The preventative maintenance checklist is a fundamental tool for keeping manufacturing equipment running efficiently. However, with the advent of smart maintenance technology, the preventative maintenance checklist as it is commonly known is becoming redundant. The industrial internet of things (IIoT)—combined with big data and machine learning—and augmented reality (AR) are able to both fulfill the function of the maintenance checklist and supersede its capabilities.
A preventative maintenance checklist is a schedule for inspecting and servicing manufacturing equipment. It is essentially a list of all the parts that need checking, and how often and what they need to be inspected for. Complex equipment may contain some parts that require inspection weekly and others that only require inspection once a year. Depending on the equipment, the checklist may dictate preventative servicing, such as replacing or repairing components, usually based on the manufacturers’ recommendation. The checklist also functions as a record of inspections and servicing for future reference.
From a contemporary perspective, preventative maintenance checklists are a noble, but primitive, solution for ensuring equipment uptime and efficiency. They suffer from two essential inefficiencies: rule of thumb schedules and human error.
For the purposes of a maintenance checklist, how often a machine should be serviced tends to come from the manufacturer’s recommendations. These recommendations are based on normal usage. However, if the machine has been worked especially hard, a component may wear out before its service is due. This could cause unplanned downtime or develop into a more serious fault if left unchecked. Equally, if it has been underutilized, it could last another year. Replacing it in line with the manufacturer’s recommendations would cost unnecessary parts and labor; a cost made more significant when multiplied by the number of machines in a typical plant.
Every machine on the factory floor has its own maintenance checklist. Each checklist may contain many different components, all with differing maintenance schedules. The more complex the maintenance schedule, the more room there is for human error. Mistakes may be made in the inspection and servicing itself. Dates may be missed. Documentation may be inaccurate. Any such mistakes on the checklist can lead to further errors in the future, compounding the original error.
One of the primary benefits of Industry 4.0 technology to manufacturers is in making maintenance smart. The principal technologies are the industrial internet of things and augmented reality. The former enables radically enhanced preventative maintenance. The latter reduces the scope for human error.
The IIoT improves preventative maintenance efficiency by:
By equipping machinery with IIoT sensors, manufacturers gain access to real-time condition monitoring—a constant stream of machine health information. At its most basic, notifications can be automated in line with an existing preventative maintenance checklist. But rather than inspecting equipment manually, technicians can take readings remotely, reducing the time required for inspection. However, the real potential of the technology is in the use of advanced, predictive analytics; machinery is actively monitored, and technicians are notified when readings drift out of spec. Servicing can then be scheduled to prevent serious faults from occurring.
AR narrows the space for human error in manual inspections and servicing. Digital work instructions can form standardized checklists, providing a centralized record and schedule of inspections and servicing. The instructions themselves can be viewed on AR displays as intuitive step-by-step instructions, overlaid onto the physical machinery. Visual cues can indicate relevant components while contextual media can be used to explain what to look for. Digital capture can record the inspection and verify its completion.
Preventative maintenance checklists have long been the bedrock of ensuring equipment uptime. However, when performed according to a prescribed schedule, preventative maintenance can lead to wasted resources. Smart maintenance technologies such as the IIoT and AR can both reduce the administrative burden of maintenance scheduling and optimize the use of maintenance resources—while ensuring dramatically improved uptime and OEE.