Sitting Work vs. Standing Work in a Lean Manufacturing Workplace

I recently spent 3 days standing on the shop floor while leading a training event for future kaizen facilitators. I spent probably 8.5 hours per day standing, 60 minutes sitting (lunch, breaks), and 30 minutes walking around the 100 square meters occupied by the pilot cell.
If I hadn’t been doing this sort of thing for the last 12 years I imagine my feet would have been tired. It’s something you get used to. It takes about two weeks. But converting a workplace from sitting work to standing work is one of the bigger challenges with Lean Enterprise transformation.
As more companies go to 10 and 12 hour shifts, factory managers worry that the workers will be tired of standing by the end of the day. They will for the first two weeks or so until their muscles adjust. They may complain for longer than two weeks if the principles of Lean manufacturing (competitiveness by cutting out waste through one-piece flow) are not explained to them.
Standing work enables flow. In addition:
1. Standing work is more ergonomic. When you lift from a sitting position you are using your lower back and very little of your abdominal muscles. When you are standing you use leg and abdominal muscles as well as your arms for lifting.
2. Standing gives you greater range of motion and allows you to use vertical space more effectively for material presentation and tool location.
3. Standing enables multi process handling. When you stand, you can walk. When you walk you can move the product form process to process. Sliding along in a chair just isn’t the same.
4. Standing reduces space required. No chairs mean you need about half of the footprint per person, resulting in more compact work cells.
We do have to do something about the sore feet during those first two weeks. Look at the shoes people are wearing. Do they have thick, cushioned soles? Issue them good new shoes if not. Are they standing on concrete? Probably so. Place floor mats under the working positions to further cushion their feet.
Although few companies outside of Toyota do this effectively (if at all), rotating work positions every 2 hours to a different type of process (from standing to walking work, for instance) helps use different muscles, enhance cross training and cut down on the boredom.
I recognize that not everyone can stand all day or work at a certain pace for physical reasons. Processes should be designed around people, not the other way around. But ultimately the market determines what kind of processes will succeed in winning business from customers.
Going from sitting work to standing work is a leap for some, and it’s not something you want to attempt on your first kaizen. There are other battles you can win first. In the end a Lean process will require standing work in many places, even the office.

11 Comments

  1. Heather Gottlieb

    June 16, 2006 - 12:02 pm

    We are faced witha cell that has 11 people. Takt time = 14 seconds, CT for each operator = between 11-14 seconds. The TT is so quick, they are only doing 1 operation, so there is no movement. Do you have any suggestions how we can win the battle of having them stand? Their argument is that why should they stand, they are not moving?

  2. Jon Miller

    July 18, 2006 - 7:11 pm

    Hello Heather,
    First, a takt time of 11 to 14 second is too fast. If you can triple or quadruple the number of lines you have and make the takt time closer to th 50 second range that will be better.
    Once that is done, the workers will need to be cross-trained to do a wider range of work. This will also require walking, which is more ergonomic than standing or sitting for 8 hours per day.
    If you can not slow down the line speed, the only argument for standing is that your range of motion is increased and that you will not strain your back when lifting. For high speed sensor assembly there is probably not much heavy lifting and the range of motion for 11 seconds of work is already very limited I would guess.
    So I return to my original recommendation of creating a multi-process handling one-piece flow cell with a takt time that is closer 50 seconds.
    Design the work around the human, not around the machine.
    Best wishes,
    Jon

  3. Kevin Hop

    August 20, 2006 - 11:04 am

    I agree with the basic statements above. But if you do the math…and 11 second process with 11 people in the cell being switched to a 50 second process will be a little over a 2 person cell. Unless you have a line with all 100% auomated poka yoke quality checking in the machines this could pose a problem for quality checks of the product while it is still “open, exposed or available” so that the next person in the line can do the important “double check”. In other words you would only have one succesive check available in this cell. Not good. In addition a 2 person cell is highly vulnerable to absenteesim, training periods, etc. I recommend something closer to a 30 second process with 4 people. A typical Toyota or Honda engine line or small parts line has a takt around this time. In conclusion 11-14 seconds is not acceptable for human labor – if you can not change it then automation is your next step. Though something closer to a minute in takt is more ideal it is not always feasible. As a rule of thumb though don’t get under 30 seconds. It is ergonomically and mentally numbing. Good Luck.

