Post on 01-Feb-2016
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QUALITY CONTROL ANALYSIS
STATISTICAL QUALITY CONTROL WHAT IS SQC??
SQC is a mathematical study used to investigate a manufacturing process to determine its precision and accuracy.
It is used to check and improve the quality control of a manufactured part.
Ensure products or services are designed and produced to meet or exceed customer requirements and expectations.
USING THE STATISTICAL PROCESSCONTROL ANALYZER
SPC EQUIPMENT
DIGITAL CALIPERPOWER SUPPLY
SPC PROCESSOR
CABLE
DIGITAL CALIPER PARTS
INSIDE MEASURING JAWS
OUTSIDE MEASURING JAWS
LOCK SCREW
MEASURING THUMB SCREW
DIGITAL WINDOW
DEPTH MEASURING
NEVER GONNA LET YOU DOWN
CABLE CONNECTED TO SPC ANALYZER
Cable tab lines up with slot in socket
NEVER GONNA RUN AROUND AND DESERT YOU
SPC ANALYZER BUTTONSClear limits
Clear entry
Feed paper tape
Enter data
Enter upper & lower tolerance limits
Statistical analysis of entered data
NEVER GONNA MAKE YOU CRY
ABBREVIATIONS FOR STATISTICAL DATA TERMS
USL - Upper statistical limit of tolerance LSL - Lower statistical limit of tolerance N - Number of samples taken or data points Max - Maximum value of largest sample Taken Min - Minimum value of smallest sample Taken R - Range of values taken
More Abbreviations X bar - Mean of all samples taken O n - STANDARD DEVIATION OF ENTIRE population of samples O n-1 - Standard deviation of a sample of entire population P - Percentage of defective samples (Parts out of specs) Cp - PROCESS CAPABILITY SHOWS precision of process Cpk - Process capability shows both accuracy & precision
SPC ANALYSIS STEPS USING TOLERANCES
Press (CL) key to clear limits Press (TOL LIM) key to set upper and
lower statistical limits of tolerance used Zero digital caliper Manually set caliper to upper statistical limit Press (data) key to set USL (will show on tape as (lmt) Manually set caliper to lower statistical limit Press (data) key to set LSL (will show on tape as (lmt)
The rest of the Steps
Press (TOL LIM) key to show tolerance limits on paper tape as (usl) and (lsl)
Now use the digital caliper to enter measurements of the sample and press the (data) key each time
Repeat above step at least 10 times to get 10 samples Press (stat) key to perform a statistical analysis of all the
samples entered Press (feed) key after printing stops to advance paper
SETTING UP SPC
Press (ON) key
Tape will show
*Print On*
Press clear limit (CL) then total limit (TOL) tape shows
*Limit Clear*
SETTING UP SPC
•Turn (on) caliper
•Slide jaws together
•Press zero key
SETTING UPPER TOLERANCE LIMIT
Manually set USL of .115 thousands on caliper then press DATA key. This will show on tape as (lmt)
SETTING LOWER TOLERANCE LIMIT
Manually set LSL of .105 thousands on caliper press data key. This will show on tape as (lmt)
CHECKING TOTAL LIMIT
*NEW LIMIT DATA* LSL 0.1050 USL 0.1150 TOTAL LIMIT .010
Now press total limit key the tape should read as shown below with a tolerance of .010 or USL-LSL
MEASURED SAMPLES OF A PART
Take 10 measurements of the part by pressing the data key after each measurement. This can be done in two different ways as shown.
Sample being measured in 10 spots
ANALYSIS OF DATA TAKEN
After all measurements are taken with the caliper and entered into the (SPC) press the (STAT) key for a full analysis of data
Data analysis is printed on paper tape
THE TAPE
LimitsTolerance
Readings
Statistical data
Histogram