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Total productive maintenance (TPM) is the process of using machines, equipment, employees and supporting processes to maintain and improve the integrity of production and the quality of systems.
According to Aberdeen Research, the average hourly cost of downtime across all businesses is $260,000, and it seems to be rising. This figure is up from the 2014 data of $164,000. This is especially concerning since nearly all industrial and manufacturing production is accomplished using machines, making it largely dependent on those machines operating continuously.
So, how can you help remedy this issue? Total productive maintenance (TPM) is the process of using machines, equipment, employees and supporting processes to maintain and improve the integrity of production and the quality of systems. Put simply, it's the process of getting employees involved in maintaining their own equipment while emphasizing proactive and preventive maintenance techniques. Total productive maintenance strives for perfect production. That is:
Since the goal of total productive maintenance is to improve productivity by reducing downtime, implementing a TPM program can greatly impact your overall equipment effectiveness (OEE) over time. To do this, preventive maintenance should always be at the forefront of everyone's mind. For example, running machines with the mindset of "we'll fix it when it breaks" is not an option with total productive maintenance. A TPM program helps get rid of this mindset and turns it into one of putting machinery at the core focus of an operation and maximizing its availability.
Improving OEE through TPM is often done by forming small, multidisciplinary teams to address core areas such as preventive and autonomous maintenance, training employees who operate machinery, and the security and standardization of work processes. Total productive maintenance focuses on the efficient and effective use of the means of production, meaning all departments should be involved. These small teams work together to increase productivity and decrease downtime through equipment reliability.
Going from reactive to predictive maintenance is one of the biggest advantages of implementing a TPM program. Reactive maintenance or "firefighting" is costly, as you're not only footing the bill for machinery repairs but also dealing with the cost of unplanned downtime. Let's take a look at some of the direct and indirect benefits that result from total productive maintenance.
|Benefits of Total Productive Maintenance|
|Direct Benefits||Indirect Benefits|
|Less unplanned downtime resulting in an increase in OEE||Increase in employee confidence levels|
|Reduction in customer complaints||Produces a clean, orderly workplace|
|Reduction in workplace accidents||Increase in positive attitudes among employees through a sense of ownership|
|Reduction in manufacturing costs||Pollution control measures are followed|
|Increase in product quality||Cross-departmental shared knowledge and experience|
Traditional total productive maintenance was developed by Seiichi Nakajima of Japan. The results of his work on the subject led to the TPM process in the late 1960s and early 1970s. Nippon Denso (now Denso), a company that created parts for Toyota, was one of the first organizations to implement a TPM program. This resulted in an internationally accepted benchmark for how to implement TPM. Incorporating lean manufacturing techniques, TPM is built on eight pillars based on the 5-S system. The 5-S system is an organizational method based around five Japanese words and their meaning:
The eight pillars of total productive maintenance focus on proactive and preventive techniques to help improve equipment reliability. The eight pillars are: autonomous maintenance; focused improvement (kaizen); planned maintenance; quality management; early equipment management; training and education; safety, health and environment; and TPM in administration. Let's break down each pillar below.
Implementing autonomous maintenance involves cleaning the machine to a "baseline" standard that the operator must maintain. This includes training the operator on technical skills for conducting a routine inspection based on the machine's manual. Once trained, the operator sets his or her own autonomous inspection schedule. Standardization ensures everyone follows the same procedures and processes.
In addition, focused improvement increases efficiency by reducing product defects and the number of processes while enhancing safety by analyzing the risks of each individual action. Finally, focused improvement ensures improvements are standardized, making them repeatable and sustainable.
Additionally, planned maintenance allows for inventory buildup for when scheduled maintenance occurs. Since you'll know when each piece of equipment is scheduled for maintenance activities, having this inventory buildup ensures any decrease in production due to maintenance is mitigated.
Taking this proactive approach greatly reduces the amount of unplanned downtime by allowing for most maintenance to be planned for times when machinery is not scheduled for production. It also lets you plan inventory more thoroughly by giving you the ability to better control parts that are prone to wear and failure. Other benefits include a gradual decrease in breakdowns leading to uptime and a reduction in capital investments in equipment since it is being used to its maximum potential.
Possibly the biggest benefit of quality maintenance is it prevents defected products from moving down the line, which could lead to a lot of rework. With targeted quality maintenance, quality issues are addressed, and permanent countermeasures are put in place, minimizing or completely eliminating defects and downtime related to defected products.
When discussing the design of equipment, it's important to talk about things like the ease of cleaning and lubrication, accessibility of parts, ergonomically placing controls in a way that is comfortable for the operator, how changeovers occur and safety features. Taking this approach increases efficiency even more because new equipment already meets the desired specifications and has fewer startup issues, therefore reaching planned performance levels quicker.
Aside from the obvious benefits, when employees come to work in a safe environment each day, their attitude tends to be better, since they don't have to worry about this significant aspect. This can increase productivity in a noticeable manner. Considering safety should be especially prevalent during the early equipment management stage of the TPM process.
Now that you have an understanding of the foundation (5-S system) and pillars on which the TPM process is built, let's take a look at how to implement a TPM program. This is generally done in five steps: identifying a pilot area, restoring equipment to prime operating condition, measuring OEE, addressing and reducing major losses, and implementing planned maintenance.
Using a pilot area to begin implementation helps gain more acceptance from staff when they see the benefits that come out of the process. When choosing equipment for a pilot area, consider these three questions:
If this is your first time implementing a TPM program, your best choice is typically the first approach – the easiest equipment to improve. If you have some or extensive experience with total productive maintenance, you may choose to correct the bottleneck. This is because you can build temporary stock or inventory, making sure downtime can be tolerated, which minimizes risk.
