For those of us who don't have 20/20 vision, driving at night can be quite difficult, especially if it is raining. Under these conditions, the last thing a driver wants to do is take his eyes off the road to search for some button on the instrument panel, door panel or radio. Therefore, it is critical that any graphic or text that the driver must see be well lighted. If there is too little or too much light, a “hot spot” can occur that makes the panel or button difficult to view.
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This automated painting system was custom manufactured for GM Nameplate. It includes an overhead multi-axis gun mover, universal controller and ARTomation software.
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There was light. While most of us take it for granted that the interior of our cars will be properly lighted, GM Nameplate (GMN), Portland, OR, certainly does not. GMN manufactures and finishes a variety of switch units, such as those used to control a car's power door locks, power windows or stereo. The switch units are molded from an elastomer that is coated with a translucent ink and then an opaque ink. After the inks are cured, the opaque ink is removed where the appropriate graphic or text should be using a laser etching process. Next, the switch units are cleaned to remove any dust generated from the laser etching process. The final step involves the application of a clearcoat to protect the switch unit. By coating the elastomer parts in this way, the coating captures the light. “It turns the elastomer part into a fiber optic cable that pipes the light around and illuminates your text or graphics because you've turned on a function or turned on the headlights,” explained Scott Birch, elastomer products manager at GMN.
According to Mr. Birch, “The type of system that was previously used was a x-y gantry spraying device with multiple heads at different angles to reach down into certain areas. It wasted a lot of ink and put a lot of ink into the air that ended up in the filters of the spray booth. Also, it put a lot of ink on the fixtures, causing extra fixture cleaning.” Basically, the gantry sprayer was setup to flood the spray booth with ink, which was a problem for GMN. The ink that is used to coat the switch units is very expensive, about $150 per quart. By flooding the spray booth with ink, much of the ink was wasted, increasing the cost per part. Also, because the gantry sprayer did not rely on exact spray paths, the parts were not coated as consistently as GMN would have liked. Each layer of paint must be applied at the exact film thickness specified. If it is not, the laser etching process will either remove too much or too little paint, creating the aforementioned hot spot.
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GM Nameplate manufactures a variety of switch units. These go into the door panel of a Corvette.
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And there were automated painting systems. In order to reduce the cost and improve the control and quality of the finishing process, GMN installed two automated painting systems from Advanced Robotic Technologies, Inc. Custom built for GMN, each system consists of an overhead multi-axis gun mover, universal controller and ARTomationTM integrated control software. Along with the automated painting systems, GMN installed two tunnel conveyors to transfer parts from the paint booth to the cure oven and two tunnel ovens to cure the painted parts.
The critical component of the new automated painting system at GMN is the Windows®-based software, which has changed the way the company prepares a switch unit to be painted. When GMN develops a new switch unit, it also creates a pallet that will carry the switch units through the spray booth and the cure oven. Depending on the number of colors that the switch unit is to be painted, one or more masks are created as well.
Once the pallet is created, the paint system operator loads it with parts, and a digital picture is taken of the loaded pallet. The operator then opens the picture on his computer using the automated painting system's software. To calibrate the picture of the pallet on the screen to its actual size, the operator clicks on the calibration icon, selects two points on the screen and enters the real distance between those two points. After the picture has been calibrated, the operator clicks on a point in the picture to tell the software where the multi-axis gun mover's frame of reference is. At GMN, this reference point corresponds to an exact point on one of the conveyor's rollers in the spray booth.
GM Nameplate: It's not the GM You're Thinking Of
GM Nameplate is a privately held corporation established in 1954 by Lester Green and Beale McCulloch (hence the GM). The company is a multinational manufacturer of custom product identification components, electronic input devices, injection and compression moldings and digitally printed graphics. It has the ability to integrate in-house printing, plating, molding, forming and fabricating processes for complete manufacturing solutions.
Corporate offices and a 140,000-sq-ft manufacturing facility are located in Seattle, WA. A 27,000-sq-ft plant was established in San Jose, CA, in 1981, and an 85,000-sq-ft plant was added in North Carolina in 1993 with the acquisition of Acme Nameplate. In 1995, the Oregon Division opened a new 40,000-sq-ft facility in Beaverton, OR. The company also has a manufacturing facility in Singapore.
It has received “Preferred Vendor” status from a variety of companies, including Boeing, Data I/O, Allen-Bradley, Hewlett Packard, Iomega, Fluke Corp., Motorola and others. Other customers include Delco Electronics, Eaton Corp. and General Motors.
This automated painting system was custom manufactured for GM Nameplate. It includes an overhead multi-axis gun mover, universal controller and ARTomation software.
GM Nameplate manufactures a variety of switch units. These go into the door panel of a Corvette.
