Monday, May 24, 2010
An Important Form to Speak with Data
One of the most useful forms for recording and presenting data, for speaking with data, is the production control form. I am including a sample here.
This form tells us how a production line, a production cell, or a single production operation is running hour-by-hour. When used to its greatest advantage, a manager or supervisor can walk through a department and tell very quickly what operations most require attention. The leaner the operation, the more critical this information can be. The information is recorded each hour by a production operator.
In the example above, the first column divides the day into one hour blocks. In this case, we have started at 7 a.m. and carried it through 4 p.m. The information in this column can be modified depending on the start time and the length of the shift. For example a ten hour shift would have a couple more rows. The form can have extra rows to be used when the operation is running overtime. A chart for second or third shift would have appropriate time labels in the first column.
The second column is based on takt time, the beat at which we produce to synchronize production to the customer’s demand. The example here is a takt time of 30 seconds. Two units every minute, thus 120 units in a full hour.
In the 8 – 9 hour there are only 50 minutes of productive time because there is a ten minute break. Only 100 units are planned for the hour. The 11 – 12 hour has a half hour break for lunch, so the planned production is only 60 units.
Widget production went very smoothly for the first two hours. We made seven widgets above plan. If we had made a lot widgets above plan in these two hours, we would need to question whether we have appropriately adjusted our cycle time to takt time. Do we have more people than we need on this operation? Is quality suffering because the operation is running too fast?
The chart shows us that we took a big hit in the fourth hour (10 – 11). We were 72 units below plan. In the notes column we see that there was aproblem with the crimping machine. Do we need to follow up on this? Has this failure been permenantly solved, or do we need to take steps to insure that it does not happen again?
We also have an opportunity well before the end of the shift to evaluate possible consequences. We are not going to make our goal for the day of 920 widgets. How critical is that? Do we need to take steps to make sure we meet that goal and do not harm the customer (including downstream operations that might be shut down for lack of sufficient widgests)? Should we start planning to schedule overtime this afternoon now?
In this case, we decided to schedule overtime tomorrow. We had time to reach that decision well before the end of the shift. We did not discover that we were 86 widgets short at the last minute.
We lost another 20 widgets of production in the seventh hour (1-2). This was not as drastic as the loss in the fourth hour. We do have documentation and can ask similar questions to those we asked about the earlier downtime, to determine what we need to do to prevent recurrence.
How do operators like using this form? Initially, there may be resistance. Operators may fear that the form is going to be used to judge them, blame them, and control them. The form’s purpose is to track how the production system is working. People are one part of the system, but we also can get timely information about problems with equipment, materials, production methods, and communication of information.
If the organization has a tendency to blame operators for every problem and to try to overcome each problem by demanding that they work harder and faster, it will be difficult to persuade workers to provide accurate and precise information on this form.
For some organizations, lean thinking is radically different from the present way of thinking about production. We do not ask workers to produce as much as they can. We as them to produce just-in-time, exactly what is needed, when it is needed. Takt time is a tool to help us do this. The Production Control Chart is a tool to help us do this and to solve problems in the work system with data, rather than hunches.
The application of tools and techniques does not lead to lean, world class operations by itself. Lean production requires lean thinking. Lean thinking is non-blaming. The workers in the core process, where value is added to the product are to be supported. They are not expected to do the best they can. They are provided the means and assistance to do their work better.