Leading an Effective and Efficient Powder Coating Operation
Axalta Coating Systems’ Mike Withers has some sound advice for an inexperienced painter who’s been charged with running a powder line.
Q: I’ve been put in charge of a powder coating line at my facility, and I have no paint experience. What do I need to know to lead an effective and efficient operation?
A: Let’s start with the basics: Powder coating parts is essentially a system in which a metal substrate is to receive a powder coating. First, most steel parts will be coated with some type of rust preventative, which must be removed. If the substrate is not steel, there are individual challenges that need to be addressed for those other metals. Often, parts also receive a conversion coating that enhances corrosion performance and improves powder coating adhesion. After that, the part is oven-dried, and the powder coating is applied in an electrostatic system. This makes the powder stick to the part long enough to get it into the oven, where it can then fully cure. After cooling, the part is removed and packaged to prevent damage, and then transported to the next process for assembly, either inside or outside your plant.
To get the best performance from the powder coating, individual components of your system must be within operating specification. I would first recommend that you contact your suppliers for both pretreatment and powder coating and:
- Request training on individual products. As them to explain how things are supposed to run and how to fix anything that might be out of specification.
- Ask the technical service reps to audit your system and identify any issues that need to be addressed. Ask how your company has responded to their recommendations in the past; if it did not respond favorably, don’t repeat that mistake. Your suppliers want you to be successful.
- Ask them to help establish written work procedures and to train your operators.
As a supervisor of a coating line, you must understand everyone’s work procedures to know when they are following them and when they are not. For example, it is important that you know how to titrate your pretreatment line and occasionally perform the testing yourself to verify that your operator is properly doing his or her job correctly.
Additionally, there are other important questions to ask yourself if you really want to achieve an effective and efficient operation. Are your employees using personal protective equipment (PPE)? Safety in the workspace is important for everyone. Too often, I have seen applicators spraying powder without wearing even a dust mask. (I’ll often suggest they blow their noses into a tissue to see how much of the plastic dust they are breathing in.) People all too often aren’t voluntarily following PPE requirements, and only do so when forced. Also, how well is the lighting in the application area? People cannot coat what they can’t see.
If your parts are quite heavy, there are many machines that can assist in hanging them on and removing them from the line. If you have lots of little parts, it may be a good idea to build a rack to hang and hold them offline, and then place the full rack on the line. Racking is critical to getting good parts. Parts also can be blown off in a washer if they aren’t adequately secured. If you hang 1,000 parts, the expectation is that you will get 1,000 parts off the line. Additionally, if you have a larger window in the system, like 3 feet wide by 5 feet high, and you are hanging only a single 1-foot-by-1-foot part on an individual hook, you are missing a huge opportunity to hang more parts in the same space. Racking allows you to 1) coat parts faster, so you can move on to another color or another customer’s parts, and 2) significantly improve first-pass transfer efficiency. If you spray to waste, then this is very important; even if you reclaim, it makes a difference in applied cost.
powder is electrostatically applied and requires a good ground to make the powder stick.
In my opinion, the most important tool for a coating operation is a film thickness gage. I’ve traveled all over the country to many facilities and far too often see operations that don’t measure film builds, and this seems odd to me. Everything your end customer wants in terms of coating performance and appearance relies on the coating having the correct film build and being fully cured.
Your powder coating supplier should provide technical data sheets (TDSs) that tell you the performance characteristics of specific powder coatings. These will also tell you the recommended film thicknesses and cure schedules. If you apply too much powder coating, you will be wasting money. If too little, you will have premature corrosion or off-color concerns. Follow their recommendations for film build, measuring with the film thickness gage discussed earlier. And note: Check film thickness on ambient-temperature parts only; never measure on hot parts coming out of the oven.
To futher help with getting the right film build, it helps to document your gun settings for each part you coat. If your booth is not in an environmentally controlled room, your application conditions will likely change almost daily, maybe even hourly. Powder reacts differently in 90°F and 90 percent relative humidity than it does in 35°F and 20 percent RH Use your documented settings as the starting point to coat parts, then adjust as needed.
I hope this helps some of you who are new to powder coating. You can also seek out training from the Powder Coating Institute. Lastly and most importantly, ask your suppliers for help. Your success and theirs are linked.
Mike Withers is architectural segment leader and electrocoat segment leader in the Powder Group at Axalta Coating Systems.
Question: What methods are available for removing cured powder coatings, and what are the pros and cons of these methods?
The year 2020 will be here before you know it, signaling the beginning of a new decade and bringing changes to the world as we know it.
Metal fabricators that laser-cut with oxygen take steps to prepare parts better for powder coating.