For each switch unit, GM Nameplate creates a special pallet and masking device. The pallets are used to move parts through the spray booth and cure oven. |
All of this work allows the operator to draw paint paths directly on the digital picture using simple point-and-click menus, just like any other Windows application. Because the ink that GMN uses to coat the switch units is so expensive, Mr. Birch uses an interesting technique to verify that the paint paths are positioned properly. “I bought a small pocket laser at Fred Meyer (a grocery store chain) to stick in the gun. This way we don't have to put any ink in the gun to prove the path is what we want,” stated Mr. Birch. As the spray gun moves according to the path that was drawn, the laser can be seen tracing that path on the parts, verifying the position of the paint paths.
When the paint paths have been positioned properly, the operator enters the spray gun settings for each paint path into the software. Again, this operates just like any Windows application through the use of pull down menu boxes. The operator can enter a variety of spray gun settings, including speed, angle, atomization air, fan air, flow rate, gun distance and so forth. If the operator has already created a path that he wants to use on another part of the pallet, he simply copies and pastes that to the appropriate position. Once all of the paint paths are drawn and the gun settings entered, the operator clicks the “Generate Path” icon, and the software creates a robot program that is transferred from the software to the system's controller. The only thing left to do is load the pallets onto the conveyor and press the start button.
And it was good. By taking humans out of the loop through the installation of this automated system, GMN has achieved a number of objectives, including improved quality and control, reduced costs and reduced contamination.
Previously, the switch units were coated using fixed guns. With the new system, GMN can program exact spray paths with exact gun settings, allowing the company to coat parts at the specified film thickness. “We have established consistency so that when we laser the parts we're not over burning or under burning the outer layer,” stated Mr. Birch. That means GMN can produce switch units without hot spots, which makes driving easier for all of us.
The ability to easily create paint paths and the capability to paint parts with an automated system is just one reason why the new equipment has improved GMN's quality and control. Another reason for the improvement is the system's database. “You tell it these things, and it does that. Not only does it do that, but it learns. It compiles all the jobs into a database and, it sets up its own parameters. So, when you pull up a new job, it's like taking the average of all the parts you sprayed so far. You put just a couple of parameters in. ‘Oh, this part is this high off the fixture, and we want to spray it at a distance of four inches.' It sets everything else. It allows you to get a project up and running much faster because of the way it uses the database.” That's a huge plus for GMN since the automotive OEMs are continually trying to reduce the time between conception and production.
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For each switch unit, GM Nameplate creates a special pallet and masking device. The pallets are used to move parts through the spray booth and cure oven.
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GMN also has been able to reduce the costs associated with its painting process. Compared to the company's previous system, which flooded the spray booth with ink, the automated painting system has dramatically improved the process' transfer efficiency. Since the ink GMN uses is $150 per quart, the improved transfer efficiency has resulted in substantial savings for the company. GMN has cut down on its pollution control costs as well. Because the booth is no longer flooded with ink, the spray booth's filters do not need to be replaced as often. Plus, the pollution control system as a whole operates more efficiently with the less ink in the system.
With the automated painting system and conveyor tunnel, humans are virtually removed from the actual finishing process. “This type of system has helped with contamination. It's so automated we have taken the humans out of the loop until the ink is cured. The pallets with the part go into the booth. They get sprayed, and they go out of a booth down a tunnel oven. The ink is then cured. So, we developed a fixture and pallet system that allows the parts to be sprayed to go right through the oven on the pallet. We don't have to touch the wet parts at all,” explained Mr. Birch.
Looking to the future. The database associated with the system's software has proven to be an excellent tool for GMN right now, but it could become an even more important tool in the future. How is that possible? Two words say it all: intuitive response.
What is intuitive response? Think about how the mind works when you are driving a car, riding a bike or catching a football, all activities we do without really thinking about them. Through our senses, the brain “measures” a number of variables. Based on those “measurements” and past experiences, the brain sends a number of responses to ensure that we perform whatever task it is that we are doing properly. We don't think about the “measurements” our brain is taking, and we don't think about the response that is needed. There isn't enough time for that. It all happens naturally, or intuitively.
Now, imagine if your paint system operated that way. There are a number of coating variables that can be controlled and measured: temperature of the coating and atmosphere; humidity; nozzle speed; angle of inference relative to the part surface; fluid flow; atomization air; fan air; and air volume (pressure lags and surges). Future generations of automated painting systems like the one GMN uses will be able to dynamically measure these coating variables and link them with specified results, such as film thickness, gloss and color, that are also measured dynamically, much like the human brain does.
When this happens, coating will become a closed-loop process. The coating process will be completely computer controlled, eliminating human interaction. A database, like the one used at GMN, will be updated automatically, learning as coating variables change and adjusting settings automatically based on a database of knowledge to produce the desired results. When the technology reaches this point, automated systems will operate intuitively, having the same dexterity and adaptability as humans.
Certainly, creating an intuitive response system is no easy task, but it sure looks like a possibility in the future. In the meantime, GMN has a vastly improved painting system that can compile large amounts of information into its current database to form the “brain” of the next generation painting system. Technology is a wonderful thing.
