Creating a c-chart spreadsheet to use in my department

R

riot_

#1
Hi! My name is Manuel:

i'm working in create a c-chart spreadsheet to use in my department, but i've some doubts about this and hope you can guide me a lil': "what I'll meassure or control are ""Slubs"" and for this I know that is better use a chart for attributes, but the last thief in the department use to use a X-R chart for this.

this is for a textile company and we are thinking get our ISO/TS certification, hope someone can share a spreadsheet for this.
 
Elsmar Forum Sponsor

Stijloor

Leader
Super Moderator
#2
Hi! My name is Manuel:

i'm working in create a c-chart spreadsheet to use in my department, but i've some doubts about this and hope you can guide me a lil': "what I'll meassure or control are ""Slubs"" and for this I know that is better use a chart for attributes, but the last thief in the department use to use a X-R chart for this.

this is for a textile company and we are thinking get our ISO/TS certification, hope someone can share a spreadsheet for this.
Just as an "aside" comment. ;)

Please note that ISO/TS 16949:2009 states the following:

7.1.2 Acceptance criteria
Acceptance criteria shall be defined by the organization and, where required, approved by the customer.
For attribute data sampling, the acceptance level shall be zero defects (see 8.2.3.1).
Emphasis mine.
 

Steve Prevette

Deming Disciple
Leader
Super Moderator
#3
The c-chart is strictly used for counting events that are expected to be independent from each other. The c-chart is based upon the Poisson distribution, and in queuing theory is used for a "random arrival process".

The big difference mathematically with the c-chart is that you use the standard deviation of the average as the estimator for the standard deviation.

Examples of things likely to be "poisson" include counting the following per some fixed unit of time:
Defects
Injuries (where only one person in injured)
Events
Arrivals of customers at a bank
Number of cars passing a certain location

Anything that involves a count per varying unit (injuries per 200,000 hours) or a measurement (dollar value of events per month) would not be a c-chart.

Bottom line is
1. Do you have a good theory that what you are measuring ought to be Poisson
2. Does the measured standard deviation come close to the square root of the average.
 
R

riot_

#4
Thanks for your explanation, Stijloor, with that note of the 7.1.2 I can give a better response the next time.
 
R

riot_

#5
hi Steve, I understan what you are saying, and is logical, but I've got a little confusion, this due the following criterial of xbar-r chart:

1.- The sample size is relatively small (say, n ≤ 10— and s charts are typically used for larger sample sizes) [slubs are very small defect].
2.- The sample size is constant [the defect is often in the bobbins, just the size is what matters].
3.- Humans must perform the calculations for the chart [indeed, my operators are trained for that].

but also, you are saying that the next:

Anything that involves a count per varying unit (injuries per 200,000 hours) or a measurement (dollar value of events per month) would not be a c-chart.
what I'm trying to measure are "slubs" in the bobbins to determinate the quality and procesability of the yarn, and really I don't know which could be better option (c-chart against xbar-r chart) to know that.

hope you can get my doubt.

PD. do you have any c-chart spread sheet!?
 

Steve Prevette

Deming Disciple
Leader
Super Moderator
#6
hi Steve, I understan what you are saying, and is logical, but I've got a little confusion, this due the following criterial of xbar-r chart:

1.- The sample size is relatively small (say, n ≤ 10— and s charts are typically used for larger sample sizes) [slubs are very small defect].
2.- The sample size is constant [the defect is often in the bobbins, just the size is what matters].
3.- Humans must perform the calculations for the chart [indeed, my operators are trained for that].
PD. do you have any c-chart spread sheet!?
statement 1 has no effect on use of c-chart
statement 2 supports the use of the c-chart
statement 3 - the c-chart standard deviation is one of the simplest to calculate - it is simply the square root of the average, and the control limits, once calculated, are extended forward as a horizontal line.

For c-chart spread sheet, see http://www.efcog.org/wg/esh_es/Statistical_Process_Control/SPC_Trending_Primer/daytwo/11%20C%20Chart%20Day%20Two.pdf or attached.
 

