The development of computerized control, and data retrieval for aerospace cell testing affords an excellent opportunity to incorporate three specific concepts to both manage the test area and to track product performance on a real-time basis. The adoption and incorporation of precepts fostered by this total quality management (TQM) initiative are critical to us for retaining control of our business while substantially reducing the separate quality control inspection activity. Test discrepancies are all 'equally bad' in cell acceptance testing because, for example, we presently do not discriminate between 1 or 25 mV for an overvoltage condition. We must take leadership in classifying such discrepancies in order to expedite their clearance and redirect our resources for prevention activities. The development and use of engineering alerts (or guardbanding) which more closely match our product capabilities and are toleranced tighter than the required customer specification are paramount to managing the test unit in order to remain both quality and cost effective

Brearley, George R.

Klein, Glenn C.

English

NASA Technical Reports Server

N 9 2 - 22 "742
PROFILE OF A CELL TEST DATABASE AND
A CORRESPONDING RELIABILY?Y DATABASE
George R. Brearley
Glenn C. Klein
Gates Energy Products
Gates Aerospace Batteries
PRIECEDING PAGE BLANK NOT FILMLeD
1991 NASA Aerospace Battery Workshop -27- General Topic Session
https://ntrs.nasa.gov/search.jsp?R=19920013499 2020-03-17T11:39:45+00:00Z
Abstract
The development of computerized control, and data
retrieval for aerospace cell testing affords an excel-
lent opportunity, to incorporate three specific con-
cepts to both manage the test area and to track
product performance on a real-time basis: [1.]
DoD 5000.51-G: The adoption and incorporation
of precepts fostered by this TQM initiative are criti-
cal to us lor retaining control of our business while
substantially reducing the separate QC inspection ac-
tivity; [2.] CLASSIFICATION OF TEST DISCREP-
ANCIES: Test Discrepancies are all "equally bad" in
cell Acceptance Testing because, for example, we
Introduction to the current GAB Test
i
presently do not discriminate between lmV or 25mY
for an overvoltage condition. We must take leader-
ship in classifying such discrepancies in order to expe-
dite their clearance and redirect our resources for
prevention activities.J3.] ENGINEERING
ALERTS: The development and use of engineering
alerts [ or guardbanding ] which more closely match
our product capabilities and are toleranced tighter
than the required Customer Specification are para-
mount to managing the Test Unit in order to remain
both quality and cost effective.
Unit:
The GAB Test Unit is a 3,750 square foot facility lo-
cated on the first floor of the GAB Aerospace com-
plex. It is equipped with 550 ambient temperature
test stations for NiCd Pre- Acceptance Testing and
330 environmentally controlled test stations for NiCd
Acceptance Testing. There are an additional 192 test
stations dedicated to NiH2 Cell Activation and Ac-
ceptance Testing; these stations are 100% computer
controlled including active temperature control and
pressure monitoring via strain gages. There are addi-
tional test positions utilized for electrode stress test-
ing and for flooded electrode capacity testing. This
Test Unit operates 24 hours a clay, 7 days a week and
is staffed by a crew of fifteen operators over three
shifts. Each shift includes three Test Operators, one
Total Quality Management Guide
Lead Technician, and one Quality Inspector. The
Test Unit is supported one a full time basis by an
Electronic Technician, a Refrigeration Specialist,
and an Equipment Development Engineer. Test ca-
pability spans a range of designs from 0.25 amp-hour
to 150 amp-hour capacity over a temperature regime
of -10 to + 35 C. Test capability also covers 40 differ-
ent NiCd and NiH2 programs for commercial and
military programs. The Test Unit is a dynamic, state-
of-the-art facility which performs its own mainte-
nance (tracked on a computerized database),
develops their own test equipment, and is increasing
their capability on a daily basis for computerized data
retrieval, information handling, and test control.
DoD 5000.51-G
This TQM philosophy fosters continuous improve-
ment by the real-time recognition of improvement op-
portunities through the use of data collection, various
statistical or mathematical tools for the identification
and analysis of variation, and thereafter providing
