Automotive finishing.

LAUNCHING THE VANEO

Although the minivan has become nearly as ubiquitous on North American streets as pickup trucks, the penetration of the vehicle in the European market is comparatively minuscule. But that's changing, although it should be noted that rather than calling the vehicles "minivans," they're described as "mini-MPVs"--multi-purpose vehicles. According to DaimlerChrysler, there were 250,000 MPVs sold in Europe in 1998; sales are expected to reach 960,000 units in 2004...which explains why Mercedes-Benz is Launching the Vaneo mini-MPV. The Vaneo is being built at the corporation's Ludwigsfelde plant (south of Berlin). The plant began production of the vehicles in October. 2001. The initial production rate is 50,000 units per year; according to the firm, the production could be expanded to 70,000 units.

The vehicle measures 4,192-mm long, 1,742-mm wide (excluding mirrors), and 1,830-mm high (up to the roof rails). Essentially, it is a one-box design, a box that has room to accommodate seven people (two of whom are kids).

The Ludwigsfelde plant has been producing commercial trucks since 1991. Subsequent to the announcement of the location of the Vaneo at the facility, DaimlerChrysler has invested 500-million Euros there for improving existing buildings, constructing new ones, improving the infrastructure, and training employees. For example, there is a new 20,000-[m.sup.2] body shop. The 19,800-m2 main assembly hall underwent major refurbishment. The paint shop, a 15,000-[m.sup.2] area, was completely stripped and rebuilt.

The body shop and the paint shop are connected by an 80-in long bridge. There are two main assembly lines in the body shop; 130 ABB robots are used for welding. There are ultrasonic sensors used to monitor weld quality. Four Perceptron in-line measuring units check build quality. Additionally, there are two more CNC-controlled measurement checks on the body shells before they make the trip to the paint shop.

In paint, there's pre-treatment and phosphating, followed by a cathodic dip primer. Eleven industrial robots are used to spray paint. One interesting feature of the paint shop is a DaimlerChrysler first: the use of a condensation process for drying the base coat. The Vaneo is available in 10 different colors, six of which are optional metallic coatings.

Another interesting finishing-related aspect is that the entire underbody is coated with a smooth plastic material that is said to reduce wind resistance and road noise and prevent corrosion.

From paint, it is on to final assembly where approximately 2,000 more parts are put together to create the van--the MPV, that is.

Painting with Water at Toyota

Kermit Whitfield

Toyota Motor Manufacturing Kentucky's Plant Two paint department has developed the flexibility to paint both cars and minivans in the same facility. They're painting small lots with high finish quality, all while dealing with the unforgiving nature of the water-borne process.

Let's start with some basic facts: Toyota Motor Manufacturing Kentucky's (TMMK's) Plant Two paint department is the only one in North America that paints both cars and minivans on the same line. It processes approximately 500 Camrys and Siennas per shift on two shifts. It uses solvent for primer and clearcoat, but basecoat is water-borne. From the electrodeposition process to the application of cavity wax, there are 13 distinct steps that a body-in-white goes through to become a painted body ready for the assembly line, and it all takes about 10 hours.

Cars and Minivans... Together

The simple statement that cars and minivans are processed on the same line encompasses a lot. In doing this, Toyota has chosen a path that diverges from its competitors. Most automakers find that though the flexibility to produce different body styles on the same line may be theoretically desirable, in reality the modifications that must be made to accommodate vehicles that vary significantly in size inevitably argues for a dedicated facility. However, unlike other car companies that have', dedicated minivan platforms, Toyota designed the Sienna on the Camry platform with an eye toward making both models on the same line. This has entailed some adjustments in the paint shop, but arguably far fewer than you would expect.

