Muda: The 7 Deadly Wastes

By Robert Minardi

Muda is the Japanese word for futility, uselessness or wastefulness. For our purposes, we will define it as any activity or process that doesn’t add value to our product. In other words, if a customer wouldn’t pay for it, it’s Muda. The elimination of Muda is so critical to manufacturing—including spectacle lens processing—it should be considered long before you add equipment or hire a single person. 

We’ll discuss why this is after we define the seven most widely recognized forms of Muda.

Transport

One form of Muda involves the excessive movement of product between processes or locations. Causes include:

  • Excessive space between equipment
  • Line layout that doesn’t move product  towards the correct destination
  • Employees tasked with moving materials    when it could be automated

A good indicator your lab may have an issue with this waste is if you look at your lab floor and see employees buzzing around like bees; going this way and that with job trays. Take a critical look at how jobs flow around your lab and determine if you can squeeze some extra productivity out of your line by eliminating excess transportation of materials. Spaghetti Diagrams (SD) work great for this because you can figure out the path jobs take, and then measure the distance traveled. With this data, you can determine how many feet (or miles) your employees travels in a day and work towards reducing it.

Inventory

Another form of Muda includes the use of excess raw materials, finished product and work in progress (WIP). Causes include:

  • Ordering more lenses or consumables than production demands
  • Over-producing work and having to store it till it can be processed

You can address this in your lab by ordering only the raw materials you need based on seasonal production trends and historical data. Excessive inventory uses up valuable work space and makes it difficult to find things.

However, it’s important to note that inventory isn’t limited to lens blanks or consumables. It also includes overflow from areas on your production floor. Try to deliver work to the next area “just in time” (JIT) for processing as opposed to the traditional batch and que method. Creating a buffer of work to ensure the line runs smooth is okay, but having half-a-day worth of production sitting on a table is a sign there’s an imbalance in your process. Excessive inventory needs to be constantly shuffled around, thereby slowing production and increasing the chance of breakage.

Waiting

Idle time when product is not making progress towards completion, or employees waiting for work, is another form of Muda. Causes Include:

  • Unscheduled or poorly scheduled equipment downtime
  • Running out of consumables
  • Imbalanced manpower or machinery output causing one area to wait on another

To reduce Muda here, perform preventative maintenance and calibration during non-working hours if possible. Also, identify imbalances in the process steps and try to smooth them out by adjusting equipment speeds or adding/subtracting employee duties. Implement a Kanban inventory replenishment system to ensure your line always has what it needs to run.

Defects

Product that doesn’t meet customer specification can create Muda. Causes include:

  • Employee error
  • Equipment malfunction

Sometimes it feels like breakage is the bane of our existence in the lab. In the blink of an eye, we can have stacks of it surrounding us. The secret to keeping defects under control is the unrelenting search for what causes them and the diligence to keep them from happening again. When issues arise, find the root cause of the defect and its solution. Then, use employee training, Standard Operating Procedures and QA posts to drill the new way of doing things into everyone’s technique.

As legendary UCLA basketball coach John Wooden once said, “If you don't have time to do it right, when will you have time to do it over?”

Motion

Unnecessary movement or motion of employees can also create Muda. Causes include:

  • Poorly designed work stations that cause employees to reach for tools or walk too far to perform their duties
  • Commonly used tools or necessary items not being readily available
  • Disorganized line layout or excessive space between job stations

An easy way to spot this is if you see employees very busy, yet producing little work. Every movement an employee makes should result in completing a necessary and valuable task. Also, this Muda is a huge contributor to workman’s compensation claims and lost time injuries—much like equipment, people wear out, too. Unfortunately, the technology isn’t available to swap out our worn parts. To prevent this waste, create ergonomic work stations that make it easier for someone to do their job, not harder. Some techniques for eliminating wasted motion are to have frequently use tools easily within reach and properly oriented and eliminate over-sized work areas. The goal is to keep employees as stationary as possible while they produce large amounts of work.

Over-Processing

Processing by man or machine that adds no value to your product is also Muda. Causes include:

  • Unneeded levels of quality or providing employees with vague customer requirements
  • Use of improper tools to perform a task
  • Needlessly handling jobs multiple times

Abiding by ANSI standards and ensuring all employees know exactly what the customer does and doesn’t need and/or want can reduce this waste. Remind your staff to perform the minimum amount of work on a job to achieve an acceptable result. Also, design your processes such that a job is handled once and only once per station.

“Sometimes it feels like breakage is the bane of our existence in the lab. In the blink of an eye, we can have stacks of it surrounding us. The secret to keeping defects under control is the unrelenting search for what causes them and the diligence to keep them from happening again.”

Over-Production

Processing work faster or in a higher quantity than needed leads to Muda. In fact, this is widely considered the worst of all wastes because, if you over-produce, you create all the other wastes as well. This Muda is usually the result of imbalanced output of man or machine, resulting in more work in progress than your facility can handle. It can lead to:

  • Masking of quality issues that can go unnoticed until work has finished being processed (Defect Muda)
  • Shuffling of work around that can’t be processed (Transport and Motion Muda)
  • Use of floor space to store unfinishable work (Inventory Muda)
  • Jobs sitting around waiting to be processed (Waiting Muda)
  • Handling of jobs multiple times while shuffling excessive inventory (Over-Processing Muda)

To avoid this Muda, produce only the amount of work needed to feed the next area. Even if this means slowing equipment down. While this may seem counter-intuitive, if you push work into an area that can’t process it, not only are you not producing more work, you’re slowing down the work you can process. The most common reason I’ve heard for over-producing and stock piling work is “What if we have equipment issues?” I would answer that question with a question. Why reduce your productivity year-round to be prepared for something that only happens every now and then?

“Abiding by ANSI standards and ensuring all employees know exactly what the customer does and doesn’t need and/or want can reduce this waste. Remind your staff to perform the minimum amount of work on a job to achieve an acceptable result. “

Conclusion

The elimination of Muda, at its core, is about constantly critiquing your processes and methods. Always ask:

  • “Can we do it better?”
  • “Can we do it smarter?”
  • “Can we make it easier?”

Having your waste under control is crucial because if you don’t and you try to solve your production issues with more manpower or machinery you create more waste. For example, let’s say you have a poorly designed workstation that makes one employee work too hard to accomplish a task. If you add another employee into the same type workstation, you now have two employees working too hard; effectively doubling waste.

Another example would be to pose the following question: “You have a line of edgers producing more work than your inserters can handle, how fast can you actually process work?” If your answer is, “Only as fast as the inserters can process it,” you’d be incorrect. It’s actually slower. The extra handling, shuffling and storage of the excess work produced by the edgers will slow down the inserters tremendously. Now, would adding an edger solve this problem or make it worse? Technically, you’d be creating more work, but the overall throughput of work would drop.

Yes, by adding more people or equipment, you’ll see short-term gains simply because there’s more overall work being done. But in the long run, if left uncontrolled, Muda will over-take any perceived benefit and affect your production, breakage, profits and sanity.■

Robert Minardi, ABOC, ABO-AC, has been in manufacturing for almost 25 years. He’s a certified Lean Six Sigma Black Belt with a background in quality control.


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Lab Talk-February/March 2018