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It's almost inevitable: When
conducting an ISO 9001 audit, everyone seems to miss something.
For example, when one reads "calibration" in the
standard, the mental image this conjures primarily involves
micrometers, depth gages and comparators. The intent of
ISO 9001, however, goes much further, aiming to ensure appropriate
control of all the applicable devices that are used to measure,
verify, test and accept products, and to monitor the processes
used to achieve specified results. This runs the gamut of
measuring tools, gages, samples, jigs, pH meters, test software,
oscilloscopes, torque wrenches and the like. In each instance,
it's necessary to adequately assess the use of the device
and establish controls that are appropriate.
What follow are comments and suggestions based on audits
conducted during the course of several years. Findings have
included issues relating to:
Inadequate documentation
Missed instruments
Inconsistent implementation of the process
Misunderstanding the concept
Incomplete records
This process involves the company's control of the devices
used to ensure that customers don't get defective product.
Although ISO 9001 lists several requirements, it's also
written to reflect consideration that calibration and maintenance
vary in different industries. Unfortunately, this limits
the amount of guidance that companies get in implementing
this important process.
Following is a checklist of what needs to be considered.
Not all points will apply to your organization. For some
companies, only a few will be relevant. It's important to
ensure that the instruments and devices you use to make
decisions about product acceptability are adequately controlled.
Whatever document or procedure you develop to describe and
define your process needs to be applicable to your company.
Quantity, sophistication and instrument types vary greatly.
Redundancy in the inspection process, duplicates of measuring
tools and customer requirements also contribute to decisions
on how to control your instruments and the processes you
use to maintain them. There's a lot of diversity. Make sure
your procedure describes what you do.
Define the frequency. It may be different for different
types of tools. Scheduled calibrations need to make sense.
It has to be obvious to the auditor that you've considered
manufacturer recommendations, usage and any other internal
factors. It's OK to have a three- or five-year calibration
cycle if you can justify it with proof that the gage or
device doesn't require more frequent checks.
For example, thread gages and plug gages are often put
on a calibration cycle by usage rather than a fixed schedule.
When a gage is checked out, the number of pieces that are
verified/inspected during the job is recorded on the router.
After a specific number of inspected pieces, the gage is
recalled for calibration.
Some companies simply count days in service, which is
also acceptable. Whatever you decide, make sure you stick
to your defined process.
Try to avoid using only the month and year in your schedule,
especially if the tool is critical and on a short cycle.
Also, be careful when inserting a default into your procedure
that says you can exceed the calibration date by a specified
number of days. Combined, these practices can leave you
with tools that are months beyond their recommended calibration
cycle.
Consider the following scenario: A Vernier height gage
is on a four-month cycle. The procedure states that there
is a 30-day grace period beyond the calibration due date
noted on the sticker. The schedule lists only month and
year. The gage is calibrated on April 2 (04/2002) and is
due for recalibration 08/2002. By rights, that should mean
Aug. 2. On Aug. 28, the quality control technician decides
to exercise his 30-day option. The tool doesn't get calibrated
until Sept. 30. On Sept. 29, the gage was 58 days beyond
its calibration due date and 50-percent through the next
cycle based on its four-month cycle.
Sometimes this isn't a big deal. It depends on the criticality
of the tool, prior records of calibration and any redundancies
built into the inspection processes.
Perpetuation of this kind of practice or abuse of default
grace periods erodes users' appreciation of the significance
of the quality process's requirements.
Indicate if you have tools that are for reference only.
You don't need to label every tool. But you do need to describe
how everyone knows if a tool is not to be used for product
acceptance. It's OK to say that tools that are not marked
are assumed to be uncalibrated. That requires you to be
more vigilant in making sure labels don't fall off so that
your tools don't get mixed up or used improperly.
Make sure the labels are legible. If the labels on the tools
are the primary record of the calibration and the only accessible
vehicle for communicating the tools' status on the production
floor, people must be able to read them.
Ensure that the company to which you outsource calibrations
is included on your approved supplier list. If it has a
certificate of accreditation, get a copy. If the company's
accreditation is subject to periodic renewal, make a note
to ask for a new copy when they get it.
If you do in-house calibrations, make sure you have a document
that describes the process.
