Lean Manufacturing

Safety Glasses Are a Sign of Unsafe Processes

By Jon Miller Published on March 20th, 2007

I left the training room too eager to go to gemba today and forgot to put on my safety glasses. Within two minutes one of the safety coordinators on the shop floor stopped me and sent me back to get them. Kudos to the management of this company for instilling this level of safety awareness in their people.
In order to keep kaizen going over decades, you need to be dissatisfied. In order to be dissatisfied you need have high ideals. The definition of “ideal” in TPS includes safety. A product, process or service should be safe, first and foremost. All kaizen should improve safety.
Why do most American factories require people in the factory to wear safety glasses? Perhaps it has something to do with Ralph Nader. The obvious answer is that the safety glasses protect peoples’ eyes from injury caused by flying debris. Why do we have flying debris? Safety is not built into the process.
The Japanese consultants I worked with always puzzled at why American and European factories had such inadequate guarding at the source of the debris. They used to say that safety glasses are a sign of unsafe processes. I think of safety glasses as an sign of a process that is far from ideal, just like inventory is a sign of a lack of flow or forklifts are a sign of disconnected processes.
I have not been to all Japanese factories, but I have never seen safety glasses worn in the factories I have visited. In Japan they do wear caps, called “safety caps”. These caps are thinner than baseball caps, so presumably the flying debris in Japanese factories is quite flimsy.
There is an interesting story about Taiichi Ohno. In the early days of implementing the Toyota Production System at Toyota, one of the workers in the factory who was not so eager to change threatened Ohno with a hammer. From then on, Ohno did not wear a safety cap when he went to the gemba. Part of this was to show people that he was putting his life on the line to make TPS succeed. Part of it may have been that he saw how silly it was to wear the safety cap in an unsafe workplace.
Safety glasses protect your eyes, but they can also make your unsafe processes less visible.

  1. Anonymous

    March 21, 2007 - 1:36 pm

    Maybe the flimsy safety caps were to keep hair from getting caught in equipment?

  2. Julian Liu

    March 21, 2007 - 6:03 pm

    So airbags are a sign of unsafe cars?

  3. Jon Miller

    March 21, 2007 - 7:20 pm

    Wearing an airbag on your head whenever you got in your car would be. An airbag is a good example of guarding at the source of impact.
    Machines in factories that stop or deploy a protective mechanism when a person enters the working are examples of safe processes.

  4. Pete Abilla

    March 23, 2007 - 4:45 am

    The Toyota plant I worked at in Hebron, KY requires safety glasses at all times while on the floor. The reason? No process is yet perfect; so, in the meantime, be safe while you perfect your processes.

  5. Michael Schaffner

    March 24, 2007 - 2:54 pm

    A very thought provoking post. Taking this a bit further, do many of our policies and practices indicate an imperfect process? Do we have final inspectors because our manufacturing process does not catch errors as they occur? Do we have users test software modifications before we put a new system into production because our project definition process and data structures are not what they should be? Do we do peer review of engineering design because our design procedures are not complete?
    Personally, I Pete Abilla’s comment is spot on in regard to the issue of inspection, auditing and protection methodologies. However, your question does make you stop and think about why we do things.

  6. Robbie

    April 27, 2009 - 7:38 am

    I always felt that if cars had large sharp metal spikes on the dashboard there would be fewer accidents, as well, there would be fewer injuries in hockey or american footbal with less padding. Saftey equipment causes complacency.

  7. Kyle Hajek

    February 7, 2021 - 9:21 am

    This is so dumb I had to comment on it 14 years later. Eyes are fragile and it doesn’t take much for there to be a recordable injury- corneal abrasions are common and can happen from a split second of ripped cardboard.

    In conclusion what the hell.

    • Jon Miller

      February 7, 2021 - 1:35 pm

      Hi Kyle
      Thanks for your comment. The message of the article was that prevention at the source is they key. Make processes safe. When we can’t guarantee that, we obviously need to wear protective gear.

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