  4. Paul Cheng

    May 17, 2007 - 8:26 pm

    I am new in ergo field. We are doing Lean mfg Machine Cell layout: e.g., one person runs 4 machine tools. I have had two operators complaining the cycle time of their respective machine cell goes too fast/ too short and they can not keep up with it, so they don’t get any rest at all–non stop working. Please advise. Any books you recommend to read to understand Lean mfg machine cell related ergonomics.
    I also wonder which books talk about a person should work how many seconds and rest how many seconds in one working cycle so he/she won’t be too tired–pace to last for 8 hrs.
    I visited Ford plant in Kansas. It looked like that each assembler only worked about 30 seconds within each 60-second cycle time along its long Escape SUV assy line. So, they didn’t look tired. Thanks.

  5. Jon Miller

    May 17, 2007 - 9:55 pm

    Hi Paul.
    A good industrial engineering text will provide guidelines for ergonomics. From a Lean perspective, there is a so-called 50 second rule that states that manual work should not be repeated more often than every 50 seconds. In addition, rotating jobs every 2 hours is highly recommended both for reducing fatigue and repetitive stress injury, as well as improving worker skill and cross training.
    Good luck.
    Jon

  6. Paul Cheng

    May 21, 2007 - 5:08 pm

    Dear Jon,
    Thank you so much for your lean and ergo tips. Very sincerely, Paul Cheng

  7. JACT

    October 7, 2009 - 9:22 pm

    i read the comments and all of them helping me to understand.
    we are running a 5 person cell tt=44 sec but the problem its one station it takes it 5.16 sec finish the test and the others are faster 2 min and 3 min so we can’t make continuous flow what would be your advice??
    thank you all
    JACT

  8. Jon Miller

    October 7, 2009 - 10:21 pm

    Hi Jact,
    I am not sure I understand your question. If tt is takt time, and takt is 44 seconds, no process either automatic or manual should take more than 44 seconds per piece. Unless each test cycle tests multiple pieces, the 2 min and 3 min tests are also problems. If by “5.16 sec” you mean 5 minutes 16 seconds then this is also a problem – cycle time is over takt. If it is 5.16 seconds then there is no problem.
    Please feel free to clarify your question if I have misunderstood.
    Best wishes,

  9. deb

    January 13, 2010 - 4:43 pm

    my employer is doing this backwards, deciding on expected output per hour, calculating new cycle times and “oh no, operators can’t meet new cycle times!” btw, been on feet for 2 years, still hurts… Also read that TPS started from a book by Henry Ford

  10. Ricky Naguit

    January 14, 2010 - 12:39 am

    We just recently tried the standing position process and its right that in the 1st and 2nd week worker complaint about the pain they feel in their leg but after 3 weeks until this day they are complaining of their sore feet even though we already advice to work without shoes just wear socks. Is their a good industrial cushion for this kind of working condition you can recommend to me. i already try mats but they still feel the same and their bear foot in just a few minutes is sweating.

  11. Jon Miller

    January 14, 2010 - 10:15 am

    Hi Ricky
    It sounds like you are already using mats for standing work so that is good. Make sure they are “anti-fatigue” mats and you may want to try different kinds to see what is most effective. Here are some examples
    http://www.uline.com/Grp_36/Mats?Pricode=wg651&gclid=CLXo85K9pJ8CFRwTagodGQNfsQ
    It will take a few weeks usually for the legs to get used to the new way of working.
    Also, combining standing work with some walking within the work area as well as rotating positions between workers may help reduce the fatigue.