TG Missouri manufactures interior and exterior injection molded products such as body side moldings and interior components for automotive applications. It also provides steering wheels and air bag systems. TG Missouri needed to not only reduce defects in its assembly of a "cluster", (which consists primarily of a car's dashboard spring doors and a cupholder), but also to increase its parts per minute output. With so many different components to be assembled with such speed, even with close supervision, mistakes were too common. To have a mistake-proof assembly process was an important need to achieve the company's quality goal of 0 PPM.

Training on the poka-yoke system at the TS Missouri plant.

The company received some help from Omron Electronics LLC. Omron introduced a new solution to the process, called poka-yoke, which counts the number of times an assembler puts a hand into a parts bin.

Pick-To-Light Process

The poka-yoke process features the F3W-D Pick-to-Light Sensor, which acts as a short light curtain or array sensor to count hand insertions. In addition to making sure the proper number of parts has been removed from each bin, the sensor can provide a training function used in conjunction with an operator interface terminal such as Omron's NS-Series.

Each of the parts bins on the system has a sensor on it to provide accurate assembly.

By showing the order of parts to pull, how many and where to place each one, the system can keep track of proper and improper actions like a video game. The assembler can be trained quickly to build several kinds of parts with a high level of accuracy. Errors can be fixed at the source with little additional time or resource, leading to an overall cost savings at the end of the process.

Three-Week Implementation

After TG Missouri decided to implement the poka-yoke solution, the entire system was completed and installed in three weeks. The system worked so well and helped TG Missouri meet its goals that the company signed on immediately for two more systems. Seeing the final numbers proved to TG Missouri the project was effective.

An interior dash component made by using the poka-yoke system.

"I'm excited about these new systems," says David Buxton, a machine engineer at TG Missouri. "Operators love the new poka-yoke system and this solution is a big step toward what we'll do in the future regarding defects."

The poka-yoke process is designed to be one of the most simple and effective ways to mistake-proof manual assembly processes. In addition it is designed to address the trend of more assembly functions being transferred to countries with lower labor costs. That means many companies are looking for new ways to mistake-proof their processes to prevent a drop in product quality.

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