Process Capability - Interview Case Study

J1980b

Starting to get Involved
#1
Dear All,
Could someone please help.

I recently went for an interview, for the position of Quality Engineer at a Medical Device Manufacturer. The Interview went well until I was presented with a case study. The feedback from the interview was that my answers to this case study were weak, which I can only agree with.

My question to you is....How would you have answered the following. I had 30 mins to prepare my answer for a 5-8 minute presentation and a Question and Answer session.
Case study is below

A customer has a product supplied by our company, the product is a small hub that is moulded in house, and a needle (supplied) that is inserted by automation into the hub and is an interference fit.

The customer wants to increase the outside diameter of the needle, and also make the distance from the base of the hub to the tip of the needle a critical dimension

The Mould tool for the hub is 8 cavity.
You can make any assumptions you wish, but please list them.

Questions

What are the key issues and considerations with this change? And how would you go about them?
What value process capability would you put to this?
How would you validate the changes?
 
Elsmar Forum Sponsor

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#2
First thing is there is no way to determine if the needle to hub can even have capability established with the information supplied. How the needle is located is critical. If there is a feature on the needle or in the hub that locates the final needle position as a stop, the resulting distribution will be non-normal...unless the locating is so bad that it rarely hits the stop! (Don't feel bad, a lot of people would not have recognized this. Non-normal things jump out at me, though.) If the location is only by automation (e.g. robot holds it in position - free floating in space), then it would likely be normal - and then you can attempt to hold a 1.33 Cpk if you wish. Recognizing these statistical issues comes from an area of statistics I like to call "empirical statistics." It is when you verify that the physical phenomena actually matches the statistical model, rather than assuming the data collected from the phenomena and statistically analyzed defines the physical phenomena. Empirical statistics is a little different than inferential of descriptive statistics.

It would also be good to discuss with the customer why that dimension is critical.

The net hole diameter should be held to a capability - by cavity - to ensure fit, though, as a process control. Might even need a hole size to pull strength relationship determined. Don't want the needles falling out!
 
