Advances in Model Based Measurement Reduces CMM Programming Time

With more man-hours being spent on programming work, differences in worker-created measurement programs, and inefficient programs being created due to proficiency issues, the industry has moved from 2D drawings to 3D annotated models. A number of factors, including the increased emphasis on quality control, the growing diversity of parts and components being measured, the development of more complex global supply chains and reduced product life-cycles, have led to a considerable demand for automatic measurement programming in recent years.

The latest automatic measurement program generation software uses 3D CAD and product manufacturing information (PMI) to enable one-click automated generation of measurement programs. A complex program that previously would have taken five hours to complete manually can now be completed in 15 minutes.

Today, aerospace and defense manufacturers use Coordinate Measuring Machines (CMM) to gather data and compare data to computer-aided design (CAD) models. Global manufacturing leaders such as Boeing, Lockheed, Raytheon, Ford and Deere have joined ranks with branches of the U.S. military to encourage their partners, vendors and suppliers to use automatic measurement program generation software as part of their digital product definition strategy. It is estimated that at least 35% of the original equipment manufacturers in the Department of Defense supply chain are using model-based definitions (MBDs).

A MBD is a 3D annotated model and its associated data elements that fully define the product definition in a manner that can be used effectively by all downstream customers in place of a traditional drawing. While manufacturers have applied MBD to product definition for some time, they have only recently applied it as a quality assurance process. MBD is a much more efficient method of getting CMM results for comparison to CAD models.

The uptick in MBD is probably currently highest in the commercial aerospace and defense industries, with the medical device market following suit.

Automatic measurement program generation software bypasses the old drawing-based method to directly generate and execute a model-based workflow. The CMM is configurable virtually. A MBD is imported, a set of rules applied and matched to the configured CMM, and a part program is automatically generated. A second optimization is performed to reduce the number of probe changes and to minimize path length.

CMM programmers develop rules of thumb and best practices over time. The automatic measurement method captures these rules and practices as logical if-then statements. The configured CMM, the applied rules set, individual settings and the part itself are all saved as a single related structure. A simulated execution can be run for visual confirmation. If any additional changes, such as changing the sampling pattern from flexible grid lines or changing the number of points per line are required, the program can make them instantly and then regenerate a report.

They can be saved, recalled and reused. They can also be imported and exported, so they are transportable. Individual knowledge can be generalized and become something that can be applied and re-applied in a consistent manner within the enterprise and throughout the supply chain.

The development of software that generates parts programs for inspection is changing the relationship between people and precision measurement with one click. These sophisticated software programs reduce programming time by at least 95%, compared with programming using general-purpose software, for a significant potential increase in the efficiency of measurement processes.

Benefits of MBD

MBD allows for embedded geometric dimensioning and tolerancing. The 3D CAD model incorporates all pertinent product information and high-level inspection planning data. MBD provides manufacturers with several key benefits, including:

  • Streamlined processes. The 3D-to-2D-to-3D workflow, where both the MBD and the drawings are both masters, is eliminated. The new workflow is 3D CAD- to-3D CNC CMM. Programming that used to take hours to complete can now be accomplished in minutes.
  • Reduced manufacturing costs.
  • Companies can realize a 95% savings compared to drawing-based programming methods. No physical CMM needed.
  • Component manufacturers receive a single CAD file and complete all the necessary steps to build and inspect a part.
  • All pertinent details and notes are transferred into the inspection software, reducing the risk of misinterpretation. Design changes are incorporated automatically, even on the most complex parts.
  • Discrepancies between drawing and the CAD model are eliminated. Increased efficiencies in the design-to-build and measure process.
  • Enhanced traceability. There is a direct read of the CAD model for metadata, features and characteristics with no misinterpretation.
  • Optimization. Plan parameters are easy to change. CMM configurations can be changed at any point.
  • Workflow automation. Some projects today are already fully automatic, with machines talking to machines, and humans auditing to make sure the machines perform properly.
  • Improved productivity. A CMM programmer is much more productive due to the automation of low-level programming tasks.

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