Powder Spray Gun Maintenance Manual & Common Replacement Parts

One of the biggest issues we see with existing powder coating systems is the lack of routine powder spray gun maintenance. When we ask about their maintenance routines, we find many operators and managers aren’t sure how to care for their powder guns and powder application systems. They also don’t have common replacement parts on hand and often don’t know where to identify them in their manuals.

If you’re one of those people, we can help!

Let’s start by covering some basic maintenance steps and then I’ll provide a list of replacement parts for three of the most common spray systems. To make things as easy as possible, at the end of the article I’ve also included the names and parts numbers for all the major powder gun manufacturers, so you can get the right part when you need it.

Powder Gun Maintenance: Grounding

OK, so grounding issues may or may not be related to gun maintenance, but they are a common cause of finishing system headaches. If you’re using a good quality powder and a large portion of your sprayed powder is falling to the floor or getting drawn into the exhaust filters without sticking to your parts, it may be due to poor grounding. A good ground is something you usually don’t have to worry about with a new system, but over time the system becomes less efficient without vigorous preventative maintenance.

Loss of ground can cause major problems with your finishing process, but, with a little bit of preventative care, you can avoid grounding issues and keep your transfer efficiency high. (For more information about grounding, click here.)

What causes grounding problems? They can be due to coated hooks, coated racks/hanging bars, poor grounding wire contact, gun issues, or operator error.

• Coated Hooks: Hooks start losing their ground after about 4-6 uses. You should either clean them or replace them frequently enough that your parts maintain a good ground. Baked-on powder can be removed using heat, chemicals, or mechanical action like blasting or grinding. Your hooks need immediate attention if you are getting popping sounds and small electrostatic arcs from the hooks to the racks or hanging bars.

• Coated Racks/Hanging Bars: Treat them the same as hooks. After 4-6 times through the coating process, you should grind, brush, or blast the excess powder off the rack or bar at the hook attachment areas or burn off the coating build up using a burn-off oven. Hanging bars can sometimes be cleaned using chemicals, but, because of their size, it is almost impossible to clean racks without burning off the overspray or removing it mechanically.

• Check Your Grounding Wire: The grounding wires get close to the shop floor at the point where they attach to your grounding rod. It’s easy for them to get run over by racks and forklifts throughout the workday. Sometimes there is a break in the wire that is not easily visible through the sheathing. Use the back-up grounding wire provided with the spray gun system and compare results. If you are only using the grounding wire supplied with the system or you have attached a ground wire to equipment that is bolted to the floor, you can improve your ground immensely by using an 8’ grounding rod (preferably copper) and a relatively short run of grounding wire. Bury the rod right next to the booth. You can also get a much better ground using thicker wire and better clamps to attach to your racks or conveyor. Although there isn’t a “perfect” gauge size for powder system grounding wires, bigger is better–think jumper cables instead of speaker wire. The same goes for clamps–don’t cheap out.

Pro Tip: In some areas you can measurably improve your ground by routinely pouring water into the hole where the grounding rod was buried. Slowly pour water around the grounding rod until it begins to overflow from the top of the hole. This may take only a few ounces or could take over a gallon.

• Check the Gun: If everything else checks out but there is still a lot of powder falling to the floor, getting sucked into the filters, or accumulating on the operator, make sure the tip of the powder gun (the one that has the electrode) has not been dropped or otherwise damaged. At normal settings, you should be getting some wrap coverage on the back of your parts and you should be able to feel the electrostatic field with the gun trigger pulled and your arm close to the tip of the gun. If you don’t feel your arm hairs raise when you squeeze the trigger, the probe or the main electronics could be damaged or not making contact somewhere.

• Check Yourself: People can get so used to doing a task that they assume they’ve done it correctly without checking. Even the best operators can forget to clamp on the ground wire. If you suddenly see a decline in system performance, make sure the ground wire is attached and the gun settings weren’t changed by accident.

