Standard Work Combination Sheet

My last post concluded a discussion of Takt Time.  So, if you’re working to Takt Time, how do you know when each operation in your process is supposed to start and stop?  How do you know if your operation is less than or equal to Takt Time?  And, how do you communicate that to those in the process?

The answer to all those questions is to use a Standard Work Combination Sheet (SWCS).  I know.  That’s a mouthful, but it’s an extremely powerful tool that every Lean practitioner ought to have in their arsenal.

So what does it look like?  Find one below*. 

AUTHOR'S NOTE:  I apologize that the image bleeds over into the "about the author" section of the page, but wanted to use as large a size as possible, as the clarity reduces to fit the post requirements.  

This sheet is jam packed with actionable information.  Let’s examine.

We can see that there are 8 operations to this process; can tell what each is called and how much of the time for that operation is spent doing manual (man) work, machine (auto) work and walking.  

The bottom right gives us a key for the symbols used.  There is no delay indicated in this SWCS, but we can tell how long each component of this operation takes; e.g. 32 seconds manual time and 14 seconds walking in operation #1.  Finally we can see the total of manual and walk time spent performing this process. 

From it, you can see the walking that takes place between operations 1 & 2, 7 & 8 and 8 back to 1.  You can also tell in operation #6 that the machine continues to operate (horizontal dashed line) on its own and that the operator doesn’t stand watching.  Rather, the operator moves to the next operation, #7 while the machine works away.  

The vertical dashed red line is labelled TT, indicating that it’s the Takt Time for this process.  

Now some questions for you:

1. Can this process be completed in Takt Time (TT)?
2. If you were going to improve this process, which operation would you try to improve first?  

*NOTE: I made this form in Excel.  Takes some patience, but then you can type in it.  Of course, you can always whiteout an old one and make copies.

A1.  Process takes 423 sec to complete.  Takt Time is 425 sec; hence, the process can be completed in Takt time.

A2.  The gaging process takes the longest and represents the greatest opportunity for improving the process time.  Virtually every second of improvement would have an equal effect on improving the overall process time.  Remember, the operator is actually working on the part from the previous machine cycle.  Things you might consider doing are to automate the entire gaging process; or, use more automated tools.  For example, you might use a vision system for gaging rather than a manual profilometer if the ROI is good.  

Shadow Boxes

Lean practitioners are familiar with the concept of shadow boards.  We frequently use them to organize tools so that it’s immediately evident if one is missing.  If one is, a visual “sweep” of the board  prompts the owner to stop and search until the tool is found and returned to its place.

Like shadow boards, shadow boxes are used for visual organization.  

One form of a shadow box we’re all familiar with is the egg cartons.  From grade school we’re taught how many eggs to expect in one: an even dozen.  If an egg is missing, it is visually apparent.  

In Lean, the same concept holds true.  We use shadow boxes to organize parts.  They become a visual quality tool.  Here are a few ways we can use them.

TOO FEW PARTS:  Before commencing work on the next product, a worker makes a quick visual sweep of the shadow box.  This “sweep” allows them to ascertain immediately if all the parts are present and int he correct quantity.  If they are not, the worker signals for assistance; e.g. pulls the Andon cord.  This prompts a material handler or water spider (discussed in an earlier post) into immediate action.

The mere existence of shadow boxes implies Just In Time (JIT) delivery of the exact parts required to build one product.  If there are too few, the product cannot be completed, so early identification can allow the parts to be delivered and installed within Takt Time.

TOO MANY PARTS:  While having too many parts doesn’t always stop the line, it is an equally unfavorable circumstance.  The mere use of shadow boxes implies that the correct part count is critical.  That means that the shadow box is used as a quality check: too few, or too many, both imply a defect in the supply process.  

The presence of too many parts can lead to installing too many parts in the product and cause a product defect.  That is serious problem.  

