Measurement System Analysis (MSA)

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Measurement System Analysis (MSA)
Discussions at CSIR S.A. 28-07-2005
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Measurement System
Sources of Variations
Manufacturing Process
Input Material
Process design
Product Design (Tolerancing)
Environment
Measurement
Machine
Tooling
Parameter variation
Method variation
Processing material
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Fundamental Properties of a GOOD measurement
system

• ADEQUATE SENSITIVITY 10 TO 1 RULE Instrument
  ACCURACY (and therefore Least Count) should
  divide the tolerance ( or process variation) into
  10 parts or more practical minimum point for
  gauge selection
• Measurement system ought to be in statistical
  control presence of only common causes of
  variation and not the special causes
• Variation of measurement system must be small
  compared to specification limits or process
  variation (6-sigma) more PRECISION

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Inaccurate and imprecise

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Accurate and imprecise

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Precise but inaccurate

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Accurate and precise

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U UNCERTAINITY RANDOM UNCERTAINITY FOUND THRU
CALIBRATION SYSTEM UNCERTAINITY OF
MASTER TOTAL UNCERTAINITY SQRT( RURU SUSU)
U 0.0001
RU 0.0001
NATIONAL STANDARD
U 0.001005
RU 0.001
LABORATORY STANDARD
WORK STANDARD
RU 0.01
U 0.01005
GAUGE FOR INSPECTION / TESTING
RU 0.05
U 0.05099
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Process Capability
Lower Spec. Limit
Upper Spec. Limit
6 ?
Tolerance T
Process Capability T / 6 ?
gt 1.33
Means, 6 ? lt (0.75T)
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ERROR identified through Calibration Process
Impact of Uncertainty
Lower Spec. Limit
Upper Spec. Limit
Uncertainty
6 ? Process
Tolerance T
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Questions

• Can an ISO/TS 16949 2002 certification program
  ensure systems and processes which deliver
  products which conform to a technical
  specification?
• Yes, TS SCOPE, point 1.1, states
• This international standard specifies
  requirements for a quality management system to
  demonstrate ability to CONSISTENTLY provide
  PRODUCT that meets product, customer and
  regulatory requirements
• Requirements specified in standard are
  complementary to product requirements
• Emphasis on PROCESS DESIGN to deliver conformance
  to product specifications CONSISTENTLY . Focus
  on REDUCTION IN VARIATION by asking ongoing
  capability evaluationincluding measurement
  systems variation, which an process engineer
  must evaluate during development
• Product and process approval is a requirement
  throughout SUPPLY CHAIN, which includes elements
  such as FMEAs, Control Plans, SPC MSA

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Questions

• Are customer specific MSA requirements addressed
  in ISO/TS 16949 2002 audits?
• Yes, the scope of certification includes
  ISO/TS-16949 CUSTOMER SPECIFIC REQUIREMENTS
• ISO/TS 169492002,
• POINT 0.5 Goals of this Technical
  Specification, Para 2
• This Technical Specification, coupled with
  applicable customer specific requirements,
  defines the fundamental quality management system
  requirements for those subscribing to this
  documents.
• Most of the subscribing customers (OEMs asking
  vendors to get registered to TS 16949) ask usage
  of AIAG MSA MANUAL

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Questions

• To what degree are customer specific MSA
  requirements addressed in ISO/TS 16949 2002
  audits?
• Audits wrt TS-16949 are planned considering
  business processes identified by organization to
  meet the product and customers needs and
  expectations, calibration and MSA is one of such
  processes
• ISO/TS-169492002 (Point 7.6.1 Measurement
  System Analysis)
• Statistical Studies SHALL BE conducted to analyze
  the variation present in the results of EACH TYPE
  of measuring and test equipment system.
• The requirement shall apply to measurement
  systems REFERENCED IN THE CONTROL PLAN
• The analysis methods and acceptance criteria used
  SHALL confirm to those in CUSTOMER REFERENCE
  MANUALS on measurement systems analysis

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Questions

• Would ISO/TS 169492002 auditors benefit from
  additional training in Measurement System
  Analysis?
• Certainly Yes. Rather its a REQUIREMENT.
  Otherwise how could they assess suitability and
  impact of MESUREMENT SYSTEM ERRORs on products
  quality?
• Auditor Qualification requires.
• 6 years prior experience in AUTOMOTIVE, out of
  which 4 years in Quality
• Qualification Course contents and examination
  includes CORE TOOLS APQP, PPAP, FMEA, SPC, MSA,
  etc
• Ford GM specific requirements demand even the
  internal auditors shall be trained and evaluated
  wrt knowledge on core tools including MSA.

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• Who conducts the MSA? (supplier/OEM?)
• The user of measurement system shall conduct the
  MSA
• Are FOP, (first of production), tests conducted?
• Review is Must, if necessary do it!
• Who is responsible for conducting these tests,
  OEMs or suppliers?
• Of course the manufacturer (supplier)
• Who is responsible for evaluating that the
  measurement system is capable of performing the
  required measurements with the desired level of
  accuracy?
• Of course the manufacturer (supplier)
• Do these tests form part of the control plan?
• Yes, they have to be!
• Is the understanding that an MSA addresses the
  measurement accuracy of a measurement system or
  merely its repeatability/reproducibility?
• It addresses both location (accuracy) and
  variation (precision)

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Application of appropriate method
TYPE OF GAUGE BIAS / UNCER-TANITY LINEARITY STABILITY GRR
VERNIER 0-150mm ? ? ? SKILL IN HOLDING THE JAWS PARALLALY
CMM 0-1500mm ? ? ?
SLIP GAUGES ? ? SKILL OF RINGING
PLUG GAUGE FOR BORE OF 20.025/20.000 ? ? SKILL ON BORDERLINE CASES