Manufacturing ERP Software
Manufacturing Processes—Production and Business: The Interference Diagram, Part 4

Manufacturing Processes—Production and Business: The Interference Diagram, Part 4

By Bob Sproull

Review of The Interference Diagram, Part 3

In my last post, I detailed steps 3 and 4 for constructing an Interference Diagram (ID). In step 3, our task is to quantify the time component for all interferences in order to emphasize those items with the greatest impact. This also helps us to determine a sequence of interferences to eliminate. In step 4, we formulate a list of obstacles and interferences in order to develop alternatives. We show how we can counter their negative effects with a corresponding list of Injection/Intermediate Objectives (IO). I finished the post with a figure of the Interference Diagram.

interference diagram 1

In today’s post, I will continue this lesson and then construct an actual Interference Diagram. As I have mentioned before, much of what I will present in this series is taken from one of my books, [1] Epiphanized—A Novel on Unifying Theory of Constraints, Lean, and Six Sigma, co-authored with Bruce Nelson.

Charting and graphing provide the visuals we need to understand interferences

To refresh your memory, here are the interferences/obstacles defined in our example, with a column added showing the time lost to each interference:

Obstacles/Interference Intermediate Objective/Injections Time Lost

1. Parts not available to work.

1. Parts are kitted and ready for use.

75 min/day

2. Operator on break/lunch.

2. Train an alternate crew or person.

60 min/day

3. Operator has to find his own parts.

3. Parts delivered to operator.

90 min/day

4. Operator is looking for the supervisor.

4. Supervisor notification system.

45 min/day

5. Operator is looking for paper work.

5. Paperwork follows job in the system.

30 min/day

6. Machine is broken.

6. Preventive maintenance (Priority #1).

30 min/week

Figure 2 is our completed Interference Diagram for our example. The circle contains the objective and each of the interferences is listed around a circle.

interference diagram 2

Figure 2: Completed Interference Diagram (ID)

Notice that the time impact has been added for each interference identified. To recap what we have accomplished up to this point, we have shown the interferences hindering us from producing more product from our process and shown the extent to which they are a hindrance.

Coming in the next post

In the next post, I will complete this series on the Interference Diagram by explaining how we will use the information we have collected. As always, if you have any questions or comments about any of my posts, leave a message and I will respond.

Until next time.

Bob Sproull


[1] Epiphanized—A Novel on Unifying Theory of Constraints, Lean, and Six Sigma,2nd Edition, by Bob Sproull and Bruce Nelson, CRC Press, 2015.

Bob Sproull

About the author

Bob Sproull has helped businesses across the manufacturing spectrum improve their operations for more than 40 years.

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