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About MAP

Client Profile:
This case study is based on work performed for a wire products manufacturer, who is recognized as the global market leader in this industry. The annealing process referenced in this case study represents the rate-limiting step in the manufacturing process for this client.

Project Objectives:
The objectives of this project are to:

• Maximize the throughput of product through the oven, while still maintaining the desired quality level
• Reduce the amount of time spent performing quality control inspection and testing

Process Description
Steel coils are loaded into sections 1 - 5 in the Staging Zone (green). Once staged, the coils are moved through the Heating Zone (yellow) via a conveyor system. There are 8 individual stages of the Heating Zone as represented by the numbers 2 - 9. The temperature of the Heating Zone is measured in 4 locations on the left and right side of the oven. Once the coils travel through the Heating Zone, they enter the 4 individual stages of the Cooling Zone (blue) represented by the numbers 10 - 13. After cooling, the coils enter stage 14, the Pickup Zone, where they are sampled for QC testing and taken to the next step in the manufacturing process.

Figure 1

Process Analysis
A time & condition study was performed to determine the stage at which the coils achieved the desired quality level. This study showed that the coils attained the desired quality level at stage 6 of the Heating Zone. This finding demonstrated that Heating Zone stages 7, 8, and 9 were wasted production capacity.

Additionally, a temperature study was performed to determine the temperature variation in the Heating Zone from side to side, from stage to stage, and from batch to batch. This study showed that the temperatures were out of statistical control in each case.

Process Improvement Strategy
To bring the temperatures into statistical control, a HMI/SCADA system was implemented to enable the operators to monitor the temperatures and to adjust the temperature settings to maintain the process within a determined temperature range.

Figure 2

Once the temperatures were brought into control, the conveyor speed of the oven was increased, resulting in the coils reaching their desired quality level at stage 9. This can be seen in Figure 1, as the coils do not turn gray until they reach stage 9. Note that the legend at the bottom of Figure 1 defines gray coils as meeting quality specifications.

Project Results
This project required 12 weeks to complete and an investment of approximately $274K. This investment includes professional services, hardware to establish connectivity to the oven, software configuration to provide the human-machine interface that simulates the process, and user training to leverage the computer system to monitor the process. As a result, the client:

• Reduced the annealing oven cycle time by 38%
• Reduced quality control testing by 89%