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 downtime.
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
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.
is also needed as companies push to lower costs by shedding:
- Onsite spare parts
- Onsite board or component repair, and
- Onsite technicians, maintenance engineers, etc.
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 downtime, typically;
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 maintenance manual.
You must 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 components.
Stresses such as: a.
Heat b. 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
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
Monitor & Measure the problem:
Monitor your downtime and measure or calculate what it is really costing (see
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 "problem."
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
- 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 sourced)?
- How many dollars in hydraulic module repairs (in-house or out sourced)?
- 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 downtime?
- 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 attention?
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 labor effort.
"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.
Howard C. Cooper