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Mahr Federal's PRIMAR Measuring System Benefits Combines three measurement systems in one machine Eliminates multiple setups, saving time Reduces custom programming for specific families of parts www.mahrfederal.com

Ford Collects Multiple Data With Single Mahr System
Mahr Federal's PRIMAR Measuring System

Ford Motor Co.'s Prototype Transmission Facility in Livonia, Michigan, was looking for a way to collect several kinds of data with a single machine in order to reduce a backlog of queued part performance and manufacturing processes measurement. To achieve this goal, the company chose Mahr Federal's PRIMAR universal measuring system, which combines a precision four-axis CMM, a three-axis scanning probe, a form measurement system and a gear checker.

 "The PRIMAR system replaces multiple dedicated measuring systems that have a combined cost of at least three times greater," boasts David Zhang, senior product manager for Mahr Federal. "In addition, because the PRIMAR system uses mechanical bearings and no air bearings, it eliminates maintenance problems due to the presence of oil in air supplies and the surging of air compressors."

 Although the accuracy of the PRIMAR system is comparable to other systems for 3-D measurement, form measurement and gear checking, it provides greater overall accuracy by eliminating the stack-up of error associated with multiple setups. Likewise, measurement throughput is improved by doing all three types of manufacturing process audits with a single setup. This process helps the user circumvent time restrictions by collecting more types of data on interrelated features, and more data samples, with greater accuracy over a shorter period of time.

 One challenge Ford faced was handling differential housing gear and tooth geometry. To detect potential sources of rocking within a differential gear housing, the system was used to find the difference in height from the center of the journal for each of the gear teeth as well as the perpendicularity of each gear face to the journal. There were 82 individual teeth, and more than 84 measurements were taken on each to determine the highest point.

 Because the PRIMAR system incorporates polar roundness measuring technology, it was relatively easy to automatically center and level the journals to the physical datum axis and then rotate each gear tooth in position for the PRIMAR to measure the points on the tooth's end. This approach resulted in a more accurate locating of the part, vs. the conventional surface plate or the CMM approach of computing a theoretical centerline for the journal. To measure 20 of these parts on PRIMAR takes 30 minutes each, including setup. To measure the same parts on a surface plate would have taken a couple of hours each and provided less accuracy.

 Ford is using the PRIMAR system to evaluate the dimensions of critical prototype transmission parts before and after heat treating. This study involves evaluating two cylindrical features on 82 parts. Without the single setup system, each part measured would have required multiple setups, and experts at the plant say the evaluation would have consumed five hours per part. Instead, the study involved six hours of programming and just 15 minutes of single setup and measurement time per part.

 As design engineers became more familiar with the capabilities of the PRIMAR system, they began performing more intricate measurements, such as the draft angle of a bore in the surface of a main control body, along with an evaluation of the surface of the land area. With a surface plate, this might have taken eight to 10 hours per part. The program was written in six hours and each of 10 parts was evaluated in about 20 minutes using the PRIMAR.

 To check both gear faces for perpendicularity on a conventional machine entails mounting the part, centering and leveling, measuring one face, flipping the part, centering and leveling, and measuring again. Because the PRIMAR system has a three-axis scanning probe capable of measuring in tight places, it was possible for Ford to mount the part on a V-block, center, level and then scan both surfaces all in one setup. The program took about four hours to write and 10 minutes to execute.

 At Ford, the PRIMAR system has been used to collect data critical to the completion of four projects, which Ford estimates will save the company $1.5 million annually in manufacturing costs. In one case, the process audit performed by the single setup precision measuring system triggered a small-part design change that significantly improved manufacturing efficiency.

 The Ford Prototype Transmission Facility plans to fully exploit PRIMAR's potential and experiment more with the three-axis probe. Ford is also planning on using Mahr's new Part Family Program Modules that could eliminate up to 80 percent of custom programming.

 "Now, 'Family' software eliminates 80 percent or more of custom programming by providing pre-defined subroutines for the types of measurements most frequently encountered for each part family," adds Zhang.