Attachments

Thread starter Similar threads Forum Replies Date
G Creating an Organization Chart - AS9100 AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 5
S Creating X bar R Chart using XYZ coordinates Statistical Analysis Tools, Techniques and SPC 4
T Errors & Omissions in Creating QMS Procedures AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 10
S Creating a Quality culture! AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 8
Y Creating Equipment qualification protocol Qualification and Validation (including 21 CFR Part 11) 2
R Accelerated Aging - Creating test samples - Implantable medical device Question Other Medical Device Related Standards 4
L Hazardous Waste - Tips for creating standardized training Miscellaneous Environmental Standards and EMS Related Discussions 2
M Informational Creating a post market surveillance (PMS) system for medical devices – Part 1 Medical Device and FDA Regulations and Standards News 7
J Sample size for creating a data base as a reference to a tested variable Other Medical Device and Orthopedic Related Topics 6
8 Creating Flow and Pull Game Lean in Manufacturing and Service Industries 6
B Main responsibility for Control Plans - creating and maintaining FMEA and Control Plans 15
shimonv Creating a new commercial product based on a modification to an existing product Other US Medical Device Regulations 4
R Creating WIs for a Heavy Civil Engineering Services company Document Control Systems, Procedures, Forms and Templates 19
M Creating a Plant Level Value Stream Map Process Maps, Process Mapping and Turtle Diagrams 1
T IMDS - Creating an MDS out of material and a made item? RoHS, REACH, ELV, IMDS and Restricted Substances 4
D How do I go about creating document logs and registers with the MS Excel Excel .xls Spreadsheet Templates and Tools 2
W ISO9001:2015 - Clause 7.5.2 - Requirements for Creating & Updating Documents ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 10
K Creating together Standard Definition for Prevention and Detection FMEA FMEA and Control Plans 1
Marc Creating an Internal Audit Program That Works for Your Organization Internal Auditing 0
M Creating change / Forcing change within a Company Lean in Manufacturing and Service Industries 7
A Creating a policy to evaluate the Third Party Security IEC 27001 - Information Security Management Systems (ISMS) 4
S Creating goals and objectives with targets and measurables for self-evaluations Management Review Meetings and related Processes 2
L Creating a xlsx Customer Complaint file to track Complaints Excel .xls Spreadsheet Templates and Tools 2
S When creating a 510k, which Guidance Document Wins? Other US Medical Device Regulations 9
P GS1 NHRN AIs - Creating Barcodes for Human Product Other ISO and International Standards and European Regulations 4
O Creating a Tool to Track & Verify Mistake Proofing Devices Document Control Systems, Procedures, Forms and Templates 5
B Any suggestion on creating the best paper plane that can hit a target perfectly? Coffee Break and Water Cooler Discussions 2
P Creating a PPAP document for my Suppliers APQP and PPAP 1
L Any recommendations on software for creating hierarchical workflows ? Misc. Quality Assurance and Business Systems Related Topics 2
AnaMariaVR2 Creating Global Giants from a Culture of Israeli Start-Ups Coffee Break and Water Cooler Discussions 0
R Inspection Database Picker - Creating an Inspection Report Document Control Systems, Procedures, Forms and Templates 1
P Problem with creating VSM current map Lean in Manufacturing and Service Industries 3
L Creating DHF (Design History File) for Medical Device Systems Design and Development of Products and Processes 8
Q Recommendations for criteria on creating a CAPA (Corrective and Preventive Action) ISO 13485:2016 - Medical Device Quality Management Systems 8
C Creating a Multiple Table SQL (Structured Query Language) Query in Minitab Using Minitab Software 10
C Resources for creating Process Validation Procedures Qualification and Validation (including 21 CFR Part 11) 5
B Creating an Audit Mechanism (System/Plan) General Auditing Discussions 3
A Customer Profiles - Creating a Customer 'Profile' for our Top 10 Customers Document Control Systems, Procedures, Forms and Templates 2
M Creating an Index for our Documents - Imaging Millions of Paper Records Document Control Systems, Procedures, Forms and Templates 13
N ISO 9001 based Audit Schedules: Creating and Maintaining - Template wanted General Auditing Discussions 5
P Creating a Traceability Database with Microsoft Access Document Control Systems, Procedures, Forms and Templates 7
V Creating a Cosmetic Inspection Specification for Powder Coated Painted Finished Parts Manufacturing and Related Processes 7
I Difficulty in creating a Quality Manual Quality Management System (QMS) Manuals 4
J Creating an Audit Schedule & Revamping QMS Internal Auditing 18
L How can you capture many positions held without creating a lengthy resume Career and Occupation Discussions 4
Miner Intro to MSA of Continuous Data - Part 10: Creating gauge families Imported Legacy Blogs 10
E Manufacturing Planning - Creating Improvements Misc. Quality Assurance and Business Systems Related Topics 7
R Creating Quality System and using it before it is complete ISO 13485:2016 - Medical Device Quality Management Systems 8
G Creating a "Records Policy" - Control of Quality Records Records and Data - Quality, Legal and Other Evidence 13
C Creating a Micro QMS - 4 geographical sites and 3 types of core activities ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2

Similar threads

Top Bottom