…Manufacturing a Car is Easy…
On my trip to Europe, I had an opportunity to tour the BMW plant in Regensburg.
When I retired from General Electric, the factory of the future was floundering. The person responsible for developing the factory of the future had a vision, but was frustrated by the myriad of details that had to be overcome before the vision could become a reality.
Regensburg demonstrated that the factory of the future has arrived and that the millions of details that befuddled my associate had been confronted and resolved.
The Regensburg plant produces 1,400 cars each day and makes around eight different models intermixed with each other.
While we didn’t tour the stamping plant, a video showed that automation was primarily in the form of robotic transfer devices, from the automatic loading of sheet metal into the shears and presses, to moving parts from one press to the other.
The engineering behind metal forming was resolved long ago, with dies that form sheet metal to the required dimensions that create the fit and feel of a finished automobile. Handling the thousands of pieces that eventually make up a finished automobile was the primary automation challenge.
Bringing together the thousands of pieces of metal into sub-assemblies, and ultimately into the complete frame of the car, is where robots have taken over virtually all of the required operations.
This is where the attention to details is essential.
Two details are critical.
- Each part and sub-assembly must be moved to a precise location by the robot, so that the x,y,z location in space of each location to be spot-welded is known within thousandths of an inch.
- The sequence in which each spot-weld, or other operation such as drilling, is performed must be predetermined so that the robot arms do not hit any part of the frame or collide with each other, and so the opposing electrodes of the spot welder can slide into position with the metal between them.
This information is essential, so that the motion and actions of each robot, which could potentially be dozens of robots, can be precisely programmed.
The assembling of the frame by robots has been likened to the choreographing of a ballet. The intricate motions of the robots as they move in and out, twisting and turning, is much like the movements of dancers in a ballet.
The assembled frame, with metal doors, hood and tailgate in place, is dipped into paint vats, which could be fluidized beds, with the frame and parts electrically charged so the paint, or coating, adheres to all the nooks and crannies of the metal.
The frame, with the initial coats dry, is moved into booths where robots apply the final coats of paint.
Painting operations may be the most difficult to program as the robot arm must be able to twist and turn to reach every internal and external surface of the frame, with dwell times that will ensure sufficient paint is applied, but not so much as to create sags or runs. The paint is electrostatically charged to help ensure complete coverage.
When drying is complete, the doors are removed and automatically moved to where they are assembled with windows, etc. Each door is identified so that it can be married in final assembly to the frame on which it was painted.
The interior of the body is assembled by inserting preassembled components manually, using fixtures and mechanical assistants to help reduce worker fatigue. For example, the wiring harness is preassembled and delivered in a package so that it can be inserted into the channels provided for it in the frame. The dashboard, seats and interior finish, etc, can be inserted at this time.
The chassis is assembled separately, with the suspension system, axles, brakes and internal combustion engine.
The body is then married to the chassis.
The vehicle moves down the assembly line where all the final components are inserted and the vehicle is given final tests and inspection.
Components specific to a model are delivered to the assembly line just in time to match the model for which it is intended. The doors, for example, removed after painting for assembly of the window, etc., arrive at the final assembly line to be married to the frame from which it was removed after painting. The correct wheel type arrives for the model being built. Precise fluid levels are added automatically depending on the model.
All of these variations and just in time features would not be possible without computers.
The factory of the future has arrived. Now, it is only necessary to perfect the factory by examining each remaining operation performed by humans to determine whether they could be done by robots.
Many workers have been replaced by robots, but a large number of programmers have been added to program the robots to perform the many intricate motions required for manufacturing a car.
Some operations continue to be done by humans, and this is likely to continue for two reasons. The dexterity and feel of human hands may be superior to the ability of robots to perform an operation, or, the cost to replace the human with a robot may exceed potential savings. An example might be the installation of weather stripping along the doors or tailgate.
The difficult part is setting up the factory to begin with. Once it is set in motion with everything working, manufacturing the car is easy.
All of the above has implications for battery-powered vehicles and Tesla. This will be discussed in the next article.
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There are many facets to manufacturing and the reader should have confidence in my ability to comment on the factory of the future.
I spent three years on GE’s manufacturing management program (MMP), with hands-on experience in each of the disciplines associated with manufacturing, i.e., production control, manufacturing engineering, factory supervision, materials management, purchasing and quality control.
I have had experience with processes from Therbligs to flame spray, and have probably toured a hundred factories. For example, my first assignment on the MMP program was to set up the shaft and commutator core manufacturing line for DC motors in Erie, Pennsylvania, involving machining, grinding and polishing. I was later a Unit Manager of Manufacturing involving flash welding, spot welding and painting.
Toward the end of my career, my operations experimented with robots to perform welding and grinding.
My summary of the visit to the BMW plant in Regensburg addressed some of the highlights and important distinctions between yesterday’s manufacturing plant and the factory of the future, which now largely exists.