Tech Front: Versatile Gaging System
Designated the Equator, this system is described by Renishaw Inc. (Hoffman Estates, IL) as a radical new alternative to traditional dedicated gaging. The patented design is capable of high-speed comparative gaging for inspection of high-volume manufactured parts, and reportedly can switch between parts in seconds.
Based on a scaleable and adaptable parallel kinematic structure, the system’s patented principle allows high-speed scanning and rapid moves between features, while retaining stiffness that delivers the point-to-point repeatability needed for accurate gaging. Reconfiguration of the gaging system to accommodate part design changes, or to measure new parts, is said to be possible in a fraction of the time needed for conventional custom gaging, using industry-standard DMIS programming.
Equator systems come with two levels of software, a programmable version for engineers to create DMIS programs and, at a lower price, a shop-floor system that allows those programs to be executed but prevents operators from making modifications. Both software levels include MODUS Organizer operator front-end software. In the programmable version, MODUS Equator programming software allows engineers to create gaging routines for any part. The software features the ability to program scanning measurements and touch points, using Renishaw’s SP25 compact scanning probe.
By taking the dongle provided with the programmable system and plugging it into a shop-floor system, full programming functionality is activated on that shop-floor system.
The system’s repeatable gaging technology is based on the traditional comparison of production parts to a reference master part. Remastering is said to be as quick as measuring a production part, and immediately compensates for any change in thermal conditions on the shop floor. This system can be used in factories with wide temperature variation—the user simply remasters and the system is "rezeroed," ready for repeatable comparison to the master.
Master parts do not need to be custom parts; a production part measured on a CMM can establish feature variation from CAD or drawing nominals. The results from any CMM, using any CMM programming software, can be configured to be used directly with the system’s software.
According to Renishaw, the calibrated absolute accuracy of the CMM (often located in a temperature-controlled room to ensure accuracy) can effectively, be "extended" onto the shop floor to provide calibrated traceability to system measurements. With the calibration file loaded into the Equator software, measurements made in the system can be referred back to the CAD or drawing nominals. This allows true process control with SPC packages.
Compared to dedicated gaging, this system cuts fixture costs by using fixturing that positions parts to within 1 mm of where the master was measured, which has no significant effect on system repeatability. Establishing part orientation and datums on the part itself removes the need for precision fixtures.
The Equator-specific stylus changing rack allows automated in-cycle changing of SM25 stylus modules. The modules couple to the SP25 CMM probe, allowing users to swap stylus configurations without requalifying each time. Up to six stylus combinations can be loaded into the rack at any time.
Users can integrate the system into automated cells, using the optional I/O interface to connect it to a robot, or outputting the gage results to an SPC package.
For more information on this gaging system and Renishaw Inc., telephone 847-286-9953, or E-mail: email@example.com.
Fanuc Factory Automation America (Fanuc FA America; Hoffman Estates, IL) has introduced the Series 30i/31i-L Model B high-speed laser controls, which are capable of supporting advanced levels of high-speed laser processing. The new CNCs have the capacity to deliver seamless movement between axis motion and power modulation, even in cases of high speeds when processing thin-gage materials. Laser power stabilizing characteristics deliver edge conditions on thicker materials that redefine the norm of Rz and Ra (measured length of surface roughness).
The laser control has update rates of 125 µsec, and provides up to 8 MByte of high-capacity, nonvolatile internal memory, available to store constant inventory nests that don’t require network access to activate and run during surplus machine availability. ATA or compact Flash memory cards provide an additional 2 GB of part-program storage.
An embedded Ethernet interface allows the user to integrate the CNC control system into a company network. World-wide links can be set up via the Internet.
For more information on the new controller, telephone Fanuc FA America at: 888-326-8287, E-mail: fanuc.
firstname.lastname@example.org, or go to: www.fanucfa.com.
Produces Giant Gear
MAG (Fond du Lac, WI) has developed a process that used a horizontal boring mill (HBM) and specially designed tools to cut 588 teeth in a 19-m diam gear assembly weighing 60 tons (54,836 kg). The two-piece gear assembly, made of ASTM A290 steel, consists of a 24-section track, which serves as the base, and a 12-section upper gear rack. The MAG team designed dedicated fixtures for each operation, and special tooling for cutting and finishing the gear teeth on a HBM.
In most cases the tooth involute would be generated by the machine itself, but MAG used a tool with the involute built into the cutter, which was accomplished by grinding the tooth form into the cutter first. Gear teeth were manufactured to AGMA Gear Quality No. 6 and gear accuracy standard 2000-A88. Comprised of A148M Grade 620-415 castings, the track required a special cutter to produce a 2.127° surface angle. the company's gantry-type machining centers.
For more information about MAG, go to www.mag-ias.com.
High-Speed Transport Systems
These three-axis staging/transport systems from Operations Technology Inc. (OPTEK; Blairstown, NJ) are described as suitable for a wide range of OEM applications. They feature granite bases and bearing ways, are driven by linear motors that generate no heat, and position to a fraction of a micron. In addition, these transports are close-looped to advanced, one-tenth micron linear scales that are bonded to granite X and Y axes.
With accuracy exceeding 4 µm, repeatability greater than 3 µm, and a transport speed to 30 ips (762 mm/sec), the systems feature a center drive in all three axes, to reduce asymmetric thrust and eliminate the need for a separate (slave) scale. For optimal stability, systems feature split-axis operation.
The systems’ Y-axis table and X-axis carriage "float" on air bearings, creating a friction-free operation. This configuration also permits installation in clean room environments, as no lubrication is necessary.
Each of the five transport systems, available in 12 × 12" (305 × 305 mm), 18 × 12" (457 × 305 mm), 28 × 24" (711 × 610 mm), 38 × 30" (965 × 762 mm), and 50 × 36" (1270 × 914 mm) ranges, are provided with 8" (203 mm) of Z-axis travel.
For more information on OPTEK transport systems, telephone Rich Amon at 908-362-6200 or go to:
At the University of Kentucky (Lexington) Center for Manufacturing, Machining Research Program, a project entitled: Finite Element Modeling and Analysis of Cryogenic Machining is underway. FE models that were developed by previous research group members will be extended to the case of cryogenic cooling application in metalcutting. The earlier model used a Johnson-Cook fracture strain criterion for chipbreaking and for the prediction of potential crack locations. Subsequent work then used a modified Thomason void-coalescence criterion for predicting fracture. The present work aims to study the role of void nucleation, growth, and coalescence in orthogonal chip formation for a given material, and how the evolution of these voids are affected at cryogenic temperatures. The effect on residual stresses of these voids as they coalesce and turn up at the machined surface will also studied. The final output of the research would be a finite element model and program that successfully incorporates these factors in orthogonal metalcutting at cryogenic temperatures.
For more information, go to: http://www.mfg.uky.edu/mach_lab/Israd_
This article was first published in the May 2011 edition of Manufacturing Engineering magazine. Click here for PDF.