By Winston P. Ledet
The Manufacturing Game
We have spent considerable time in the Manufacturing Game newsletter focusing on the benefits and execution of the precision domain - removing the defects at the source (Figure 1). Our philosophy has evolved based on working with clients and modeling reliability; most organizations would be advised to focus first on eliminating defects and then on making the defect removal process more efficient with a planning and scheduling process. However, there are significant benefits to the Planned Domain and this article focuses on the specific benefits that are generated through the Planned domain and the keys to a successful transition to the planned domain. Using our Dynamic Benchmarking model and data from a hypothetical chemical plant we modeled at DuPont we were able to calculate the benefits.
The Model
The model represents a chemical plant that has a replacement value of $444 millions. The plant employs 91 mechanics who complete approximately 500 work orders per week. The plant operates at an average of 83.5% of full capacity but could sell more product if the plant ran better.
The model was built during a one year process and contains dynamic relationships that characterize the maintenance operation. The data for the model was drawn from internal DuPont reports, benchmarking studies, maintenance literature, interviews, and managerial judgment. The model is organized around the flow of equipment. The equipment can flow from a state of full functionality into either the Breakdown or Planned maintenance process. Equipment enters the Breakdown maintenance process when it breaks down and remains there until it is repaired. Breakdowns are caused by equipment defects that are introduced by the operation of the equipment, poor materials, poor design, or poor workmanship. The time to repair the broken equipment depends on the number of mechanics allocated to Breakdown maintenance and the productivity of the mechanics in executing repairs. Equipment moves into the Planned maintenance process when an inspection identifies a defect in the equipment. Some of the equipment inspections are required by law and are mandatory. Other inspections, typically those involved in a predictive maintenance program, are discretionary in the sense that maintenance managers determine their frequency. The inspections are valuable because they identify problems before the equipment suffers a costly breakdown. Scheduling involves setting a time when the equipment can be disconnected from the manufacturing process flow so that it can be worked on. A poor Scheduling process can cause a disconnect between inspections and repairs. Once it is taken off-line, the defective equipment can be repaired. The time to complete Planned maintenance depends on the number of mechanics allocated to Planned maintenance and the productivity of the mechanics in completing the repair. Planning is one of the factors that effects the efficiency of the mechanics in completing Planned or Breakdown maintenance. Planning refers to the process of creating an explicit plan for doing a specific task, planning increases mechanic productivity by standardizing work practices and by making sure that the materials and necessary skills are available to finish the job.
In the base case simulation, the plant does mostly Breakdown maintenance. There is almost no manpower allocated to doing discretionary inspections or to creating job plans, the maintenance strategy can be described as reactive in the sense that the maintenance organization reacts to breakdowns instead of preventing them.
Results of the Modeling
In this section, three of the maintenance programs are implemented in the simulation model. The results of the simulations are compared to the reactive maintenance strategy that is used in the base case simulation. Although the model generates a variety of performance measures, for simplicity, the simulations will be compared on the basis of plant uptime. Using other measures, such as net present value or cost, to compare the simulations does not change the basic results.
1. Planning
The first simulation implements more extensive job planning. This policy is implemented by increasing the number of job planners by reallocating seven mechanics to planning and by adding a library of plans. The library increases the productivity of the job planners by making it unnecessary to create a new plan for every job.
The rationale for increased planning is straight forward. More planning increases mechanic productivity. Higher productivity reduces the time to repair equipment and increases equipment uptime.
Just as it was in maintenance at the plant sites, the result of adding planning in the model is disappointing. Uptime increases by only 0.5%, which would not be measurable in the plants.
There are two reasons why the planning program is unsuccessful. First, in the reactive case, most of the work is breakdown work. By definition, breakdown work is difficult to plan and adding planning has a small impact on the efficiency of doing Breakdown work. Turning mechanics into planners is wasteful if the plans don’t add much to productivity. Second, with a reactive strategy, the plants are typically overstaffed and there is not enough work to do on a day-to-day basis. Improving efficiency in their work causes mechanics to complete work faster when work is available but also lengthens the gaps when there is no work available. The net effect is a very small increase in mechanic productivity and uptime.
2. Scheduling
The second simulation implements a more efficient scheduling system. The first element of the scheduling program is to shorten the delay between the time a defective equipment piece is identified and the time it can be worked on. The second element of the program is to improve the scheduling system’s memory. When a piece of defective equipment is identified often no action will be taken on it immediately because operations needs the equipment on-line. In this situation, the scheduling system may not remember that the equipment was defective unless there is an explicit record keeping system. The second element of the policy implements an efficient record keeping system.
The rationale for the scheduling policy is straight-forward. Better scheduling should increase the efficiency of Planned maintenance and lead to fewer breakdowns. Fewer breakdowns increases uptime. However, the results of the scheduling policy are disappointing. Up time increases by only 0.8%, which would be imperceptible at the plant.
The scheduling program fails because, in the base case, the plant is doing very little Planned maintenance. Breakdown maintenance, which is most of the work in the base case, is by definition unpredictable and almost impossible to schedule. The scheduling policy does very little to improve the efficiency of Breakdown work.
3. Predictive & Preventive Maintenance
In this policy, the frequency of equipment inspections is increased, in the base case, the frequency of inspections was one every twenty weeks on average. In the predictive and preventive program, the frequency is increased to one every two weeks. More inspections should identify equipment defects before they cause failures, fewer failures should directly increase uptime.
