Lean Maintenance ™
using Six Sigma DMAIC
(Maximize your equipment
maintenance reliability - within 30 Days!)
Before putting new and
30 or 40 year old machines together into Lean Manufacturing lines, do you
know how to get the near 100% uptime required? Or, will
"maintenance" become the "tail that wags your dog"?
'Your Achilles heel?
A Barrier To Lean
To compete in today's global economy and to increase profits, many
factories are moving to "Lean Manufacturing," the next
step beyond "Just In Time." Others claim "lean"
but hedge on the concept with hidden WIP inventories because they fear
what they've seen in the past, when critical path machines go down for a
"maintenance break." Other managers simply budget for and
bolster their maintenance department with people, training, equipment and
spare parts so they can more quickly "put out the fires" when
downtime occurs. Others increase budget (expense) to hand off maintenance
responsibility to outside subcontractors. Outside service vendors may or
may not service you better, but its sure nice to be able to point the
finger outside when downtime cripples production. But, its still your
The Maintenance Problem
The underlying problem here is equipment reliability and uptime
(some call it maintenance reliability). The solution is to find ways to
eliminate unscheduled equipment downtime. The problem with downtime is
that most maintenance people think, "It just happens. Then we fix
it." The problem with downtime is, "You can monitor it, measure
it, log it, report it, track it, attack it, or delegate it, but downtime
will not go away until you "eliminate it"
- prevent it from happening in the first place.
A Solution (Lean Maintenance ™)
What? How does one "fix a machine so it
doesn't break down again"?
Answer: To prevent downtime from
happening before it occurs, you must eliminate the basic stresses that
cause the downtime.
What is needed is a methodology for protecting computers, automation
controllers, PLCs, CNC machines, etc. and protect their electronic and
hydraulic control systems from the stresses that cause malfunctions and
failures. The author has been applying this methodology and perfecting it
since 1977. He calls it "Lean Maintenance ™ for
Lean Manufacturing." This practical and most cost effective
methodology can help most any facility from data centers to telecom to
medical, from semi-conductor manufacturing to plastics & metal
manufacturing. Within 30 - 60 days, you can thus avoid malfunctions,
failures, unscheduled downtime, scrap parts, re-work, missing delivery
schedules, etc. and get the near 100% reliability, repeatability, yield,
and uptime needed to increase profits.
uptime is also needed as companies push to lower costs by shedding:
- Onsite spare parts
- Onsite board or component repair, and
- Onsite technicians, maintenance engineers,
The few skilled technicians are getting old. In 3 - 7 years most of
this rare breed will be retiring and replacements are not present in
training. "Lean Maintenance ™" can help by providing methods that
allows reduced maintenance support and reduced maintenance overhead (often
50% or better) while achieving maximum permanent reduction of unscheduled
50% reduced mechanical downtime
80% reduced hydraulic systems downtime
92% reduced electronic systems downtime
Cost of Downtime
So what is the cost of downtime? Is it something worth eliminating?
Different companies calculate or toss different figures; typically $500
per hour for a stand-alone machine, $1,500 - $8,500 per hour for a cell or
line of machines, and up to $3,500 per minute ($181,500 per hour) for an
entire auto factory line. One practical way to give your "cost of
downtime" figures a reality check is to compare them to the price you
would pay, or do pay, when you have to "farm out" a part or
assembly because your capacity is temporarily or permanently limited. What
do they charge you per hour for this capacity? That's the cost of your
downtime. Believe it. Any profit margin they have calculated in is quickly
offset by your own continued need to pay support and regular production
personnel who often stand idle. Add to this your scrap and rework costs
and you see the true hourly cost of downtime.
(Manually add your costs as calculated here.)
|Cost of Scrapped Parts
|+ Other Error Costs
|+ Cost of Hourly Downtime
|Sub Total x Hours of Downtime Hours
||$ ______ X ______Hours
|TOTAL COST OF DOWNTIME
Cost of Scraped Parts + Error Cost + Hourly Cost of
DT x DT Hrs. = $__________.____
Only after you have a firm grasp on your cost of downtime can you then
calculate the importance and impact Lean Maintenance ™ methods can
provide by way of increased profits, decreased cost of goods sold and the
impact this can have on increased market share.
In Lean Manufacturing the cost of a single machine going down for
maintenance is multiplied by the number of machines in that cell. With no
parts in inventory, a single machine going down results in no parts
shipped. Broken delivery schedules that cannot be made up, if the next
parts made are "just-in-time." It's not only lost sales, its
reduced level of integrity and less satisfied customers which can result
in long term loss of sales revenue. Downtime then results in a higher
cost-of-goods sold which means reduced ability to expand or maintain sales
and business volume.
Lean Maintenance ™ - Methodology
The key objective of Lean Maintenance ™ is to give your company the near
100% equipment uptime and reliability it demands while cutting your
maintenance expense, often by 50% or more. This is done by systematically
surveying or analyzing each machine and control system to determine which
basic stresses are effecting each machine, over time, and laying out a
scheme to protect each machine, computer, or control system from the
stresses to which it is subject. This certainly includes but goes far
beyond the normal oil change, filter change PM procedures given in the
first understand the three categories of downtime:
- Downtime from Operator or Programmer Error
- Downtime from inadequate PM procedure or
- Downtime from chronic wear & stress to
circuit boards, hydraulic components and other system
Stresses such as: a.
