Feature sponsored by Test & measurement
ENCLOSED ENCODER ENHANCES GRINDING PRECISION AND PERFORMANCE
After testing and evaluation, TGT selected global engineering technologies company Renishaw’s FORTiS enclosed encoders for its latest series of tool grinding machines. The ease of installation and other leading-edge features of the FORTiS encoder system enable TGT to optimise its machines’ performance.
stages of product development, TGT tested a range of FORTiS-S enclosed absolute encoders with resolutions from 10 nm down to 1 nm. To achieve the best overall machine performance, TGT selected the FORTiS-S encoder with a resolution of 1 nm.
MICROMA AUTO
The Microma Auto is a cylindrical grinding machine used for the preparation of cutting tool blanks such as regular drills, endmills and profile tools, and comprises four linear axes (X, Y, Z and V). Prior to machining, the tool blank is clamped by a collet on the workpiece spindle and identified by the LP2 probe system. During processing, the workpiece rotates within a V-shaped holding tool (V-block), which is mounted on the V-axis, while being driven along the longitudinal X-axis, which is the feed axis. As the workpiece enters the grinding station, it is fed between two grinding wheels (roughing and finishing wheels) that are driven along the Y and Z axes, respectively, and are perpendicular to each other. One advantage of the Microma Auto is that the whole process is completed in a single pass.
A kinematic feature of this machine is that the workpiece spindle axis (X-axis) and the V-block axis (V-axis) are on the same linear motor guideway but driven by separate linear servo motors. The X-axis and V-axis slides are attached to separate FORTiS encoder readheads but use the same enclosed absolute scale of the FORTiS dual- readhead system. The readheads feedback the X-axis position of the workpiece and V-axis position of the V-block, each with a resolution of 10 nm, to the controller. In this case, the FORTiS encoder enables a positioning accuracy of 3 µm on an axis with 150 mm of travel.
Instrumentation Monthly February 2023 One of the major advantages of using the
FORTiS dual-readhead enclosed encoder is that it simplifies the mechanical arrangement of the machine, which saves space and reduces cost. “One benefit of choosing the FORTiS dual- readhead linear encoder is that it enables faster and simpler encoder installation and servicing,” said Mr Ranganatha. FORTiS optical enclosed encoders have an innovative non-contact mechanical design that eliminates components such as bearings, springs and guidance carriages. This design minimises wear and greatly reduces the risk of breakage during maintenance and servicing, thereby extending the life of the system. FORTiS encoder readheads are equipped with
Renishaw’s patented set-up LED, and carefully designed installation accessories to ensure intuitive and right-first-time installation that is substantially faster than more conventional systems, even in restricted locations. For enhanced functionality, installers can connect the Advanced Diagnostic Tool, ADTa- 100, via a standard USB connector, to a PC running Renishaw’s ADT View software. This provides a user-friendly graphical interface of advanced diagnostic information, including key encoder performance parameters such as signal strength along the axis length. TGT technicians use the ADTa-100 hardware to connect the FORTiS encoder to the ADT View software interface during the machine assembly process. This software provides a snapshot of the real-time signal strength at different positions along a machine axis such that the technician knows where to make fine adjustments and can even enable calibration of the FORTiS encoder with the machine powered down.
RESULTS FORTiS encoders are quick and easy to install, which has helped TGT to save manufacturing and servicing time. Ranganatha explains, “The installation of the
FORTiS enclosed encoder is very simple, which has greatly improved our productivity. Using the ADTa-100 tool and after receiving the appropriate Renishaw training, our engineers can complete a single-axis installation in only 15 minutes. If only the readhead LED were to be used, I believe the speed would be even faster. The LED allows us to quickly determine the status of the encoder, improving diagnostic accuracy when the machine is faulty.” “Renishaw’s professional team often talks with us about our technology. The FORTiS enclosed encoder can be specified with many options for axis length, position resolution, and serial communication protocols, which give us much greater freedom in machine design,” says Ranganatha. “Although we are using the FORTiS encoder for the first time, we have great confidence in its design. Our latest grinding machines have been equipped with the FORTiS encoder and are now entering mass-production. We are very optimistic about the future development of grinding machines. In recent years, we have benefited from a boom in India’s domestic automotive and aerospace industries where there is a huge demand for cutting tools. We have also seen more and more competitors enter the market as the demand for grinding machines has grown. In the future, TGT will focus on optimising its machines’ performance,” concludes Ranganatha.
Renishaw
www.renishaw.com/tgt 45
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