized. While maintaining a quality washer is not easy, the reality is it is not complicated. Happy data collecting and PM scheduling!

Ted Bunton is president and Donnie Glueck is pretreatment and powder paint specialist at Troy Chemical Industries.