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 Understanding
Takt time
by
Mark Gooch, Simpler Consulting
Takt
Time, the relationship between what has to be done and the time needed
to do it, is the heartbeat of the process. It is a very simple
calculation; available time divided by customer demand. Yet a phrase I
often hear at lean events is, “Takt time doesn’t apply to us.”
Why is this? Why
is Takt time so difficult to understand and so often ignored?
Let’s start with two of the most common causes.
1.
I don’t get it
People
often confuse Takt time with the touch time or cycle time. They look
at Takt time as the amount of time they have to get the job done. When
Takt time is 92 seconds, (or whatever it might be) people think they
have just 92 seconds to complete a job that may take more than three
hours to perform. Thus the claim, “Takt time does not apply to
us.”
The
92 seconds is actually an indicator that their system needs to be
adjusted to yield a part or activity every 92 seconds. There will be
multiple steps inside the process, each taking varying amounts of
time. To balance the flow, each task needs to be reviewed in terms of
the 92 second Takt time and actions need to be taken to bring tasks
within Takt. This creates even, predictable flow, but it does not
suggest or drive the touch time to be completed within 92 seconds.
Suppose
you are a shopkeeper and 25 customers walk through the front door
every hour. If your store wants to provide service at all times (with
no visible breaks to the customer), the formula is simple; available
time is 60 minutes and demand is 25 customers. Divide 60 minutes by
your customers (60/25) and you get 2.4;
Takt time equals every 2.4 minutes a customer needs to be
served.
The
fact that a customer requires seven minutes to be served has no
relevance to the Takt time, but it does help us with a proposed
staffing model. Divide your Touch time by Takt Time (7/2.4) and you
get 2.9, or a minimum staffing level of three people.
2.
My demand varies
Demand
is rarely smooth. How do businesses deal with varying demand?
They batch flow and force even larger variation in delivery for
an already variable demand.
Suppose
you make widgets. Week in and week out, demand is 200 on Monday;170 on
Tuesday; 230 on Wednesday; 300 on Thursday; and 240 on Friday. Your
company looks at total demand of 1,140 and produces a lot/batch of
1,200, two batches of 600, or worse yet, one monthly batch of, 5000.
The
total demand of 1,140 will be met, but not in the manner the customer
desires. In fact, if the weekly approach is used, the customer sees no
delivery until close of business Friday (4 days’ need has been
missed) and your company probably has excess, over-produced inventory.
If the monthly batch is produced, this situation is aggravated by
four-plus weeks.
This
is just from the customer’s perspective. What’s happening inside
your business? Nothing
for the job is in work, then a lot of 1,200 or perhaps 5,000 comes
along. It shoves everything else to the side: all other work waits
until this one job moves through each progressive work center. Does
this help level your flow? Nope:
you have created more variation.
Consider
the option of producing to Takt time. A forty-hour work week (assume a
one-shift operation) equals 2,400 minutes. Subtract scheduled breaks
(one 10 minute break daily) = 2400 – 50 or 2,350 minutes. Available
time divided by demand looks like this: 2,350/1,140 = 2.06 minutes
Takt time.
Once
the process steps are balanced and smoothed to the Takt Time, your
company begins producing 228 units daily. The customer receives 200
units on Monday (as ordered and 28 units are set aside); 170 units on
Tuesday (as ordered and 58 set aside); 230 on Wednesday (as ordered
and 2 are pulled from stock); 300 on Thursday (72 units are pulled
from stock); and 240 on Friday (12 are pulled from stock). The
customer receives exactly what he wants daily and your company does
not have a feast or famine flow.
Now,
explore how you can apply Takt time to your business. How can it apply
to maintenance, services, order entry, invoicing?
Have fun with it and give me a call if you get stumped, have a
creative use for the tool or need some other help. Until next time.
Mark
Gooch has held senior level positions with GE Aircraft Engines,
Goodrich Aerospace and Williams-International. He has worked with operations
ranging from 15 people to organizations of 30,000. Contact Coach Gooch
at 641-620-1320; E-mail: mgooch@simpler.com.
This article appeared in the
August/September 2005 issue of MRO Today magazine. Copyright 2005.
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