guidance for reduction and elimination of this vari-
ance depending upon the nature of the common
cause or special cause. Specific improvement oppor-
tunities addressed within the Test Unit include: a]
reduction in test discrepancies; b] reduction in per-
formance variation within a lot; and, c] reduction in
lot-to-lot performar;ce variation.
Reduction in Test Discrepancies
Over the past three years, the Test Unit has signifi-
cantly reduced the number of test anomalies through
the elimination and reduction of Special Causes.
Chart No. 1 graphically displays how personnel in the
Test Unit lowered the number of discrepancies by
the applied analyses of Man, Method, Machine,
Materials, and Environment in order to understand
the role of each, and their associated interactions:
MAN: The Test Unit now employs skilled, trained
and competent technicians. On each of the three
shifts, there is a Lead Technician, three Test Techni-
cians, and one dedicated QC Inspector. In addition,
there is a full time maintenance technician and refrig-
eration specialist.
MACHINE: Numerous equipment additions include
1] Failsafe Devices for preventing cell reversal, for
ensuring proper transitions of test procedure, audible
warning devices; and, usage of data loggers; 2]
charge/discharge status indicators; 3] refurbishment
of existing equipment and adoption of customized en-
1991 NASA Aerospace Battery Workshop -28- General Topic Session
vironmental chambers; and, incorporation of com-
puter control on 40% of the environmental chambers.
METHOD: We are constantly improving our
method of operations by reviewing our training and
bv the validation of functional procedures, adoption
of trend analyses, standardization of temperature
control, and standardization of test instructions. One
specific example is the Extended Pre-ATP wherein
32F and 86F performance tests are used to emulate
the forthcoming acceptance test.
MATERIAL: Product as well as the accompanying
data package undergoes a substantial review prior to
transfer from the fabrication shop into the Test Unit.
Reduction in Performance Variation
Further red uction of variation within the Test Unit is
hampered somewhat by the currently imposed con-
tractual obligations and restrictions. Whether we
consider performance variation within a lot or con-
sider lot-to-lot perlormance variation, two addi-
tional steps must be taken. These steps include the
adoption of a classification scheme for test discrepan-
cies, and the incorporation of internal performance
guidelines. The present Failure Reporting and Cor-
rective Action System (FRACAS) is both labor and
time intensive. Presently our FRACAS ksa conglom-
eration of inputs from MIL-STD-1520C (Corrective
Action and Disposition System for Nonconforming
Material) and 40 plus Program Offices. The MIL-
STD states in part that a Minor Nonconformance
does not adversely affect any of the following: [a]
health or safety, [b] performance, [c] interchange-
The concept of internal customers within Gates dis-
allows the unilateral transfer of material internally
and this concept will be formalized into a series of
Delivery Review Boards throughout the entire fabri-
cation and test process.
ENVIRONMENT: The physical environment in the
Test Unit has expanded and substantially improved
to maintain more stable temperature and humidity.
This was accomplished by improvement and dedica-
tion of the air conditioning units, usage of more hu-
midity monitoring devices, and a restructuring of the
coolant control systems for the environmental cham-
bers.
i
ability, reliability, or maintainability, [d] effective use
or operation, [e] weight or appearance. Most of the
customer contracts parrot some or all of this specifi-
cation; but, no where are definitive examples pro-
vided to guide the shop, test, or inspection personnel.
To compound this issue, one customer specification
spends 20 plus pages defining failures, power-on fail-
ures, discrepancies, nonconformances (Type 1 & 2),
deviations (functional and performance), anomalies,
and out-of-family conditions while still not providing
for quantitative descriptions to be used at the shop
level. By default, all Test Discrepancies in cell Ac-
ceptance Testing become Major Nonconformances
and are "equally bad." For example, we presently
do not discriminate between ImV or 25mV for an
overvoltage condition, nor do we discriminate be-
tween 1 amp-minute or 10 amp-hour for low capacity.
Classification of Test Discrepancies
The standardized definition, and classification of
