Automotive manufacturers in particular are leaving no stone unturned in their efforts to drive cost out of their gear production and inspection processes. For many, the wasted time needed to transport finished gears to the lab — and the additional time needed for parts to work their way through the queue — represent a significant and very expensive bottleneck. The need for faster gear inspection and the process modifications that go with it have never been more acute. Of course, this is driven by low noise, increased power density, greater reliability, and other demands that have made gears more complex and inspection requirements much more comprehensive in recent years.
The Search For A “Shop-Hardened” Solution
While no truly shop-hardened inspection system has existed until now, the problem has become so pressing for many gear manufacturers that some have resorted to putting conventional inspection systems on the shop floor. These systems, built for lab conditions where temperature, vibration, and contamination variations are a fraction of what can be experienced on the factory floor, simply haven’t performed well. Even a minimal temperature fluctuation of a few degrees Celsius can require a typical inspection system’s probe to be recalibrated — a time-consuming process involving tearing down a work setup, installing a calibration sphere, re-establishing table center and axes, and then setting up the workpiece again. Then, factor in the detrimental effect that vibration and airborne particulates can have on an inspection system designed for the much more pristine conditions found in the lab. So, the challenge remained: how to build an inspection system robust enough to withstand conditions in the widest possible range of working environments, while still retaining all the precision and advanced functionality required by the leading gear manufacturers.
The 300GMS®P: Starting From the Ground Up
While the logical starting point for Gleason’s development effort was the 300GMS® analytical gear inspection system, featuring the most advanced inspection capabilities, it was also evident that the 300GMS was not built to adequately address all three major issues facing any shop-hardened development effort: vibration, temperature, and contamination.
In an environment where simply a person walking, a pump vibrating, or a forklift driving by can create enough vibration to void an inspection, it was clear that the machine base, in particular of the new machine, would need to be a new design and potentially even made of a material other than the granite typically used. Granite’s “rock-solid” stability makes it an ideal base material when temperature variations don’t exist. But it will deform with wide temperature swings of the type experienced on the shop floor, thus affecting X-, Y-, and Z-axis alignment and table position. Meehanite cast iron, on the other hand, is a proven and predictable shop floor workhorse. The use of this material for the new 300GMS®P shop floor machine is coupled with a completely new patent-pending H base design with active leveling system. The new base design consists of a bottom base with four air springs mounted on risers, which support the machine work platform. These air springs detect and automatically compensate for vibratory forces on the fly, such that the machine work platform (axes, table, and workpiece) is both isolated from and immune to vibration. As shown in Figure 1, the new 300GMS®P performs extremely well compared to the 300GMS within the widest range of acceleration and frequency.
Built To Take The Heat and Resist Contamination
The high precision guidance systems used to position linear and rotary axes on inspection systems are inherently susceptible to even minor temperature changes. The use of enclosed glass scales ensure exceptional accuracies, but come with a thermal coefficient. The 300GMS®P development effort addressed this challenge with a new type of scale made from 64FeNi material (64-percent iron, 36-percent nickel) that has essentially zero thermal expansion within the typical shop floor temperature range. While scales of this material type must be left open rather than enclosed, they are exceptionally resistant to dirt. In addition, the 300GMS®P’s unique design helps mitigate the collection of ingressing particulates that potentially will build up on scale surfaces and reduce accuracy and reliability.
The 300GMS®P incorporates a system of new software and sensors that work in combination to detect and compensate for typical thermal fluctuations found on the shop floor. This ability to identify and apply compensation for factory-floor temperature influences in real-time contributes greatly to 300GMS®P’s exceptional accuracies in an uncontrolled temperature environment (see Figure 2 and Figure 3).
In addition to the use of highly dirt-resistant scales, the 300GMS®P features a new bellows design to deliver much higher resistance to the airborne contaminants typically found in the factory. While little attention was given to the cloth material used in the past (other than it being lightweight and not prone to deformation), a better woven material coated with PVC is now used. This new approach provides the needed protection along with a light weight and improved “tracking.”
The Best of Both Worlds
With the 300GMS®P’s proven ability to deliver exceptional accuracies (2 microns) within a temperature range of 15 to 40 degrees Celsius, gear manufacturers now can put lab-level inspection right next to their production machines. In the case of the 300GMS®P, this means faster access to today’s most advanced gear and non-gear inspection capabilities, including:
- Complete gear inspection, from fine pitch gears as small as .2 module, to shaft-type gears up to 450 mm in length, as well as surface finish measurement on gears down to 1.2 module. It’s even capable of 3D measurement and analysis typically performed by a CMM.
- GAMA™ 3, the object-oriented Windows® 7-compatible operating software that puts a host of powerful features right at the operator’s fingertips, creating a simple, intuitive human/machine interface. (See Figure 4.) With GAMA 3, creating a new program is as easy as point and click, and it can be done in a few easy steps regardless of experience level, language requirements, or the gear or application type. GAMA 3 now supports VDI/VDE 2120 GDE (Gear Data Exchange) capability as standard, reducing the need for redundant programming and allowing gear data/parameters to be transportable between different machines. This HTML-based standard is just one of the advanced features incorporated into this robust platform.
- Compact, highly ergonomic, and variable workstation placement. With factory floor space at a premium, users will appreciate that the 300GMS®P is about 31 percent smaller than the 350GMS®, but with only a 15-percent reduction in machine volume capacity.
- An Advanced Operator Interface (AOI) with dual display SPC, voice, photo, video, QR code/barcode read/import, and environmental monitoring/recording.
- Equipped with high-accuracy 3D scanning probes with a broad range of styli, a stylus calibration library, and easily accessible probe storage in the storage cabinet at the operator’s workstation. A six-position Automatic Probe Change (APC) is also available. (See Figure 5.)
The 300GMS®P is a gear inspection system that operates just as reliably on the shop floor as it would in a tightly controlled lab environment. Manufacturers of complex, high-quality gears for automotive, aerospace, and other industries with like-sized gears can now put this advanced metrology system in close proximity to their production machines.