What is wrench time and how to use itDownload your guide to using maintenance metrics
What is wrench time?
Wrench time (also referred to as tool time) is a type of maintenance metric that measures the amount of time technicians spend performing work on a piece of equipment as part of the total time it takes to complete a job. In other words, it quantifies the time employees spend working with a “tool in hand.” Wrench time is usually measured by job, or as a weekly, monthly, and quarterly average.
The key to using wrench time effectively is to focus on identifying obstacles and frustrations that prevent work from being done. Measuring wrench time also informs management of potential red flags with processes or equipment that need to be investigated.
Keep in mind that the amount of time technicians spend with “tools in hands” will never be an accurate indicator of overall team productivity, asset reliability, or downtime. This is best done by using a CMMS software to automate your work order scheduling, streamline communication within your maintenance team, and measure the KPIs that matter most to your operations.
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Internal vs. external wrench time
Internal wrench time refers to the amount of time that maintenance technicians within the company spend doing actual maintenance work. External wrench time is wrench time conducted by third-party contractors hired to complete specialized tasks.
There are a variety of factors that influence external wrench time, including outsourcing maintenance procedures, engaging in clearance processes, and fulfilling regulatory requirements.
What wrench time doesn’t measure
When measuring wrench time, it’s important to be aware of what this metric doesn’t measure and won’t be able to tell you. Wrench time calculations do not include the time it takes to obtain parts, tools or instructions, or travel associated with those tasks.
Wrench time also won’t tell you if workers are performing the job on time. If a maintenance tech takes three hours to complete a task, that’s not to say that the job couldn’t be done in two hours. It also doesn’t provide insight into the quality of their work.
In other words, you can measure what work has been performed, but you do not know how effective or accurate it was. This is why some businesses skip measuring wrench time altogether and focus on defining and measuring other maintenance KPIs.
What is a good wrench time?
Typical numbers observed for wrench time are in the 25% to 35% range, meaning technicians typically spend 65% to 75% of their time without “tools in hand”. For example, a maintenance tech who works a 10-hour shift spends an average of 2.5 to 3.5 hours engaged in actual maintenance tasks throughout the day.
How to measure wrench time
There are four ways to measure wrench time, each possessing its own level of accuracy.
1. Statistical method
This is the best approach to tracking wrench time as accurately as possible. A methodical statistical approach ensures that every technician has an equal chance of being observed and that the observation sample is big enough to represent the actual work being performed over time.
2. DILO (“Day in life of”)
With a DILO method, you have an observer who is following selected technicians throughout the day to establish a baseline.
There are two big problems with the DILO method. The first is that the particular day measured doesn’t represent how an average day at the facility looks like. The second is that technicians might act differently if they know they are being observed. This is only natural human behavior, especially when you think your job is at stake.
To reduce the tension between the observer and technician, it is important to communicate that the purpose of the wrench time study is not based on the technicians' abilities or work ethic, but instead on finding inefficiency and problems that stop them from performing more maintenance work.
3. Work sampling
Work sampling is when observers visit the plant floor at set intervals, look at the technicians, and mark if they are performing maintenance work or not. The problem with work sampling is that it doesn’t account for people and specific tasks that are not visible. For example, technicians could be travelling, in the storage room, out to lunch, and so on.
As with the DILO method, expanding the timeline of the work-study should make the results more accurate. That is, running the study for a couple of weeks instead of a couple of days.
This is when technicians record their own wrench time. By asking technicians to track wrench time on their own, you open the doors to two potential problems. The first is that they might not track time accurately, or they will inflate the time because there is an incentive to overreport if they believe this will impact their paycheck or cost them their job.
Because of these reasons, it is common for self-reporting wrench time to reach 70% or more, while the more realistic numbers suggest that average wrench times are around 30%. This big discrepancy is the reason why this method is rarely recommended.
That being said, the self-reporting method is appealing because it requires no additional investment and is the easiest to implement.
To make self-reporting more accurate, you can take the following measures:
- Explain that the main purpose of calculating wrench time is to improve the overall performance and productivity of the maintenance department.
- Use a CMMS that lets you track time spent on maintenance work directly inside a work order.
- Be explicit about what activities are considered non wrench time tasks and what should be measured as wrench time.
How to use wrench time
Wrench time is a common tool for maintenance analysis, but it’s often used the wrong way. Wrench time is often directly associated with maintenance productivity. Because it's also a metric tied to technicians, they usually (and unfairly) get the blame for low wrench time. This leads to wrench time inflation as technicians fudge the numbers to avoid getting into trouble.
Low wrench time is often rooted in poor maintenance planning, inefficient processes, a lack of resources, and broken communication. It rarely has anything to with the ability of the maintenance tech. This ultimately leads to bigger backlogs, more reactive maintenance, and increased labor costs.
To use wrench time in your maintenance analysis, start with the jobs that have the lowest scores. Review these jobs step-by-step with your maintenance team to identify where unclear or incomplete processes are causing delays. When focused on improving productivity, wrench time is valuable in finding these bottlenecks and inefficiencies, resulting in more value for your team’s time and money.
Reasons why wrench time is low and how to fix it
There are a variety of reasons why wrench time can be low.
1. Poor maintenance planning and scheduling
A lack of adequate maintenance planning and scheduling has the ability to really impact wrench time. This can occur if spare parts and tools aren't available at the necessary time, if there's poor communication between maintenance workers, if excessive travel time causes delays, or if machinery that needs to be worked on is not ready for maintenance (for example, the technician has to wait for cleaning to be completed).
The easiest way to eliminate these issues is with a mobile CMMS. Teammates will be in various locations throughout the day, so being able to have 24/7 access to your CMMS is crucial to ensure proper communication about planning and scheduling.
Additionally, a CMMS enables you to indicate within the work order the required tools and parts a technician will need. It also has a maintenance calendar for faster scheduling, access to reports for tracking and measuring maintenance work, alerts when inventory is low, and push notifications if task priorities change.
2. Too much reactive maintenance
In relation to wrench time, the problem with reactive maintenance is that when equipment breaks down, technicians could spend their whole day putting out fires across the plant floor. Without proper tracking and management, there could easily be a lack of spare parts to fix the problem.
Additionally, technicians could get interrupted in the middle of the job with calls about new issues. This can cause confusion over priorities and what to do next, and create a general lack of processes that slows technicians down at every step.
The best way to deal with that is to transition to preventive maintenance or condition-based maintenance, and integrate with a CMMS that can support this proactive work and your maintenance goals.
3. Waiting on spare parts and tools
To save on costs and space, there can only be a limited number of tools and spare parts kept in inventory. But this needs to constantly be monitored and replenished. If technicians have to frequently wait for a certain tool to become available before they can perform their task, a lot of time is wasted that could have been better spent elsewhere.
This issue can be tackled by implementing best practices for managing spare parts inventory and ensuring that maintenance managers (or whoever is responsible for maintenance planning) schedule work in a way that takes the number of available tools into consideration.
In your work order software, set low-quantity alerts for stockroom supplies. Whenever a technician uses a part for repair work, they can indicate doing so on their mobile device. This automatically signals the software to alert management when to order critical components. Having the right parts on hand goes a long way in reducing idle time and increasing wrench time.
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