Page 75 - Die_and_Molds_User_Guide_7861458_2017

Table 54 Chip Thinning Factor KTH for BALLPLUS Toroidal Inserts with
Nominal Diameter D and Corner Radius R
D=12 D=16 D=20 D=25
ap/D
ap R3 R4 ap R3 ap R3 R4 ap R3 R4 R5 R6
0.01 0.12 3.2 3.6 0.16 2.8 0.2 2.4 2.9 0.25 2.2 2.6 2.9 3.1
0.02 0.24 2.2 2.2 0.32 2 0.4 1.8 2.1 0.5 1.6 1.9 2.1 2.2
0.05 0.6 1.4 1.7 0.8 1.3 1 1.2 1.3 1.25 1.1 1.2 1.3 1.5
0.1 1.2 .1 1.3 1.6 1 2 1 1 2.5 1 1 1 1.1
0.15 1.8 1 1.1 2.4 1 3 1 1 3.75 1 1 1 1
0.2 2.4 1 1.1 3.2 — 4 — 1 5 — 1 1 1

Example
In a die-making shop mill HCE D25-A-L170-C25 with insert HTR D250-R5.0-QF IC908 planned to
be applied for rough milling of a mold insert cavity. The cavity material is stainless steel AISI 420F.
The proposed cutting parameters are as below: the depth of cut – 2.5 mm, the width of cut –
17 mm. A rigid machine tool performs milling; and the cavity is properly secured in the workholding
fixture of the machine tool. Find the programmed spindle speed and feed.

Basic feed for tooth fzo for groups 12-13 is equal to 0.14 mm/tooth (Table 53), chip thinning factor
KTH for 25 mm dia. insert, 5 mm corner radius and 2.5 mm depth of cut (Table 54) – 1. Hence, the
programmed feed will be 0.14 mm per tooth.
In accordance with Table 51 the recommended starting speed is 120 m/min. Effective diameter
De=25-2×5+2×√(2×2.5×5-2.5²)=23.7 (mm) that contains ~95% of the insert nominal diameter
(25 mm). Therefore, the spindle speed can be calculated with the reference to the nominal
diameter and it will be 1000×120/(π×25)=1528 (rpm). Correspondingly, the feed speed becomes Milling Tools
0.14×2×1528=427.8 (mm/min).

Fig. 20

Ap ≤ R Fv
R
α°

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