It can be challenging to determine when it’s time to update or replace your coating line. As with all older industrial machinery, ovens, pretreatment washers, and spray booths can become increasingly temperamental as their key components reach the end of their service lives. There have also been changes in codes, such as NFPA 33 and NFPA 86, that may make your existing finishing equipment obsolete from a safety standpoint.
Before you decide what action to take, it can be very beneficial to hire an outside company to evaluate your equipment. If you are considering replacing your system, you need to get an objective opinion that isn’t colored by company politics. Expert information can be provided by a finishing process consultant, an industrial machinery service company, or a finishing equipment supplier such as Reliant https://reliantfinishingsystems.com/ Getting an honest evaluation is especially important regarding safety features such as airflow switches and high temperature limiting devices, which in-house maintenance personnel often disable in order to prevent downtime.
With ovens that have been in service for 10-20 years or more (especially after having been decommissioned for an extended period or purchased as used equipment), deterioration of the insulation can be a problem. This is particularly true if the oven has ever been moved. You can tell that an oven has compromised insulation if the outside surfaces get too hot to touch. During handling, mineral wool insulation can break down and settle if it has gotten damp due to exposure to moisture or from the inside surfaces of the panels “sweating” and causing condensation to get trapped in the insulation. The greatest area of concern is at the top of the wall panels. They may no longer have insulation inside because it has shifted down during handling.
Damaged temperature probes and/or wiring connections that have developed issues are another common problem with older ovens. If the oven does not hold a consistent temperature during operation or shuts down due to the high temp limit being reached, probe replacement or wiring repair might be needed. This is especially true if the display on the control panel appears to erratically jump from one temperature reading to another for no reason. The signal strength from temp probes is quite low compared to the wires connected to the motors or other controls, so even a slight bit of damage to the wiring or a loose connection can cause major problems.
Older ovens also tend to have issues with the burner section of their heaters. The burner may have damage from improper handling, inadequate maintenance, or simply from extensive operation, especially at higher temperatures. It is important to check the gas plumbing connections at the burner’s gas train and inspect the area where the flame is discharged into the heat unit’s airstream. It is not uncommon for parts in the combustion area to be degraded or distorted by heat over time. With indirectly-fired models, heat exchanger failure is relatively common on ovens that have been in operation for 10 years or more.
On belt-driven booth and oven fans, you should check to make sure the belts are in good shape, properly aligned, and properly tensioned. Avoid over-tightening the belts to help prevent bearing wear! Noisy bearings can be an indicator of future failures. Checking motors and making sure they have appropriate amp draws is also a critical step in determining how much life your old equipment may have.
With older booths, the accumulation of overspray on the exhaust fan(s) can be a serious problem. Fans can become so heavily caked with powder that they move only a fraction of the air they once did. It’s also common to see booth and oven motors covered with baked-on powder and shop dust. This can shorten motor life and represents a safety hazard.
If you’re using an automated multi-stage pretreatment washer, examining the appliance’s tanks, pumps, exhaust fans, and other major components is absolutely necessary. These parts are exposed to moisture and chemistry that can cause significant deterioration, particularly if your chemical titration is on the “hot” side. It is also very common for nozzles to become clogged over time. The spray pattern from these nozzles can be much less effective than when the appliance was new.
After checking key components, it’s wise to have the structural integrity of your pretreatment equipment, booths and ovens checked. This is critical if you’ve had accidents in the past, such as forklift collisions or fires, if your operators are rough on the equipment, or your maintenance practices have been lacking.
In addition to assessing the general state of your finishing equipment, it’s advisable to have a line audit performed. This is where the system’s performance is methodically evaluated. A typical audit will include an assessment of several finished parts to look for finish defects. It can include airflow measurements for booths and ovens, pretreatment chemistry analysis, and other tests. It is also common to have your drying and curing ovens tested with a data recorder, such as a DataPaq. The technician performing the audit can ensure the ovens are operating as intended and the curing oven is functioning at the correct temperature for the powders you are using.
Finishing equipment can last for several years with proper maintenance and adjustment, but there comes a point where most shop owners and finishing managers make the decision to quit supporting equipment that has become unreliable or more costly to repair or upgrade than it’s worth. Finishing system providers like Reliant are then asked to propose a replacement system. In a few situations, an equipment provider may integrate only one or two pieces of new equipment (usually ovens) into an existing line if the other appliances are still in good working order. It’s important to find a finishing equipment supplier who can work with you to provide a solution that will perform well for you and your company.