Dimensional measurement and the analysis of the data from it has always been the foundation of the quality assurance function. This is true for manufacturing operations of all sizes. People are measuring parts throughout the manufacturing enterprise, evaluating the data in various ways and making substantive decisions based on the results. So what's wrong with this picture?
Simply this: an enormous duplication of effort resulting in wasted time and needless expense. Until recently, no one had taken a systematic look at metrology processes with an eye toward eliminating this waste, and even if they had, the software and hardware tools did not exist. Now they do. Here is a sampling of error-prone inefficiencies waiting to be eradicated:
• Transferring design intent to measurement systems on paper when it could be embedded in the computer-aided design (CAD) model.
• Writing and debugging inspection programs manually when software can do it better and faster.
• Developing separate measurement programs for different models and types of measurement devices when a single program can do the job.
• Remeasuring parts that have been measured and evaluated elsewhere.
• Moving parts off a computer numerical control (CNC) machine for measurement when on-machine probing can do the job.
• Inspecting a part with the wrong equipment because doing it correctly would require writing another program.
• Training personnel to use different measurement software packages on different types of machines when it is possible to use the same basic software regardless of the device.
Wringing inefficiencies out of metrology operations by carefully analyzing and improving its processes is the idea behind the emerging discipline of enterprise metrology. By tightening the links among design, manufacturing and evaluation, enterprise metrology eliminates wasted effort; streamlines measurement data collection, storage and evaluation; and ensures that information is published wherever and whenever needed.
Six simple rules
Six simple rules for implementing enterprise metrology solutions can guide manufacturers and those who design systems.
1. Capture design and intent as soon as possible and do it electronically. Manufacturers should extend the common practice of using CAD models as a template for programming coordinate measuring machines (CMMs) to other measurement devices, such as vision systems. Unfortunately, the design intent, geometric dimensioning and tolerancing (GD&T) data is not typically part of the CAD model. It arrives separately, usually in the form of a marked-up blue print. This leaves the door open for data entry and drawing interpretation errors. Close the door quickly on this problem by going one step further. Take advantage of the GD&T capabilities of the latest CAD systems to build intent into models as they are created. Turn CAD models into inspection plans to reduce errors and improve programming efficiency downstream.
2. Make sure the software for operating and controlling the measurement systems has a common look, feel and functionality. Using common software dramatically decreases the amount of training required for using a new measurement system. Users become proficient faster because they do not have to remember a multiplicity of procedures for performing similar or identical tasks. Common platform metrology software is currently available for a wide range of equipment including CMMs, vision systems and probe-capable CNC machines.
3.Automate inspection system programming and share the programs among various measurement devices. Most metrology software packages use CAD models as the starting point for measurement system programming. With various systems, automation opportunities range from simple point and click tools that allow users to select features quickly and generate measurement points to special modules that read inspection plans, or GD&T information, embedded in the CAD model. The latter automatically generates inspection sequences that require little subsequent editing. In addition, common-platform measurement software allows for the sharing of programs among multiple brands and types of measurement equipment.
4. Collect measurement data to a common database that is open to best-in-class analytical tools.
All measurement data, no matter the source, should flow into a consolidated database readily accessible to best-in-class analytical tools. For many users this might just mean a good statistical process control (SPC) package. Others may wish to look further and evaluate data with specialized modules or report on special types of parts like gears and blades. Analyze all data often and in as many ways as desired. With a common database there are no barriers.
5. Automatically generate reports that leave no doubt about what is important.
A good reporting package can distill volumes of raw dimensional data into a few pieces of concise information that make it easy to understand manufacturing processes and to recognize and correct anomalies when they appear. It must include tools for producing standard reports on a schedule and for generating special reports that look deeply at any aspect of a manufacturing operation. Some reports may be as simple as a few numbers indicating tooling offset adjustments. Others may include complex graphics, diagrams and charts. Of great use are reporting packages that can include CAD models in their output. They can, at a glance, graphically highlight actual and potential problems before they result in costly scrap and rework. Whatever the case, reports must make their points quickly and accurately.
