# Calculating PPM - Multiple product lines and multiple type of parts

5

#### 56flh

When your company produces multiple product lines that run from intricate custom machined assemblies to screw machined parts off of a multi-spindled automatic, how do you calculate PPM?

I have received questionaires from customers with a space to enter one number and then other spaces for improvement anticipated for the next few years. Some of these customers we sell the above mentioned diverse amount of products. This one PPM number I have to enter would be totally different based on those large, intricate items we may sell 1000 pieces of vs screw machined products that we sell hundreds of thousands of pieces.

At this point I am baffled by the validity of six sigma calculations.

#### bobdoering

Trusted Information Resource
Most likely you have customers rubber stamping rudimentary quality notions trying to meet some either self- or customer-imposed criteria.
It is equivalent to asking McDonald's "How much food do you sell?" What? Does that include drinks? In units? In lbs? It's "over-the-bow" statistics (using the term 'statistics' loosely), right up there with Cpk.

If they do not specify the ppm calculation, assume ppm rejected of shipped product. Then, identify your goals for improving upon that (if not already zero).

At this point I am baffled by the validity of six sigma calculations.
You are not alone...

#### Statistical Steven

##### Statistician
Super Moderator
When your company produces multiple product lines that run from intricate custom machined assemblies to screw machined parts off of a multi-spindled automatic, how do you calculate PPM?

I have received questionaires from customers with a space to enter one number and then other spaces for improvement anticipated for the next few years. Some of these customers we sell the above mentioned diverse amount of products. This one PPM number I have to enter would be totally different based on those large, intricate items we may sell 1000 pieces of vs screw machined products that we sell hundreds of thousands of pieces.

At this point I am baffled by the validity of six sigma calculations.
This is using Six Sigma, but just math.

Part Defects Volume % Defective PPM
1 3 5000 0.06% 600
2 7 5000 0.14% 1400
3 40 10000 0.40% 4000
4 2000 160000 1.25% 12500

Combined 2050 180000 1.14% 11389
Average 4625

So combining the data leads to an overall PPM rate of 11389. If you want to use the average PPM across all products it would be 4625. I believe the combined approach is best.

C Calculating the Lead (Pb) ppm from the Plating Layer RoHS, REACH, ELV, IMDS and Restricted Substances 6
Calculating PPM for bulk-type product Statistical Analysis Tools, Techniques and SPC 1
B The correct approach to calculating Internal Scrap ppm Statistical Analysis Tools, Techniques and SPC 3
J Calculating PPM for a Supplier on a Specific Defect - Excel .xls Spreadsheet Wanted Statistical Analysis Tools, Techniques and SPC 7
C Calculating PPM for Customers - Is this fudging PPM #'s? Statistical Analysis Tools, Techniques and SPC 22
A Calculating Customer Returns ppm QS-9000 - American Automotive Manufacturers Standard 11
Calculating Defect Rate (PPM) from a Cpk value Capability, Accuracy and Stability - Processes, Machines, etc. 8
D Calculating PPM - Standard practice to calculate PPM from parts returned? Statistical Analysis Tools, Techniques and SPC 25
Calculating Risk Estimation ISO 14971 - Medical Device Risk Management 28
Calculating Ppk for Design Verification - Variable Sampling Design and Development of Products and Processes 15
Help needed in choosing the method of calculating the minimum sample size Internal Auditing 12
True position, calculating theoretical distances General Measurement Device and Calibration Topics 0
Lean: Conducting Capacity Study, calculating Cycle times on laser cutting machines Lean in Manufacturing and Service Industries 2
Calculating Carbon Footprint in the Organization Miscellaneous Environmental Standards and EMS Related Discussions 2
Calculating your KPIs ISO 13485:2016 - Medical Device Quality Management Systems 7
Calculating Heat Dissipation Manufacturing and Related Processes 1
Calculating Defect Rates ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 4
Formula for Calculating NoGo Major Diameter for UN gages Inspection, Prints (Drawings), Testing, Sampling and Related Topics 4
Calculating a weight for a machine for the CE label CE Marking (Conformité Européene) / CB Scheme 0
Remote Support - Calculating Number of Employees IATF 16949 - Automotive Quality Systems Standard 2
Calculating Tolerance of a Panel Meter with a 2 degrees of an Arc General Measurement Device and Calibration Topics 0
Calculating LCL, UCL, Cp, and Cpk in an Excel Spreadsheet Statistical Analysis Tools, Techniques and SPC 3
Product Development - When to start calculating Process Capability Capability, Accuracy and Stability - Processes, Machines, etc. 3
Calculating Reliability for Subsystems in Series Reliability Analysis - Predictions, Testing and Standards 15
Calculating (3rd Party) Audit Days for Company with Seasonal Employees General Auditing Discussions 3
T Formulas for Calculating Coefficients for RTD / PRTD Calibration According to ITS-90 General Measurement Device and Calibration Topics 5
J Calculating part variation from historic data for GRR study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
P Purpose of calculating Ta, Tb & R Square in Linearity Study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
P Purpose of calculating Uncertainty value in calibration study Measurement Uncertainty (MU) 5
M Calculating MTBF for plug-in PCI cards Reliability Analysis - Predictions, Testing and Standards 2
J Calculating impact force, expressed in lbs, of a 5 lb weight dropped 48 inches Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
M Calculating Cpk when sample size equals to 1 Capability, Accuracy and Stability - Processes, Machines, etc. 12
D Calculating Cpk on Non-Normal Data Distribution Capability, Accuracy and Stability - Processes, Machines, etc. 10
K Calculating Capability of a process when data is skewed in the upper range Capability, Accuracy and Stability - Processes, Machines, etc. 4
A Calculating Accuracy for a Multimeter General Measurement Device and Calibration Topics 1
M Calculating Coefficients for an RTD (Resistance Temperature Detector) Probe General Measurement Device and Calibration Topics 3
T Calculating Plating/Coating Weight for IMDS RoHS, REACH, ELV, IMDS and Restricted Substances 3
D Calculating Lower and Upper 3 Sigma Control Limits Statistical Analysis Tools, Techniques and SPC 2
M Calculating Adequate Receiving Inspection Sample Size Statistical Analysis Tools, Techniques and SPC 2
M Calculating Capability of Delivery Performance Capability, Accuracy and Stability - Processes, Machines, etc. 5
K Advice on Calculating Control Chart Control Limits Statistical Analysis Tools, Techniques and SPC 13
B Calculating Combined DPMO and Sigma Level for Two or More Different Work Areas Six Sigma 3
G Calculating the Fraction Defective Confidence Interval for a Lot Statistical Analysis Tools, Techniques and SPC 2
A Calculating Combined Measurement Uncertainty - VDA 5 Measurement Uncertainty (MU) 1
B Calculating Precision to Tolerance Ratio Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 9
D DPPM - Calculating the Defect Rate of a Software Test Statistical Analysis Tools, Techniques and SPC 9
L FMEA - Calculating RPN = S*O*D FMEA and Control Plans 3
I Shewhart Constants vs Central Limit Theorem in calculating Control Limits Statistical Analysis Tools, Techniques and SPC 18
B Please share a template for calculating Cp Cpk Document Control Systems, Procedures, Forms and Templates 3
S Is a Stable Process (within Control Limits) required for Calculating Pp, Ppk? Capability, Accuracy and Stability - Processes, Machines, etc. 6