Shadow boxes can also help in the early detection of wrong parts.  If the process (standard work) calls for four bolts all 3/4” in length, and one is clearly longer, that’s a potential defect.  In effect, the operator only has three bolts and needs to take the same action as if there were too few parts.

As with shadow boards, each part has its own spot in the shadow box.  For instance, the nuts that went with the four bolts addressed above would be in their own slot.  Likewise, washers, cotter keys, rivets, etc would each have their own slots.  Once the shadow box is set up, those slots stay the same.

A well laid out shadow box allows the operator to grab the right parts without taking their eyes off the product.  For example, if the operator knows that the 1/4” lock washers are in the fourth slot from the left, they run their fingers along the top of the slots and count  1 - 2 - 3 - 4.  When they hit “four,” they grab the washer in that slot.

Not every circumstance calls for shadow boxes, but it is one of the arrows in the quiver of a good Lean practitioner.  Don’t hesitate to apply the concept when conditions call for it.

Takt Time

“What?”

That’s usually the first question the uninitiated ask.  “Are you saying tack time?” is the next.  Those of you using Lean know the answer, but let me just refresh. 

Takt is a German word meaning pace or tempo, as in the pace of a piece of music.  In an orchestra, pace is usually governed by the speed of the conductor’s baton.

In Manufacturing, Takt Time is the pace at which your process needs to operate in order to meet customer demand.  It is calculated by dividing Available Time by the Customer Demand.

Available Time is the worker’s scheduled time, say 7:00 AM to 3:30 PM (8.5 hours), less any breaks, lunch, meetings, cleanup time, etc.  So, in the following example, Available Time is ___________?

Scheduled time: 8.5 hours = 510 minutes

                   Breaks 2 x 15 = - 30 minutes

                   Meetings - 0 minutes

                   Lunch - 30 minutes

                   Cleanup - 12 minutes

                                            - 72 minutes

Available time = 510 - 72 = 438 minutes

Demand = 40 pieces per day 

“Cool.  So what?”

Takt Time (TT) tells us how long we have to build one part.  If we exceed Takt time even once during the building of today’s 40 pieces (but stay on pace for the rest), we will not get all 40 built.  We’d have to work some overtime.  A goal of Lean is to work NO OVERTIME; so, we always need to work within Takt Time.

“No Problem,” you say.  “I’ll give my workers 40 minutes to get it done and we’ll never exceed Takt Time.”

That’s no good either.  You’ll either rush workers and get poor quality; or, you will need to assign more workers.  Neither is acceptable.

Note — and this is huge — we don’t care how long it currently takes your workers to build one of these parts.  That time, by the way, is called Cycle Time (CT): the time to  build one good part.

Ultimately, our objective is to make CT less than or equal to TT.   In order to achieve that, we typically use a Standard Work Kaizen event, but that’s for another post.  

Summarizing, you’ve learned about Available Time, Takt Time and how to calculate both.

What’s a Water Spider?

Most of us are familiar with material handlers.  They drive lift trucks, push carts or carry plastic tubs of materials to their point of use.  In Lean, however, we try to eliminate this non-value adding job by placing materials close enough to the operator that the operator can easily retrieve them.  

There are times, however, when material replenishment requires someone other than the operator.  For these tasks, we turn to a water spider.

FUNCTION:  The function of the water spider is to replenish the materials used at each station so that the production personnel can focus on the process of adding value.  Once every Takt Time* the water spider walks the entire length of the assembly line and places the exact materials required to make one product at each station.  The water spider then returns to replenish and starts all over.  Water spiders are typically only used when Takt Time is three minutes or greater.

So, when might you use a water spider?  Usually three things govern their use.  They are:  exact part, exact place, exact count.  

EXACT PART:  When the product varies and different parts are required each time it is assembled, the water spider is used to place the exact parts required for the next assembly at each station.  The change in part(s) often signals the assembler what product they are to build next.

EXACT PLACE:  Placement of parts can be critical.  When an operator knows that a part is always in the same place, they don’t have to take their eyes off their work to grasp the next part.  This allows them to devote their full attention to their work.

