MRO Magazine

Feature

Equipment Ledger


In the June 2019 issue of MRO, the focus of my article was what equipment restoration means and how the driving force to sustain equipment reliability is to have a strong commitment to the restoration process.

This article will focus on the most time-consuming element of the restoration process: the equipment ledger. Be prepared to invest several months identifying every equipment wear component. Everything from bearings, belts, bushings, couplings, and cylinders, to gearboxes, motors, and rollers. Every component needs enough specifications and part information in order to be easily purchased from a vendor.

The ledger generally consists of two parts.

First is the assembly drawing that identifies the location of the equipment wear components, and second is the ledger document that lists the specifications of each component. The assembly drawing can be the CAD drawing of the machine, or, in absence of that, a simple cartoon drawing. Whichever one you use, every component is shown and given a number that corresponds with the ledger.

A simple assembly drawing (left) and a detailed ledger; together, they include every aspect of the components in a clear and concise template.

The second important use of a completed ledger is to determine the maintenance strategy for each component. Some will have time-based replacement frequencies or time-based inspection.

Remember, the goal is to sustain a piece of equipment in like-new condition. With a complete ledger, maintenance staff can determine what type of preventive maintenance plan the machine requires to sustain long-term reliability.

For facilities that manufacture the same product, equipment ledgers and drawings may be shared plant to plant as the equipment is similar. To enhance this process of plant sharing, some companies have developed master component lists that list every mechanical or electrical component that is found on production lines. This approach requires a lot of upfront work by a team that knows and understands the equipment and processes.

In the past month, our team has completed a master component list. It took nearly 18 months and has hundreds of components. The payoff is that every one of the 14 manufacturing facilities can use this master component list to develop their ledgers, taking only a fraction of the time it would take for each plant to do it individually. Without the master component list a typical plant with approximately 500 to 600 pieces of equipment would take nine to 12 months to create a full ledger. It takes this long because of the availability of the equipment to remove guards and dismantle assemblies to document the wear components. This is especially true in older facilities, where drawings and equipment documentations are scarce.

On the other hand, newer plants normally have drawings and component lists from the equipment manufactures, which certainly speed up the ledger creation process. The newer the plant and equipment, the faster and more economical the ledger development will be. Documentation will be readily available, and there will be very few, if any, undocumented equipment modifications.

Some companies have opted to hire outside resources to develop the ledgers. These vendors will come on-site and gather the data for you. They will examine the available equipment drawings and documents and compile the information into a ledger document. Whatever is not available in documentation, they go into the field and remove guards to gather the component details. Again, this can be a time-consuming process based on equipment availability and the number of people used to gather the data. The average time for an outside vendor to complete 500 pieces of equipment in an older factory is approximately six to eight months at a cost of $200,000.

Whether we use in-house or external resources, the cost is significant. However, equipment ledgers are the key building blocks of the restoration process. They provide a complete understanding of the equipment and their components in order to develop a preventive maintenance strategy.

Now we start to comprehend the magnitude of a restoration. The more equipment in the facility, the more complex and time-consuming process. And, with that, the cost will escalate. Be prepared, the cost and timelines shared here are real. Be assured, though, that the cost is worth it, provided the rest of the restoration steps are followed and completed.

Most important, the process must be sustained; as new equipment is added or modified, the ledgers must be updated. Equipment ledgers are where restoration and reliable long-term equipment begin.


Peter Philips

Peter Phillips of Trailwalk Holdings, a Nova Scotia-based maintenance consulting and training company, can be reached at 902-798- 3601 or by email at peter@trailwalk.ca.
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