CUT-OFF CALCULATION
The calculations set out below are intended as guidance for band saw machine operators. There are a number of different opinions that exist as to the correct calculations for different material types, and this guidance does not attempt to disprove other opinions. The guidance is offered as a reference rather than as strict technical instructions.
EXAMPLE OF CUTTING CALCULATION Material : Austenitic stainless steel (SAE 316) Formato : Round
TUBE OR STRUCTURAL MATERIAL CUTTING Do the same, calculating the material area, choosing the tooth (page 14), speed and cutting rate (pages 54 and 55), however correct the cutting time, by multiplying the time calculated by the correction factor, according to the table below.
CUTTING CALCULATION: Use all the measures in centimetres to get the area in cm² .
Dimension: 101.6mm (4”) Speed: 21 to 24 m/min.*
Cutting Rate: 10 to 13cm2 min* *according to the chart on page 55 TC = Tempo de Corte
ROUND area = D 2 x 0.7854
CR A
CT=
CT = Cutting Time A = Material Area
Cutting Time Correction Factor
Thickness (e) mm
CR = Cutting Rate Cutting Time = 81.07 cm2 ÷ 13cm7/min. Cutting Time = 6:14 minutos Band saw machine used : 56330 (page 49) Blade to be used : Primalloy’ ™ (page 18) Tooth : Variable Pitch 3-4/P (page 14) Catalogue No. : 3920 x 34 x3-4 Primalloy CUTTING OF OTHER DIMENSIONS Multiply the speed indicated in the tables pages 54 and 55 by the following factors.
2.5
2 to 5
SQUARE area = L 2
2
6 to 10
1.7
12 to 15
1.4
20 to 25
1.2
30 to 60
Note: when dry cutting, adjust the feed pressure to about 40% 50% of the normal cutting rate (use data on pages 54 and 55). Note: dry cutting reduces the blade life
RETANGULAR area = E x L
For Duratec™ Super FB Carbon Steel Blades: adjust the feed pressure to 50% of the normal cutting pressure and the Cutting Rate to 85%.
HEXAGON area = L 2 x 2.598 E 2 x 0.866
Dimension / mm
Factor
CHIP ANALYSIS Thick and heavy chips with normal material color indicate high cutting feed 1. Thick and blue chips indicate high speed and cutting feed 2. Thin chips with dark coloration indicate low feed and high cuttingspeed 3. Flexible chips, spring type, with clear material colour indicate ideal cutting condition.
< 13
1.20
13 - 25
1.10
25 - 50
1.07
50 - 125
1
125 - 250
0.92
250 - 600
0.85
> 600
0.75
ROUND TUBE area = (De 2 - Di 2 ) x 0.7854
HARDENED MATERIAL CUTTING
If the material to be cut has hardness abovethat specified in the tables (pages 54 and 55), multiply the speed and the cutting rate (decreasing speed and increasing cutting time) by the factors below.
SQUARE TUBE area = Le 2 – Li 2
1
2
Factors
Difference between expected and found hardness
Blade Speed
Cutting Rate
3
4
Up to 40%
0,75 0,60
0,75 0,54
From 40% to 75%
0,50
0,40
From 75% to 100% ( max. 40HRC)
44
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