The main accommodation is that the Sienna can only use two of the three basecoat/clearcoat lines. This is chiefly because it only takes two lines to handle Siena production volumes, and some modifications in paint flow rate are necessary, but also because Toyota wants to maintain one line for exclusive' production of the Camry. The basecoat painting process on a Camry takes 118 seconds. But because of the greater surface area for the Sienna, a process time of 150 seconds is required. So, Toyota sets aside, one line that can' crank through its bread-and-butter product at the fastest pace allowable, instead of reducing the line speed of all three.

This all gets sorted out by computer in a large staging area. After bodies are primed and masked they roll on their dollies into the staging area. As they cross the threshold, a magnetic plate on the bottom of each dolly is read which tells the sorting computer what color the body is to be painted. Based on this information the computer moves the dollies onto one of four tracks that lead to each basecoat booth.

The Vagaries of Water-borne

Plant Two paints only two bodies on its water-borne basecoat lines before flushing the lines and bells with alcohol and de-ionized water. This is a lot of purging, but Dale Beatty, assistant manager of the department, says that otherwise the paint would dry on the bell and shaping air plate, leading to uneven paint application or "spitting." He points out that the water-borne material is uniquely problematic on this count since the solvent-based clearcoat is applied to 14 cars before the lines are flushed.

Having a paint lot size of only two theoretically enables Toyota to be more flexible in synchronizing supply and demand and giving dealers only the car colors that they want. In reality, given that both the Camry and Sienna are only available in 10 colors apiece, any advantage may be non-existent. However, the fact that Toyota can effectively paint and build in such small increments could weigh in their favor as the industry moves toward a quick-build, quick delivery pull system. For example, Toyota's arch nemesis Honda builds in comparatively gargantuan lots of 30.

The chief advantage to using water-borne paint is clearly the environmental benefit of the reduction in toxic solvents, but that benefit comes at a price. In addition to the increased purge rate, water-borne material is much more sensitive to humidity changes. Beatty says that optimum humidity for the paint booth is 72% with a window of acceptable variance set a mere +/- 3%. If a malfunction in the automatic humidity control equipment causes an unacceptable spike, an alarm sounds that brings immediate attention lest the body in the

booth need re-painting. If the humidity is too low, the basecoat dries too quickly and loses luster. If it is too high, the water is incompletely flashed off of the body and later boils up through the clearcoat, marring the finish with a phenomenon called "popping."

Incremental Improvements

As is typical of Toyota's. continuous improvement culture, refinements tend to come in small increments in the paint department. One example is a recent switch to an air-assisted nozzle for applying sealer to weld seams. Toyota uses a lot of sealer on its bodies-in-white, and in the past it was all applied in a continuous bead that, often had to be spread by hand. By making the simple change of adding the air-assisted nozzle, which lays down a flat spray of sealer that does not need to be spread, the company was able to eliminate one process and reduce almost a pound of sealer per car for a cost savings of sixty-one cents a unit.

More surprisingly, the paint department has increased the quality of the paint finish by shutting down part of the line. When plant two became operational in 1994, one feature of the paint line was an automatic wet sanding machine.

Primed bodies would first pass through a manual wet sanding area and then move into the sanding machine that would give the body the once over and send it on to a shower of de-ionized water. Toyota's engineers thought that the combination of the sanding machine and the shower would result in a body largely free from the dirt and impurities that are the bane of a uniform finish. However, just the opposite happened.

The machine created significantly more sludge than the manual sanding alone and the shower could not clean it off with sufficient thoroughness. So the machine, which had started out as a technological point of pride, was shut down. And after re-focusing emphasis on better manual wipe down techniques, dirt-related problems dropped.

Back to Basics

TMMK is currently putting a big emphasis on training in an effort to eliminate paint flaws. It has started a program called "Target Zero Seeds" that aims to remove every particle of dirt and dust, known as "seeds," from the bodies before they are painted. To do this, the company went back to basics and re-trained workers in the basic problem solving skills of the Toyota Production System (TPS). It then launched a program called "Practicals of Paint," or POP. Through POP, team leaders from different parts of the paint shop spent time learning the fundamentals of areas outside of their own--including such hands-on exercises as mixing the chemicals used for electrodeposition. Cheryl Jones, general manager of Paint at TMMK, says that the key purpose of this cross-training is to give workers a broader perspective that she hopes will lead to higher quality. On a little less esoteric level, POP also teaches skills like the proper way to wipe down a body so as not to leave any of those inimical little seeds.

