A software-driven comparative gage-Renishaw’s (Gloucestershire, UK) Equator system-is already starting to soften up the cost for numerous hard gages at aero-engine component maker Meyer Tool Inc. (Cincinnati). In its pre-launch application, one Renishaw Equator gage has eliminated at least four costly hard gages in a new work cell. The company’s custom hard gages can cost up to $20,000 each to design, build and maintain, according to Beau Easton, quality manager at the company.
Meyer Tool designs, builds and maintains dozens of these costly gages every year for in-process measurement. Down the line, design changes on a part can add another $3,000 to $10,000 to reconfigure and qualify an existing gage.
Cutting the Cost of Hard GagesFor in-process dimensional measurement, Meyer Tool principally relies on work-cell-based point-to-point contact gages, using pneumatic digital probes. Hard gages in the machining cell give fast feedback but are expensive. Design/build of the part nest can cost $6,000, plus probes at more than $500 each, as well as verification studies and maintenance, Easton explains. “If we are producing a make-complete nozzle, there could be six to 10 fixtures, each with six to 20 probes, and if a feature or tolerance on the part changes, it adds time for the gage to be altered and verified,” he says.
When shown Renishaw’s Equator comparative gage and offered a pre-launch trial, Easton and SPC (statistical process control) Manager Bridget Nolan says they immediately recognized its potential. “We got involved with Renishaw’s introduction of the system and provided parts,” Nolan says. “Renishaw programmed them, and the results matched our coordinate measuring machine (CMM) results, whose group sets up, maintains and programs the company’s gages, fixtures and instruments.”
Comparative Gaging, Mastering and RepeatabilityThe Equator system uses the comparison method of mastering and measuring familiar to anyone who uses dedicated gaging systems. A master component with features of known dimensions is used to “zero” the system, with all subsequent measurements compared to this part.
The key to the Equator system is a highly repeatable and radically different metrology mechanism based on a parallel kinematic structure. This mechanism is lightweight, allowing rapid motion, yet very stiff and repeatable. The system uses Renishaw touch and scanning probes, styli and stylus change racks, and Modus Equator programming software.
Cost-wise, three to five hard gages in a Meyer Tool work cell can all be replaced by one Equator-and the Equator can be used for multiple parts, switching between them in seconds, as well as reprogrammed for many other parts over its life.
Assigned To a Lean CellThe first Equator system is currently assigned to a lean machining cell in Meyer Tool’s shop. Demonstrating its adaptability, it integrates with Meyer’s Orion SPC system, maintaining a familiar look for machinists and shortening the learning curve. Orion communicates with the Equator’s Modus software, presenting the operator with results in the form of dimensional data and SPC charts that allow the operator to determine computer numerical control (CNC) offsets. “Keep in mind, the machinist sees variable data and can compare the current part with recent measurements, so it’s not just a pass/fail determination,” Nolan explains. “The parts must meet tolerances of ±0.001 to ±0.003 inch. Inspection time varies with the part but typically takes two to six minutes, well within the TAKT time of the cell, so the system easily keeps pace with machining operations.”
Measurements Traceable to Absolute CMM StandardsThe Equator measurements at Meyer Tool are correlated with those from a CMM, using a CMM-calibrated master part. “The master part sets the values the Equator expects to find inside its measuring envelope while the software automatically applies the compensation values from nominal taken by the CMM,” Nolan explains. “It must check within 10% of allowable tolerance from nominal.”
There is no need to remaster on every part change, though Meyer does remaster on a three-hour schedule to compensate for changes in the plant’s temperature. “The Equator system memorizes the master parts and validation scores, so we can switch parts as many times as needed during the three-hour window, and not have to remaster,” Nolan says.
The Soft Solution to Hard Gage CostsWith more than 100 hard gages costing $10,000 to $20,000 each throughout its facilities, Meyer Tool recognizes the potential cost advantages of a flexible, software-driven gaging system. “We are still expanding our knowledge and capabilities with the Equator system, but have high expectations it will ultimately alleviate a large part of our cost burden for hard gages,” Easton adds.
BenefitsThe Equator uses touch and scanning probes, styli and stylus change racks and programming software.
Cost-wise, three to five hard gages in a Meyer Tool work cell can all be replaced by one Equator.
The Equator can be used for multiple parts, switching between them in seconds, as well as reprogrammed for many other parts over its life.