6. Use electronic technology to get reports where they need to go quickly.
Ubiquitous LANs, Internet access and intranets mean that lack of infrastructure is no longer an obstacle to expediting reports to those who need them, whether they are in the next office or on the next continent. New Web-based publishing tools developed in response to the emerging demands of enterprise metrology will soon make it easy to answer the who, what, when and where questions that bedevil information managers everywhere.
Vision metrology
Is it possible to integrate all types of measurement within the framework of the enterprise metrology concept? Not yet. However, much integration is possible even between such disparate technologies as tactile and vision measurement.
Recently, a three-year research and development program sponsored by a developer of metrology software extended the capabilities of its PC-DMIS metrology software platform to meet the unique requirements of vision measurement. The efforts of nearly a dozen software engineers, focused initially on the complex task of controlling the variables of vision measurement, such as lighting, magnification and image capture. Then they integrated their solutions into the core software. The result was a complete set of vision metrology tools coupled with powerful operating and CAD-based programming capabilities CMM technicians have routinely enjoyed for years. This new approach to vision measurement incorporates many of enterprise metrology rules:
• Design and intent. For the first time, vision systems can use CAD models for automated and semi-automated programming.
• Control and operation. Common software for vision systems and CMMs dramatically reduces the training needed for operation and programming.
• Programming. Vision metrologists, by default, have access to all of the automated, free-form programming, editing and proofing tools built in the software platform. Plus, users can share programs among different types of measuring machines or adapt them to multisensor measurement systems.
• Open database and analytical tools. Vision measurement results automatically go to a consolidated, open-
architecture database. This makes it readily accessible to a wide range of applications including SPC software, analytical programs and reporting packages. Better yet, all of the other measurement software packages running on the PC-DMIS platform send data to the same place, making it possible to track parts through the entire manufacturing process, while making it easy to manage data and eliminate the duplication of data and information.
• Reporting packages. The vision package has full access to the reporting capabilities of the underlying software. These include a powerful, graphical reporting engine that makes it simple for programmers to include CAD models in their output. So, vision measurement software, which is graphically oriented, can now generate a full range of graphical reports that simplify and expedite decision making.
• Publishing. Bringing vision measurement into the framework of enterprise metrology simplifies the job of targeting and delivering analytic reports to the appropriate audiences in a format most useful to them.
Vision measurement used to be a specialized branch of metrology and vision metrologists worked in an esoteric world, using arcane programming tools and techniques. Enterprise metrology brings vision measurement more into the mainstream by making vision equipment, programming tools and the data generated far more accessible to everyone.
Enterprise metrology is an exciting new way of looking at metrology. It stresses the electronic integration of design intent information, measurement software, metrology databases, analytical tools, reporting packages and publishing capabilities. Because the infrastructure required to share data and information is already present, enterprise metrology does not involve any unusual new costs, but it does allow for unusual new savings by giving manufacturers a panoramic view of their operations.
Manufacturers will use this knowledge to eliminate departmental and systemic barriers to making goods better, faster and with less duplication of effort. Enterprise metrology is the management system that finally orchestrates the various aspects of lean manufacturing to achieve the best overall return on investment. Q
Steve Logee is director of business development for Wilcox Associates (North Kingstown, RI). For more information, e-mail [email protected] or visit www.wilcoxassoc.com.
Quality Tech tips
• Wringing inefficiencies out of metrology operations by carefully analyzing and improving its processes is the idea behind the emerging discipline of enterprise metrology.
• Enterprise metrology eliminates wasted effort; streamlines measurement data collection, storage and evaluation; and ensures that information is published wherever and whenever needed.
• New Web-based publishing tools developed in response to the emerging demands of enterprise metrology will soon make it easy to answer the who, what, when and where questions that bedevil information managers everywhere.
