10 Questions You Should to Know about Powder coating line manufacturer

Answers about Powder Coating

Ok since we have two questions about the Eastwood powder coating system, I will combine them in one answer.

The first question is about "starter sets for powder coating"...The only company that I am aware of that makes complete kits for hobbyist (homeowner) powder coating is Eastwood. I had a hand in helping them select the ovens for their program and a few other technical issues over the years. They started out buying a "powder coating gun" from a China supplier that is pretty low-tech, but gets the job done. Sears and Summitt both have homeowner guns as well, but no ovens, etc. This gun uses a TV "fly-back" transformer to charge the powder during application, a far cry from industrial grade equipment. But it does not have the $4k price tag as the industrial equipment either. Once they had a gun, they needed all the other stuff to execute the powder process. They came up with a line of cleaning chemcials, cure ovens, booths, etc. to support the hobbyist and haven't looked back. Their real money maker is the powder they sell. Average powder coatings cost between $2.50 to $5.00 per pound (except the real sexy stuff) but come in one pound to 300 pound containers (automotive and appliance manufacturers buy their powder in pound totes!). Since the average homeowner does not need that much powder, Eastwood buys regular powder in 50 pound quantities and re-packages it into small containers. The price ends up at around $50.00 per pound. Nice business model!

To perform powder coating safely you need a spray gun, powder spray booth (designed for powder), cleaning method, and cure oven. The most expensive piece is the cure oven. You need the gun to charge and atomize the powder to get it to coat and stick to the part before placing it into the oven. You need the spray booth to contain the overspray and collect it for disposal (industrial users often re-use the overspray). Without a booth, you could have an explosion. You need a cleaning system to clean the parts before your apply the powder, because any paint job is only as good as the surface you apply it to. You need the cure oven to heat the part above 250 degrees F to melt and cure the powder. Do not use your wife's cooking oven, as the next meal may not taste like you expect! Check the Eastwood website for current prices of these equipment components.

As for the question about clear coating over the silver (chrome) powder...Silver (chrome look-a-like) powders look great but have insufficient mechanical properties. They will scratch and mar easily. This is why they reccomend applying the clear over the top of the chrome powder. The clear can get cloudy, as seen in your picture, due to several issues. First, the quality of the clear powder may not be that great. Second, the thickness of the clear can affect the clarity of the coating (too much clear will get cloudy). Third, the clear can cloud up if it is under or over cured (under baked or over baked). Fourth the clear can cloud up if the oven does not have sufficient exhaust (oven contaminants).

Clears and chromes are "high risk" powder coatings, as they are very finicky to apply and still look good. Start out by buying a good clear powder. Apply it at less than 3 mils (0.003 inches) thick. Check cure by dipping a q-tip in MEK and rubbing it on the surface. The clear coating should not become sticky or tacky after 25 double rubs (one double rub is one single back & forth motion). If it does get soft, it is under cured. Finially increase your oven exhaust, if you have one, to improve the quality of the cured clear coating.

Sorry for the lengthy reply. It is just the Engineer in me comming out! Sorry folks, but since the weather got so nice in the Northeast the last couple of days I was out in the garage working on my 89 SC and did not check the posts for this thread lately. I check my emails frequently, but did not see anything from the SCCoA forum letting me know there were a few more posts!

Following are the next group of answers to the recently posted questions:

"I'm just using a kitchen oven (not the one we cook food in) I guess doesn't have much exhaust. A fan does kick on on it sometimes. Maybe I should figure a manual override for the fan?"

A kitchen oven does not have much exhaust at all, as it is designed to keep heat in and smoke out of your kitchen! Paint curing ovens on the otherhand have a heat source (gas burner or electric element), a circulation fan (convection heat type oven), and an exhaust fan. The heat source provides the heat energy, the circulation fan delivers the heat energy to the part, and the exhaust fan removes the by-product of combustion (natural gas only) and the by-products of powder cure. Having an oven with an inadequate heat source, no circulation fan, and inadequate exhaust will combine to cause numerous problems.

I recently answered a similar question for my Powder Coating magazine column last week:

Question: " i have been trying to powder coat a set of 350 chevy heads and when i shoot the heads with wet black powder and then cook them the powder is not flowing out it comes out as if it was never cooked. how can i get the parts to flow out. is it that the heads are soaking up the powder. please help me with this. i am baking at 500 degrees thank you for your help chris"

Answer: "Chris:

The 350 C.I.D. Chevy motor is very reliable. I had one in several vehicles over the year. However, I prefer the horsepower or the higher revving 327 C.I.D.

