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Essential Steps to Determining Production Work Cell Efficiency

written by: Ian Johnson • edited by: Michele McDonough • updated: 5/19/2011

When it comes to increasing production throughput in a given work cell, companies must be able to keep track of lost time, identify root causes, and use the information to calculate the production cell's productivity rate. From that, the company can then eliminate lost time altogether.

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    Eliminating Lost & Idle Time in Production Cells

    For manufacturers looking to increase their production throughput and lower cycle times, few actions are as impactful as determining the company’s manufacturing productivity rate in a given work cell. Often a source of great confusion, determining productivity rate and efficiency is nowhere near as difficult as it might seem.

    In an ever increasing competitive world economy, manufacturers must have a solid grasp on their production capacity, lower their cycle times, and must find ways to eliminate idle and lost time in all its forms. It amounts to capturing idle time, identifying actual work time and setting the stage to eliminate the root causes of downtime and delays. So, what are the steps to calculating a company’s manufacturing efficiency?

    1. Determine Actual Hours Worked in a Given Work Cell

    Like a surgeon operating on a patient, workers must have clear work instructions, a clean bill of materials and their tools and equipment within reach. Each of these items listed plays a huge role in work stoppages. Essential to determining the productivity rate is to first determine the actual hours worked during a production run. These are the essential criteria that need to be determined.

    • Total hours of paid work time.
    • Total time taken for lunch, and breaks.
    • Lost or idle time in production, regardless of cause.

    For example, let’s assume a company runs two 10 hour work shifts a day. Of each 10 hour work shift, how much time is allocated to lunch and breaks? For this example, we’ll assume 1 hour for lunch and two 20 minute breaks. In this case, the employees could only realistically work 8 hours and 20 minutes total, and that’s if they were 100% efficient. No employee is capable of that! Therefore, the question remains, of this remaining 8 hours and 20 minutes, how much of this time is actual work time and how much is lost time due to delays?

    2. Capture Lost Time and Identify Root Causes

    There are many companies who use an MRP (Manufacturing Resource Planning) to track work orders and determine their appropriate cycle times in a given production cell. However, while these MRP programs show what the cycle times are, they in no way show how to improve those times, or what the delays are caused by. That’s why even companies that have MRP systems still prefer to see work done with their own eyes, in order to identify causes of downtime. In this case, it amounts to actually standing at a work station and tracking lost and idle time as it occurs. It’s certainly not the greatest use of anyone’s time, but it’s an investment in improving the company’s production capacity.

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    Eliminating Idle Time & Calculating Productivity Rate

    When capturing lost time, ensure to properly document every single root cause, regardless of how small it may seem. Lost time in manufacturing comes in a number of forms, and a couple of seconds here and there may not seem like much, but taken as a whole, these seconds can add up over time. Be sure to stop and start time accordingly, and come up with a common reference for similar stoppages. For instance, if a piece of equipment continues to stall, put the lost time under "machine stoppages". Include a brief description and summarize lost time at the end. Eventually, there will be a summary of root causes and their appropriate times.

    3. Amalgamate Information and Calculate Productivity Efficiency

    From step 2, the company has been able to determine how much lost time occurred, and how much actual work time took place. What’s the next step? Well, it amounts to using a simple calculation to determine the productivity rate. We’ll assume the company gathered the following information.

    • Available work time: 500 minutes (8 hours & 20 minutes)
    • Total lost time due to delays: 90 minutes (1 & ½ hours)
    • Actual work time: 500 minutes – 90 minutes = 410 minutes
    • Productivity rate is calculated by taking actual work time and dividing it by available work time: 410/500 = 82% production efficiency

    For companies that simply can’t come to terms with how much is produced within the time they pay for work, this is a simple and extremely effective way to shine a light on the causes of work stoppages. Surprisingly, this 82% is a good percentage, especially considering that some companies are as low as 50%! Many businesses forego the necessary maintenance on equipment, or upkeep of their bill of materials and assembly drawings, because they simply aren’t aware of how much time is wasted. With this approach, a company can not only see the impacts firsthand, but document these causes and set strategies to address them.

    Maximizing cycle times in a given work cell is all about tracking lost and idle time, identifying its root causes and setting the stage to eliminate those causes all together. Companies must be aware that improving the cycle times and production throughput in one work cell, without properly addressing the next cell in the chain, will simply create a larger backlog in the process.