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5S is a methodology for organizing the
workplace. It is based on a five step process.
The initials stand for five Japanese words
that do not have exact translations, but
a common attempt is:
SEIRI Sort: eliminate
clutter and discard items that are not needed
regularly. Items not immediately required
are 'red tagged' and moved to a holding
area. After a period of time the items that
have not been used are discarded, or removed
to a separate store.
SEITON Set in Order: organize
the work area. This can include shelves,
cabinets, shadow boards and so on. Everything
should have a place, and it an item is missing
it should be apparent.
SEISO Shine: Clean the
work area. Cleaning should then become a
regular activity.
SEIKETSU Standardize:
Determine the 'best practice' and standardized
it
SHITSUKE Sustain (or Self
Discipline): Continue to keep the workplace
clean and organized. Everybody should get
into the habit of doing their '5S' duties
daily, leaving their workplace clean and
tidy when they knock off.
5S is an excellent starting point for
process improvement. The organization gets
a significant efficiency benefit for little
cost, it also encourages ‘systems
thinking’. Managers and employees
may be resistant at first, but nobody can
argue with the logic because we all know
that keeping up with the 'housekeeping'
saves time in the long run. This can be
the foundation for a systems approach.
The use of lights as visual signals. Lights
with three colors, red amber and green are
often used. Green is normal operations,
amber means routine action required, red
means abnormal action, immediate attentions.
For example an andon might be used to trigger
material replenishment. Green means no action,
amber means time to replenish and red means
stockout, immediate action required.
The time from the beginning to the end
of the process, It includes move, queue
and process time:
Kaizen is a process of continuous improvement.
Normally processes become less efficient,
and produce lower quality, as the machinery
and equipment ages. The idea of Kaizen is
to not only maintain the equipment to keep
it as good as new, but to continue to make
minor modifications that tailor it better
to the process, for example making it interface
better with upstream and downstream handling,
part supplies and so on.
The workforce should be involved in Kaizen
improvements through suggestion schemes
and team based activities.
Kaizen is long term continuous improvement.
Kaizen Blitz is a version that involves
a highly focused effort that lasts around
a week. It involves everybody in the section/department,
and may involve stopping production.
A kanban system is a 'pull' system of production
as opposed to the traditional 'push' system.
Products are made in small batches to meet
the immediate demand. Typically each batch
will only be sufficient for a few hours
of consumption,
The Kanban is typically a card that authorizes
production. When a batch is made the kanban
travels with the batch to the next production
stage. When that production stage starts
to use the batch the kanban is returned
to the producing station, thus authorizing
the next batch.
If a producing station does not have any
kanbans it does not produce anything. Thus
if demand slows down, or even stops, the
production rate will slow down or stop.
The producing station will not continue
to produce to 'get ahead'. The kanban system
reduces inventory and forces stations to
be more efficient, responsive and achieve
faster changeovers.
The use of small batches achieves a more
regular flow of work and thus actually reduces
the amount of stockouts.
The system described is a simple 'single
card' systems. There are more complicated
variations on this.
Lean manufacturing is a system of production
based on eliminating 'muda', the term meaning
waste in its broadest interpretation.
Lean manufacturing involves:
- eliminating defects, achieving perfect
first pass quality
- eliminating all non-value adding activities
- continuous improvement (kaizen)
- using pull systems of production (eg.
kanban)
- flexibility, ability for quick changeovers
and immediate response to changes in demand
- long term relationships with suppliers
involving strong and open communication
Waste in its broadest sense. The seven
wastes of manufacturing are:
- overproduction
- waiting
- transporting
- inappropriate processing
- unnecessary inventory
- unnecessary and excess motion
- defects
A device that prevents a mistake being
made. or makes a mistake immediately obvious.
An example; A nut had to be tightened with
a torque spanner, but this could be forgotten
and it be left hand tight. The design was
modified so that the assembly could not
be removed from the fixture until the torque
spanner had been brought to the correct
torque.
Another method would be to dispense exactly
the right number of parts for an assembly
into a cup. Any parts left over are immediately
counted. The various instruments, towels,
swabs etc. used in surgical operations are
counted before and after the operation.
Despite this, because of the large numbers
involved, items are sometimes left inside
the patient. A method of tagging all items
with transponders is being developed. After
the operation the surgeon waves a wand over
the patient and this beeps if an item is
detected.
Documents that specify how a process is
to be carried out. In an organization that
complies with ISO9001 the procedures would
be compiled into the quality manual.