Include employees across all aspects of your business (operators, maintenance personnel, managers and administration) in the pilot selection process. It's a good idea to use a visual like a project board where you can post progress for all to see.
The concept of restoring equipment to prime operating condition revolves around the 5-S system and autonomous maintenance. First, TPM participants should learn to continuously keep equipment to its original condition using the 5-S system: organize, cleanliness, orderliness, standardize and sustain. This might include:
Once you've established a baseline state of the equipment, you can implement the autonomous maintenance program by training operators on how to clean equipment while inspecting it for wear and abnormalities. Creating an autonomous maintenance program also means developing a standardized way to clean, inspect and lubricate equipment correctly. Items to address during the planning period for the autonomous maintenance program include:
Step three requires you to track OEE for the target equipment, either manually or using automated software (as long as it includes code tracking for unplanned stoppage time). For details on how to calculate OEE manually, reference Reliable Plant's article on OEE. Regularly measuring OEE gives you a data-driven confirmation on whether your TPM program is working and lets you track progress over time.
Since the biggest losses in regard to equipment are the result of unplanned downtime, it's important to categorize every unplanned stoppage event. This gives you a more accurate look at where a stoppage is occurring. Include an "unknown" or "unallocated" stoppage time category for unknown causes.
It's recommended that you gather data for a minimum of two weeks to get an accurate representation of the unplanned stoppage time and a clear picture of how small stops and slow cycles impact production. Below is a simplified example of a top 5 loss chart. Each loss is categorized and is in descending order from the loss that causes the most downtime to the loss that causes the least.
|Top 5 Loss Chart|
|Loss Rank||Loss Category||Lost Time (minutes)|
|1||Equipment Failure: Filler Jam||400|
|2||Equipment Failure: Bottle Labeler Down||250|
|3||Setup/Adjustments: Bottle Change||170|
|4||Setup/Adjustments: Label Change||165|
|5||Equipment Failure: Bottle Jam||10|
|Total Lost Time = 995 minutes (16.5 hours)|
Once you've got a data-driven snapshot of where your top losses are, it's time to address them. This step uses the previously discussed pillar of focused improvement or kaizen. To do this, put together a cross-functional team of operators, maintenance personnel and supervisors that can dissect the OEE data using root cause analysis and identify the main cause(s) of the losses. Your team's process might look something like this:
The last step of the TPM implementation process is the integration of proactive maintenance techniques into your program. This involves working off the third pillar of planned maintenance. Choose which components should receive proactive maintenance by looking at three factors: wear components, components that fail and stress points. Identifying stress points is often done by using infrared thermography and vibration analysis.
Next, use proactive maintenance intervals. These intervals are not set in stone and can be updated as needed. For wear and predicted failure-based components, establish the current wear level and then a baseline replacement interval. Once these have been determined, you can create a proactive replacement schedule of all wear- and failure-prone components. When doing this, use "run time" as opposed to "calendar time." Finally, develop a standardized process for creating work orders based on the planned maintenance schedule.
You can optimize maintenance intervals by designing a feedback system. Things like log sheets for each wear- and failure-prone component where operators can record replacement information and component condition at the time of replacement will be key. Additionally, conduct monthly planned maintenance audits to verify the maintenance schedule is being followed and the component logs are being kept up to date. Review the logs' information to see if adjustments to the maintenance schedule need to be made.
You may have noticed the implementation process negated four of the eight pillars: quality management, early equipment management, safety and TPM in administration. So, when should you introduce these activities? They should be instituted as needed. Let's take a look at some examples.
Implementing a total productive maintenance program offers relatively short-term success. The trick is sustaining that success over the long term. This starts with the employees. If employees buy into the TPM program, envision the improved future of the company and can see how this improved future benefits them, it can create a powerful sense of cohesiveness. Rewarding achievements is an excellent way to strengthen the established cohesiveness among employees.
Another way to achieve sustainable improvement with your TPM program is by having engaging, active leadership. This shows the importance of the program through not just words but actions. Engaging leadership prevents employees from slipping back into old habits and breathes new energy into the process on a regular basis.
Finally, don't overlook kaizen. Continuous improvement helps your TPM program adapt to changing environments and keeps the program from becoming stale and employees from becoming disinterested.
In the past, American industries have been reluctant to implement total productive maintenance into their current processes. In fact, a survey done by the Manufacturing Research Center showed that only 27 percent of respondents said TPM was a current business initiative, but only 6 percent said they were fully implementing it. Additionally, only 5 percent of respondents said TPM was their plant's approach to maintenance and reliability.
Despite this lack of interest, plants around the world are reaping significant benefits from making total productive maintenance the focus of their maintenance efforts. A study published in the International Journal of Innovative Science, Engineering & Technology found that, in a small-scale polymer company, the OEE value before TPM implementation was 75 percent. After a TPM program was implemented, OEE improved to 85 percent, and a better quality rate was achieved. The study further revealed how profitability increased by 12 percent, as breakdown and maintenance costs dropped sharply (80 and 20 percent) while labor efficiency increased. Many other tangible and intangible benefits were also uncovered as a result of implementing a TPM program.
One of the most discussed case studies for TPM implementation is that of Latin American brewing company Cervecería Cuauhtémoc Moctezuma, makers of six beer brands including Tecate, Dos Equis and Sol. This article lays out the company's TPM success in detail, showing how total productive maintenance plays out in a real-world scenario.