Measuring wrench time in the shop and how to get more out of it

Updated Mar 27, 2013

You hire mechanics and technicians to repair and maintain equipment. But do you know how much time they actually spend, tools in hand, doing exactly that?

If you don’t, you’re not alone. According to Ricky Smith, senior reliability advisor for GPAllied, a global manufacturing and reliability consulting firm, in most organizations, most mechanics and technicians spend at best 20 to 30 percent of their time with a wrench or tools doing their primary job.

The rest of their time is taken up with secondary activities. Some of these are necessary, such as travel time for the service truck. But as the chart below shows, a lot are the result of poor planning and organization.

In an efficiently run shop, with world class performance, direct labor or wrench time should be 55 to 65 percent of their time, says Ricky.


Measure it first

Ricky, who has been doing maintenance and reliability work and consulting for 40 years, recommends a wrench time study for organizations that want to improve their shop efficiency and productivity. But unlike the old cliché of an efficiency expert walking around with a clipboard and stopwatch, the modern wrench time study takes advantage of PDAs (personal digital assistants) and self-reported activity.

“We can come in and train people on how to use the PDA but they can do it themselves too,” he says. They come with software and instructions that any shop supervisor should be able to manage. The PDA devices are available online. (See the Resources box at the end of the article for more information.)

Activity and Time Spent:

  • Direct labor (wrench time): 29%
  • Obtaining material/parts: 23%
  • Waiting : 17%
  • Travel: 17%
  • Searching for information: 7%
  • Administration: 7%
  • Source: GPAllied


Digital data

The process involves giving the PDA to a technician to carry with him for a week or so. The PDA will prompt him at regular intervals to simply press a button that describes the activity his coworkers are engaged in at the moment.

“The guy with the PDA will do it separate from his work,” Ricky says. “On those days all he does is randomly walk around and observe what the other people are doing.”

Some people say they can’t afford to take a person off the tools, he says. But managers have to remember why they’re doing the study in the first place – to make everybody more efficient. Ricky recommends you use your top people to do the data recording and avoid anybody with attitude. “They have to care about the people and want to help them become more efficient in their job,” he says.

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In the past, efficiency studies have had a bad reputation among workers, Smith says, and this negative perception has to be addressed up front. “If your goal is to eliminate staff then you shouldn’t use a wrench time study,” he says. “The only reason for a wrench time study is to identify the delays that cause maintenance to be less efficient. A wrench time study is not about finding which of the mechanics is goofing off. It’s about the quality of the planning process and how the organization uses the planning process.”


Understanding the data

Several people should carry the PDA over the course of several weeks. “You’ll need 1,200 to 3,000 observations to get a statistically valid wrench time study, Ricky says.

Once you have your data collected you can look at the percentages of time spent on various activities and begin to understand where your inefficiencies lie. What typically eats into wrench time? Ricky offers this list:

• Traveling to and from the workplace

• Breakdowns in planning (emergencies, urgent work, waiting for parts or people)

• Training

• Meetings

• Breaks

• Administrative issues

It is given that some of these activities are necessary, but in the typical shop there is lots of room for improvement. And most of the improvement can come from better planning and interdepartmental communication to eliminate bottlenecks.

For example, the shop often plans for a piece of equipment to be delivered at a certain time and ready to work on. But if operations delivers the piece late, or if it’s covered in mud and has to be pressure washed, those delays eat into wrench time.

Parts access can also create a bottleneck. Some schedulers assume the parts are going to be ready when the mechanics are ready, but that isn’t always the case. The schedule is made up on assumptions like these that frequently cause considerable loss of wrench time.


Communicate, don’t criticize

As a shop or equipment manager, once you’ve identified these bottlenecks, you have to be careful about how you go about removing them. You don’t barge in and tell everybody else how to do their job, Ricky says. “You have to start cleaning your own house first, before you bring in other people. That’s why I believe maintenance has to start the process. You don’t have the credibility to tell others to do something different if you haven’t done it yourself first.”

Things aren’t going to change overnight. “If material management is a problem and you’re losing time over it ,you need to sit down with whoever is in charge of it and let them be part of the solution – not point your fingers at them, not telling them they’re doing something wrong,” Ricky says.

Instead, a wrench time study looks at the way the organization uses the information that comes from the planners and how each of the departments within an organization work together to get something accomplished.


Whittle away at inefficiencies

There’s no point in doing just one wrench time study, Ricky says. After you’ve identified bottlenecks and inefficiencies with the first study you can execute a plan to reduce them. Within six months to a year you’ll need to measure again to see how well your plan of action works. A typical result might look something like this:

“Once you start this in your culture, it never stops,” Ricky says. After your first few wrench time studies you’ll want to come back to it every two years or so. “You want to be constantly improving your operation and not get back to where you were before. Most companies will regress if they don’t continue it,” he says.


Multiple benefits

Once you’ve got your processes standardized, repeatable and efficient, not only does wrench time increase, but employees enjoy their jobs more and machine uptime increases as well.

When the mechanics show up and the parts are kitted up and waiting for them, the plan contains all the necessary information and detail, and the machine is there, clean and ready to work on – at that point your mechanics are going to be motivated and everybody is happy, Ricky says.

Another benefit for the company is the dramatic impact increased wrench time has on MTBF or mean time between failures. MTBF is a measurement of how much time passes between failures or repairs on a machine. The chart below shows a composite of MTBF studies and how a fleet can go from an average of less than 50 hours between failures to almost 300 hours between failures when wrench time is boosted to 60 percent.

The impact that has on machine uptime is obvious and will almost always garner favorable attention from the company owners and managers.

Ricky cites an example of work he did with a large power company, whose CEO decided to drop in on the training. He intended to stay for an hour and wound up staying five days.

“The first time you have a senior executive in there, they’re going to get it,” he says. “It will change the whole organization, but you can’t talk about that at first because you only control maintenance. You don’t have to show them, or send them an email or brag about it. Just let them become aware of it. They will see equipment reliability going up. People will be more satisfied in their work. There will be less absenteeism, better morale and less turnover.”


About our expert

Ricky Smith started out as a heavy equipment mechanic for the army in 1972 and got a degree in industrial education from the University of Georgia. He is a Certified Ricky Untitled 1Maintenance and Reliability Professional, as designated by the Society of Maintenance and Reliability Professionals, and is a member of the Association of Equipment Management Professionals. He is also a Lean Six Sigma Blackbelt. In his last army tour of duty he served in Iraq as a maintenance company commander from 2004 to 2005 supervising more than 200 technicians, mechanics and soldiers.



PDAs and work studies software





Association of Equipment Management Professionals,

Society of Maintenance Reliability Professionals