Toyota Way Fieldbook : A Practical Guide for Implementing Toyota's 4Ps

156 THETOYOTAWAYFIELDBOOK

repeating increment. In our case, the pattern has a four-day repeating sequence

and each item is leveled (the totals are equal) every four days. Toyota typical-

ly uses a monthly window for leveling, but it is based on a repeating multiple of

one day. Note: The main vehicle assembly line has a repeating pattern on a short

pitch frequency depending on the particular mix of vehicles produced, but the

supporting operations that are producing to a supermarket or “selectivity bank”

are producing to a different pattern that is a derivative of the primary pattern.

Notice that in the alternative pattern the total in days one, three, five, and

seven exceeds the daily goal. This is not a major problem since the amount is

within reasonable limits (normally a maximum of 10 percent). In most cases

when working with actual demands, the numbers don’t work out as evenly as

this example. For the first attempt, get the numbers as close as possible. After

you’ve had the opportunity to produce based on a level schedule, you will gain

a clearer understanding of the true need and will adjust the pattern accordingly.

It is much easier to calculate a leveled schedule than to actually produce

according to the plan! At first it’s likely that you will discover many obstaclesthat

prevent adherence to the schedule. These obstacles need to be systematically

identified and corrected so stability can be achieved (track causes for missing the

heijunka, and use the problem-solving method to eliminate them). The leveled

schedule should now be considered the “voice of the customer.” It is not the true

Table 7-3. Alternative Leveled Production Pattern

Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8

250 250 250 250 250 250 250 250

220 220 220 220 220 220 220 220

210 210 210 210 210 210 210 210

256 0 256 0 256 0 256 0

250 250 250 250

150 0 150 0 150 0 150 0

0 240 0 0 0 240 0 0

0 0 0 180 0 0 0 180

180 0 0 0 180 0 0

0 0 0 140 0 0 0 140

0 225 0 325 0 225 0 325

1,336 1,325 1,336 1,325 1,336 1,325 1,336 1,325

1,325 1,325 1,325 1,325 1,325 1,325 1,325 1,325

A (ED)

B (ED)

C (ED)

D (EOD)

E (EOD)

F (EOD)

G (E4D)

H (E4D)

I (E4D)

J (E4D)

Other

Total

Goal

ED = every day; EOD = every other day; E4D = every four days.