Page 44 - machining_titanium_05_2019

MILLING TITANIUM The mill has 6 teeth, hence feed speed Vf=0.45 × 6 × 310=837 (mm/min) or approx. 33 ipm.

Maximum depth of cut (DOC) apmax (the catalogue data) for the mill is 0.8 mm (.0031 in).
Necessary ramping angle for milling lengthwise
αr≈ tan-1 (apmax/(L-d))=tan-1 ( 0.8/180)=0.25° (Fig. 22), while for milling
widthwise αr≈ tan-1 (apmax/(W-d))=tan-1 (0.8/110)=0.65°.
Due to the maximum 0.9° ramping angle for the mill (the catalogue data), ramping in
both directions with reaching the maximum DOC in the end of the pass is possible.

apmax αr

L
Fig. 22 Ramp-down milling

Table 27 - fzo for FF SCEM and MULTI-MASTER Heads
Basic feed fzo, mm/tooth (ipt)
Family Diameter d, mm (in)
Designation
1 (.037) 2 (.075) 3 (.125) 4 (.160) 5 (.200) 6 (.250)
SOLIDFEEDMILL and EFF-S and 0.02 0.1 0.16 0.2 0.2 0.2
MULTIFEEDMASTER MM EFF (.0008) (.004) (.0063) (.008) (.008) (.008)
MULTIFEEDMASTER MM FF

Basic feed fzo, mm/tooth (ipt)
Family Diameter d, mm (in)
Designation
8 (.315) 10 (.375) 12 (.500) 16 (.625) 20 (.750) 25 (1.000)
SOLIDFEEDMILL and EFF-S and 0.21 0.25 0.25 0.3 0.32 0.35
MULTIFEEDMASTER MM EFF (.0083) (.01) (.01) (.012) (.126) (.138)
0.37 0.37 0.45 0.48
MULTIFEEDMASTER MM FF
(.0146) (.0146) (.018) (.019)
Example
Find cutting data for high feed milling a workpiece from titanium Ti-10V-2Fe-3Al, which will be
machined by a reinforced special MULTI-MASTER tool carrying
two-flute head MM FF120R2.0-2T08 908.

On the assumptions that the whole technological system is rigid, from Table 7 basic
cutting speed Vo=53 m/min (174 sfm) Table 7, and from Table 9 Km=0.56.

Initial cutting speed Vc=53 × 0.56 × 1 × 1 ≈ 30 (m/min) or 97 sfm.
Spindle speed n=1000 × 30 / (π × 12)=795 (rpm).

Basic feed fzo is chosen from Table 27: fzo=0.37 mm/tooth (.0146 ipt).
Feed rate Vf=0.37 × 2 × 795=588 (mm/min) or 23 ipm.

Tooth structure and feed per tooth
There are two kinds of MULTI-MASTER fast feed milling heads: four- and six-flute MM EFF
and two-flute MM FF. The recommended feed per tooth fz for MM FF heads is 1.5 times more
than for MM EFF ones. The reason is a tooth structure. If the teeth of the multi-flute heads MM
EFF are produced by grinding cylindrical blanks similarly to solid carbide endmills, the teeth
of “economy-type” two-flute heads MM FF are pre-shaped by sintering and then are merely
finished by grinding. The high-impact structure of a sintered tooth ensures greater fz.

42 ISCAR