What's Next

TMMK will soon be able to put the lessons they have learned while wrestling with the temperamental water-borne process in Plant Two to good use in Plant One. That paint department, which deals exclusively in solvent-based paint, is scheduled to undergo a major overhaul within three years that will give it the capability of painting with both solvent- and water-borne materials. The move is part of a Toyota initiative to convert to water-borne paint systems in its plants worldwide. It will mean reconfiguring the line to add ovens that can flash water from the basecoat, but will also include replacing equipment and robots. This project is sorely needed since, according to Jones, the Plant One equipment is "so old you can't even buy replacement parts on the market anymore." The combination of new, more efficient equipment and the institutional knowledge gained from years of dealing with the water-borne process should further increase the capabilities of the quality leader. And that should make Toyota's competitor s a little nervous.

RELATED ARTICLE: LIMITED PALETTE: LIMITED EDITION

One way to make a statement about the comparative rarity of a vehicle is through the use of exterior paint. Case in point is the just-introduced 2002 Audi TT--the ALMS Commemorative Edition TT, that is. The acronym stands for. "American Le Mans Series," which Audi has been dominant in of late, picking up both drivers' and manufacturers' titles during the past two seasons.

Only 1,000 of the vehicles are being produced. And the cars are being painted with just two colors: Either Misano Red or Avus Silver. (Those who buy the standard coupe can choose from Brilliant Black, Raven Black (pearl), Denim Blue (pearl), Moro Blue (pearl); Aviator Gray (pearl), Desert Green (pearl), Amulet Red, Lake Silver (metallic), or Brilliant White.) Both pearl-effect colors are nicely accented by special 18-in., nine-spoke cast alloy wheels. There are a host of interior features that are special to the ALMS model, as well, such as color-coordinated interiors, with the red car being tricked' out with a silver silk nappa leather interior and the silver car getting red interior material.

(Beneath the special paint, by the way, there is a 225-hp, 1.8-liter, five-valve turbocharged twin-cam engine; a six-speed manual gearbox, and quattro permanent all-wheel-drive.)

Will Audi be painting 500 of each color? No. According to a company spokeswoman, they will be painting batches of each then, depending 'on demand, painting more of whatever color is 'most in demand.

"The ALMS Commemorative Edition TT is Likely to be coveted by enthusiasts and collectors," says Len Hunt, vice president, Andi of America. And we're sure plenty more people would covet it, too-but that's what "limited" is all about.--GSV

The 2002 ALMS TT comes in red or sliver. And only 1,000 will be produced.

COMPACT DISPENSING

Although the Electromatic XVI can apply fluids ranging from adhesives to silicones, fragrances to water, it can also handle coating. This device weighs 15 oz., operates at 2,000 psi, and typically fires at in excess of 1,800 cycles per minute. There's an internal 24-v DC solenoid coil that eliminates the need for additional values. All wetted parts are stainless steel, and because there is just one moving part, high-speed drip-free operation is said to be ensured and maintenance minimized. Fluid can be supplied to the applicator by pump, pressure tank, or gravity feed. It's available from Spraymation (Ft. Lauderdale, FL). To learn more, write in 110 on the Reader Service Card.

SKIP PAINTING

Well, it isn't a case of entirely skipping painting, but 3M Automotive (Livonia, MI) has developed a film that can be used in place of paint on door and window sashes, B-pillars, and other areas of a vehicle. Scotchcal Blackout Film is available in high-, medium- and low-gloss levels and is said to meet OEM specs for durability and performance similar to or greater than requirements for paint. By employing a special fixture, the film can be affixed at production speed. Any flaws detected during application can be simply addressed by peeling the film off and applying a new piece. Fine-Line masking, VOCs, and paint booth are all non-issues. To learn more, write in 111 on the Reader Service Card.

