Most people will be familiar with the concept of lean manufacturing. (If you aren’t, we suggest you come back to this article later on.) Companies venturing into lean must apply lean thinking across the board – and that includes maintenance, which is, on average, the second largest expense after energy costs. But lean maintenance is an elusive concept that is not crystal clear to everyone.
If you’ve Googled “lean maintenance”, then you found the following definition:
“[lean maintenance is] a proactive maintenance operation employing planned and scheduled maintenance activities through total productive maintenance) (TPM) practices using maintenance strategies developed through application of reliability centered maintenance (RCM) decision logic and practiced by (self-directed) action teams. Lean maintenance generates a desirable outcome by minimizing consumption of inputs. Lean maintenance represents adopting lean principles into the Maintenance, Repair and Overhaul (MRO) operations. It could reduce unscheduled downtime through optimizing maintenance support activities and maintenance overhead. The lean tools are representing the lean principles for the implementation process. To effectively achieve lean maintenance improvement, key lean tools such as Value Stream Mapping (VSM), 5S, visual management need to be employed. A comprehensive lean tools developed for maintenance activities within an organization include 5S, TPM, overall equipment effectiveness (OEE), Kaizen, Poka-Yoke, process activity mapping, Kanban, computer managed maintenance system (CMMS), Enterprise Asset Management (EAM) system and Takt time.”
Yes, we Googled it too. And we got exactly 2210 matches for that definition. It is an accurate definition that covers a lot of ground… but it’s a lot to unpack. So we set out to interpret it! If you want to do the same, keep reading.
What is lean manufacturing, and how does it apply to maintenance?
Lean thinking focuses on being more efficient by cutting non-value added activities. (Non-value added activities, or NVA, do not add value to the product itself, i.e. scheduling, setting up equipment, inspections, billing, etc.). NVAs are considered waste, and therefore must be reduced to the absolute minimum. Lean philosophy is also linked to the 5S principles: seiri (sort), seiton (straighten/ organise), seiso (shine/ scrub), seiketsu (standardise), and shitsuke (sustain/ self-discipline).
With lean manufacturing, the aim is to establish a high-quality, streamlined system that delivers products at the pace demanded by customers. There should be no wait times, no downtime, and no defects. It’s impossible to achieve this without planned maintenance, only there’s a catch. Inspections, monitoring, overhauling, rebuilding, repairs and even routine maintenance are all NVAs. So the challenge is, how can we reduce maintenance “waste” to a minimum using the 5S?
The “8 Wastes of Lean” applied to maintenance
According to lean manufacturing, waste is divided into 8 categories. The easiest way to tackle them is to see how they apply to maintenance. Let’s see:
- Overproduction. Overproduction is one of the wastes of lean manufacturing. In maintenance, this corresponds to unproductive maintenance – preventive or predictive maintenance activities that are performed more often than necessary.
- Defects. Defective products are a big no-no in lean manufacturing (or maybe it’s just common sense). In maintenance, these are poor maintenance and repairs.
- Excessive transportation. Excessive transportation means parts and supplies are not at hand, which means personnel wastes time. Uncentralised maintenance that requires technicians to search for documentation and tools is the culprit here.
- Inappropriate processing. Data-driven decisions are our bread and butter, but you need to find the right KPIs. Collecting unnecessary data, or failing to collect important data, or not looking for root causes will also cause “inappropriate processing” in maintenance.
- Waiting. Perhaps this is the most self-explanatory waste of lean. Waiting for documentation, tools, and parts has no place in lean maintenance.
- Unnecessary motion. In maintenance, this is directly related to non productive maintenance. Why should your technicians be on the move to inspect an asset monthly, without taking into consideration its condition?
- Excessive inventory. Poor inventory management, whether it’s understocking or overstocking, comes with a cost. MRO inventory limits things to absolutely necessary materials and supplies, and “just-in-time” efforts and kanban tools try to receive goods only when needed.
- Underutilisation of employees. Another fatal mistake is to have high-skilled employees in charge of menial tasks. One possible solution is Autonomous Maintenance and TPM, which distribute maintenance responsibilities.
Lean maintenance techniques to avoid waste
Avoiding the wastes we listed above is what will point you in the direction of many of the strategies mentioned in our first definition, including:
- Total Productive Maintenance, which is the base of lean maintenance, and whose end goal is zero breakdowns, with zero downtime, zero defective products, and zero work accidents.
- Autonomous maintenance, one of the eight pillars of TPM, makes teams more self-reliant and independent, freeing high-skilled technicians for heavy duty maintenance. One of the steps to be successful with autonomous maintenance is establishing a visual management system (through labels, for example), which is also very lean.
- Reliability-centered maintenance and condition-based maintenance – instead of time-based maintenance that does not take into account the likelihood of failure – to avoid excessive preventive work. Condition-based maintenance includes vibration analysis and ultrasound testing, for example.
- MRO Procurement and storerooms, in order to organise inventory more efficiently, improve turnaround times, avoid understocking and overstocking. If you’re performing usage-based maintenance, then it helps to know the rate at which products should be completed. It’s the German intruder in Japanese lean: takt time.
- Value Stream Mapping (VSM) and process activity mapping to visualise the complete process, which will avoid duplication of tasks, excessive motion, transportation, and waiting.
- Kaizen improvement events, which promote continuous evaluation and improvement – continuous improvement being another pillar of TPM – in terms of time management, resources, and quality. Sometimes these happen at a very fast pace, which is known as “Kaizen blitz”.
- Track OEE to make data-driven decisions, and improve OEE continuously. Since OEE is the product of availability, performance, and quality, you’ll also need to add MTTR and MTBF to your list of KPIs.
- Use Root Cause Analysis (RCA) tools, including FMEA, in order to find the root cause and prevent future problems. RCA can also be used to test asset or product design and eliminate features that would require maintenance later on. This is known as design-out maintenance, and it’s usually reserved for assets with high maintenance costs and criticality. You can also achieve this through other lean tools like Poka-Yoke.
- Employ a CMMS, or another asset management system, in order to establish a work order system, priorities, and monitor all of your KPIs with ease. And don’t forget this system should also be lean, so avoid software with unnecessary features that will only create visual noise. You’ll want a modular app with a customisable dashboard.
There are several strategies you can employ to succeed at lean maintenance. In a sense, it’s a never-ending topic – nobody has a foolproof recipe. But you can now see how they all fit together, and how each impacts your performance.