LNS Alpha 538, Instruction Manual

Page: 110 / 115

CHAPTER 9: MALFUNCTIONS 9-15
ALPHA 538/552
2.4. Material
(18) Bars
To obtain a perfect insertion inside the collet of the bar feeder, 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.
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.
(19) 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.
(20) 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.
(21) 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.
(22) 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.