Powder Gun Maintenance: System Cleaning

Keeping your gun system clean should be part of your routine maintenance. A few different types of system cleaning/flushing should be done on a regular basis to keep your gun in good shape.

• End of Day: If you’re NOT changing colors for the next shift, flushing the powder through the hose is a basic end-of-day cleaning routine. To do this, pull the pick-up tube out of the powder box or disconnect the hose from the hopper and pull the trigger until no powder is discharged. Remember, powder in the lines can lead to big start-up surges and possible impact fusion (slightly melted powder) sticking in the corners and hard to reach areas.

• It’s also a good idea to wipe down or blow off the gun/unit every day, which will help keep powder from building up on the displays and possibly fouling the electronics. While cleaning up, check out wear items for possible replacement.

• Color Change: Like above, flush the old powder and lightly clean all components. In addition, break down the gun and either shoot a foam earplug through the powder hose to scrape powder out of the line or change hoses. Investigate wear items for possible replacement (see below).

• End of Week: Repeat your color change clean but take extra time looking at all the places where powder is building up. Use cotton swabs, like Q-Tips, and isopropyl alcohol to clean those hard to reach spots that are not blown out adequately by air. Check all wear items and replace if needed. Blow out the gun stand, especially in the vibratory box crevices. Sweep around gun area. Finally, wipe down both the display and the gun with isopropyl alcohol.

Wear Parts and Extra Hoses

Wear parts and hoses are the main extra items you need in order to keep your system running (barring an electrical component failure). Powder coating media is somewhat abrasive and there are a couple areas that take most of the punishment in manual systems.

Venturi Sleeve: The most common wear part is the venturi sleeve. This is the white plastic nozzle that the hose assembly hooks up to on the powder pump. Different manufacturers call it by different part names and numbers but I’ll refer to it as a venturi sleeve. The sleeve takes the powder and condenses it for travel up the hose to the gun. It accelerates the powder by condensing the volume of air, so the sleeve naturally gets hit with pressurized particles. The wear from the propelled powder hollows out the tube and sometimes cuts grooves into the sleeve. If it goes on for too long, the powder pump starts to become less efficient and the gun will surge.

Before that happens, you should check the sleeve every time you do a color change or end-of-week cleaning. This is a very inexpensive part, so it is worth having a couple around as replacements.

Powder Hose: The next replacement item you’ll want on-hand is an extra powder hose. Hoses can get run over, cut, pinched, and damaged by just about everything that takes place in a typical shop environment. I always recommend keeping at least one or two precut hoses available for quick replacement. Another use for extra hoses is quicker and more thorough color changes. If you only have three main colors, then there are advantages to having three hoses to insure less powder contamination and quicker color changes. If you clear coat, I highly recommend a hose dedicated solely to clear coat. Hoses also need a couple fittings which are wear items themselves. All manual guns have connections for the gun and the pump at opposite ends of the hose.

Powder Gun Tip: The last common replacement item I recommend always having on-hand is an extra gun tip. Tips take a lot of punishment from both the powder and the shop environment. With a lot of powder use, the tips can start to warp and cause application issues. Also, if the gun is dropped (and it will be), most likely it is going to land on the tip. Fortunately, the electrode is usually protected.

Where can you find replacement parts?

The “big three” professional-quality powder application gun manufacturers, Wagner, Gema, and Nordson, use different names and catalog numbers for the wear parts I’ve mentioned above. To help you find the part you need quickly, I’ve included the names, descriptions and part numbers you’ll need when ordering the parts for your particular powder gun system.

Venturi Sleeve

Hoses

Hose Connectors to Gun

Hose Connectors to Pump

Gun Tips

These are the main items I would always keep at your facility to prevent a lengthy production stoppage due to a simple powder gun issue. If your budget allows, a secondary gun system is always good to have as a back-up. That way you always have at least one gun in operation if the other needs to be sent off for major repair.

For more information about the different powder gun systems, check out my comparison article here. If you’d like even more information about powder coating in general, along with equipment guides that explain what you’ll need to get professional quality powder coated finishes, check out our Resources page.