Understanding an automated system’s maintenance needs

Aligning maintenance with risk tolerance

One of the first considerations when planning automated system maintenance is the operation’s tolerance for the risk of downtime. The type of application, market and customer often dictates the type and frequency of maintenance activities required by a facility.

“If the automated system is deployed in an operation that is fulfilling e-commerce orders for customers who expect their shipment to arrive within a day or two, then unplanned downtime is not an option,” says Jake Heldenberg, Head of Solution Design at Vanderlande. “The maintenance and support activities need to be much more proactive and professional to minimise the chance of a system failure.

“And if the system is serving retail stores – particularly larger ones selling general merchandise – they are quite comfortable with availability rates of around 98 to 98.5%,” he adds. “It’s OK if the warehouse gets a few shipments out late, because the stores already have a certain number of days of inventory. The chances are lower that the retailer will lose a customer if one item is out of stock.”

Different maintenance methodologies

Within the U.S. Department of Energy’s Operations & Maintenance Best Practices guide there are different types of maintenance methodologies, including the following.

• Reactive Maintenance – this approach avoids all maintenance activities until the automated equipment stops working. The agency estimates that 55% of operations take a reactive approach. When a system is new, companies may be lulled into a false sense of security, because the chances of failure are low. However, waiting for the system to break prior to servicing can be costly in terms of unplanned downtime, repair or replacement needs, as well as secondary equipment failures and increased labour costs due to inactivity and overtime.
  
• Preventive Maintenance – a much more cost-effective method in which preventive maintenance activities are performed on a schedule, based either on regular time intervals (such as quarterly) or automation run-time targets. This practice is more likely to identify and correct impending component failures before they cause significant downtime. The resulting increase in reliability can save a business between 12 and 18% in costs compared to reactive maintenance programmes.
  
• Predictive Maintenance – these activities are scheduled based on the actual operating conditions of the automation, as determined by collecting and analysing functional data. With equipment providers increasingly offering internet of things (IoT)-enabled functionality, automated systems have sensors and devices that track maintenance indicators, such as temperature, energy consumption, vibration, noise and humidity. Utilising predictive analytics to inform the timing of service can cut maintenance costs by as much as 30%.

Key maintenance service strategies

To ensure an automated system achieves the desired uptime rate, an operation should employ key maintenance and service strategies. These can be performed by in-house technicians, a team supplied by the automation’s original equipment manufacturer (OEM), or outsourced to a third-party service provider. 

If present, the operation’s maintenance team should receive initial training on best practices for servicing the automation as part of the installation and deployment. In addition, it’s wise to stock recommended spare parts such as belts, lubricants, bearings and other components on site – based on their likelihood of failure. The OEM should provide a list of these spares as part of the deployment.

Optimally, services (or service offerings) as a minimum should include a technical assessment, cleaning, and lubrication of system components and consumable parts. These should also incorporate planned maintenance activities, including adjusting and replacing worn parts based on a predefined schedule. Condition-based adjustments, replacements and repairs should also be part of a predictive maintenance programme. Moreover, remote monitoring and technical support need to be available when required.