The description of the problem you are having tell me that you are not heating the cylinder heads to a point where the powder coating even melts, yet alone cures. If the powder on the part looks the same when you take it from the oven as when you put it in the oven (still a powder and not a coating), then it is time to evaluate what you are using to heat your part.

This problem has to do with the weight (mass) of the cylinder heads and the energy capacity of your heat source. I have lifted my share of Chevy heads over the years and from my recollection they weigh about 100 pounds. Considering that the cylinder head is made from steel and has a specific heat of 0.125 BTU per pound it will take 4,375 BTUs to head one cylinder head to 350 degrees F (the average cure temperature for powder coating). If you put this cylinder head into an oven whose heat source has an energy capacity of 1,000 BTUs per hour, it will take 4.375 hours to get the cylinder head up to temperature and an additional 25 minutes to fully cure the powder coating. That is almost five hours of “baking time”! However, if you use an oven with a heat source that has an energy capacity of 10,000 BTUs per hour it will take less than an hour. This relationship between the energy capacity of heat sources and cure time can easily be related to horsepower and speed; “The more you have the faster you will go!”.

I frequently tell my clients that the size of their oven burners determines how fast their products will achieve the desired powder cure temperature. I often tell them that you can cure a 10,000 pound part using a cigarette lighter, it will just take a couple of hundred years. The same goes for you. If you are trying to cure your cylinder heads in a toaster oven, then I hope you are very patient, as it will take quite a while to melt, flow, and cure the powder. Remember the old racer’s adage: “Go big or go home”. Of course, they were talking about engines (horsepower), but you get the point." Powder Coating Safety

Makes sense.
Oh yeah, and whats gonna blow up if you don't have a booth?

Powder coatings are "organic" in nature and, as susch, will combust if mixed with the right amount of air. The same thing applies to any organic dust, such as baking flour, sugar, etc. I am sure you have heard of tragic cases where a sugar mill or flour mill had an explosion. Well powder coating materials are just as dangerous! Believe me, as I have investgated numerous powder coating lines that had fires and explosions, some of which had fatalities!

The risk with powder coating is dramitically lower than using solvent type liquid paints (i.e. laquers, etc.). However, that does not mean that they are not dangerous in their own right.

Powder coatings will not combust (burn) in the container as there is too much powder (fuel) and not enough air. Same goes for the opposite condition, where a small amount of powder is mixed with a lot of air, the powder will not combust either. The problem occurs when powder coatings are atomized with just the right amount of air. This "just-right" mixture is between the "lower explosion limit" (LEL) and the "maximum explosion limit" (MEL) and is often the exact mixture of powder and air at the gun applicator tip. If a source of ignition is present with this "perfect mixture" the powder cloud will ignite! The result is a fireball that releases a tremendous amount of energy. If this energy is expended in a small area (what is called containment) the result is an explosion.

It is just like your SC engine works: gasoline is mixed with air and ignited in a contained area (the combustion chamber) and the resultant explosion sends the piston in the opposite direction. Ignite the same gasoline/air mixture in an open cup, and a fireball will happen, but no explosion since there is insufficient containment .

Most explosions happen when powder coating ungrounded (or improperly grounded) parts. The part will absorb some of the electrostatic energy used to charge the powder (so that it sticks to the part before curing). If the part is improperly grounded (more than one megohm = one million ohms resistance), the part will eventually become saturated with electrostatic energy and discharge to the closest ground (typically the gun tip). This results in an arc (ignition source) much like when you discharge static electricity in the wintertime after shuffleing your feet on a carpet and touch the light switch. The ignition source and the powder/air cloud cause a fireball at the end of the gun, the person spraying the powder usually screams and drops the gun, and the fire goes out harmlessly as the gun trigger is released stopping the power/air from fueling the fire. This event usually requires a change of clothes for the powder sprayer, at least their pants anyways!!!

However, if the person has been spraying a lot of powder in an enclosed garage, without ventilation, and there is a large cloud of power, then the next sound they hear is St. Peter asking them what they did back on earth to get into Heaven! The large powder cloud provides a significant energy source or fuel and air and the garage provides the containment...a very bad combination. The energy released from such an explosion is awesome. I have seen 40 feet of cinderblock wall moved 20 feet in a powder explosion!

Now that I scared the Sh-t out of you, it is time to bring you back to reality. Powder coating is the safest method of painting, except for using laytex paint and a brush. Follow these important rules for safe powder coating:

1. Spray powder coatings in a powder coating booth that is designed with proper airflow. This ensures that there is not enough powder and too much air to have a combustion fireball (except right at the gun tip).

2. Always coat parts that are properly grounded. Use a ground wire attached to an electrical ground or cold water pipe at one end and attached to the part at the other end.

