Is tool wear a special cause? No...

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#1
Tool wear is common cause. It is a cause intrinsic in the process and can not be eliminated. It affects every part. Special causes are not intrinsic in the process, and do not affect every part - such as tool breakage, start-up, warm-up, etc. It is non-random - in fact it is a function.

The thinking that tool wear is a "special cause" arises from a narrow view that anything that fails a Western Electric rule is no longer common cause, and therefore special cause. That, however, is only true if a Shewhart chart is appropriate in the first place. With tool wear a a main variation, it is not.

Because variation from tool wear is non-random and not independent, Shewhart charts are not applicable. Their inputs must be random and independent for their statistical requirements to be met.

Never fear, however, since there is a charting methodology that deals with the sawtooth chart and resulting non-normal continuous uniform distribution that arises from toolwear/adjustment. It is the X hi/lo-R chart. It has been around for years and is extremely effective. See CorrectSPC!
 
Elsmar Forum Sponsor
Thread starter Similar threads Forum Replies Date
J Acme Thread Gage Tool Wear Measurement General Measurement Device and Calibration Topics 11
A Tool Wear Rate/Replacement - Turning/Facing Manufacturing and Related Processes 1
C Is tool wear monitoring and MTBF of machine parts considered as PdM? Manufacturing and Related Processes 6
B Sloping control chart to take care of tool wear - Details needed Statistical Analysis Tools, Techniques and SPC 5
K Monitoring Tool Wear for Predictive Maintenance - Data evaluation methodogy IATF 16949 - Automotive Quality Systems Standard 5
S To take into account the tool wear during calculating control limits Statistical Analysis Tools, Techniques and SPC 6
M Short Run SPC with Tool Wear Statistical Analysis Tools, Techniques and SPC 2
D Monitoring Tool Wear - Seeking: Suggestions on a database for Monitoring Tool Wear Manufacturing and Related Processes 3
Q Tool Wear Control Charts to Help Control Machine Tool Offsets Statistical Analysis Tools, Techniques and SPC 6
F QS-9000 Clause 4.9.g.1 - Preventive Maintenance - Tool Wear Predictive Maintenance QS-9000 - American Automotive Manufacturers Standard 1
G APQP Scope and scale tool APQP and PPAP 2
B FAR/Prime Contractor Flow-down Tool - AS9100 AS9100, IAQG 9100, Nadcap and related Aerospace Standards and Requirements 3
R Does any here use an internal auditing tool that works on different platforms? Internal Auditing 3
O Dimension Measurement Tool Recommendation General Measurement Device and Calibration Topics 21
Y Commanded life cycle management tool IEC 62304 - Medical Device Software Life Cycle Processes 1
GreatNate Excel PPAP Tracking templates or tool wanted APQP and PPAP 1
E Standards Management Tool Quality Tools, Improvement and Analysis 1
E ISO 9001:2015 - Record requirements for out of calibration tool ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 28
Mikael PDCA as a project tool Quality Tools, Improvement and Analysis 5
M Minitab tool to evaluate PM (Preventive Maintenance) process Using Minitab Software 6
M Informational Health Canada has launched an e-Learning tool to aid in understanding the premarket regulatory requirements for medical devices in Canada Medical Device and FDA Regulations and Standards News 0
John Broomfield Workplace by Facebook - Any other organizations using this collaborative tool? Misc. Quality Assurance and Business Systems Related Topics 0
A Overkill? Using the 3L5W tool on non-conformities Nonconformance and Corrective Action 3
I Tool Control Marking Voiding Warranty AS9100, IAQG 9100, Nadcap and related Aerospace Standards and Requirements 1
F Quality Tool box talks ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 8
D VDA 6.4 Audit checklist - Production tool suppliers VDA Standards - Germany's Automotive Standards 1
I Tool maintenance and calibration procedure - Calibrating tools/equipment AS9100, IAQG 9100, Nadcap and related Aerospace Standards and Requirements 3
bobdoering "nds" or Number of Discriminate Samples - the Necessary Tool to Work With "ndc"! Imported Legacy Blogs 0
G Design and development of user centric audit report visualisation tool Design and Development of Products and Processes 5
G Web based tool for benchmarking audit findings Benchmarking 6
J AS9100D Clause Brain Fade - Tool was past due for Calibration AS9100, IAQG 9100, Nadcap and related Aerospace Standards and Requirements 11
R New Tool from Omnex - IATF Gap Assessment IATF 16949 - Automotive Quality Systems Standard 0
C Upgrading from ISO 9001:2015 to IATF 16949:2016 - Anyone have a gap analysis tool? IATF 16949 - Automotive Quality Systems Standard 2
I Veeva installation and the Loader Tool Document Control Systems, Procedures, Forms and Templates 3
M IATF Tool for Leadership and Planning - 2017 IATF 16949 - Automotive Quality Systems Standard 0
Icy Mountain ISO9001:2015 & IATF 16949:2016 Gap Analysis Tool IATF 16949 - Automotive Quality Systems Standard 7
K Looking for Calibrated Tool Shadowboard Substrate Ideas AS9100, IAQG 9100, Nadcap and related Aerospace Standards and Requirements 5
Marc SAS vs. R vs. Python: Which Tool Do Analytics Pros Prefer? Statistical Analysis Tools, Techniques and SPC 6
P Tool for Measuring - Do I have to do more than one Gage R&R for the PPAP? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
J Pneumatic & Electrical Torque Tool - Calibration/Verification of 'Power Tools' General Measurement Device and Calibration Topics 2
M Excel Leadtime Analysis Graphic Tool with Macros Enabled Lean in Manufacturing and Service Industries 0
D Medical Device Software Tool Validation - Compilers! IEC 62304 - Medical Device Software Life Cycle Processes 7
J What kind of Tool and Gauge in IATF 16949 Clause 8.5.1.6? IATF 16949 - Automotive Quality Systems Standard 1
J CNC Machine Tool Calibration - 6 dof Calibration Interferometers General Measurement Device and Calibration Topics 1
P Using Bugzilla as a Quality Reporting Tool Quality Assurance and Compliance Software Tools and Solutions 11
Marc Hackers unleash smart Twitter phishing tool that snags two in three users IEC 27001 - Information Security Management Systems (ISMS) 7
D Proper Tool to Measure Wall Thickness (ISO 3611 - Micrometers) Manufacturing and Related Processes 7
N Tool frequency change - Data Analysis needed Statistical Analysis Tools, Techniques and SPC 9
V What tool do you use for systemic issues? Problem Solving, Root Cause Fault and Failure Analysis 2
C Software Planning Tool for Equipment Qualifications, Process Validations Software Quality Assurance 3
Similar threads


















































Top Bottom