Vibration c. Oxidation
& Corrosion d.
Dirt build-up e.
Electrical voltage transients and current surges f.
Hydraulic contaminations of dirt, water & acids, etc.
Six-Sigma, ISO-9000 and TPM books and strategies often cover the
first two issues (above), yet they often get passed over. "Lean Maintenance ™"
stresses the importance of all three (above) and focuses on the third.
"It's like preventing fire hazard," You can have fuel stored or
flowing anywhere, but do away with oxygen and heat and you cannot have a
fire. Similarly if you do away with the chronic stresses that cause
'maintenance fires,' then you cannot have maintenance malfunctions,
errors, failures, rework, scrap and downtime. The beautiful thing about
this method is, for the most part, it's all "one time
installation" of protective devices to produce ongoing savings. It in
no way changes your current product flow, personnel, procedures,
operations, or policies. Yet, you are able to reclaim older or less
reliable systems to near 100% uptime." You might call this kaizen
for maintenance reliability, or how to
jump from "four sigma" to "six sigma."
Sigma, D.M.A.I.C. - Steps to implement Lean Maintenance
Define the problem:
Unscheduled equipment malfunctions and the resulting rework, scrap parts,
downtime and lost production.
Why is this a problem?
Because now days the machines and computers do all our work. If you don't
believe it, just go unplug all your computers and machines for two or
three days and see how much product goes out the back door. Watch the 99%
decrease in information or services provided. We must realize that the
machines and computers are productive employees of the company. The
machines are just as much employees as the humans. Each is paid a per hour
wage based on their value to the companies products and services. Usually
the machine's wages are much higher than human wages. When they take a
break, make a mistake, or take a day off, the company looses profits.
To state the problem clearly, reminds me of a plaque that used to hang in
my mother's kitchen which read, "When Momma ain't happy, ain't no one
happy." Maybe we should hang a plaque in the company office that
reads, "When machines ain't runnin', ain't nothin' gettin'
done!" That's the problem.
Monitor & Measure the problem:
Monitor your downtime and measure or calculate what it is really costing
If you have a CMMS (computer maintenance management system) or a good
purchase order and work order system, then we can estimate the potential
savings and increased profits that should come from addressing this
report the following (from the past year)
- How many "work orders" or "tickets" for
maintenance assistance on unscheduled downtime have you had the past
few months, and the past year?
- How many hours of unscheduled downtime, from your CMMS or "work
orders." How many maintenance hours by in-house or by contracted
support personnel? How many electrical, hydraulic, mechanical?
- From your "purchase orders," how many dollars in equipment
- How many dollars in electronic module repair (in-house or out
- How many dollars in hydraulic module repairs (in-house or out
- How may dollars spent on hydraulic fluid?
- How many dollars spent on hydraulic oil disposal?
- How many hydraulic systems?
- How many machines or computer controlled systems are employed here?
- Where are the most critical areas or departments needing equipment
reliability? (Critical Path Machines)?
- What is your average "cost per hour" for equipment
- Multiply this hourly "cost of downtime" by the total
downtime hours in #1 & #2 above.
you had eliminated 70% - 92% of #12, is it a number worth your
it worth the Companies attention?
Analyze how to solve or eliminate the problem:
Your maintenance engineer, or an experienced consultant or contract
engineer should analyze and identify, for each computer, each machine and
each control system how to, in the most cost-effective way, protect or
harden the equipment form the above stresses. Have them write a report
detailing, machine by machine, or system by system, the exact means to
protect from each these stresses (as each may apply) giving protective
device model numbers, connection points and installation instructions
along with costs for each and a total cost summary. The investment needed
can then be justified against increased uptime benefits, reduced
maintenance labor and repair parts costs and increased profits that will
come from item #12 in the above measurement section.
Then Install and Implement
Installation instructions from above should be specific enough that your
own maintenance personnel can easily and quickly install the needed
protective devices, methods, or changes.
Controlling the project
Controlling Lean Maintenance ™ in the future should require little to no
effort. Steps taken to avoid hydraulic system malfunctions and downtime
can actually reduce by 90% current labor for hydraulic system PM and
scheduled downtime, while prolonging machine tool life. Most other methods
are single step protective methods that need no future monitoring or PM
"Lean Maintenance ™" is basically equipment reliability
focused and reduces need for maintenance troubleshooting and repairs. Lean
Maintenance ™ comes from hardening equipment from the real causes of
most equipment downtime -- not just fighting symptoms. Any maintenance
engineer or manager can begin Lean Maintenance ™ by protecting
automation, electronics, hydraulics and computer-controlled equipment from
the root causes of malfunctions, failures, and downtime-chronic stress
discussed above. Circuit board failures, hydraulic system failures and
other malfunctions are only symptoms, not the underlying cause of
unscheduled equipment downtime.
After 25 years of experience,
Amemco helps companies like yours implement Lean Maintenance ™ in 30 -
60 days, which means;
- Increased Profits,
- Near 100% uptime required for Lean
- Greatly reduced maintenance overhead, and
- Reduced dependence on outside support.
Maintenance ™ is
maximizing uptime, yield, productivity, and profitability.
Howard C. Cooper