The What, Why, How of Wrench Time

Doc Palmer

Let us share a few words about wrench time: What is it? Why is it important? And, how do we measure it?

What is wrench time?

Wrench time is a measure of crafts personnel at work, using tools, in front of jobs. Wrench time does not include obtaining parts, tools or instructions, or the travel associated with those tasks. It does not include traveling to or from jobs. It does not include time spent obtaining work assignments. Obviously, it does not include break time. These tasks are often necessary to get work done, but are not “wrench time.” The craftsperson is in a delay situation. We should also ask ourselves whether the crafts personnel perform tasks efficiently while they are on tools in front of jobs. This is a legitimate question, but not answered by wrench time. Nonetheless, if we increase the time employees are “on the job,” we should get more work done.

In addition, planning should increase the efficiency of a craftsperson while on a job if the plan provides helpful instructions and provides a time standard for a good technician performing the expected work without unanticipated delays.

To define something as wrench time or not, I find it helpful to consider what I would be willing to pay for if I hired someone to do a job. Would I be willing to pay for someone getting a part? No, I would have wanted them to have that part available to begin with.

Why is it important?

Industry experience shows that typical workforce wrench time is between 25 and 35 percent. Planning and scheduling can help raise this rate above 50 percent. One of my earlier Reliable Plant columns stated what this means in monetary terms. For now, accept that increasing a workforce at 25 percent up to 50 percent would double the labor. A 30-person workforce would perform the work of 60 people. You can see this is a vital issue.

My sixth principle of planning states that wrench time is the primary measure of planning and scheduling effectiveness. The purpose of planning and scheduling is to increase productivity. It’s not to prepare job plans or operate the CMMS. Planners might prepare job plans or operate the CMMS, but that’s not the purpose of planning. The job plans and CMMS help the planners in their goal to increase productivity. Wrench time best measures this productivity.

How do we measure wrench time?

Before we discuss how to measure wrench time, let me first say that formally measuring wrench time isn’t a requirement to implement helpful planning and scheduling. Wrench time studies are easily seen as obtrusive and heavy-handed. Implementing a fundamentally sound system that plans most of the work and schedules each crew with a weekly goal of work improves wrench time whether it is measured or not. In addition, the metric of work orders completed per month shows a dramatic increase when the scheduling effort takes off.

Nonetheless, plants can measure wrench time in-house with reasonable accuracy with a limited number of days and in a manner acceptable to crafts personnel. First, use an agreeable, in-house supervisor as the observer who knows everyone. This avoids putting numbers on hats or other perceived demeaning methods to identify people. Second, announce the study ahead of time to the crafts during breaks or other convenient settings. Frame the observations as finding out what delays are hindering work, not as measuring whether people are lazy. Third, use a sampling method, sequential or random, to insure each person has an equal chance of selection. Fourth, five days of sampling two people each half-hour of an eight-hour shift produce accurate enough results to confirm a 35 percent wrench time with a plus or minus 7 percent accuracy. Often, this result makes the study worthwhile as the plant discovers it does not have 80 percent wrench time as commonly thought. Plus or minus 7 percent is also accurate to confirm a productivity increase.

A plant might move from a range of 28 to 42 percent to a range of 43 to 57 percent, a definite improvement. (Certain statistical tests also exist to confirm improvement even if the ranges overlapped.) In addition, a study would quantify delays such as parts, tools, instructions, traveling, etc. with better accuracy than plus or minus 7 percent because delay areas are smaller. E-mail me to receive a sample wrench time study that compares delay areas.

Doc Palmer

Doc Palmer, CMRP, is the author of ‘Maintenance Planning and Scheduling Handbook.’ He has nearly 25 years of industrial experience as a practitioner working in the maintenance department of a major electric utility.

Improving Estimating Quality

Estimating lays the foundation for planning, scheduling, and management of business critical projects. It is also critical for budgeting, bidding and contracting. Achieving consistent, quality estimates is critical to business success. However, many companies lack systems and procedures to ensure consistency in estimating across the enterprise and easily define, benchmark, and refine corporate estimating standards. The potential long term benefits of instituting an effective solution to this problem are enormous.

Proactive Approach to Shutdowns Reduces Potlatch Maintenance Costs

Effective shutdown management is critical to the operation of mills, for without well-planned and executed shutdowns, equipment reliability suffers, and the mill pays the price in poor quality and lost production. Becoming proficient at managing shutdowns is a way to reduce overall downtime costs so that shutdowns themselves do not consume the savings they are capable of generating.

Start Designing a Planning and Scheduling Program

If you need to implement a new planning and scheduling program, you’re probably discovering that the task can be rather daunting. But there are ways to achieve an environment that will support a planning and scheduling program that works with what you already have in place and takes into account what your team is able to manage throughout implementation and beyond. If you take a closer look at what you already have, putting the final touches on a successful planning and scheduling program may not really be that big a beast to tackle.

Equipping Crews for Cost Savings with Standard Job Plans

Standard Job Plans (SJPs) are the product of the planning process. Work crews that have access to well documented SJPs perform higher quality and more consistent work. Using SJPs, effort isn’t wasted on searching for needed information while in the field. SJPs streamline the planning process by allowing planners to refine past plans instead of starting from scratch for each job. SJPs also support a positive plant culture by providing a mechanism for continuous improvement.

Bill of Materials: A List of Parts to Streamline Maintenance Work Management

No other element of the technical database provides as much value to planning as an accurate bill of materials. Bills of material are a list of parts that are used on the equipment. When developing BOMs, focus on parts used for routine maintenance, repair, and operation of the equipment. Individual parts should contain a minimum amount of information including: a consistent and organized name, manufacturer and their item number, price, lead time, and quantity needed for the equipment.

AAA Best Practices Make the Difference

The technical database is all the information needed to plan and schedule efficiently and effectively. Having the eight components of the technical database in place will allow quick determination of the what, how, how long, who, and when of a maintenance job. Application of three simple best practices will generate the most value from the technical database. Focus on developing a technical database that is accurate, accessible, and applied.

Planning and Scheduling in the Process Industry

Since there has been tremendous progress in planning and scheduling in the process industry during the last 20 years, it might be worthwhile to give an overview of the current state-of-the-art of planning and scheduling problems in the chemical process industry. This is the purpose of the current review.

The What, Why, How of Wrench Time