User's Manual Part 3

♦363♦ MEGAM.O.L.E.® Help System Guide
B: Statistical Process Control (SPC) Background Information
This appendix deals with the subset of SPC that is incorporated into MAP Software. It
does not address general SPC principals. A working knowledge of general statistical
principals and SPC terms is assumed and is not addressed here. There are many good
basic SPC books where this information may be obtained.
Reflow and Wave Solder operators, engineers and production managers are expected
to understand their soldering process so as to deliver quality products cost effectively.
This is a continuous process.
First, the machine must be checked for consistency. A standard or typical set up should
be routinely checked prior to any process set point determinations, or actual production
run machine checks. Only after the machine has been determined to be operating
correctly and not experiencing abnormal variation, should data from the machine be
utilized. SPC is all about identifying common or normal variation from abnormal
variation.
Second, the correct process set points must be determined for a particular product.
Utilizing the M.O.L.E. profiler, the correct set points for a particular product may be
determined. These set points, if selected correctly and followed, should deliver the
maximum throughput of quality product.
Third, the machine must consistently deliver the correctly determined set points. SPC
will help identify common or normal variation from abnormal variation. Checking the
machine using your M.O.L.E. profiler and the MAP Software with its SPC capability will
help ensure that the machine is consistently performing to its set points and your
expectations.
Fourth, repeat the above three steps. Continuous improvement is a never-ending cycle.
Check the long-term variation of the machine by graphing typical set point samples.
Using the M.O.L.E. profiler, recheck/adjust part number specific set points to maximize
your quality throughput. Check the machine during a part number run to control the
machine variation from that part number’s actual ideal set points.
While SPC had its start in high volume repetitive operations, SPC is applicable to many
other types of operations as well. However, SPC can be difficult to apply to short runs.
Short runs may be runs that take a long time to process, runs in which multiple samples
are difficult to collect, and runs where samples are difficult to place into subgroups or
runs where small quantities are run.
The MAP Software charts will be more meaningful to the user if SPC charts are
generated based on data sets that have the same set points each time.