Last edited:
Thread starter Similar threads Forum Replies Date
M Measuring Capability of Process with Multiple Specifications Capability, Accuracy and Stability - Processes, Machines, etc. 6
L How to evaluate the process capability of a data set that is non-normal (cannot be transformed and does not fit any known distribution)? Capability, Accuracy and Stability - Processes, Machines, etc. 12
T Final process capability results - What I am supposed to present? Cp and CpK? APQP and PPAP 11
Q How to perform Process Capability for true position Statistical Analysis Tools, Techniques and SPC 10
L IATF 16949 Cl. 8.3.3.2 Manufacturing process design input - Process capability IATF 16949 - Automotive Quality Systems Standard 1
Y Process Capability for Non-Normal Data - Philosophical Questions Capability, Accuracy and Stability - Processes, Machines, etc. 6
M Process Capability in a High Precision Environment Capability, Accuracy and Stability - Processes, Machines, etc. 7
V Product Development - When to start calculating Process Capability Capability, Accuracy and Stability - Processes, Machines, etc. 3
S Proving Process Capability of a Packing Machine Capability, Accuracy and Stability - Processes, Machines, etc. 6
ncwalker Process Capability Study - Aggregate vs. Individual Processes Statistical Analysis Tools, Techniques and SPC 24
V Process Capability for parameters with non-normal distribution. Capability, Accuracy and Stability - Processes, Machines, etc. 16
J Process Capability - How much percentage of tolerance? VDA Standards - Germany's Automotive Standards 3
S Regression Control Chart - Process Capability Statistical Analysis Tools, Techniques and SPC 18
M How to determine Process Capability using Minitab 17 Capability, Accuracy and Stability - Processes, Machines, etc. 6
B Process Capability - Changing Limits to Improve Cpk or find Root Causes? Capability, Accuracy and Stability - Processes, Machines, etc. 6
B Long Term Process Capability from miltiple Machines and Fixtures Capability, Accuracy and Stability - Processes, Machines, etc. 3
E What Data do we need for Welding and Repair Process Capability? Six Sigma 1
K Calculating Capability of a process when data is skewed in the upper range Capability, Accuracy and Stability - Processes, Machines, etc. 4
S What is the difference between Process Capability and Machine Capabilty Capability, Accuracy and Stability - Processes, Machines, etc. 13
V How to Assess Process Capability at the Development or Optimization Phase Capability, Accuracy and Stability - Processes, Machines, etc. 6
C Minitab Binomial Process Capability Analysis Chart Explanation Using Minitab Software 1
kedarg6500 Sample Size for Short Term & Long Term Process Capability Capability, Accuracy and Stability - Processes, Machines, etc. 2
J Is it the same process capability or performance in 8.2.3.1 and SPC? IATF 16949 - Automotive Quality Systems Standard 1
E Binomial Process Capability Sample Size - Variables Data Capability, Accuracy and Stability - Processes, Machines, etc. 4
M On Subgroups in Control Charts and Process Capability Statistical Analysis Tools, Techniques and SPC 3
N SPC and Process Capability Using a Romer Arm Statistical Analysis Tools, Techniques and SPC 6
J Interpreting Process Capability results and ratios Capability, Accuracy and Stability - Processes, Machines, etc. 1
J Go or No-Go Process Capability Quality Tools, Improvement and Analysis 8
S Process Capability with Negative Exponential Distribution Capability, Accuracy and Stability - Processes, Machines, etc. 4
C Process Capability - Attribute Data Analysis (Template) Document Control Systems, Procedures, Forms and Templates 0
C Process Capability - Variables Data Analysis (Template) Document Control Systems, Procedures, Forms and Templates 0
A Cnpk (Non-Parametric Capability Analysis) to assess whether the Process is Stable Capability, Accuracy and Stability - Processes, Machines, etc. 7
V Process Capability to reconfirm the Inspection Frequency Manufacturing and Related Processes 3
B Sample Size based on Process Capability Indices (Pp/Ppk)? Capability, Accuracy and Stability - Processes, Machines, etc. 20
P Calculating Process Capability from Data of attached spreadsheet Statistical Analysis Tools, Techniques and SPC 4
D How to measure Process Capability for Homogeneous Batch Manufacturing Capability, Accuracy and Stability - Processes, Machines, etc. 4
A Burrs affecting measurements and Process Capability Capability, Accuracy and Stability - Processes, Machines, etc. 7
G Assessing Process Capability on Variation (Hardware Adjustment Mean Shift) Capability, Accuracy and Stability - Processes, Machines, etc. 4
D Calculating Upper-CL/Lower-CL and Process Capability Statistical Analysis Tools, Techniques and SPC 8
V Defining Subgroups and Importance of Subgroups in SPC and Process Capability Statistical Analysis Tools, Techniques and SPC 6
T Process Capability - Understanding what Process Capability Indices mean Capability, Accuracy and Stability - Processes, Machines, etc. 17
Q TS 16949 Process Capability Requirements - Cpk ≥ 1.67 on All Key Parameters? IATF 16949 - Automotive Quality Systems Standard 8
S Process Capability questions - Calculating Cpu using Minitab Six Sigma 6
C Sample Size Calculation Formula for Process Capability Statistical Analysis Tools, Techniques and SPC 25
D Capability Analysis for Packing Process in Food Manufacturing Capability, Accuracy and Stability - Processes, Machines, etc. 11
Q When to use Cpk or Ppk for a Process Capability Study? Capability, Accuracy and Stability - Processes, Machines, etc. 14
S Process Capability on Basic Dimensions Capability, Accuracy and Stability - Processes, Machines, etc. 10
D Process Capability Study which involves MMC (Maximum Material Condition) Capability, Accuracy and Stability - Processes, Machines, etc. 8
E Process Capability Analytical Tools Statistical Analysis Tools, Techniques and SPC 1
B Overall Process Capability - Simple question if you know how to answer it! Statistical Analysis Tools, Techniques and SPC 3

Similar threads

Top Bottom