Putting Accuracy on the Table
YMT Technologies Tooling Division has recently signed an exclusive UK agency contract to supply the Detron range of high precision NC rotary tables. Under this new agreement the Yeovil-based company will assume responsibility for the sale of Detron’s extensive range of CNC rotary and tilting rotary tables in the UK, which includes pre-sales technical support, stocks of popular items and spare parts being held by YMT at its impressive facilities.
Detron Machinery has extensive experience of developing and manufacturing CNC rotary tables as OEM equipment for leading machine tool manufacturers as well as for retrofitting. As Jason Short, YMT Technologies’ Tooling and Equipment Manager, points out: “This agreement is the result of a long and comprehensive search of all the manufacturers of high precision rotary tables around the world. Having shortlisted Detron and visited its manufacturing facilities in Taiwan, it did not come as a surprise to me that in our benchmark tests the company’s rotary tables proved to be at least as accurate as the best offered by any Japanese manufacturer. In most cases the rotary units’ accuracy was even better than claimed.”
A number of significant features ensure the levels of precision achieved, including the design of spindle bearings, braking mechanism and dual lead worm with backlash adjustment. The spindle is supported by large bearings, radial and axially preloaded to resist heavy horizontal and vertical cutting loads.
Offering more clamping force than conventional disk braking systems, Detron uses a full circumference hydraulic clamping design. Synchronised clamping on the entire hardened and ground table circumference provides maximum rigidity for heavy cutting applications, and maintains the central datum point of the unit. The clamping mechanism is located close to the work table surface thereby avoiding any table deformation and accuracy deterioration.
The efficient transfer of drive from the servo motor to the rotary face is carried out by a specially designed dual lead worm, which has larger full depth tooth engagement for heavy cutting applications. A variable pitch thread on the worm allows backlash error to be quickly eliminated. To keep the co-efficient of friction to a minimum the worm wheel is manufactured from a high tensile aluminium bronze alloy while the worm is made from nickel chrome-molybdenum hardened to over HRc 60. Mounted at the bottom of the rotary table the worm is completely immersed in lubrication fluid for an increased service life.
Highly capable, the entry level GX-P series of rotary NC tables is available with 125, 170, 210 or 255 mm diameter work tables and can be loaded with raw material weighing between 50 and 150 kg, while the GV-SB range offers higher clamping forces and can be specified with 170, 210 or 255 mm diameter work tables with a permissible workload of 75 kg. The GF series of tilting rotary tables are available with 125 mm diameter work tables with a tilting range of +40°/-120°, the larger 170, 210, 255 and 320 mm diameter work tables have a tilting range of +30°/-120° and accommodate workpieces from 50 up to 200 kg.
“All the Detron NC rotary units are tested in our workshop before they are delivered to the customer. However, any unit is only as good as the engineer fitting it,” claims Jason Short. “This is why our engineers have received full product training, so they have practical knowledge of the rotary table as well as a wealth of experience on the machine tool’s CNC system. This makes interfacing the rotary or tilting rotary unit straightforward."