# State of the Part, Today's SPC Environment

### To the uninitiated, Statistical Process Control enthusiasts can seem like wild-haired mad scientists, ever in search of new targets for their methods as they carry on amid a storm of charts and graphs.

Fittingly, it was a doctor of physics working for a company known for its lab work -- Bell Telephone Laboratories -- who is credited with first using SPC techniques. But SPC concepts aren't on the fringe. In fact, they've been in use ever since Dr. Shewhart first developed his control charts at Bell Labs nearly 100 years ago.

SPC now is a definitive feature of the modern factory and is used far and wide across the spectrum of manufacturing settings.

Topics:

# CATIA Symmetry and 3DCS Mirror

## Useful tips on quickly creating symmetrical models and duplicating data.

This Tips and Tactics will display how both Mirror and Symmetry work together to reduce modeling time and create symmetrical models.

The Symmetry function in CATIA V5 is used to create a symmetrical mate to a part or assembly. This allows users to quickly craft only half of an assembly, and then mirror the other half to create a perfectly symmetrical product.

Topics:

# Where Is DCS Getting These Numbers?

How do you know your results are accurate? Here are some methods of calculating your Confidence Interval

Dimensional Control Systems 3DCS® is a variation analysis tool that uses Monte Carlo simulation to predict the results of a set of measurements [Dimensional Engineering News, June 2009]. After a variation model is built in 3DCS®, a Monte Carlo simulation can be performed to provide the following statistics:

Descriptive statistics - calculations made directly from the sample data such as mean, minimum, maximum, standard deviation, percentage out-of-spec, confidence intervals, etc.

Inferential statistics – estimations based on a curve-fitting algorithm such as estimated low, estimated high, estimated percentage out-of-spec, etc.

Topics: