Reactions to out of control X bar and R charts?

J

Josh Smith

#1
I am curious as to how other organizations have written their procedures for reacting to out of control points up or below the control limits, 7 consecutive points running above or below the centerline, and 7 points trending up or down?

Our reaction plan on the control plan states that when the process has violated these rules. Supervisor will be notified by quality auditor, suspect product will be isolated and verified by other means (i.e 100% inspect), the process will be adjusted to bring back into a state of control, and process changes will be noted on the process change log sheet.

Does this sound reasonable? Or is it painting us into a corner for QS-9000?

Looking for input?
 
Elsmar Forum Sponsor
A

auditor16949

#2
The procedure is basically OK. The QS-9000 auditor may ask if you have identified and eliminated the special cause of variation acting on the process.
 
I

Indywine

#3
Keep in mind that 7 points in a row usually reflects a change in the process. However, it could be associated with a learning curve after training. I wouldn't suggest blindly changing the process without trying to understand why there is a new trend.

Jim
 
L

lyman

#4
Our procedures which were written by engineering and approved through manufacturing centered the responsibility for initial monitoring of SPC and any related trends with the floor operators. We tied our SPC as much as possible with our computerized manufacturing system so that if the chart showed an OOC point the equipment automatically was no longer available to production until such time that someone from Engineering reviewed the situation and released it. The procedures for trends directed operators to OCAPs which either dictated that a change to equipment settings be made (if appropriate)with the requisite documentation, or that the process be shut down and Engineering and Manufacturing Management be notified. The biggest challenge we faced with this allocation of responsibility was making sure that there was enough information in our computerized record so that Engineering could evaluate the situation to begin effective corrective or preventive action. The second biggest challenge - getting Engineering to document what they did!
 
B

Brian Dowsett

#5
I think you also could make some reference to process capability.
For instance if you have a very good Cpk value, seven points in one direction definitely merits some attention but may not merit 100% inspection.
In a previous job, our reaction plan was in the form of a flow chart, with some decision boxes based on proven process capability.

regards

Brian
 
A
#6
"We tied our SPC as much as possible with our computerized manufacturing system so that if the chart showed an OOC point the equipment automatically was no longer available to production until such time that someone from Engineering reviewed the situation and released it."

I am looking for ways to connect SPC to the manufacturing system. Looking after your reply, I was wondering if you could elaborate more on how to accomplish this system.


Abhinav.

:thanx:
 

Caster

An Early Cover
Trusted Information Resource
#7
Hmmm.....quality auditor, supervisor, engineering

Everyone involved but the operator? SPC was supposed to be a tool for the machine operator to control her process. Are they out of the loop?

Can't they just make adjustments and carry on? Assuming a decent capability, a trend may not be bad product but just a signal to perhaps change worn tooling.

The more the operator knows about SPC, the better.

At least thats the theory. We don't do any better here, but I hope some people get to run SPC right.
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#8
agree with Caster on the capability part. you state that "suspect product will be isolated and verified by other means (i.e 100% inspect)". I hope that you mean only product suspected of being out of tolerance?
As Caster points out a capable process can go out of control and all of the parts can be perfectly in tolerance nd acceptable.

The other comments regarding operator involvement are also pertinant. Keeping in mind that are processes that the operator cannot troubleshoot. I've worked with both and sometimes you just dont' want the operator touching anything...
 

Steve Prevette

Deming Disciple
Staff member
Super Moderator
#9
"We tied our SPC as much as possible with our computerized manufacturing system so that if the chart showed an OOC point the equipment automatically was no longer available to production until such time that someone from Engineering reviewed the situation and released it."

I am looking for ways to connect SPC to the manufacturing system. Looking after your reply, I was wondering if you could elaborate more on how to accomplish this system.


Abhinav.

:thanx:
You are welcome to make use of our trending procedures on the internet at http://www.hanford.gov/rl/?page=1144&parent=169. Just recently (December 2007) the Institute of Nuclear Power Operations published a 20 page extract of our procedures in one of their "best practices".
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#10
Another question is whether an X-bar-R chart is even appropriate for the process. It seems to be rubber stamped on every process. I have seen automated SPC systems choke precision machining operations - because they were using the wrong statistics - and have unplugged them and replaced them with paper charts the correct statistics. Made everyone happy. Don't fall into the X-bar - R trap. It is not a universal tool. :cool:
 
