B5.54 standard up to CAT work.
Caterpillar's R&D supports improvements by investigating new process technologies, developing process modeling and simulation techniques, working on thermal compensation, and monitoring machine accuracy and reliability. The latter point - monitoring and quantifying machine accuracy and reliability - is where ANSI B5.54 comes in. It addresses the 50% of workpiece errors that are attributable to the machine. ANSI B5.54 consists of a suite of tests focusing on four major areas: 1) environmental tests to determine how the machine responds to its environment (thermal, vibration); 2) machine performance tests to assess the machine's alignment accuracy before a part is cut; 3) cutting performance tests to assess the robustness of the machine (i.e. its stiffness and power availability); and 4) testing to determine if parts can be cut within tolerance and with low variability.
Mr Feuchter believes that the B5.54 standard has application across the entire life of the machine tool. It can be used to "footprint" the machine early on, provide information about its performance during its production life, and even help quantify it and possibly add value once the machine is to be disposed of through resale. Caterpillar is using the technique to evaluate machines for acquisition by comparing machine tool capability among different builders; to develop specifications and acceptance criteria; to quantify production performance periodically, and to solve problems and determine maintenance needs. In addition, suppliers of purchased components are being asked to monitor their machines as well. Caterpillar's first use of B5.54 was for buying machining centers. In the past, acceptance was based on machining large quantities of parts the machine was purchased to make, today the company is asking its purchasing units to accept machines based on their capability to perform across an entire work zone.
The basic quality tools used to measure performance under ANSI B5.54 are the telescoping ballbar, spindle dynamic analyzer, and the 5D laser. The spindle dynamic analyzer evaluates the spindle's bearing condition, including run out and thermal growth errors - errors that are important as they contribute to form and surface texture problems on components. Approximate cost: $20K
The telescoping ballbar has gained the most acceptance because it can quickly check a machine's performance without removing the piece part from the fixture, can be easily used by the operators, and software directs repairs from a prioritized list of machine problems. The ballbar has significant advantages over the artifacts such as mechanical squares, tests a much greater range of characteristics, is portable, and easy to use. Approximate cost: $6K
The 5D laser is much more efficient than conventional lasers in that it requires only one setup and one pass to measure five errors - compared with five setups and five passes. Significant time savings, days can be cut from the evaluation process. Approximate cost: $40K. Acceptance of B5.54 thus far has been good. Next, the company intends to develop its use for lathes and grinders.
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|Title Annotation:||Caterpillar Inc.'s use of ANSI B5.54 standard in research and development efforts|
|Publication:||Tooling & Production|
|Date:||Oct 1, 1998|
|Next Article:||Machine vision focuses on quality.|