discrepancies occurring in cell Acceptance Testing is
necessary for us to manage the Test Unit and to
avoid the untimely delay of customer level material
review for insignificant issues. As regards our exam-
ple of low capacities of I amp-minute versus 1 amp-
hour, both conditions are subject to a Gates
Anomaly Report, an internal Material Review meet-
ing, customer contact and approval to continue, and
Customer Material Review. Table Nos. 1 & 2 con-
lain standardized definitions which should be applied
to discrepancies which occur within acceptance test-
ing,and are endemic to starved NiCd cells and NiH2
cells.Thereafter, discrepancies are classified as to
whether they are Critical, Major or Minor; and, then
to whether the discrepancy ksa Cell Response Dis-
crepancy [such as pressure or capacity], or a Test
Control Discrepancy [such as time or temperature].
By this classification scheme then, our example for
discrimination of overvoltages shows lmV to be a
Minor Discrepancy versus the 25mV as a Critical Dis-
crepancy. The use of this classification scheme must
respect the Customer Specification, and the use of
potential Engineering Alerts. There is provision for
an automatic retest when any of the defined Minor
Discrepancies occurs. Obviously these definitions
and the retest provisions require customer approval;
however, the presentation of these definitions at the
NASA Battery Workshop is expected to expedite
their acceptance. The adoption of these or similar
standardized definitions will significantly improve the
resolution of discrepancies when they do occur.
1991 NASA Aerospace Battery Workshop -29- General Topic Session
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More importantly, we will benefit by applying our re-
sources to the prevention of Major and Critical dis-
crepancies.
Engineering Alerts
This rededication or redirection of the Technical
Staff to resolving and preventing Major and Critical
Discrepancies allows the development and internal
implementation of Engineering Alerts. Much like Up-
per and Lower Control Limits in classical Shewhart
Analysis, the Engineering Alert [previously called
Tollgates or Guardbanding] provides performance
limits which more closely match our product capabili-
ties and are tolcranced tighter than the Customer
Specification. This is the first step in identi_ing and
reducing Common Causes and the accompanying
variation, or performance dispersion. Tables 3 & 4
contain the Engineering Alerts to be applied to NiCd
Reduction of Lot-to-Lot Performance
i
The full implementation of computerized control and
data retrieval allows the development of databases
that allow us to track and reduce performance vari-
ation in long term multi-year programs. By definition,
this database becomes the baseline or embryo for the
Conclusions and Recommendations
1. We have introduced you to the current Test Unit
and shared the plans for improvement; we have dis-
cussed the Improvement Opportunities available
through reduction of Test Discrepancies, and
through the red uction of variation within a lot and
variation from lot-to-lot.
2. Standardized definitions of test discrepancies for
both product lines in Acceptance Testing have been
i
Pre-ATP and to NiCd ATP performance testing.
These are non-normalized limitations for several rea-
sons: [1] this removes one more crutch or excuse for
non-performance; and, [2] software sub-routines for
real time normalization of multiple data points ap-
pcars counterproductive and very demanding of com-
puter memory. Similar Engineering Alerts for Nil-I2
performance testings are being developed and will be
implemented following successful implementation of
those for the NiCd cell product line. Necessarily, the
entire program is dependent upon the continued im-
plementation of computerized control and data log-
gers.
Variation
Reliability Database. Further development of this
Reliability Database is dependent upon develop-
ment of indexing schemes by cell configuration or by
plate type since there exists little parity between plate
design and cell design.
proposed; implementation will begin on an individ-
ual program basis via customer approved Engineer-
ing Change Notices.
3. Engineering Alerts are proposed for internal usage
and are already being implemented on the NiCd
product line.
1991 NASA Aerospace Battery Workshop -35- General Topic Session



Profile of a cell test database and a corresponding reliability database

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