COLOR CONTINUITY

Despite suggestions to the contrary, automotive color choice doesn't change all that much over a person's lifetime, according to Robert Daily, color marketing manager at DuPont Herberts Automotive Systems (Troy, MI). "It's generally accepted that each generation will carry into their retirement years the same desires in terms of houses, clothing, recreation, whatever," he says. "This extends to color. Each generation gravitates to the colors that were hot in their heyday."

One can only hope Daily is wrong, or--judging from some of the cars currently on the street--edgy styling may not be the only surprise once Generation X hits the luxury market. Daily, for his part, is certain good taste will win out. "The Gen Xers, because they're not as affluent at this point in their lives, tend to buy more entry-level vehicles," he explains, "and they tend to be painted in brighter, more primary colors." These colors, he insists may continue to be popular, but will become more muted over time. "Your favorite color today," Daily insists, "is not the same shade as the one you picked when you were six."

Nor are color choices the same around the world. Silver (18.4%), medium gray (17.3%), and white pearl (14.8%) are the top three colors in North America's luxury segment. Yet, 36% of Europeans order silver/gray vehicles, with blue metallic (18%) and black (13%) next. Just 6.0% of European car buyers order a white vehicle. Conversely, Japanese buyers order 43% of their vehicles in silver/gray, 35% in white, and only 8.0% in black. This is a big change from just 20 years ago when 60% of Japanese cars were ordered in white.

"Americans see white pearl as a luxury color, but you'd be hard pressed to find that color in Europe," says Daily. "White is the color for company cars over there." As a result, Daily says it has been tough convincing European automakers to offer the color in North America. Volvo was one of those car makers. Finally, after years of trying, Volvo relented. The Swedish concern has added 2,500 white pearl S80s to its 2002 production.

CAS

THE PROCESS IS KEY

Accurate, efficient application of material is now a defining characteristic of robots for the paint shop. It's not the arm that's important--it's what it can do.

Fanuc Robotics (Rochester Hills, MI) actually has its North American roots in the auto industry: when it began, it was known as GMFanuc with the "GM" referring to, well, GM. What's more, the initial product that really established the vendor in the auto industry was a painting robot. Consequently, one could argue--as Jon Karr, vp of the firm's Paint Shop Automation Group, does--that the company has a solid background in providing paint automation to automotive.

Interesting enough, however, Karr says that today, the emphasis isn't as much on the robot arm per se as it is on the process. The arm is a given; what the arm can actually do is what matters most. So the technical developments in this area tend to be focused on improving the process: painting robots are designed around the dictates of the process. (Yes, this may seem obvious today, but remember that sometimes the apparent glitz of the technology blinds one from seeing the obvious.)

From a macro sense, one of the goals in automotive paint facilities--one that is undoubtedly more critical today than ever before--relates to what Karr calls "economies of application." In other words, there is a focus on putting the paint where it is needed: on the vehicle. Not only does the paint cost money, but it is also expensive to deal with the waste that results when the paint doesn't go where it is supposed to. The process objective is to improve transfer efficiency. One of the ways this is being realized is through the utilization of rotary bell sprayers that operate at comparatively high rates (40,000 rpm and higher) and provide efficient application of the paint material.

Charged Up. One trend that has been gaining momentum over the last several years is the use of water-borne paint. Karr notes that there is a particular difficulty in the switch from solvent-based to water-based, which is that of charging the paint for purposes of electrostatic application. Water is, after all, highly conductive. An apparent problem is that the electrical charge can go up into the system (following the stream of paint back to its source) or that the charge will be dissipated in the fluid. Working with its partner Sames Corp., Fanuc Robotics is offering what's called the "AquaBell," which is a direct-charge paint applicator for electrostatic application of water-borne paint.

