By Jim Kerr
What does it take to make a new car? The answer is hundreds of millions of dollars, years of time and thousands of people. Ford’s new 2012 Focus started rolling off the production line on January 3rd at their Michigan Assembly plant in Wayne, Michigan. Ford spent 550 million dollars converting this former SUV plant into the latest flexible assembly line.
The Michigan Assembly plant started producing station wagons in 1957. Over the years, the plant has built Broncos, F-series trucks and recently, Expeditions. With large SUV demand declining and C-car platform vehicles such as the Focus leading the way in new car sales, the writing was on the wall for this aging plant. Two years ago, the transformation started. The interior of this 2,866,000 square foot building was gutted; last year, an empty building stood on the 140 acre site but things were far from quiet. Five hundred and fifty million dollars later, this facility incorporates the latest in both assembly line design and procedures.
Today, you see a bright, modern facility with the latest electronic controls and aids. It starts in the body shop, where the flexible manufacturing process enables several different body styles to be built, one right after the other. The plant will start production with the 2012 Focus, followed later in the year by the Battery Electric Focus. Other body styles of similar size will be added in the future.
To accomplish this flexible assembly, programmable robots are used to align and weld the body structure. Each vehicle and sub assembly is given a bar code and each is scanned as it reaches the line. When a vehicle body moves to a welding robot, the scanned information tells the robot exactly where to place the welds for that particular body design. As parts are added to the vehicle during the assembly process, the computer information is used to ensure that the correct parts, options and colours are used for each specific vehicle.
More than 80 per cent of the robots can be programmed for different procedures at a moment’s notice. The location of sheet metal is done with programmable locators and clamping. Several robots, about the size of a small breadbox, grab side panels and clamp them together within a fraction of a millimetre before the welding starts.
After the body structure is together, along with doors, hood and trunk, it heads off to the paint shop. Ford is using a new state of the art 3-wet paint booth system where primer, colour coat and final clear coat are all put on wet in one booth right on top of the previous wet coat. This process is not only quicker, it reduces emissions too.
As the bodies move down the line, equipment automatically changes height to optimize worker ergonomics. Every process is standardized to reduce errors and electric power wrenches are used to tighten bolts and nuts. Computers at each station monitor the number of tightening turns and torque applied to each fastener and if something isn’t correct, the line stops so corrections can be made immediately.
Inspections are a key part of the assembly process. Every vehicle goes through an air leakage test, where air is pumped into the interior and through an access panel over the rear side window. A 59 litres/second flow rate is the maximum target, and this test checks for proper sealing weatherstrips and body gaskets. Every car also goes through a 20 minute water test where the car is literally drenched while a technician inside inspects for water leaks before interior panels are installed.
Another test station puts the car on dynamometer rollers and tests for transmission shifting, engine operation and acceleration and vehicle braking, including the park brake. Final paint inspection occurs in a “light tunnel,” where hundreds of special fluorescent lights show any imperfections on the body surface. Inspections and testing occur throughout the assembly process.
The whole assembly line transformation was designed virtually. Computer-generated equipment, people and parts simulated every process and movement down to the fraction of a millimetre to ensure it would work efficiently when the actual physical operation started. Processes like that make this assembly line now the state of the art in vehicle manufacturing.