Measurement System Analysis (MSA) Discussions at CSIR S.A. 28-07-2005
Dec 24, 2015
Measurement System
ManufacturingProcess
Input Material Process design
ProductDesign
(Tolerancing)
Machine ToolingParametervariation
Methodvariation
Processingmaterial
Environment
Sources of Variations
Measurement
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
NATIONAL
STANDARD
LABORATORY
STANDARD
WORK
STANDARD
GAUGE FOR INSPECTION / TESTING
RU = 0.0001
RU = 0.001
RU = 0.01
RU = 0.05
U : UNCERTAINITY
RANDOM UNCERTAINITY – FOUND THRU
CALIBRATION
SYSTEM UNCERTAINITY – OF MASTER
TOTAL UNCERTAINITY – SQRT( RU*RU + SU*SU)
U = 0.0001
U = 0.001005
U = 0.01005
U = 0.05099
Process Capability
Lower Spec. Limit
Upper Spec. Limit
6
Tolerance = T
Process Capability = T / 6
> 1.33
Means, 6 < (0.75*T)
Impact of Uncertainty
Lower Spec. Limit
Upper Spec. Limit
6 Process
Tolerance = T
ERROR identified through Calibration Process
Uncertainty
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 evaluation…including 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
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 16949:2002,
• 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
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-16949:2002 (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
Questions• Would ISO/TS 16949:2002 auditors benefit from additional training
in Measurement System Analysis?
• Certainly Yes. Rather it’s 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.
• 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)