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Global Economic Report

Roberts invade Czech Republic

By Russ Olexa

In the 1970s and '80s autos from the former U.S.S.R. that included what is now Eastern Europe were at best of dubious quality, mostly because the design, engineering and manufacturing technologies were stuck somewhere in the '50s.

For Skoda Auto, one of the only surviving auto companies in the former U.S.S.R. located in the Czech Republic, auto manufacturing is as cutting edge as it gets. In fact, the company, wholly owned by VW, has been invaded by robots, over 500 of them, which are now a major part of assembling a car to assure high quality.

Even though labor is inexpensive in the Czech Republic, where the average auto production worker makes from $600 to $1,000 per month, automation is important in keeping quality high at Skoda and gives the company the flexibility it needs to easily change models when marketing demands it.

In Mlada Boleslav, about 50 km north of Prague, Skoda has a manufacturing campus reminiscent of Henry Ford's original factory system where just about every operation was centralized in one massive area. The company even produces its own engine blocks at a foundry onsite and offers housing to its employees. They have two other manufacturing facilities not on the central campus but still in the Czech Republic. It also has plants in India, Ukraine, Bosnia and Herzegovina, and Kazakhstan, and is active in nearly 90 countries throughout the world including China.

With 26,742 employees, Skoda builds four different models: Octavia, Roomster, Fabia and Superb, several of which have a resemblance to VW models. In the late 1800s the company was started by Laurin and Klement bicycle builders located in the same city. In 1905 Laurin and Klement built its first car called the Voiturette A. Later the company merged with the Skoda machinery manufacturing company and went public.

In November 1989, Czechoslovakia regained its political independence through the peaceful "Velvet Revolution" and became autonomous of the U.S.S.R., and on Jan. 1, 1993, the country amicably split in two, creating the independent Czech and Slovak republics. In 1991, VW bought a controlling interest in Skoda, eventually owning the company through successive stock purchases in 2000. In 2005 the company produced 492,111 vehicles. All metal parts are produced by the company, while plastics, seats, wheels and tires are handled by outside suppliers, one being the U.S. company Johnson Controls. The company also invites its suppliers to locate within its campus area to keep part flow to an absolute minimum, following the tenets of lean manufacturing that the company embraces.

Stamping/blanking operations
To build its cars, Skoda starts with coiled steel stock either blanked and then stamped or blanked and stamped in a transfer or progressive press operation at its facility in Mlada Boleslav. At Skoda they have some of the latest equipment for both transfer and progressive stamping operations. Because of the company's adherence to lean manufacturing tenets, the stamping area is so clean that you could probably eat off the floor. Cleanliness is crucial along with keeping dies at the ready and class-A body parts ding free during transportation and ready for secondary operations.

All Skoda body panels are galvanized, even ones that are above the belt-line of the car. Some automotive companies would instead use a tailor-made blank to cut the expense of using a fully galvanized part. The only parts that are not galvanized are some stamped sheet-metal components that are internal to the body and will never be affected by the elements.

At one stamping facility on its campus, Skoda has 35 mechanical presses for body parts arranged in six stamping lines. It also has one automatic line, five manually operated lines, two transfer presses, six machine table shears, one washing machine and one baling press. At another location on the campus, they also have two heavy-duty press lines that use in-die transfer tooling with vacuum fingers to pick up stampings, two transfer press lines, two hydraulic presses, one notching line and one set of table shears.

One of the transfer press blanking lines uses a German-built Schuler 6,600-ton press. Another 3,000-ton transfer press is a German-made Muller Weingarten that runs at 22 strokes per min. All presses that are located on the main stamping facility are mechanical, but the company does have several hydraulic ones at another area of its facility.

On one of Skoda's progressive press lines, coil is washed, straightened, inspected and blanked at 60 strokes per min. Blanks are either stamped or sheared depending on the shape. They are then palletized and stored for just-in-time (JIT) delivery.

Skin panel metal thickness is either 0.6 mm or 0.8 mm while reinforcements for the frame are made with material up to 1.2 mm thick. The majority of the steel coil stock is galvanized except for some used for internal body-structure parts.

Karel Redlich, production manager, says that the company strives to do lean manufacturing and has developed a 15-min. die change for even its largest 30-ton die sets by using the same size bolsters, quick-disconnect die-attachment systems and other equipment that allow fast changes. Up to four die changes per day are accomplished. Usually one production batch creates enough stamped parts to build cars for up to six days.

For class-A surface parts, die cleanliness and oil placement are critical for an acceptable stamping. Operators in the stamping area work two 12-hour shifts per day.

As being part of the VW group of automobiles, the basic sub-chassis for each Skoda model is produced by VW at another manufacturing facility, usually in Germany. Sub chassis are delivered to the Mlada Boleslav factory and married to different sheet metal to produce the various Skoda models.