Thread starter Similar threads Forum Replies Date
B Allergic reactions complaints for a protective apparel (impervious gown) Customer Complaints 4
Q How do you overcome knee jerk reactions from upper management on CA? Quality Manager and Management Related Issues 18
R WinSPC - Operators not noting any reactions to Out of Specification conditions Statistical Analysis Tools, Techniques and SPC 3
B Control chart and sample time Statistical Analysis Tools, Techniques and SPC 1
DuncanGibbons Manufacturing Plan vs Material Specification vs Control Plan Manufacturing and Related Processes 4
J Control chart for huge sample size Statistical Analysis Tools, Techniques and SPC 9
K Contamination Control - Class Is medical devices (Clause 6.4.2 ISO 13485:2016 (E)) ISO 13485:2016 - Medical Device Quality Management Systems 10
J 510(k) for a control kit for an external IVD test kit 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 1
T Assessing Hazard-Related Use Scenarios where control measures exist through standards IEC 62366 - Medical Device Usability Engineering 14
adir88 Documenting Risk Control Option Analysis ISO 14971 - Medical Device Risk Management 2
T Design Control Procedures later in the Development Process ISO 13485:2016 - Medical Device Quality Management Systems 6
L AS5553 Clause 3.1.7 e "Control packaging material ..................reused" AS9100, IAQG 9100, Nadcap and related Aerospace Standards and Requirements 0
T Attributes SPC study - Attributive control (Go gage) Statistical Analysis Tools, Techniques and SPC 5
K Process Mapping - Inputs/Outputs/Detail Activities/Control points/Measurement? Process Maps, Process Mapping and Turtle Diagrams 4
S Should safety checks be included in the Control Plan? IATF 16949 - Automotive Quality Systems Standard 4
D Infrastructure: Equipment, Work Environment and Contamination Control ISO 13485:2016 - Medical Device Quality Management Systems 4
Q Relabeler for patent expired product - design control responsibilities? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 2
J How to make Quality Control plans Quality Tools, Improvement and Analysis 4
I Document Control on Log Files ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 6
Q Tracking Procedure Revisions (Document Control) Document Control Systems, Procedures, Forms and Templates 9
C Document Control Stamps - Does anyone still stamp their documents? Document Control Systems, Procedures, Forms and Templates 21
D Supplied Product on Control Plan - Lot ranging in 40,000 pcs per product FMEA and Control Plans 3
D IEC 62304 Risk Classification - With and without hardware control IEC 62304 - Medical Device Software Life Cycle Processes 2
J Antiviral Mask or Mask to Mitigate or Control Corona Virus Manufacturing and Related Processes 21
A UDI and Design Controls - Labeling change via the Design Control process 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 1
I Control of Documentation Distribution - Document Control ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
S Inventory Control - Any thoughts would be appreciated ISO 13485:2016 - Medical Device Quality Management Systems 2
H SPC for special characteristics - CSR - Control of SC and CC Statistical Analysis Tools, Techniques and SPC 1
T Control of downloaded document copies by employees Document Control Systems, Procedures, Forms and Templates 3
T Document control ISO 13485:2016 ISO 13485:2016 - Medical Device Quality Management Systems 5
M Is there any pre-defined Control plan format/template acc. VDA? VDA Standards - Germany's Automotive Standards 0
B Record Management - Does the QMS need to control templates of records? Records and Data - Quality, Legal and Other Evidence 17
O Inventory control ideas - I have an open stock room with a "sign out" book Manufacturing and Related Processes 9
V IATF 16949 8.4.1 Control of externally provided processes, products and services - Should the CB be on our Approved Supplier List? IATF 16949 - Automotive Quality Systems Standard 10
R Process control documents - Context of API Spec Q1, Clause 5.7.1.3 Other ISO and International Standards and European Regulations 0
D Performance specification as a Risk Control Measure, EN 14971 ISO 14971 - Medical Device Risk Management 7
L Form-dependent position prevention control FMEA and Control Plans 1
S CQI-23 - Molding System Assessment - Control of part weight IATF 16949 - Automotive Quality Systems Standard 5
D Change Control - Product Name Change and its associated labeling EU Medical Device Regulations 7
S Degree of control of distributors - PMS EU Medical Device Regulations 2
M What is "setup control chart"? Statistical Analysis Tools, Techniques and SPC 2
Jimmy123 What is the difference between Error Proofing and Controls? ISO/IATF 16949 - Control Plans FMEA and Control Plans 16
V IS/ISO/IEC 17025:2017 Clause 7, sub clause 7.11 Control of data and information management ISO 17025 related Discussions 1
C Design Control - Ways of capturing inputs from manufacturing Other Medical Device Related Standards 5
G Control Plan - Include the processes for each sub component? APQP and PPAP 2
U Change Management vs Change Control? Design and Development of Products and Processes 4
F Control of medical device IFU content Other Medical Device and Orthopedic Related Topics 3
Jimmy123 FMEA - Preventive vs Detection Control FMEA and Control Plans 7
R Software change control process and defect tracking ISO 13485:2016 - Medical Device Quality Management Systems 1
V ISO 9001: 2015 Production drawing Control ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
Similar threads


















































Top Bottom