LNS GT 326-E, Инструкция по эксплуатации, Страница: 147 / 218

9 - 32
9 TROUBLESHOOTING GUIDE
GT 326-E
9.5.4 Material
Bars
To obtain a perfect insertion inside the collet of the bar feed
system, the bars must be chamfered concentrically (at the rear) at
30°. At the feeding process, it is recommended to deburr the bar
at the front, to avoid possible catching during the introduction of
the bar inside the spindle.
In some cases, when the diameter of the bar is close to the
external diameter of the collet (see assembly of pushers), the rear
of the bars must be machined to the inside diameter (D) of the
collet. The length of the machining (L) must be at least 30mm.
Tubes
To prevent mixing the oil from the feeding process and the cutting
oil from the lathe, it is recommended to put a plug in the rear of the
tubes to be machined.
Profiled material
It is recommended to install a bushing, inside the clamping device, with the same inside profile
(+ 0.2 mm) as the bar.
The rear of this collet and the front of the bars should be flat. During the loading cycle, a slight
rotation of the spindle (about 30 RPM) is desirable.
Bars straightness
Performances may vary, depending on the material machined, the length of the bar, etc. To
obtain optimum output, the bars must be straight. If the torsion of the bars exceeds 0.5 mm/m,
performance will automatically be reduced in regards to speeds of rotation while vibrations will
increase accordingly.
In this instance, the quality of the guidance is not the cause.
Material composition
In general, the difficulty increases with the specific weight of the bar. Steel bars are relatively
easy to guide.
Because of their great flexibility and specific weight, brass bars are relatively difficult to guide at
high speeds. Aluminum bars of aluminum are very easy to guide.