Robots invade
At one of the body production shops at Skoda, over 500 robots are used for everything from laser welding/cutting operations to handling cameras to check welds and body part fits. The facility has over 110,000 sq. m. At this plant they do the laser soldering for the Skoda Superb model's roof.

Robots also give Skoda flexibility in producing the different model configurations for each car. For instance, Skoda's new Octavia has 50 variants, such as hatchback, with or without a sun roof, and notchback. This model alone uses 222 robots, producing 97 percent of the car at this facility.

Keeping it together
Skoda uses three different methods of joining sheet-metal pieces together to form the body shell: clinching, laser welding/soldering and spot welding. Clinching is a mechanical fastening that eliminates the weld spots that are produced by joining the two pieces of metal together. During spot welding the zinc is burned off the metal causing it to be prone to corrosion even after painting, because the paint doesn't adhere well to the area. "But a clinched joint isn't as strong as a spot weld and you need more of them," says Pavel Richter, manager of the body shop.

In a unique operation that brings together the two large side panels and the roof of the Superb for joining, the parts are mechanically clipped together. Robots are then used to align the parts to a specified tolerance instead of employing a jig system. This allows Skoda to have flexibility in joining sheet metal together and different variations of the car. Also the company no longer needs the time to set up sheet metal in a positioning system and has eliminated it altogether. They have found that robots have the accuracy to precisely place the parts together. For the roof attachment, instead of laser welding the three stamped sheet-metal sections together, they are soldered together using a copper solder fill strip in the joint.

For this laser soldering operation, a Trumpf HL3006D pumped-diode YAG laser resonator is used. The laser beam is linked to the robot using fiber optics.

After soldering, the joint is cleaned by a robot using a metallic bristle brush and then checked using a robot with a video camera system that verifies that there aren't any minute holes or pits in the seam larger than 0.2 mm. If any are found, the car body is pulled off line and sent for rework. Later, when the car goes for paint, the seam is covered with polyurethane.

There are a number of reasons the company solders the roof together rather than laser welding it. The area is visible and Skoda requires the best surface quality to have the juncture invisible when the car is completed. Soldering can offer this. Because of a loss of material in the juncture if it was welded, welding without adding material to the area wouldn't provide the best surface quality. Because of this, a simple welded juncture would have to be covered in the roof gutter channel, increasing material costs.

Also, soldering easily provides the necessary water tightness that welding wouldn't. What's more, if the zinc coating on the metal varies, it can adversely affect a weld joint. Soldering allows joining together coated steel parts of different steel thicknesses (if the metal should vary), and the copper solder provides a rust barrier where an exposed welded joint would have its zinc coating burned off during the welding process causing it to be prone to corrosion while also leaving pores or gaps. The technique offers better overall appearance of the sheet metal.

VW supplies all the chassis for Skoda. With all the various models, the company found an unusual technique to get a perfect bumper match for each car. After the body is almost entirely assembled, there is a structural boxed frame member that is part of the chassis in front of the car. The boxed frame member is purposely left longer than needed so it can be cut and adjusted to properly fit the front bumper system.

On the top fender above the boxed frame member, there is a hole that is placed in the fender's flange area where it attaches to the inside wheel-well sheet metal. A robot using a camera optically aligns this fender hole with the boxed frame and communicates using ultrasound to another robot on how much of it to cut off to align the front bumper attaching point. Two robots come into the frame area, one on each side, and laser cut the boxed frame. Then a bumper attachment support plate is added over each cut boxed frame member. Finally the support plate is laser welded using robots again. This allows a perfect fit for the bumper system on the car. In fact, with this system, the defect ratio in the process is an ultra-low 0.3 percent.

Even the eight holes for an optional roof rack are cut by robots for a precision fit. Later a vacuum cleaner run by a robot cleans out any dirt in the holes.

Keeping up quality
After spot welding by the robots, welds are manually checked for quality using portable ultrasound equipment by Skoda workers. This eliminates the need for destructive testing devices.

And once the bodies are fully assembled, one out of about 20 are pulled offline and checked for proper fit either using a DEA comparator system that checks the entire body or a contact-less photo camera system that does a point cloud of specific dimensions between sheet-metal parts, comparing it to CAD drawings for proper dimensioning.

Even though Skoda has the capability to measure 100 percent of its car bodies, the company, as most manufacturers, relies on its manufacturing process to keep everything in tolerance and only checks one out of 20 bodies unless the part-to-part dimensions start to trend out of the given tolerances. Richter says that there are only "five to six relevant dimensions" that are critical on the bodies at this phase of construction.

After the body is constructed and checked, it goes to the paint shop for primer and finish color, then on to other areas for completion.

Karel Porkorny, corporate communications, mentions that VW has had a great influence on the manufacturing technologies at Skoda through the years. Asked why would VW want to invest in a car company that has very similar models, Porkorny says that VW wanted an open door into Eastern Europe and an area that had inexpensive labor rates. But still, VW believes that to get the needed car quality, advanced technologies must always play a part. FFJ

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