EXACT COUNT:  Count can be used as a quality check.  When the operator knows that the water spider has placed the exact number of parts in the exact place, it allows them to perform an ongoing quality check.  If they run out of parts early, it means they’ve assembled a part in the wrong place.  If there are parts left over, the assembler stops the line, because the product is not fully assembled.

WHO:  One might think that a water spider is an entry level job, but it is not.  The water spider is usually the most experienced assembler on the line.  They understand the product being built, how to perform every step in the production process, how it is tested and what quality checks are performed on it.  Should anyone need to step away from the line, the water spider can backfill any position. 

* When part count is not critical and parts don’t vary from product to product, the water spider might place enough parts at each station to make multiple products.  When this occurs, the water spider walks the entire line in multiples of Takt Time; e.g. if Takt Time is 300 seconds, the water spider might walk the line every 1,800 seconds (30 minutes) and place six new parts at each station.  The water spider may also be used to move finished goods at the end of the line before returning to replenish.

Hansei

Akio Toyoda, President of Toyota, testifying before the US House of Representatives

A lot of Lean practitioners dislike the use of Japanese words.  However, some concepts don’t easily transcend culture.  Hansei is one of those.

Hansei, commonly translated “time out” (as in giving a disobedient child “time out”), is a much deeper concept in the Japanese culture. It means to reflect on and acknowledge one’s mistake (or one's success), seek it's root cause and resolve to improve.

As with time out, Hansei almost always requires withdrawal from others so as to go inside oneself, to discover not only what went wrong, but why (root cause).  

Equally important, Hansei for a mistake requires contrition and resolve.  After getting to the root cause of the problem, one expresses sorrow and resolves to change for the better (Kaizen).  The key here is preventive measures to avoid this problem in the future.  

With a success, one seeks to know the root cause so as to repeat, and improve on, it.

Similarly, Hansei-Kai is Hansei done by a group.  It bears all the same traits of personal Hansei, but is conducted as part of a larger group.

So what? How does Hansei apply to business?  Let's put this concept in context.

BACKGROUND:  On August 28^th, 2009 Toyota became the center of news, when a Lexus ES350, driven by an off duty California Highway Patrolman, accelerated out of control and killed all four occupants.  

What made this crash front page news was that the events leading up to the crash were captured in a 9-1-1 call from the driver’s wife.  Coverage of what was later called “Sudden Unintended Acceleration,” or SUA, grew world-wide, badly tarnishing Toyota’s reputation as one of the world’s safest and most dependable auto makers.

Waive for a second the fact that the National Highway Traffic Safety Administration (NHTSA) had been investigating similar problems with Toyota vehicles since 2002 and, in each case, exonerated the auto manufacturer (http://www.safetyresearch.net/toyota-sudden-acceleration-timeline).  Within Toyota, the problem was taken much more seriously.

Although never recorded, what appears to have occurred within Toyota was Hansei-Kai.  What leads me to say that?

ACKNOWLEDGEMENT & CONTRITION:  On February 24th, 2010, Akio Toyoda, President of Toyota, stood before the U.S. House of Representatives and “profusely apologized and took personal responsibility”^[1] for the sudden acceleration problem that led to the recall of millions of Toyota’s vehicles. 

Mr. Toyoda went on to state, “I extend my condolences from the deepest part of my heart.”^[2]

ROOT CAUSE ANALYSIS:  In a prepared statement to the U.S. Congress, Mr. Toyoda cited as the root cause of the SUA problem not poor design, nor poor craftsmanship, nor poor maintenance, nor operator error.  Instead, he said, “I would like to discuss what caused the recall issues we are facing now. Toyota has, for the past few years, been expanding its business rapidly. Quite frankly, I fear the pace at which we have grown may have been too quick.”[3]

RESOLVE:  In the end, Toyota recalled almost 10 million cars and began an internal campaign to rededicate itself to safety.  Although not publicly stated, it is presumed that care in future growth was one of the many Kaizens within the leadership team of Toyota.

