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Probes also can be used to measure tool wear indirectly by inspecting the area of the workpiece being machined by the tool. is requires a high precision probe and a mechanism to bring it into contact with the workpiece. is technique is particularly useful on turret lathes, where the probe can be installed in the turret so the measurement becomes part of the programmed machining cycle. It's an excellent application for a wireless system. HMCs present a more complex mounting challenge because they often use rotating tables and/or pallet loading. One way to handle the situation is to place a wireless touch-type toolsetter on each pallet that communicates with a common receiver located on the machine. is arrangement can be used for toolsetting, tool measurement and tool breakage detection with a relatively simple and inexpensive wireless touch probe. An alternative solution is to mount the touch probe on an automated "pop-up" bracket that moves into position to measure the tool or workpiece and then retracts during the machining operation. Depending on the specific machining environment, this might be a good application for either a wired or wireless system. Lathes present a different set of challenges for toolsetting and breakage detection because they can use both live and non-rotating tools. An operator to place a contact probe on an electric arm that moves it into contact with the non-rotating tools on a turret. ese arms are available from Marposs pre-engineered to fit the specific lathe brand and model. Since contact technology is of limited value for rotating tools, however, pairing a contact probe with non-contact technology is often optimal for lathes. One such system uses a laser to verify the rotating tools and a touch probe to scan the non-rotating tools. It's neither pure contact nor pure non-contact, but rather a hybrid system configured to meet a specific set of require- ments on a particular type of machine tool. Such a hybrid system is also useful when thermal compen- sation is required on a high-precision machine tool. A laser can only measure in two dimensions since one axis must be fixed. e touch probe can be used to generate the third axis data, however, to complete the measurement. e laser used in those systems is one of two major non-contact technologies available today. e other is based on a camera application. e difference is essentially that the laser detector measures a shadow and the camera detector measures a positive image. e difference is significant. Laser systems are sensitive to beam size and require that about 50 percent of the beam is blocked by the tool to work effectively. If the beam is larger than the tool, significant inaccuracies are introduced into the measurement. is makes the use of laser system problematical for small tools. Because the camera system measures an actual image, it is less limited by tool size. is makes it the technology of choice for micromachining applications where tools can be as small as 0.002 inch or 0.003 inch in diameter. Because the camera system counts actual known-size pixels in the image, it can achieve the slightly better resolution than the 0.2 micron possible with a laser. e Marposs VTS visual toolsetter has the capability of measuring static tools, including lathe tools, in a matter of seconds. Camera systems do have limitations, though. e VTS visual toolsetter, for example, has a maximum diameter capability of 45 mm and a minimum diameter of 10 microns. It also has a 500-micron window for measuring a complete tool, and beyond that, can only image an edge. Where the camera is justified, however, its cost certainly is not prohibitive. On a machine such as the Makino IQ-300 micromachining center, a Marposs VTS system would represent less than 3 percent of the total capital investment. Considering the value of the parts produced on that system, the cost of the machine tool and tooling, and the fact that there is no other technology available for that application, represents a bargain. For those who don't compete in that esoteric marketplace, however, the laser represents a solid choice for non-contact applications. It's more economical, costing typically 25 percent of the price of a camera system. It's able to detect and measure tools rotating at any speed, which reduces cycle time. Also, it's extremely flexible. On a machine such as a Swiss automatic, for example, where access to tooling is limited and space for mounting a toolsetter or breakage detector is virtually non-existent, a laser still can be used with a bit of innovation. One customer built a special bracket that places the laser in the machine's spindle where it can measure all of the tools. Obviously, this system interrupts production, but it has proven to be cost- effective for this particular application. Another customer mounted a laser to measure only a few critical tools in the turret using a custom bracket. Here again, it's not a comprehensive solution, but it has proven to be cost-effective for this application. Mounting a laser on a VMC is generally not difficult. Most applications require simply attaching the laser, or even a touch setter, to a raised block that's affixed to the table. Mounting a laser on a HMC is a bit more difficult because the laser needs to move with the table that often rotates and/ or is loaded with pallets. One component of the laser system, either the transmitter or receiver, needs to be below the table top to provide clearance while the other needs to be high enough above the table to clear the top of the workpiece. Typical solutions include a motorized "pop-up" or a "goal MICROMACHINING 38 PRODUCTION MACHINING :: JUNE 2017