We've been working for more than a decade with the Detroit Three automakers as part of their continuous quality improvement programs.
One of the more interesting projects we've been involved in is for a sports car assembly line. On this line, data is captured for virtually every aspect of every process, in spite of the fact that automotive assembly still involves lots of manual work.
We designed and implemented the line with their kitting, sequencing, and error-proofing systems, and we integrated automated vision inspection solutions, as well. Finally, we delivered automated work instructions to the operators, and monitor the current status of equipment via factory information systems. The result is that their warranty costs continue to decline while their quality continues to improve, and it's all about teamwork to design the right combination of manual operations, automation, and information infrastructure.
The project began when the automaker was in transition from pneumatic tooling to dc electric tooling. They wanted to have better insight into the manufacturing process and then track quality beyond the plant to create a "life history" for the vehicle. Their ultimate goal was to improve quality through better data. This was especially important with the high-profile sports car that continues to be one of their flagship products.
Tracking technology was implemented to create awareness of vehicle position throughout the entire production process. Where conveyance is involved, software and controls were integrated with the existing conveyance systems. Where there's no conveyance, a robust method of vehicle identification was put in place, such as bar codes, RFID, or 2D pin stamp marking.
Once positional awareness was in place, the next challenge was to interface with the customer's existing scheduling system so that we could generate data about each individual vehicle's parts and processes, from engine to keys. From there, we designed a user-friendly interface at each station so that the operator could easily understand the requirements for each specific vehicle. The Assembly Information System shown in Figure 1 provides that interface.
With positional data fully integrated and available at each station, new configurable software was put in place to make sure that:
- The precisely measured torque is applied before advancing from the station;
- the correct parts are selected through the bar code scanner or vision ID, then installed in the correct sequence and location;
- the correct sports car badging was verified by vision inspection;
- all serialized components (e.g., air bags, tires, key sets) are collected to be traceable throughout the life of the vehicle.
Before final shipment, we had to integrate a final pass-fail system. A user-focused interface was created for the existing gatekeeper system that had previously been used only for manual processes. This system is the final go/no-go vehicle evaluation before shipment.
Prior to automated error-proofing, inspection operators would visually inspect the vehicle and then touch a button to indicate pass/fail. To seamlessly incorporate the automated error-proofing information, a similar operator interaction was designed. The inspection operator's experience didn't change -- the pass/fail button is still in place and the operator still visually provides the final inspection. The difference is that now all of the error-proofing and inspection data is incorporated into their final inspection.
Since the original error-proofing and inspection system was designed, it's been rolled out to all North American sites and is moving internationally. The system's capability has been expanded so that it now interfaces with fluid fills, test systems (inline and end-of-line), headlight alignment, and virtually all other processes that generate data. At this and other customer locations, automated work instructions, torque testing, and error-proofing has been extended into offline production and repair centers.
Kitting and sequencing systems have also been put in place so that each vehicle's specific parts arrive at each station in synch with production. Once parts and part kits are at station, a "smart pick" system minimizes the walk path and operator time to install all required vehicle parts for that station.
The bottom line for the automaker is improved quality. By all measures, vehicle quality has improved significantly, including better owner-measured vehicle experience and lower warranty costs. An additional benefit of a complete error-proofing system is improved efficiency through better line balancing and throughput.
- Greg Giles, a manufacturing execution systems director at RedViking, leads a team of electrical and software engineers to design and execute error/mistake proofing, traceability/birth history, part kitting and sequencing, MES/OEE, and energy management systems. He holds a BS degree in Electrical Engineering from the University of Michigan.