Developing Planned Maintenance for the Shop

By Vlad Bacula
Production Manager
Advanced Technology Services, Inc.

In a competitive global busines environment, successful manufacturing managers have embraced lean strategies to keep their production humming and to sustain profits. But it is problematic when managers attempt to apply an ad hoc lean strategy to factory maintenance.

Unfortunately, a lack of strategic planning in many plants today causes assets to deteriorate.

The long-term consequences of such short-term decision-making can cost the manufacturer deeply, and can include declining manufacturing efficiencies, late customer shipments, declining machine availability, and declining product quality.

Most manufacturers acknowledge that taking good care of their equipment is generally smart business. It’s usually a lack of understanding about the correlation of effective maintenance and plant performance that leads to poor decisions. Once managers understand that the proper level of manufacturing maintenance can help to sustain profits, better decisions are made.

Total Productive Maintenance, commonly abbreviated TPM, is a holistic approach to equipment maintenance that trains and involves operators and support personnel, institutionalizes continuous improvement and embodies the overall Lean culture of an enterprise.

While Total Productive Maintenance can be implemented as a stand-alone process; it is most effective when deployed as an integral part of the overall cultural transformation that takes place as the enterprise adopts and implements a Lean business strategy.

Total Productive Maintenance is one of many Lean tools that engage all employees to eliminate waste, improve equipment reliability and overall business performance.

Total Productive Maintenance is not a short-term program; it is a lifelong commitment that requires a certain discipline about the fundamental way people and organizations care for their equipment.

The major misconception about Total Productive Maintenance is that it is a “Maintenance Process.

To be successful, Total Productive Maintenance has to be an integrated part of the business strategy that is driven and monitored by the operations area of the business and embraced and supported by leadership.

Maintenance plays a key role in helping to establish and support the Total Productive Maintenance process; but so do operators and other support functions.

Communication and training are also key elements required to successfully implement Total Productive Maintenance.

Prior to deploying Total Productive Maintenance, an organization should assess the management and operator support level within the facility; review prior Lean process implementations; and the level and sophistication of maintenance personnel and systems.

One of the outputs of the Total Productive Maintenance process is the refinement and redistribution of maintenance activities that are required to maintain specific critical equipment.

If the current maintenance personnel and system are incapable of adequately scheduling, executing and monitoring basic preventative maintenance (PM) activities, these processes should be implemented and allowed to mature before trying to deploy Total Productive Maintenance.

Otherwise, Total Productive Maintenance will fail quickly; which will also decrease or kill the ability to successfully implement Total Productive Maintenance in the future.

Total Productive Maintenance
Total Productive Maintenance should be deployed initially on constraint or critical equipment.

Characteristics such as the Overall Equipment Effectiveness (OEE); the condition, potential availability, and breakdown history of the equipment, and the openness and skill of the operators and support personnel for each constraint process should be reviewed.

The goal is to choose a piece of equipment that, when completed, will have a significant impact on the facility, will successfully prove out the Total Productive Maintenance process and will build the beachhead for the cultural transformation that comes from the team-based, bottom-up implementation of the process.

A team of 6 to 10 people that includes operators from each shift, a production supervisor, at least two maintenance personnel and representatives from the production planning, process engineering, quality and safety departments is developed for the specific project.

The team receives training on each aspect of the Total Productive Maintenance process and participates in hands-on exercises required to execute it.

While it is important that the proper tasks required to maintain the equipment are identified, documented and allocated during this process, it is equally important that the team develops, commits to and owns both the process and the results.

It is likely that not all of the items the team identifies will be completed by the end of the process. These items need to get captured on an action-item list and incorporated into future continuous improvement weekly area meetings.

All Total Productive Maintenance tools should be treated as living documents that will be revised as improvements are made.

Properly implementing Total Productive Maintenance can dramatically improve productivity, quality, safety, performance to schedule and, ultimately, the company’s bottom line. In most cases, the intangible benefits gained through properly implementing the process in a standardized team-based approach are equally valuable.

Predictive Maintenance
Predictive Maintenance (PdM) techniques are also invaluable in helping to determine the condition of production equipment to predict when and what type of maintenance should be performed. This approach offers cost savings over routine preventive maintenance where tasks are performed only when needed.

There are many predictive maintenance technologies, and some have become standard in many industries. Those standard technologies include: thermographic assessments, vibration monitoring, oil analysis combined with wear particle analysis, ultrasound measurements, and motor current analysis.

Predictive technologies enable the gathering of equipment health data much like a doctor conducts a physical, blood analysis, and X rays on a human.

These actions do not fix the problems, but can find them in a very early stage, not easily detected by visual or other basic inspection of the equipment. In short, monitoring the equipment health and making maintenance decisions based on these conditions can prevent catastrophic failures and extensive downtime.

Thermography or thermal imaging creates a visual picture of temperature. This tool allows a technician to find temperature differences, usually abnormal hot spots that are typically associated with problems due to high electrical resistance, or excessive mechanical friction.

By using thermographic assessments technicians perform maintenance only on the components that need attention, and rectify the problems before more costly failures occur.

Ultrasonic measurements are used to find process leaks such as air, gas, steam, or vacuum leaks, or to detect low speed bearing defects, or to find electrical arching problems, known as a Corona effect, and to determine the proper amount of lubricant that is to be applied to high-speed bearings.

The application of this tool in leak detection is based on the fact that most leakage problems produce a range of sound. That sound, when properly detected and measured, provides data on the location and severity of the leak.

Oil analysis is one of the key components of predictive maintenance and includes: lubricating and hydraulic oil analysis, spectrochemical analysis, and wear particle analysis.

Oil analysis determines the condition of a lubricant. Spectrochemical and wear particle analysis determine the condition of equipment based on concentration and composition of wear particles.

Oil analysis is a proven method to predict and prevent certain maintenance problems before they occur.

It also helps to ensure that lubricants are performing as expected.

As a predictive maintenance tool, oil and spectrochemical analysis are used to schedule oil change intervals based on the actual condition of the oil, or the analysis data can be used for maintenance decisions.

For example, monitoring the amount of trace metals in successive oil samples will indicate wear patterns of parts in the equipment and will provide an indication of impending equipment failure.

Vibration analysis is used to find problems such as misalignment, out of balance conditions, and bearings defects by taking and recording periodic readings.

Maintenance personnel can compare these readings to a baseline or trend and make appropriate decisions.

When wear reaches a certain level, the bearing is scheduled for replacement before it fails. This reduces the amount of reactive maintenance and insures that replacement occurs with minimum impact on the production schedule.

Motor Current analysis is a technique used to diagnose problems in electrical motors by monitoring input electrical signal.

This technique can diagnose problems such as broken rotor bars, abnormal air gaps, and shorted turns in low voltage stator windings. Quite often, motor current analysis is used in combination with vibration analysis.

In conclusion, regardless of which technique is used, the ultimate goal is to identify imminent failures and to make a prognosis of the remaining useful life of analyzed component.

This enables corrective maintenance action to be undertaken on the identified failing component at a convenient time, allowing better planning of maintenance work.

Many predictive techniques can be used to check for the same problem.

For example, a problem indicated by an oil sample could also be checked by vibration monitoring or thermography.

Knowing how to use the tools and where to apply them is important to a successful program. The impact on the business is what creates the return on investment, so choosing the right predictive technique is critical.