Using work station balancing to increase productivity.
Work station balancing is an analytical method for assessing and redistributing work flow. Its great advantage is that it helps identify inefficiencies that are not readily apparent. For example, test volume may have increased or decreased slowly over time in one area of a department without any corresponding change in work assignment. Or a new instrument may have increased efficiency to the point where the technologist assigned to that work station may not be fully utilized.
With some alterations, industrial work station balancing can be applied to the laboratory's main production shift, usually the day hours, with revealing results. Let me explain how it works.
The first step in work station balancing is to identify the status quo: to determine what tasks currently belong to each station. A work station may be defined in terms of a single physical location or tasks performed by one technologist at several sites during a shift.
If work stations are not part of the laboratory organization, they can be designated for our purposes through an examination of scheduling. For example, a lab technician may spend all day processing specimens or running a chemistry analyzer. Each of these represents a work station.
The natural flow of work can also be a clue to work stations. Blood cultures may pass from one technologist at a plate inoculation bench to another working on selective identification. This represents two work stations. In a very small laboratory, with technologists moving around from department to department, certain related tasks might make up a work station. For an example of how work stations and tasks ued to be organized in our chemistry lab, see Table I. We identified 10 tasks assigned to 7 work stations.
The next step is to set up a precedence chart (Figure I). This is simply a flow chart of the information in Table I. It shows the order in which work station tasks are performed in a department. Such tasks as specimen processing, logging, and centrifuging will always be first on the precedence chart, and recording and charting results will always appear last. Some tasks will be parallel on the chart; that is, they will be performed by different techs concurrently, representing different work stations.
On the precedence chart, we also write in a completion time for each task. The figure can be rough--an average time for completion of the bulk of the work in a typical day. The clearest measurement will be on a task that has a finite volume and is performed only once a day: Reticulocyte counts, for example, may be prepared, batched, and counted only once on a shift.
For an ongoing task--like running a large continuous flow analyzer--completion time equals the productive working time during a shift. In the case of two types of tests that are performed on alternate days, consider the combined tests as one task. Our laboratory, for example, runs HDL cholesterols on Tuesdays and Thursdays and electrophoresis on Mondays, Wednesdays, and Fridays. The task is called HDL/electrophoresis, and it is assigned an average completion time.
Don't worry too much about exceptions, such as occasional special procedures or major maintenance on the hematology analyzer. Remember, you are just compiling rough figures here.
Scanning Figure I, we can see a major discrepancy between the times spent on tasks at work stations C and D. The obvious question is why these variations weren't noticed before. The answer is that they evolved gradually over a long period of time.
At work station D, increasing workloads steadily raised the completion time. The assigned technologist could no longer limit work on profiles to the morning and have the afternoon free for other duties--occasional batches of less frequently ordered manual procedures and preparation of specimens to be sent out to a reference lab.
At work station C, on the other hand, a larger, faster automated instrument had been introduced. Technologists gradually whittled down completion time as they became more proficient on the instrument. The chemistry supervisor took a close look at the station and concluded that 120 minutes a day was a reasonable completion time.
Much the same thing had happened at work station F, which was originally created for the manual transcription of results throughout the day and patient charting. With the introduction of a laboratory computer system, work that had taken a full day to perform now took only an average of 90 minutes.
It's clear from these figures that tasks are unevenly divided among the work stations. The question is how to reassign them in the most efficient manner. That brings us to the "greatest number of following tasks" rule--a bit of jargon meaning that each task is evaluated in terms of the tasks that must precede it and might follow it, based on priorities and the daily task completion times.
To determine which tasks might follow other tasks, we set up the chart shown in Table II. It lists each task, its completion times, tasks that must be performed first and their completion times, and all possible following tasks, given the time constraints of the day. (To determine productive time in a day or shift, subtract obvious nonproductive periods--such as lunch, instrument start-up, and maintenance--from hours on duty. The times need not be exact, just close enough for a good approximation. A reasonable productive time might be 420 minutes or 7 hours out of an 8-hour shift.)
The purpose of this chart is to recombine tasks into hypothetical work stations that will be more efficient, on paper, than existing work stations. Then we can go on to determine the feasibility of the hypothetical assignments.
Let's look at the tasks we have outlined and see how they can be recombined. In the case of tasks 1 and 2 (logging and centrifuging), it appears possible to follow with any or all of the remaining tasks. Certain factors limit our choices, however. For example, this work station requires constant coverage to receive and process specimens as they come in. Therefore, the technologist performing tasks 1 and 2 cannot go on to operate a chemistry analyzer or perform RIA procedures.
Using this reasoning, the only feasible following tasks are 7 and 9 (preparing specimens to be sent to the reference laboratory and charting results). We conclude that tasks 1, 2, 7, and 9 are closely related to one another and constitute a reasonable and feasible new work station in chemistry.
Next we look at task 3 (performing electrolytes, glucose, BUN, and creatinine). Although it may be followed by several of the other tasks (based on the time necessary to perform them), none of the combinations is feasible because task 3 requires coverage for the entire shift. Therefore, it stays a work station unto itself.
As you can see in Table II, we followed the same pattern of analysis with the rest of the tasks. The result was that we condensed seven actual work stations into five hypothetical work stations. This redistribution of work solved several major problems, most notably the highly uneven amounts of time spent productively at the various work stations (see Figure II).
However, before hypothetical work stations can be translated into practice, the supervisor should take several factors into consideration. First, the very nature of laboratory work runs counter to all principles of operations management. Stats must be attended to as soon as they arrive in the lab. Workload fluctuates seasonally and even daily. Every technologist has experienced a sudden temporary surge in volume for a particular test--no doubt one that was featured in a medical journal that month.
All these factors underscore the fact that task completion times must be taken as averages only. New staff members can affect that time dramatically until they get the hang of things. Another problem the supervisor must look for is the technologist who may be dragging out a task to fill the day.
Idle time at a work station must be considered in evaluating the hypothetically balanced department. Is there too much or too little idle time? Idle time at the beginning of the shift can be used for daily setup and maintenance of automated instruments. If idle time seems excessive, the supervisor can delegate added tasks to a station. Such tasks include quality control work or writing new procedures, which can be done between batches and during other lulls.
You may also decide that there is not enough idle time at another work station after balancing. For example, the analyzer that performs chemistry profiles may require more setup or maintenance time. In this case, it may prove more productive to have a technologist start work earlier in order to set up the instruments.
While all of these considerations may make workload balancing seem unrealistic in the lab setting, they are offset by the method's ability to uncover inefficiencies due to underutilization or an overburdened work station.
At the very least, work station balancing can provide insights into workload allocation and priorities that may lead to other cost and time saving strategies.
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|Author:||Callahanb, Barbara B.|
|Publication:||Medical Laboratory Observer|
|Date:||Jun 1, 1984|
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