Statistical Process Control System
Helix Systems, Inc. produced a comprehensive Statistical Process Control (SPC) program for a major household products manufacturer which is currently being used by factories in the U.S.A. and overseas. The program runs under IBM OS/2, Windows 3.1, Windows NT and Windows 95.The program contains many custom features, several unique to this application:
- It provides for the entry and display of two types of data - numerical
sample data and attribute data (counts of defects of various types).
- Numerical data entry can be performed in three ways: (1) by manual entry
via a keyboard; (2) by semi-automatic entry via an instrument such as a scale; and
(3) automatically via a SCADA package. Two SCADA packages are currently interfaced -
the Infact system and Intellution's FIX/DMACS® system.
- Alarming is done on all data entry. For manual and semi-automatic entry,
alarms are displayed at the time of entry. Alarms generated by a SCADA package
can be returned to that package for display to the operator if desired.
- An extensive, user-friendly interface is provided for configuring
individual tests and selecting which test to make active for data entry
and display. This is critical to operator acceptance, since
each test description contains over 30 items, and a typical installation
can require 200 to 400 different tests.
- Data is kept in a proprietary database optimized for speed of access. The
database is usually networked so any SPC program at a facility can display test
data gathered anywhere within the plant.
- Individual test data can be displayed in a variety of formats:
- Standard XBAR/R chart format. The time base can be selected from one hour
to one month. A cursor allows display of detailed data for any selected
data point, and time period for expanded display. Alarms (if any)
are shown for each point as well as various specialized comments - such as shift
change or machine adjustment.
- Histogram format. Histograms of XBAR/R data can be displayed for any
time period desired.
- Attribute data can be displayed using pareto charts. Attributes are divided into three categories - minor, major or critical. The amount of defects in each category for each type of defect are shown in color on the pareto chart.
- Standard XBAR/R chart format. The time base can be selected from one hour
to one month. A cursor allows display of detailed data for any selected
data point, and time period for expanded display. Alarms (if any)
are shown for each point as well as various specialized comments - such as shift
change or machine adjustment.
- There is also extensive summary data display capability:
- Data from the same type of test and location with different
products at different times (such as different products processed on the
same packaging line on different days) can be displayed on an XBAR/R type
display, with each test displayed in different colors. This can
be very useful in determining if different products cause different
problems with the same equipment.
- Data from up to 8 different tests can be displayed in XBAR/R format
over the same time period. The data is normalized and displayed as a
different color for each test.
- Any number of different attribute tests can be combined into a single pareto chart.
- Data from the same type of test and location with different
products at different times (such as different products processed on the
same packaging line on different days) can be displayed on an XBAR/R type
display, with each test displayed in different colors. This can
be very useful in determining if different products cause different
problems with the same equipment.
- Archiving of data in the database and retrieval of archived data is
provided.
- The program has extensive on-line help keyed to individual menu items and dialog box fields. An application help facility also allows user generated help keyed to specific tests.