Procedures are not as detailed as Work
Instructions.
A Pull System is a type of production system
in which production is triggered by demand.
Usually when an item, or small batch of
items, is 'consumed' a kanban triggers replenishment.
Kanbans 'pull' product through each stage
of production.
This differs from a traditional 'push'
system where production is scheduled to
meet anticipated demand, and then 'pushed'
through production.
A diagram that shows the movement (usually
of people) during a process. Its purpose
is to identify potential improvements to
the layout to remove unnecessary movement:
I prefer a string diagram that marks out
the layout with colored string (I like embroidery
thread) wrapped around drawing pins; it
gives a more striking visual impression.
Standard Work is work in which
the sequence of job elements has been efficiently
organized and is repeatedly followed by
a team member. It is an important prerequisite
for successful implementation of Kaizen
and many other aspects of Six Sigma.
The aim is to synchronize
takt time and cycle time. Takt time is daily
operating time divided by the required quantity
per day. Cycle time is the actual time the
process takes.
The time interval between
consecutive items in a production system
necessary to meet customer demand.
If the daily customer demand
is 40 items and there are 400 minutes of
production time then the takt time is 10
minutes.
The takt time is the 'heartbeat'
for a Just In Time production system ('takt'
is the German word for a conductor's baton).
The idea is that production should be paced
to produce one item every ten minutes rather
than periodic batches.
An alternative type of system
to a Kanban system. The Theory of Constraints
is based on the idea that any production
system has one or more 'bottlenecks' that
limit the output. Increasing the capacity
of any work station, other than a bottleneck,
serves no purpose.
TOC was developed by Eli Goldratt
who wrote a book called 'The Goal' to illustrate
its operation. He used the analogy of a
group of schoolboys on a long and hard walk
to an overnight camp. One fat child lagged
behind and the others had to keep stopping
whilst he caught up. Eventually the leader
(the author) realized that sometimes the
fat boy had to wait in a queue when the
group had to negotiate a section that could
only be taken one at a time. It was better
to put the fat boy at the front where his
progress was never impeded. They also inspected
the fat boy's rucksack and found it overweight
and full of unnecessary items that they
either discarded or distributed to the fitter
members. (hope I haven't spoiled the book
for you)
The amount of work that passes
through the system in a given time. In the
Theory of Constraints the throughput is
constrained by the bottleneck process.
| Total
Productive Maintenance |
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Maintenance methods include:
Breakdown Maintenance:
Fixing things when they break
Preventative Maintenance:
Preventative maintenance includes both periodic
maintenance (at regular intervals, as with
a car) and Predictive maintenance, which
monitors the condition of parts in order
to use them to the end of their service
life
Corrective Maintenance:
Improving equipment so that preventative
maintenance can be carried out reliably
Maintenance Prevention:
Studying existing machines and designing
out the prevent failure, make maintenance
easier and prevent defects.
Total Productive maintenance
draws on the methods above, but is based
on the principles of lean manufacturing,
including 5S , standard work, Kaizen etc.
Its main distinction is that the routine
maintenance and minor repairs are carried
out by the operators. This involves modifying
the machine to facilitate inspection and
maintenance (making access easy, making
panels transparent etc.)
The time that the product
is actually being worked on, and value is
being added. This is typically only a small
proportion of the total production time,
most of the time is taken up by moving,
queuing etc.
See Total Productive Maintenance
A novel approach to process
mapping that incorporates lean principles.
It looks at the process as a 'value stream':
The figure is a fragment from
the text 'Learning to See' by Rother and
Shook, the key text about value stream mapping.
Visual factory is a term used to describe
a lean manufacturing environment where information
is displayed by using charts, signs and
'Andons'. Thus the immediate status of activities
is clear to everybody.
The information may include:
process measures; reject
rates, achievement to target, run charts,
KPI's and progress etc.
work instructions; the
standard work instructions, often in visual
form using photographs, samples, flow charts
etc. rather than written descriptions.
safety information: visual
identification of safe areas and hazards
other relevant company information
The Work that is in various stages of production
between raw material and finished product:
I prefer 'Work in Process', because in
many production systems it is languishing
in queues rather than progressing!
See Work in Progress.
The instructions that specify how a task
is to be carried out. The level of detail
should be appropriate to the skill and training
of the operator.
Wherever possible, work instructions should
use diagrams, pictures and other visual
aids - possibly video, rather than the written
word. |