3. Eliminate all sources of ignition during spray operations. No smoking, no welding, no grinding, etc.

4. Cover all electrical devices within five feet of the spray area with air tight bags. Actually code requirements call for "dust tight explosion proof" electrical devices in this area, but they are very expensive.

5. Always wear a dust mask and safety glasses to protect your health when powder coating. Powder Coating Wheels

If the center caps are the aluminum ones you can powder them. The earlier wheels have metal centers, right?

Yeah you will want to strip the wheels to bare metal.

Here are my recommendations for having your Aluminum wheels powder coated:

1. Remove the existing coating by either chemical stripping or media blasting. Do not use thermal stripping methods (burn-off oven) as the + degree heat will anneal (soften) the aluminum. NEVER USE THERMAL STRIPPING METHODS ON MAGNESIUM WHEELS, AS A FIRE WILL OCCUR THAT THE FIRE DEPARTMENT WILL HAVE GREAT DIFFICULTY EXTINGUISHING (AS WATER APPLIED TO BURNING MAGNESIUM WILL EXPLODE)! Acceptable blast media is Aluminum Oxide, CO2, or Plastic. Do not use steel based media, as it will start corrosion sites under the coating (galvanic reaction with the aluminum). Sand as a blast media has all but been outlawed (silicosis health problems).

2. Ask your powder coater if they can apply a chromate conversion coating to the aluminum wheels before powder coating. Sometimes reffered to as Alodine, this conversion coating will increase the service life of the coating by a factor of 5, or more.

3. Select either a TGIC polyester or Acrylic powder for your color, as these are the formulations that the original manufacturer used and are best suited for this application.

4. Consider using a clear coating over the color, for a better "depth of finish" and better wear life.

5. Instruct your powder coater to cure the coatings on the wheels at a temperature below 325 degrees F. This will ensure that you do not anneal the temper (hardness) of the aluminum. They will have to cure the wheels longer at this lower temperature, but it is the safe way to go!

This recipe will provide wheels that look great, will last a long time, and will not change the metalurgical charateristics of the wheel.

You have questions, we have answers. In each issue of PCT, our extensive network of powder coating experts provides information to help you with your powder coating challenges. Let us know what’s keeping you up at night and we’ll do our best to help you get a good night’s sleep!

With competitive price and timely delivery, ZHYAO sincerely hope to be your supplier and partner.

Weighing Volatility
Q: I’ve been asked by our Environmental and Safety Department to provide information on the volatile content of the powder coating material used in our plant. After reviewing the Safety Data Sheet (SDS), I noticed that this information is not listed. From my understanding, powder coatings typically contain very low or near-zero volatile organic compounds (VOCs). Is this the reason why the volatile content is not listed on the SDS? If not, could you please advise where I can find this information?

A: You are correct that the volatiles in powder coatings are minimal, and as such, they are not typically listed on the Safety Data Sheet (SDS). If this information is required, specialized equipment is needed to accurately measure these small amounts. The use of analytical balances and a precisely controlled heat source means that this procedure is best suited for laboratory environments rather than production settings. The analytical balance used for this testing must be capable of weighing to a precision of ±0. grams.

There is a specific test designed to quantify the percentage of volatile materials emitted during the curing cycle of powder coating. In this test, the sample is added to a tared aluminum dish and weighed. The dish is then baked, cooled in a desiccator, and reweighed. The volatile content is determined by calculating the difference in weight.

It is recommended that this test be conducted by the powder manufacturer or a qualified laboratory.

Under Control
Q: We currently operate a conveyorized powder coating line that includes a five-stage washer, dry-off oven, powder booths, automated powder application equipment, and a cure oven. As we are in the process of quoting new business, our potential clients have requested that we demonstrate the control of the powder coating system parameters. What exactly are the clients expecting from us?

A: Manufacturing processes naturally exhibit variations that can impact the quality of the finished product. To understand the causes of these variations, manufacturers often turn to Statistical Process Control (SPC) methods. These methods help determine whether the processes are under control. Once any causes of variation are identified, corrective actions can be implemented to increase productivity, improve product quality, reduce rework or scrap, and lower operational costs. SPC techniques shift the focus of quality control from final inspection to ensuring quality during or before production.

Statistical Process Control (SPC) is defined as the application of statistical techniques to monitor and analyze a process and its outputs. In most manufacturing settings, it is impractical to measure every parameter that could affect production performance. Therefore, sampling methods are used to monitor specific characteristics of the process. By employing well-conceived sampling techniques, manufacturers can predict the output of a process. This cycle of sampling, predicting, feedback, and control is at the core of SPC.