This kind of response doesn’t come from speechwriters or “spinners,” but from deep introspection.  In short, while never acknowledging that they had done so, it is evident from their actions that Hansei-Kai led to Toyota's deeply insightful acknowledgement, contrition, root cause analysis and resolve.

---

[1] An Apology From Toyota’s Leader, The New York Times by Micheline Maynard

[2] Ibid

[3] http://www.theguardian.com/business/2010/feb/24/akio-toyoda-statement-to-congress

Total Productive Maintenance (TPM)

Lean concepts like Standard Work and Just In Time are predicated on dependability: dependability of materials, dependability of workers, and dependability of equipment.  It’s this latter subject that I want to address in this post.

A standard maintenance program uses maintenance personnel to perform routine functions like oiling and lubricating equipment.  When a machine fails, the maintenance department repairs it; yet, rarely brings it back to it’s original specs.

In a preventive maintenance program, machines are maintained prior to failure.  These programs are often like the 15,000 mile checkup on a car.  The mechanic performs all the routine functions specified by the checkup and then runs a diagnostic to give the owner advance warning about potential problems.

How does productive maintenance differ from these?  First, the goal of a productive maintenance program goes beyond merely keeping machines running.  In a TPM Kaizen event, machines are cleaned, restored to their original specifications and then minor changes made to improve both the functionality and longevity of the machine. 

In addition, the Kaizen event establishes areas that need to be attended to at least once a day.  These points are marked on the machine and on an operator’s dashboard (usually a laminated card with photos of the machine and the numbered locations of all inspection points matching those on the machine).  It then becomes the operator’s (not the maintenance department’s) responsibility to check these points, and perform any minor maintenance indicated, at least once a shift.

This means the operator oils and lubricates, looks for leaks, reads all gage values and calls maintenance immediately when anything is not what it should be.  The operator also keeps the machine wiped down and dusted as a way of ensuring that it's constantly being inspected for leaks, broken hoses, broken gages, broken sight glasses, etc.  In short, the operator is the first line of defense in maintenance of the machine.

A quick story:  A colleague of mine was touring a plant in Asia and found a bumper sticker on the side of a machine that had a red heart in it.  Since it was in Koren, he asked his guide what the sticker meant.  He was told that it translated “I love my machine.”

Seeing the quizzical look on my colleague’s face, the guide went on.  “This man’s livelihood is derived from that machine.  Not only his, but also his family’s and extended family’s; sometimes even others in his community."

When workers are able to make that connection between their equipment and their livelihood, it changes their perspective about preventive maintenance.  This relationship frequently leads Lean organizations to assign responsibility for each piece of equipment to a single operator.

Often as part of the TPM Kaizen event, the “capability” of a machine is determined.  The machine’s capability is a measure of it’s ability to reach and hold tolerances.  These capabilities are then used in the designing of new products and in choosing to which machine to assign new designs.

Now, the maintenance department is not off the hook.  First, it works with operations to monitor drift of the machine’s capability.  When the machine cannot hold tolerances, it is shut down or at least slated for PM.  Notice: the machine is still making good parts.  It's shut down because it can't hold tolerances.

Beyond that, the maintenance department establishes a program to perform critical maintenance functions for which the machine needs to be shut down; e.g. replacing hoses or gears.  These preventive maintenance events are placed on the operations and maintenance calendars.  Every effort is made to maintain the machines on those dates, but some organizations allow operations to shift the date, one time, to the right or left on the calendar.  TPM is taken so seriously that there is no additional shift allowed.

In summation, TPM is a critical part of Lean.  As I said at the beginning, an organization cannot really establish standard work, or meet Takt Time, until they have established a TPM program on their equipment.

Upgrading Standardized Equipment

I’m an engineer by training and for years specified new equipment for my employers.  When my colleagues and I went looking for new equipment, what did we go looking for?  The newest, the latest, the most bells and whistles.

