by Jim Kerr
For anyone interested in automobiles, the vehicle assembly plant has to be a source of fascination. Behind the security fences and inside huge buildings, a synchronized ballet goes on almost around the clock. General Motor’s truck plant in Oshawa is one of three assembly plants in North America building the Chevrolet Silverado and GMC Sierra pickup, and the Oshawa plant is the lead plant for production of these vehicles. Here’s a peek inside.
No matter how well prepared one is, the first sight inside the plant is overwhelming. Over three football fields in length and covering 3.1 million square feet of floor space, the building is filled with motion in every direction. Narrow transport lanes separate the assembly line into sections. Forklifts move pallets of parts in a continuous stream from receiving docks to line stations and “just in time” delivery of parts means there is seldom more than a few hours of parts sitting in stock.
Moving silently on one of hundreds of Automated Guided Vehicles (AGV’s), the truck cab rests on the AGV’s base, while the truck box sits above it. The doors are somewhere else, and workers at each station are installing assemblies into the cab, but I am getting ahead of myself. The real assembly starts with a shower of sparks shielded by amber curtains.
In a far corner of the plant, the raw sheet metal stampings are welded together to make the body of the truck. Almost completely welded by 490 robots, the body construction zone is compact and too busy to walk through. Only line maintenance personnel and robotics operators enter here. This complex part of the plant is where a truck begins its life. With the body welded together, inspectors scrutinise the panels for flaws before they move off to the paint plant. Everything for the truck is painted at once: doors, hood, fenders, box, tailgate, and cab move as a unit through several stages of prep and finishing before re-entering the assembly line. Because paint finishes can be damaged by dust, hair, and chemicals, everyone has to pass through a clean room and be suited up before entering the paint line. Because of this rigid quality control, few people ever enter the paint plant.
While the bodies are being painted, work goes on in the chassis and powertrain lines. Bare frames sit upside down on one of 165 chassis AGV’s while the suspension, drive axles, fuel tanks and exhaust system are installed. Overhead cranes lift the heavy components, while workers guide them into place with an ease that only comes from thousands of repetitions. Once the chassis is assembled, the AGV moves to a huge two story behemoth that picks up the frame, turns it over, and sets it on the AVG again ready for engine, radiator, and headlamp installation. Engines pass down the “dressing” line where accessories and transmissions are installed before setting them into the chassis. Then on to the “marriage” station. Here, a machine larger than a house sets the cab and box gently onto the chassis for the first time to become a truck.
Before the bodies are set in place, dashes, windows, seats, and all cab electronics have been installed at stations on the body assembly line. Doors have gone their separate way to be completed, and meet up with the body again later. Down the final line, wheels are tightened with automated torque wrenches and the fenders and hood are bolted on. Finally the side mouldings and decals are installed before the fuel tank is filled and the truck roars to life.
Before the final inspection, the trucks are driven onto rolling wheel aligners for steering adjustment and headlight aiming. After that, everybody is an inspector, ensuring the truck meets GM’s and our expectations.
It takes 21 hours from the time the first weld is placed until the truck drives out the door ready for delivery. During this time, over 2000 different part numbers have been installed on the truck by 3500 people working in three shifts.
The assembly line is a choreographed chaos that sees each truck built to a unique order. It is absolutely amazing that all the parts for each truck are sitting at the right place and installed at the right time, but it happens to over 1300 vehicles a day at this plant alone. That is the fascination of the assembly line.