Flow production - 3rd condition
From: Norman Bodek
U-shape line·parallel line
I remember on one of my first trips to Japan in the early 1980s
visiting Brother Industries and seeing 12 machines producing products in a manufacturing
cell with hardly any operators. This was in comparison to factories in America with one
person standing or sitting in front of each machine.
There are many advantages to having a U-shaped line:
1. With a straight line even with the operator walking from machine to machine you have
the waste of returning to the beginning of the line for picking up the unprocessed work
after completing the finished work. A U-shaped line, resembles the letter U in
the alphabet. To eliminate this waste you want to make the inlet and outlet of work as
close as possible. This is called "principle of the same I/O". If the location
of unprocessed work and the location of finished work are made close than waste of
returning to the starting point will not occur. In most cases, a, U-shaped
line is for one product. For a line of more than two kinds of products often
"parallel lines" are adopted.
2. There is a need for multi-skilled workers to run the various different machines; making
jobs more interesting for people and giving more flexibility to the company.
3. To make sure the lines can produce in taht time requires eliminating machine problems:
downtime, faulty processing, and surely no defects should be produced.
4. As machines are linked within the cell virtually all work in process is eliminated. I
remember prior to my first study mission to Japan and seeing mountains of inventory at an
Oldsmobile plant in Tarrytown, New York turning over inventory around four times a year
while NipponDenso a Toyota prime subcontractor had a turn over ratio of 350 times a year,
less than one day.
5. Transportation is kept at a minimum as, at first, each machine is just a few feet away
from each other.
6. The person is more important then the machine. I have visited over 250 plants in Japan
and to date have never seen a person standing and watching a machine. In the opposite, I
have visited numerous plants in North America and always see people watching a machine.
Somehow our accountants in the past confused us to think that the machine was more
valuable than the person and that the machine must always be producing parts while people
were not as valuable an asset and could just stand, wait and watch. In a U-shaped
line, the machine can wait for the person, producing only what is needed when it is
7. When orders increase you can add additional people to work within the cell to handle
the flexible volume.
8. The machines are outfitted with simple grasping and unclasping features so that the
worker can easily load and unload each machine as they walk around the cell.
9. Total Productivity Maintenance (TPM) is vital to keep the machines in the best of shape
for when one machine goes down all of the machines must stop and wait until that one
machine is brought back up. Greater pressure is placed on maintaining machines in top
condition when you do have a U-shaped Line.
I wrote a new book with Chuck Yorke titled All You Gotta Do Is Ask which helps you
discover the hidden creative power resting within every single worker. I am sure you will
enjoy our stories, the examples and learn more about the fabulous results obtained by
companies applying these very simple techniques.