As I discussed in my post on Standardization of Equipment, buying the latest and greatest often militates against sound business practices, but what happens if the newest equipment provides a technological advantage? 

The answer is simple: design your own equipment modifications.  Who better than you?  Who knows your product better?  Who knows your equipment better? 

Moreover, if you modify your own equipment, you keep your modifications internal and avoid giving your competition insights into how you’re achieving your unique results. 

To do this, you either need to develop internal machine design & modification talent, or enter into a contract with a firm who can provide those capabilities.  In Toyota-speak, this concept is called “Moonshining.”  It refers to the practice of using inexpensive, and often repurposed equipment, in the manufacture of (alcoholic) products.

High on the list of modification techniques is simplicity.  Changes should be as easy as possible to install, use and maintain.  They must also be standard and interchangeable. 

In the photos (above), I’ve provided an example of a machine shop workhorse: the Bridgeport vertical milling machine.  The design of the base machine (illustrated by the photo on left) has changed little since it was introduced prior to WWII. 

One of the few disadvantages of this machine is that it is all manual.  That means that variation from part to part could be significant. 

As new CNC equipment was introduced, many machine shops moved in the direction of new designs and manufacturers; however, the manufacturer of the Bridgeport, and aftermarket suppliers, developed add-on computer systems that turned the manual mill into a CNC mill (photo on right). 

Applying the CNC upgrade gave users the best of both worlds: tried & true equipment, matched with the latest in technological advancements.

The take away from this example is that there are many advantages to upgrading existing equipment as versus buying new.  To recap, they are:

• Continued ease of use
• Same spare parts
• Same maintenance training
• Same operator training
• Ability to seamlessly flex operators from one machine to another
• Improved capability

Standardization of Equipment

Most of us are familiar with Standard Work and the need to have only one standard way we build a product or provide a service.  We know that having only one way to do things makes our processes more reliable.  Standardizing equipment provides the same benefits.

I’ve been in plants where there were machines from 5 or more different Original Equipment Manufacturers (OEM’s), all performing the identical function.  I’ve also been in factories in which they had standardized on a single OEM, but had multiple different models of the same equipment.

Although there are a plethora of reasons to standardize equipment, I’d like to focus on only three: spare parts, maintenance and operator “flexing.”

SPARE PARTS:  Consider this.  Most OEM’s change key components of their machines whenever they change the overall design. When you have multiple models of the same OEM’s equipment; or, the equipment of multiple OEM’s, that means maintaining spares of each unique critical part.  Failing to do so could mean prolonging downtime by days, weeks or even months.

MAINTENANCE:  Each time you add a different machine design, it means training maintenance personnel in the maintenance of each new variation, or purchasing an expensive repair contract.

OPERATOR “FLEXING”: Flexing is the practice of moving operators from one process or machine to another as demand changes.  When a process has multiple types of machines, it often limits the number of operators trained to perform their job on all pieces of equipment.  That, in turn, reduces the ability of leaders to flex, thus limiting their ability to react to changes in the product design, market or workplace.

I’ve been in factories that had been around since WWII.  There were seven or more different models of machines from the same OEM performing the same job.  Can you see how big the problem becomes when you try to stock all those motors, gearboxes, control station components and ancillary spare parts?  The cost of all those parts ties up valuable working capital.  

Then factor in the cost of the brick and mortar necessary to warehouse them all.  That space generates no income, nor can it be used for anything else.

So, rule of thumb: find the most reliable equipment and, as you expand, purchase more of it: same make, same model.  

Where should you look?  The used equipment market.  Often, there are firms that specialize in refurbishing such equipment before it even arrives at your facility.

RECALL: 

• you only need to store spare parts for one model
• you can train maintenance personnel in maintaining only one model
• you can train operators in operating only one model

Each of those will provide you competitive advantage in the world of ever hastening global competition.