|Crowds flocked to see Sodick's 3D metal printer at the Jimtof show.|
|Micron-level tolerance over a wide work area is promised by the MP4800 wire-cut EDM unit from Mitsubishi Electric (above) and the SL600P from Sodick (below).|
Mitsubishi Heavy Industries (Tokyo) set a new standard for tool machining precision with its The MVR Ex vertical precision milling machine series. Employing a thermally stabilized column construction, the machine tool reportedly enables dimensional tolerances of 1 µm on horizontal surfaces and 8 µm on vertical surfaces, even if the ambient temperature in the tooling shop changes by as much as 5.5°C. "Such precision can be used to fabricate tooling that does not require any polishing," says Engineering Manager Takayuki Kume.
Spindle speeds of 5000 rpm for planar mating surfaces (800 mm/s feed rate) and 8000 rpm for planar molding surfaces (1500 mm/s feed rate) are possible with the MVR Ex. An engine under cover injection tool was on display at the Mitsubishi Heavy Industries stand. Although machining paths were visible on the tool, it was extremely flat to the touch.
Also on display at Jimtof was a double column type machining center from Toshiba Machine Corp. (Tokyo) optimized for tooling applications. The MPJ-2640M features a spindle speed up to 6000 rpm, 32% faster attachment changes and 37% faster automatic tool changes. "A 3D measurement 'Direct Scale Tester' indexing head is also built into the machine tool for profiling of molds," notes Makoto Ishibashi, Senior Expert, Export Group, Machine Tool Sales at Toshiba. 10% faster tool head acceleration/deceleration in the high speed mode, and 17% faster acceleration/deceleration in the high accuracy mode are also realized with the new machine tool.
In the EDM field, Mitsubishi Electric's wire-cut MP4800 unit now employs linear shaft motors rather than ball screws for motion control. This enables faster movement and consumes less energy. The MP4800 can machine with a pitch tolerance of 1.5 μm over an X-by-Y stroke of 740 x 150 mm. Other key performance parameters include circular accuracy of 0.98 μm, surface roughness of 1.5 μm and taper accuracy of +0.01° (+5 μm).
Automatic wire threading is also reportedly greatly improved through use of a wire electrode annealing structure. A chiller system is also used to cool the dielectric fluid. This process is synchronized with the machine casting, where fluid is also circulated through key areas of the machine structure.
Sodick (Kaga, Japan) also brought linear motor drive to its EDM units, reporting a cutting accuracy of +1 μm over a plate with maximum hole pitch of 550 x 350 mm. The SL600P features a host of new functions, including a high-speed automatic wire threading unit, a wire tension servo function, "barrel effect-free" control (barrel extent of 3 μm for first machining pass in a material of 100-mm thickness), and TMP control that improves surface roughness during second pass machining, reduces the barrel effect and reduces adhesion to brass.
Sodick also presented its all-new 3D metal printer at Jimtof, which was perhaps the highlight of the show. A brief introduction and photographs are shown here. Sodick demonstrated the OPM250L's application in conformal cooling tooling inserts for PET bottle preforms at Sodick, which reportedly enable 2.5-times faster cooling time and 30% cycle time reduction.
The tool building process in this 3D printer entails the layering of 10 layers of metal powder (maraging steel), with each layer measuring 50 μm, that are selectively sintered, followed by conventional machining with spindle speed up to 45,000 rpm. This regular machining at 0.5-mm intervals means very deep fine detail can be machined into the insert. The OPM250L can handle a maximum workpiece size of 250 x 250 x 250 mm.
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