This doesn't have to be elaborate. It can be the manufacturer's
recommendation for calibration, a bulleted list, a form,
a flowchart or a brief procedure. It should describe the:
- Standard to be used
- Environment
- Method
- Acceptable limits
- Process for adjustments
- Record retention
Again, if you're doing in-house calibrations, make sure
that the standards you're using (often a set of gage blocks)
are calibrated using a standard traceable to the National
Institute of Standards and Technology.
It's perfectly acceptable to say that certain gages (like
special jigs) are verified prior to each use. Just make
sure that the operators or inspectors can describe how it's
done and that they're using calibrated devices for the verification.
It's also acceptable to say that certain devices are never
calibrated; steel rules and tape measures are typical examples.
You may state that they are periodically checked and discarded
if they're found to be damaged or worn. Make sure you can
back this up.
Review the certificates of calibration you get from calibration
houses. Certificates of calibration are quality records.
It's not uncommon to find errors or omissions on certificates.
Verify that the tool ID numbers are correct and the date
for the next calibration matches your schedule.
The certificate should state the results of the calibration,
the standard used (tool or device) and the date it's due
for recalibration.
The calibration house may state that detailed records
of actual results are available upon request (rather than
included with the certificate). Thisis something that should
be periodically verified; consider it part of your supplier-monitoring
program.
The instruments you're using for inspection should be adequate
for the measurements you need to take.
This actually dovetails with the need to verify capacity
as part of the contract review process. You need to ensure,
especially with new customers, that the tolerances they
require don't exceed your measuring-tool capacities. Your
internal auditors can help with this. As part of the audit,
they can select random prints on the shop floor and verify
the accuracy (i.e., number of decimal places) of the micrometers
and other gages that are being used for the job.
Instruments need to be properly stored. Auditors notice
when tools appear to be poorly maintained.
If a scale is off by a known amount, it's OK to use it,
provided the variation is communicated to everyone who is
using it. Be prepared to prove that it is.
You need to be able to assess the integrity of test software
or electronic devices that are used for product acceptance.
How well-protected is the software from inadvertent adjustment?
Would you be able to tell if the files had been corrupted?
If color is a measurable attribute of your product, you
must protect your test samples from fading or discoloration.
When the device that you use for product acceptance is a
specially designed jig or a "known good" sample,
make sure that it's revised when there's a design change.
You might want to make it a step in the design process.
If your product's integrity can be compromised by extreme
temperatures or excessive moisture, you need to verify or
calibrate your thermostats and barometers. How critical
is the accuracy of the oven? What happens if the material
stored in a freezer rises above a certain temperature?
Don't forget to calibrate gages that are used to control
processes. Often an operator will set up a machine and make
adjustments until he or she gets an acceptable first piece.
The machine is then allowed to run with minimal product
inspections. It's logical to assume repeatability if there
are no variations in the machinery. Therefore, the automated
process, rather than an inspection, monitors product quality.
In these instances, any gages on the machinery (e.g., pressure
and temperature) need to be considered for calibration in
order to ensure adequate control of the process.
Have a contingency plan when you suspect that nonconforming
product might have been released to the customer because
of a faulty gage.
This doesn't mean an automatic recall procedure; it means
that there should be criteria for deciding when to contact
the customer. It should include such considerations as:
- Was the product that was accepted using an out-of-calibration
instrument shipped out?
- If the product was shipped out, would the defect be
obvious to the customer as soon as the product was received?
- Would any undetected (potential) nonconformance have
rendered the product unusable?
- Would the defect have been detected at another inspection
or operation before it was shipped out?
- Does the potential defect affect the function of the
product? Can you get a concession from the customer?
- Do you need to recall all products immediately?
- Do you need to alert any regulatory agencies?
Give thorough consideration when documenting this process.
If your measuring devices are relatively uncomplicated,
you don't need an elaborate and cumbersome procedure. Describe
what you do and then comply with whatever procedure you
ultimately develop.
Denise E. Robitaille is a consultant, writer and trainer.
She is also a lead assessor and certified quality auditor.
Much of her work involves assisting companies with implementing
and maintaining ISO 9001-compliant quality management systems.
She is also the author of The Corrective Action Handbook,
The Preventive Action Handbook and The Management Review
Handbook, all available from Paton Press (www.patonpress.com).
Letters to the editor regarding this article can be sent
to letters@qualitydigest.com.
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