Take control of your powder coating process with iControl and PowderPilot

When an accountant looks into your powder booth as you’re painting what does he see?

Money streaming out the end of a spray gun. (It’s probably the same thing your powder salesman likes to see too !)

Want the background on how we can save you powder ? Read on, otherwise link direct to the products iControl or PowderPilot

If you need to put 60 microns of powder on a part – what does every extra ten microns anywhere on the part mean to you? It should mean lost profits.

Clearly, powder flow control – the number of Kilograms per hour coming out of the spray gun must be linked to controlling the bottom line. And it is.

As an analogy, think about the fuel-economy computers they put into cars that tell you how many Kilometres per litre the car is guzzling. Step on and off the gas a lot and watch the economy drop quickly. Put on the cruise control and you can observe the immediate improvement in engine efficiency.

So it is with regulating the flow of your powder guns. You need to keep your powder flow regulated at the optimum level for maximum savings.

Like cruise control, modern powder systems can provide a “closed loop” control over powder flow. After all, the pressure of most plant compressed air (which is the main artery of the powder delivery system) changes all the time. Without regulation the system would react every time the input air source changed.

But evidence shows that the manual regulators that have been popularly used for many years have some inherent limitations when it comes to accuracy and precision. By accuracy we mean how consistently they deliver powder once set and by precision we mean how close to the desired value they can be adjusted to in the first place.

Consider one experiment where operators were asked to manually set a powder regulator to a target flow rate of 214 grams/minute – and to do this independently twenty times. The precision of this setting was then accurately measured. The results are show on the graph below. Compare this with the precision offered by an electronically controlled system with more precise electronic flow capability (iFlow from Nordson).

The results are easy to see, the impact easy to understand. Manual regulators cannot be easily set, even by experienced personnel to repeatable flow rates. The flow will sometimes be lower (perhaps causing quality problems and rework) and often higher (meaning wasted powder costs). Like our automobile cruise control analogy, it’s like trying to put your foot on the gas to produce a speed of 50 miles per hour many times in a row. Sometimes you will be slower sometimes risk a speeding ticket.

Now let’s take a look at what happens once you do set the flow rate to a given value. Say a regulator is set to 170 grams/minute and the actual output measured during production. Here are the results of such a test.

Once again the results are not hard to interpret. Traditional regulators simply don’t provide the same consistent output as a more sophisticated closed-loop design.

Imagine trying to keep your living room temperature at a comfortable 68 degrees without a thermostat !

It is as impractical to keep making adjustments to the heater as the outside temperature changes as it is to keep adjusting the powder regulator for changes in pressure drop from the plant air supply. The answer lies in measurement and automated control.

When we speak of measuring flow – what do we mean ?

When we measure powder flow, we are measuring the output produced by the powder pump in the system. This pump can be greatly affected by certain conditions like the air pressure feeding it. The old computer adage of “garbage in – garbage out” applies here. As the air pressure to the powder pump changes, so does it’s ability to deliver a consistent powder flow rate. That’s because the length and diameter of the powder delivery tubing varies and regulating pressure alone is not enough to ensure consistent flow.

The Nordson iFlow closed loop control system solves this problem in two steps. First by measuring the pressure of incoming air to the pump and comparing it to the preset baseline value. As the pressure varies from the baseline, the electronic module sends control signals to the pump to increase or decrease the flow to compensate for the variation in input air.

For those familiar with the philosophy of process control the methodology is the same in controlling the quality of the powder flow as it is in the manufacturing process as a whole. By identifying a key variable; the fluctuation of input air to the powder delivery pump and controlling it’s effect we can keep the process under control and produce with greater quality.

For all the theory, how does better flow control really perform on an actual production line ?

Nordson recently measured the savings at a typical production facility. This manufacturer of decorative hardware for the furniture industry runs a first-class powder line with attention to detail. Their conveyor line runs 0.9m x 1.8m racks of parts at a speed of 1.8 metres per minute on eight-hour shifts each day. The customer agreed to measure their powder consumption and film build on parts before and after installing closed-loop flow control to determine its effectiveness.

Before installing iFlow, the hardware manufacturer was averaging 65 microns of powder per part. By installing more accurate flow control the average mil build was reduced through controlling the variation in film thickness to 57 microns per part. This resulted in a savings of over £26,000 in powder annually.

We are all familiar in our everyday life with better control over costly resources, whether it’s cruise control in our cars, or electronic thermostats in our home.

Now this money saving technology is available for powder systems. If you are not taking advantage of better control technology you are simply wasting money.

Nordson has two products that incorporate iFlow modules to allow you to take control, and Start Saving Today.

Our iControl unit is a controller for powder spray guns and gun movers, and comes complete with a touch screen.

Our PowderPilot system controls the full powder application system, including guns, gun movers, booth functions, recycling, and even links via Profibus to customer networks.