Case Studies: Benefits of Wireless Bore Gaging
Cases for the high-efficiency gearboxes produced by Fertigungstechnik Nord (Gadebusch, Germany) are machined from solid castings. By locating all of the bearing bores in the one-piece cast case, the Nord Unicase housing eliminates all torque and lateral forces from the sealing faces of the bolted-on cover, producing a compact, yet robust gearbox.
As might be expected, however, this design approach requires extremely high accuracy in the production machining processes that produce the cases. It also creates a challenging environment for the subsequent quality assurance gaging operations required.
Nord machines its Unicase housings in a single setup on large computer numerical control (CNC) machining centers and gages the bores at an adjacent workstation. Total Unicase production is more than 280,000 units annually in a variety of sizes and configurations. Each of them requires 12 or more different quality assurance gaging operations.
Gadebusch Plant Manager Steffen Timm has extensive experience with networked automatic gaging systems used in the plant’s shaft manufacturing area. These systems, supplied by Marposs (Auburn Hills, MI), automatically measure production shafts and provide compensation feedback to the controls to maintain quality.
That approach is not feasible in the case machining area. “Equipping them all with fully automatic measuring devices would be too expensive and economically unfeasible,” Timm explains. But Timm has been able to obtain many of the same benefits by changing from conventional cable-connected plug gages to M1 Wave wireless gages from Marposs.
The most obvious benefit of moving to a wireless solution is the elimination of cables, and that is no small advantage when a typical workstation has a dozen or more gages, each with several yards of cable attached. The safety impact of removing those cables from the working environment is self-evident, and eliminating the maintenance cost associated with them produces significant operating cost savings as well.
Timm has found that the new gages have additional benefits. For example, eliminating the cables also removes a major source of interference and incorrect gage readings that cost his employees precious time at the machines.
“There were bores that would be detected as out of range owing to an error linked to the cabling system. This would lead to defective goods and incorrect tool settings,” Timm says.
“The new wireless gages have substantially reduced the error rates. Combined with the display electronics in the form of networkable PC technology and the process-oriented software solution, the new measuring systems ensure a high measuring reliability. In addition, we implement traceable documentation of the measured data we manually collect in our casing manufacturing plant,” Timm adds.
Self-Contained Wireless GagingThe self-contained Marposs M1 Wave wireless gages use Bluetooth wireless technology for data transmission. Unlike other wireless systems that use plug-in transmitter dongles, the M1 Wave allows full freedom of movement to inspect the cases while they are still clamped in the machine-all with no risk of false readings due to cable interference or defects.
M1 Wave wireless gages are based on the Marposs M1 Star EBG (Electronic Bore Gage), which has interchangeable heads mounted on a common handle. The EBG heads incorporate an electronic measuring cell that directly generates the measured value, eliminating the conventional mechanical transmission using tapered needles or push rods to actuate a transducer. The handle contains the Bluetooth electronics and power supply to produce a completely self-contained gaging system.
Because the M1 Star EBG eliminates all of the delicate mechanical components used in a traditional gage, it provides a high level of precision. The electronic transducer ensures a reproducibility of less than 0.5 micrometer.
Easy AnalysisM1 Wave wireless gages can be connected to various Marposs display devices including the E4N Wave column, the Merlin mini-PC and the E9066T thin-panel industrial PC, as used by Nord. At 50 millimeters thick, the E9066T can be wall or swivel mounted, integrated into a control panel, installed on a swivel arm, or used as a tabletop device as it is at Nord.
The gearbox manufacturer also uses the integrated Ethernet network adapter to connect benchtop units to a plant computer for higher-level data collection and analysis.
Nord displays and analyzes measured data using Marposs’s Quick SPC software for Windows operating systems. Timm especially appreciates the menu-driven test processes that guide the operator step by step through the measurement sequence. Operators can program their own work processes onsite using the Windows interface.
The system is intelligent enough to monitor trends and adjust inspection frequency based on process stability. This eliminates the need for 100% inspection of every part, and guides operators through dynamically generated partial test routines via on-screen prompts.
An integrated Q-Das statistic server is used for data analysis. The system also supports archiving in a variety of formats via network or external data storage media.
In the production environment at Nord, Timm’s operators have found them to be sturdy and precise. Altogether, a good outcome for a project that started out simply to eliminate a bunch of troublesome cables.