Data gathering in fast forward.

The ultimate goal of metrology is to give manufacturers the ability to "dominate their process" by effectively linking design intent with manufacturing capability. This process control capability is an important milestone on the road to reduced costs, improved throughput, and quality assurance.

Dimensional data are the common denominator of every metrology application, and how efficiently it is gathered and analyzed determines the value that metrology can add to manufacturing operations.

Today there are machines that measure not only position and location of features, but also automatically measure the 3D shape and form of workpieces, and use that information in conjunction with CAD systems to provide insights into the manufacturing operation. These machines are called scanning CMMs, and during the last decade, their prices have come down while their capabilities have increased significantly.

Scanning provides more data points for analysis in the same amount of time, or often in less time, than conventional single-point touch trigger probe techniques. The more data points, the more accurately the shape of the part can be defined. Bridgetype CMMs using conventional point-to-point probing technology can gather data points at speeds of up to 1.7 seconds per point. If the minimum number of data points required to define a diameter is between 6 and 16, it takes a CMM 10.2 to 27.2 seconds to generate reproducible results.

Using high speed scanning to measure the same diameter produces results calculated with 600 data points calculated in less than 10 seconds. The high speed data collection rate makes it possible to determine dimension, position, and form simultaneously with high repeatability and accuracy.

Only a few years ago, CMMs capable of this type of performance were financially out of the reach of all but the largest manufacturers. Today, precision measuring systems that use continuous analog scanning probe heads--so accurate that they can measure changes in the part's surface elevation as a proportion of the measuring tip's deflection over its full range--are reasonably priced.

Continuous analog scanning sends an uninterrupted stream of data back to the system's computer for analysis. To assure data integrity, new scanning CMMs feature improved construction. Stiffer drive mechanisms to reduce vibration, bridge designs that reduce mass, and precision machined guideways all contribute to improved functionality for scanning applications. Some new machines coming on the market now combine and optimize temperature and accuracy compensation systems, motion controllers, and advanced algorithms to specifically support high-speed, high-accuracy scanning applications. This advanced technology facilitates high speed scanning applications by automatically generating scan and probe paths and inserting moves to avoid obstacles.

The days of companies having several different software packages to gather and analyze dimensional data are coming to a close. Enterprise-wide software is the trend. This software will handle every measurement and inspection task, from simple dimensional checks to complex reverse engineering jobs, quickly and efficiently. This new software is designed to work with any measuring system or instrument on the shop floor or in the lab.

What distinguishes Brown & Sharpe's XACT Technology software is its native file-access capability allowing CAD models to be used "as is" without being translated when they are downloaded to the measuring system. This direct download capability assures that no dimensional detail is lost during the transfer.

Visual Basic programming language provides for a variety of "plug and play" programs to be developed for the software by third-party developers. Using OOP/COM programming, users can create their own features and tolerances to add to the part data base.

With inexpensive scanning CMMs and the capability to effectively harness the power of massive amounts of dimensional data through CAD/CAM systems, virtually every manufacturer can exercise a level of dimensional data analysis never before possible.