Plant management and financial stakeholders are locked in a constant struggle with their plant lines. Equipment-based losses can eat into the facility’s bottom line. But is maintenance to blame for these losses? Or is there a deeper issue at work?
Understanding the six big losses
In manufacturing, there are 16 major losses. A «loss» is considered any impendence on a 24/7/365 calendar in which you are not producing a product or service and/or at its most effective and efficient means possible. Some losses are needed, others are not. With the needed losses, such as planned maintenance, the goal is to drive out ineffective and inefficient items or practices. Other losses, like breakdowns do not need to occur and can be driven out completely.
Within these 16 losses, there are 8 equipment losses. Planned Maintenance downtime losses and Lack of Demand losses impede on loading hours. They do not count towards your OEE. The other 6 are what is called the 6 big losses. These losses should be measured through what is called OEE, or Overall Equipment Effectiveness. OEE was derived from TPM, or Total Productive Maintenance.
Availability, simply put, is the ability for the asset(s) being available for use of production. The main loss in this category is time to produce. There are 2 buckets of losses in the Availability category:
1. Startup/Setup/Adjustment losses
A startup loss is a loss due to waiting at startup. An example of this could be waiting for an oven to heat up. A setup loss is a loss due to the wrong setup of an asset, for example, a size change of a box machine, not properly setup to the right specification. An adjustment loss is a loss due to improper setup, tightening, etc. that would cause the machine to fail. An example would be a bracket coming loose due to improper tightening after maintenance or setup. These buckets are normally owned by Operations.
2. Breakdowns/Process Failures
Breakdowns is normally defined by TPM standards to be any stop 10 minutes or more and requires a part to get the asset back into operation. A process failure is normally defined as any stop 10 minutes or more and does NOT require a part. An example of this would be that someone accidently hits an e-stop. Typically, maintenance owns the breakdown bucket. Operations owns the Process Failure bucket.
Performance losses are losses that impede the effectiveness of the time given to produce. When an asset malfunctions temporarily or an anomaly occurs somewhere in the line, the plant’s performance metrics decline.
3. Minor stops
Typically defined as a stop of 10 minutes or less, a minor stop may or may not require maintenance intervention. They are typically the largest loss bucket within OEE. They normally become part of the picture and are never measures. An example of this would be a corrugate jam on a box machine. This shuts down the asset, or possibly the line, for normally a minute or 2. These types of things happen quite frequently and are never resolved.
4. Speed Losses
Speed losses are any losses that occur under the design rate of the machine. There are normally two main contributors to speed losses. The first is equipment design flaws. It has been my experience in most plants that I have been in that they slow down equipment because «It just runs better that way.» The problem with this is that you are masking the losses within the system and not putting them to rest. This is normally due to poor design specifications. The other reason for speed losses is that as assets are utilized over time, they may begin to slow down. Lubricant deficiencies, debris and physical wear and tear all contribute to slower cycles and loss of performance.
Quality Losses are losses that impede efficiency of the process to produce product. A quality loss is defined as a defect in the output of a line. When a line outputs an inefficient yield or that yield is damaged or expired, quality metrics decline.
5. Production rejects/rework
Output failures take up resources and lower the value of the line. Output may need to be reworked or scrapped entirely. These errors often stem from operator inexperience or damaged assets.
6. Startup rejects/rework
When an asset is adjusted prior to production, it may produce reject output. This output costs resources and reduces the final yield.
Assessing a line within the context of the six big losses can help stakeholders determine where to allocate resources.
Looking at the role of culture
Culture plays an important role on a plant’s ability or inability to drive out losses and improve plant performance. Nurturing a Culture of Reliability and Continuous Improvement should always be the focus. This type of culture is focused on education, training, and striving towards being the best they can possibly be.
It is my experience in performing loss analyses within facilities, that of the 6 big losses, the top two are minor stops and speed losses. They make up close to 70% of the total plant equipment losses. Breakdowns, which is owned by maintenance, makes up typically 10% of the losses.
So if maintenance makes up only 10% of plant equipment losses, why is everyone so adamant that fixing the maintenance department will fix the plant loss issue? I believe this answer is two fold. First, most organizations do not truly know what their plant losses are and second, maintenance loss are visible. Most plant losses are what I consider «hidden», which means that we either now that they exist, but do not measure them or we do not know that the even exist. We dump everything into the lap of maintenance because we think that maintenance should fix anything anytime anything happens to a machine. This couldn’t be further from the truth. Also, maintenance losses are visible, meaning that when there is a breakdown on an asset, the whole world knows the line is down. Also, in the morning meetings, this breakdown is talked about as the culprit as the reason as to why we did not hit our production numbers.
So as a maintenance manager, how do you combat this? The way you combat this first, you have to understand your plant losses. Next, you have to have your data in order. When you go into the morning meeting, what did you do to make sure this same failure mode doesn’t occur again? Things break and that’s okay. When it continues to happen, that’s when you have a problem. Also, how much product should you have produced yesterday? How many of those widgets were directly lost to the breakdown? So the question to be asked is what happened with all the other widgets that were supposed to be produced? Beginning to ask these questions will get others to start to think through the process. Then offer solutions to problems and offer your support. The greatest thing a maintenance department can do is to develop some credibility. By offering solutions towards the elimination of plant losses and implementing them with any sliver of success, will begin the change in the culture needed for success within the organization.