Quality Scan: CAMM Improves Quality
A new concept in quality control, computer-aided manufacturing measurement (CAMM) is the third and final stage of the computer-aided revolution that has been ongoing for nearly three decades. Like its predecessors, CAD and CAM, CAMM makes its users more productive and helps them to add value through access to the original design data in CAD. The difference is that this piece of the computer-aided tool set is for manufacturing engineers and mechanics who must design, build, and operate the lines that put products together.
By using CAMM software and hardware, manufacturing engineers can exploit the original data to build tooling, troubleshoot fit problems in prototyping and production operations, and analyze trends for long-term quality control.
Besides using CAMM as a process-design tool, engineers and assembly mechanics can also use it for troubleshooting. As mechanics encounter mismatches due to temperature variation, and as abuse takes its toll on fixtures, manufacturing personnel can deploy CAMM tools (“soft” gages such as articulated arms, and software) to troubleshoot fit problems as they occur. The tools also help them analyze process feedback and identify trends in order to plan corrective action.
Using electronic models in such a manner on the plant floor is a relatively new phenomenon. Although nearly all manufacturing enterprises use CAD models at the design stage, and roughly three-quarters of all single-part manufacturers use them in CAM for machining and forming deliverables, only 5% of assembly plants use them on the floor. The investment in CAD data is wasted at the point in the product development cycle where most production work occurs.
Assembly operations have historically resisted true CAD integration aimed at measurement and capitalizing on the up-front investment in an electronic model for two reasons. First, manufacturing engineers and mechanics lacked robust, easy-to-use computer hardware that gave them access to CAD models on the floor. The second barrier has been a lack of software for presenting CAD information in a convenient fashion to manufacturing people with minimal computer experience. As a consequence, manufacturing engineers and mechanics have learned to rely on hard gages and work instructions, and find ways to work around fit problems, rather than working from the original design data and comparing deliverables to them.
With CAMM, manufacturing engineers and mechanics can use graphical reporting and process control to publish measured results instantly on a plant-wide basis without interrupting production for costly quality inspections. Manufacturing can use viewers, CAMM tools that software vendors write so that users can look at and work with only the relevant portions of large, complex CAD files.
The easy data collection possible with CAMM tools, and its instantaneous analysis, breach the past barriers to CAMM. Shop-floor workers with no computer experience can measure complex 3-D hardware of unknown orientation in an environment that includes obstructions, noise, and temperature fluctuations.
As a computer-aided technology for verifying and troubleshooting the assembly and fabricating operations that put pieces of hardware together, CAMM is the logical next step for using computer-aided tools to bring products to market. Again, the electronic model created by the designers is at the core of the technology. Engineers can access data during line-design and layout. While on the production line, mechanics can measure a complex 3-D surface with a soft gage, compare the measurements to the original CAD data, and archive or report the results for SPC for any workstation or the entire plant.
CAMM’s power goes beyond troubleshooting. At the next level, quality control can compare regular, in-line measurements of assemblies and tools—or a statistical sampling of them—to the original CAD for statistical trend analyses and long-term process control.
Inexpensive CAMM hardware and software finally gives manufacturing engineers and mechanics&8212;at small companies as well as large ones—the tools they need to participate in the computer-aided revolution. By having direct access to the original design in CAD, and by having the tools at hand to use the data, they can compare product and tooling to the original design on the shop floor. Once production begins, the ability to compare immediate feedback to the original design gives manufacturing the ability to keep assembly costs from soaring out of control.
This article was first published in the April 2006 edition of Manufacturing Engineering magazine.