Don't wait until it's broke

After spending many years in manufacturing facilities, I have discovered that the number of ways to perform a task is as varied as the people working there. Facility and machine tool maintenance is no different. Each organization has a unique approach.

Although varied, the methods and philosophies fall into one of three categories: “if it ain’t broke, don’t fix it;” preventative maintenance; and total productive maintenance. The first approach simply does not work in today’s manufacturing environment, and can lead to unplanned downtime. However, limited resources, time constraints, rising costs and other variables can cause a shop to inadvertently adopt this attitude. Other times, management does not feel routine maintenance is warranted. In either case, it is not uncommon to find shops that don’t have formal maintenance programs.

However, machine operators often take ownership of equipment when the machines are only used by a small group of people. They frequently refer to equipment as “my machine” and notice small changes in its condition, changes that can indicate imminent failure.

When operators take ownership, they tend to safeguard the machine by performing routine maintenance, such as cleaning and monitoring fluids. They also tend to be less aggressive with operating parameters, which can extend operating life and minimize breakdowns but lengthen cycle times.

When a machine is shared among several operators, it is difficult to get them to take that type of ownership. As the level of ownership decreases, the likelihood of machine failure increases. These environments are usually multiple-shift, high-production plants where machines are manually loaded and operated. These organizations typically have formal PM programs.

An effective PM program includes the manufacturer’s recommended service at scheduled intervals. Changing fluids and filters are the most common activities, but good PM should include inspection of items known to wear or fail on a consistent basis, as well as cleaning, adjusting settings and correcting alignment issues.

Total productive maintenance is the most advanced form, and considers more than just basic maintenance; it works to maximize machine efficiency.

TPM is proactive and uses data to drive decisions about maintenance schedules. TPM prompts maintenance to frequently change components on machines that may appear to be in good condition. If data shows the component has a predictable life, it will be replaced during planned downtime to prevent a failure from interrupting production.

TPM also examines the operating parameters of a machine. In cases where a machine is running faster than necessary, it may have its speed reduced to minimize wear. On the other hand, if the machine is capable it may be adjusted to operate faster.

In high-production environments where machine tools are still manually loaded and operated, it is difficult to implement TPM. This is because the data necessary to properly establish program parameters is often inaccurate, and one operator usually operates a machine differently than another.

While these factors make predicting component life a guessing game, these companies often have a strong maintenance staff, one that is capable of fast and accurate troubleshooting. Organizational experience has also taught them which spare parts to keep in inventory. Having skilled personnel and access to spare parts minimizes the impact of downtime.

Facilities that operate machines unmanned or have processes that require little operator intervention will have the easiest time implementing TPM. Because data collection is accurate and machining parameters are stable, predicting component life is much easier.

Unmanned production minimizes variations in production rates. It is easy to produce the needed quantities when production rates do not fluctuate, allowing equipment to be removed from service at planned intervals for maintenance.

TPM is sometimes referred to as total preventative maintenance. Although technically incorrect, it is an accurate way to describe the maintenance programs of many manufacturers. TPM is difficult to implement, but the principles are sound and can guide the development of a successful PM program.

A balanced approach is probably the most cost-effective and practical one for most companies. Adopting TPM principles, encouraging operator ownership and implementing a strong PM program will maximize uptime. CTE

About the Author: Christopher Tate is engineering manager, combustion shop, for Mitsubishi Hitachi Power Systems Americas, Savannah (Ga.) Machinery Works. Email: chris23tate@gmail.com.