The unit has two main components. The rotary bell head and a paint gun voltage block system (called "AccuStat"). The paint is actually contained in a reservoir within the body of the applicator. Because it is contained and charged, there isn't the problem with the charge going anywhere other than where it needs to be. There is also a benefit to this setup from the standpoint of material conservation. The amount of paint material is loaded into the canister based on the specific requirements of the task to be performed. What happens is that the robot positions the AquaBell at a docking station. The gun is cleaned, and then the required amount of paint is put into the reservoir. The robot then proceeds with the painting operation. In the mean time, the control system determines what color will be required next so that it is prepared for when the robot returns with the gun.

On Track. According to Karr, there are two different approaches that are typically used in automotive paint shops: stop stations and line tracking. In European automotive assembly plants, there apparently is a combination of the two: when it comes to painting cut-ins (e.g., inside doors, the decklid, hood), the moving line stops. Karr says that while a paint shop is typically automated., performing cut-in painting is where there are still manual operations to be found. That's because the closure panels need to be opened and closed. So to automate this and to have a moving line it is necessary to have a device (e.g., a three-axis opening robot) that opens the door and a painting robot that "knows" where the vehicle is in space as it moves along and then paints it. Once the painting is complete, then the other device shuts the closure panel. When the vehicle is stopped, this is pretty straightforward. But Karr says that with demands for high hourly throughput (e.g., 50 jobs per hour), the tracking line is the most efficient, especially when the tremendous cost of paint booths are taken into account. (E.g., to get the same type of throughput as tracking with stop stations, it would be necessary to have multiple stations. This means multiple robots, air handling systems, etc.)

Another area where robots are finding application is in repair areas. In this situation, painted bodies are inspected with a vision system. If a flaw is detected, coordinate information defining its location is sent to the robot control. The robot then goes to that position and sands the area in question. The vehicle is then sent to the repair area. Karr says that this system is meant to minimize the number of flaws that might pass undetected when the job is done manually.

And with the continued popularity of pickup trucks, there is another area that robots are finding use in finishing applications: spraying bed liner material into the pickup box.--GSV

BEFORE THE JOB

One of the aspects of robotic body painting that Carl Traynor, senior director of Marketing, Motoman, Inc. (West Carroilton, OH), emphasizes has more to do with what goes on before the task is done rather than during the operation.

Simulation.

Traynor says that the real benefit of simulation for painting is that the process is "path intensive," so it is essential to make sure that the robot arm is traveling along the proper route for efficiency, both in terms of where the arm goes and how it applies materials to the bodies (the right place in both cases means no waste). The MotoSim simulation package, Traynor says, is pretty much a fundamental to many of the robotic applications that Motoman's robots are applied to. He also notes that there are solid connections to the major simulation packages available from other vendors, as well.

When asked about differentiation between Motoman robots and those of its worthy competitors, Traynor cites the extensive laser cutting applications that those robots are applied to: Given the diameter of a laser beam (especially as contrasted to the size of a spray from a bell or a gun), precision location is a must, as is steady by fast travel.

The robot that he cites as particularly advantageous for body applications is the PX 2900 (the number relates to the length of the arm in millimeters). He suggests that the arm length is beneficial in that it probably eliminates the need for an external seventh axis to provide range, even for big bodies (e.g., pickup trucks). By eliminating that external axis, both the complexity of the installation and programming are minimized. Which means getting things done before painting can be expedited.

COAT IT

Looking for a means by which metals can be coated with anticorrosion fluids or lubrication oils, one that is not only precise and uniform but comparatively waste free? The people from United Air Specialists (Cincinnati maintain that the TotalStat system does the trick. It is an electrostatic system, one that uses what is termed "soft spray" technology, as opposed to the harder spray of air pressure-based systems. The system is said to be so mist- and over-spray-free that no fume hoods or exhaust systems are necessary. The system's pump works in conjunction with the speed of the line for the material being coated (thereby assuring coating thickness consistency). To learn more, write in 112 on the Reader Service Card.