Feedback and control play crucial roles when applying SPC to powder coating. The powder coating process consists of several stages, including part pretreatment, powder application, and curing. By identifying and monitoring variations at each stage, appropriate controls can be implemented to minimize the risk of producing defective powder coated parts. Moreover, SPC allows for more consistent application of powder coatings to precise standards, which helps reduce reject rates and improves production efficiency. With fewer rejects and more efficient coating processes, production costs can be significantly reduced. Identifying and understanding the sources of variation enables manufacturers to take targeted actions to eliminate or minimize these discrepancies.

Data collected for statistical analysis in SPC can be categorized into two main types: variable data and attribute data. Variable data is obtained by measurement, and it applies to parameters such as chemical concentrations, temperatures, spray pressures, KV readings, phosphate coating weights, and coating thickness. To analyze variable data, X-bar (average) and R (range) charts are commonly used. R charts track the range of values, while X-bar charts plot the average values. The two charts have a similar format, and in some cases, the lower control limit (LCL) may be omitted from the R chart.

On the other hand, attribute data is gathered by counting occurrences. For example, counting the number of defective parts in a sample represents attribute data. Several types of attribute charts are available for statistical control, with the most commonly used being P charts and NP charts. NP charts are employed when sample sizes are consistent, allowing the count of non-conforming (defective) units. When sample sizes vary, P charts are used to track the proportion of non-conforming units, typically expressed as a percentage.

If you want to learn more, please visit our website Powder coating line manufacturer.

When establishing an SPC program for powder coating, it is vital to consider the entire production process. Begin by identifying each phase of the process, its key characteristics, and the current methods used to evaluate and control those characteristics. Analyze this information to pinpoint potential areas of variation that can be addressed through SPC. By using this data, you will be able to present to your existing customers and any potential customers that you have control of your processes.

Hanging by a Thread
Q: We are in the process of purchasing a new powder coating line for the parts that we fabricate. They include some small and large sheet metal products along with some structural steel frames. We have been told that to get the most throughput through the system we need to have new hangers and racks manufactured to fit our line. What are the most important items we need to consider when we are designing and fabricating them?

A:For both safety and a successful coating process, it is crucial that the hangers are made from materials that effectively ground the parts, such as steel. The hangers must also have reliable contact points where the parts can hang securely. Ideally, the contact points should be sharp, as any powder buildup will be scraped off when the part is hung.

The hangers must be designed to hold the part securely in place during normal conveyor movement, particularly during the powder coating process. Any erratic motion could lead to defects or inconsistent coating thickness. Key considerations include the impact of conveyor turns, inclines, declines, and stopping/starting actions. The hangers must also be capable of supporting the weight of the parts without causing deflection or excessive vibration.

The spacing between the hanger hook points on the conveyor should be sufficient to prevent parts from touching each other, especially during vertical elevation changes or when navigating horizontal turns. It’s important to account for the possibility that the outside corners of the parts could touch during turns, or that the center of gravity could cause a part to swing and collide with another. Additionally, the design should allow for proper drainage of the parts as they move through the washer. Ensuring that water or pretreatment coating material can drain off the parts prevents pooling or contamination.

If multiple parts are hung on a rack, the design must ensure that no part is shielded from the powder guns due to interference from the hanger or other parts. Any obstruction could lead to bare spots or other defects in the coating. The hanger design should also consider ease of loading and unloading to reduce labor requirements. Hangers that are difficult to load can result in improperly aligned parts or parts that do not make proper contact with the hanger points.

While many off-the-shelf hangers and racks are available at lower costs, custom-designed hangers may sometimes be necessary to meet specific operational needs. If you opt to design your own hangers or racks, it’s important to strike a balance. Avoid overengineering—hangers should be as universal as possible to accommodate multiple part types. This reduces the need for custom hangers for each specific part, saving time and cost in the long run.

Cutting Out Outgas
Q: I have a few questions about zirconium pretreatment on hot dipped galvanized pipe. Should I be outgassing the pipe before the zirconium application? Also, do you need to outgas again after the application? Your input would be greatly appreciated.

A: Hot dip preparation is challenging due to the galvanized steel and the sealer used. It is recommended to use a fluoride etch prior to applying zirconium to help break down the surface as part of the preparation process for the zirconium application. Additionally, it is recommended to outgas the part after the pretreatment washer, in the dry-off oven, before applying the powder. Typically, the part temperature should be approximately 50 degrees Fahrenheit above the powder cure temperature to ensure that the part will not outgas during the cure cycle, which would cause defects. Following these guidelines will eliminate any outgassing issues typically experienced when coating over cold hot dipped galvanized parts.

Contact us to discuss your requirements of Powder coating booth. Our experienced sales team can help you identify the options that best suit your needs.