Are You Collecting Enough Data?

Does the data from the machines on your shop floor answer the top 3 questions?

1. What is my production WIP?
   • Is it an approximation or an exact count?
   • Do you know how much WIP is in each step of the process?
2. At which step in the process is spoilage occurring?
   • Is it a generalization, or do you have visibility into each unique step in the process?
3. What is my OEE?
   • How accurate is your OEE?

Improved data collection leads to more valuable insights.  Data is collected with cameras, sensors, and PLCs.  It is important to get visibility into your line at the right locations, so data is complete and meaningful.

Here we are using an example two-piece can making line and discussing:

• Where sensors should be placed?
• What information can be provided with additional sensors?
• Attributes to monitor by machine type (e.g., Cuppers, Bodymakers/Trimmers)

Two-Piece Can Line Example

First, you need to know where there is already visibility into your line.  Where are your sensors?

In this example, the line is currently running with only 2 sensors (the green dots).  What would be the benefit of adding 15 additional sensors, or even 20 additional sensors?

Current Visibility Sensor Locations (2 sensors)

• Current sensing locations will allow you to calculate rough estimates for OEE.
• You can group sections of production equipment and count machine cycles, but you will not have complete visibility on each unique step of the process.
• Work-in-process (WIP) could vary wildly by approximation.
• Loss through much of the process will be completely unknown.
• You do not have accuracy in determining where the loss occurs with the current setup, but only a general awareness of what section it may occur in.
• There is no way of knowing exact WIP counts.

Critical Visibility Sensor Locations (15 additional sensors)

• Counting product outfeed at the end of each product that could potentially create spoilage or hold a significant WIP would provide machine-level OEE and supports bottleneck analysis.
• Using machine cycles and some logic additions, you can get a much higher resolution on where the product is located throughout the line.

Complete Visibility Sensor Locations (20 additional sensors)

• By placing a sensor at both the infeed and outfeed of all machines, you have complete visibility into every step in the process. This allows for a complete OEE calculation on every piece of equipment and full awareness of WIP between each machine.

NOTE:  One complication is the wider conveyors that could be conveying many cans in a row. Traditional sensing methods cannot be utilized effectively in these areas; therefore, a more complex sensing method, such as vision cameras, may be required. Or, a simpler option is to track infeed and discharge per machine immediately before and after wider conveyors.

Example Attributes To Monitor By Machine Type (Cuppers, Bodymakers/Trimmers)

With the sensors collecting data, here are some of the attributes which can be monitored.

With this information, the questions asked at the beginning of this article can be answered with confidence.