The predictive and preventive program is counterproductive as uptime falls by 2.4%. This surprising result is caused by the interaction of several factors. First, increased inspections draw manpower away from repair work. This would be fine if the inspections resulted in repairs that prevented breakdowns. Unfortunately, many of the inspections find defects but, without an efficient scheduling system, the inspections do not result in equipment repairs and the equipment fails while it is waiting to be scheduled. The man-hours spent on inspections are wasted for the lack of a good scheduling system. Second, some of the inspections do result in repairs but without a planning system, the repairs are done inefficiently. This increases the time to repair which decreases uptime.
4. Synergy between Policies
The analysis presented above suggests that there should be strong synergy between the maintenance policies. Model simulations reveal this to be the case. The combination of planning, scheduling, and predictive and preventive improves uptime by 4.1%, The combination of these three policies with an improved maintenance materials supply process increases uptime by 5.1%, Clearly, it is the combination of the four policies that generate the gains that were expected from a Planned maintenance process.
Overall, the analysis of the model can be distilled down to two basic conclusions. First, a structural analysis of the maintenance system demonstrates that it is unlikely that maintenance programs will be successful if they are implemented separately. Second, there is a great deal of synergy between the policies. The combination of planning, scheduling, predictive and preventive maintenance yield the expected benefits of the Planned Maintenance approach while the individual components, taken individually, produce small benefits in the long term.
Comments (5)
The simulations presented here are excellant arguments to help justify a comprehenisive, synergistic move to proactive maintenance. However, the gains won't be instantaneous. Addressing the short term costs (which may extend for a year or more), including possible initial lost uptime and initially higher costs, incurred in changing the culture by offsetting them with the longer term gains is not addressed. This is the argument that management must be convinced to support in order to "sell" the culture change. The bow-wave effect for a move from reactive to proactive needs to be defined and quantified for the specific organization, and combined with simulations such as this in order to make the business case for the culture change and to educate and convince management of the benefits of the change and what to expect so that there are no suprises in the short term that might cause reverting back to past, comfortable practices.
Very good article, but needs to be expanded upon by those wanting to apply the concepts presented.
1) Posted 1:58 pm, 05 August 2009 by Don Reed
You can also Google "The Manufacturing Game" which is based on the same ideas. This is a very good exercise for teams who want to focus on defect elimination.
Terry O
Reliabilityweb.com
2) Posted 6:38 pm, 05 August 2009 by tohanlon
BUT .....when you ADD to the previous elements, an integrated approach to Defect Elimination/Reliability Improvement, then you get much greater benefits again.
3) Posted 3:26 am, 06 August 2009 by Fred Black
The message that we are trying to get across today is that Reliability has to be owned by the mill, it has to be a comprehensive approach to all aspects of the operation, care, and maintenance of the equipment, and it is a journey where the various elements support one another in a synergistic manner.
We, there is one other reliability manager working with me, have been at this now for about 2 years. In the sites that have begun the journey we have seen an improvement in performance, OEE, of approximately 1.5%. The sites that have not begun the process are exactly where they were (which is about 5 - 10% below where they should be.) We have also seen the real maintenance costs decrease at the sites undertaking reliability by a total of about $15 million per year while the costs have increased by $4 million at the mills that have not started on the reliability journey.
One final finding directed toward Don's comment of the increase in cost and effort to be expected as the journey begins. We have warned to the mills to expect this. We have told them to expect 6 months - year of real challenges as they seek to implement "New" processes and activities while they still have to keep the assets running that are not yet reliable. What we have seen is much less of a bump in costs and in some cases a much quicker improvement than we anticipated.
Here is what we believe are the reasons for this.
1) In most mills the initial steps include implementing a "Bad Actors" process and an RCA methodology to begin addressing the worst offenders creating process downtime.
2) We are very intentional about putting operations into a leadership role in reliability. This is a major paradigm shift for most of our sites. However, the awareness of their responsibility and the training we provide to help them take practical steps to improve the reliability of the equipment they work with has a much bigger impact than we initially imagined.
3) And as I mentioned above the company has had many reliability consultants in the mills before so there is a latent understanding of some of the aspects of reliability, even if they aren't practicing them. So when we present our Reliability Model which covers all aspects of reliability in a coordinated manner, it is not the same as starting from scratch.
Keep up the good work Winston and Terry O. Your helping those of us trying to make headway working in the trenches.
4) Posted 8:24 am, 23 March 2011 by Dan Moss
Thanks for the comments. It sounds like you are making some good progress. Lately, we have been focusing on many small projects to implement change to avoid the "worse before better" bump and that seems to help. We get many small teams working on different sources of defects to accomplish the task and to create working relationships across functions. These seem to help.
You may also be interested that we are in the process of publishing our second book "Level 5 Leadership at Work" through Terry. In this book, James (the hero of our first book "Don't just fix it, Improve it") is promoted to head up the corporate reliability initiative and to help them make the same transformation that he did at the Atlanta plant. It sounds like he has the same kind of job that you have. I would be interested in your comments on that book when we get it published.
Winston
5) Posted 4:26 pm, 23 March 2011 by Winston Ledet