Band Sawing Tool Steel, Cutoff and Contour Speeds

Sawing is how a tool steel bar is cut to length and how a die block is roughed out before any other machining. A band saw does it with a thin, continuous blade, and the published speeds for tool steels are set grade by grade rather than for tool steel as one material. The tables below give those speeds for cutoff sawing and for contour sawing, with the blade materials and band widths that go with them.

What a band saw will cut

A power band saw works best in the hardness range of about 180 to 250 HB. Steels up to about 400 HB, and some free-machining steels up to 450 HB, can still be sawed, but only at reduced cutting rates. Band sawing uses a thinner blade than hacksawing or circular sawing and cuts a kerf of about 1.6 mm (1/16 in.) against 7.9 and 9.5 mm for the other two, so less power is needed and less material is turned into chips.

On a contour machine the blade can also follow a shape rather than a straight line, which is why a band saw is often used to rough out a die outline in sections instead of milling it. The speeds that follow are starting points from published practice, and the grade of the steel and the thickness of the section both move them.

Cutoff band sawing speeds by grade

In cutoff sawing the band makes a straight cut only, and the source table is built on a 25 mm (1 in.) wide high-speed steel band cutting scale-free rounds 75 to 125 mm (3 to 5 in.) in diameter. It holds for solid bar stock up to 450 mm (18 in.) thick. Heavy scale on the work calls for a lower band speed and a lower cutting rate and it shortens band life, especially when thin material is being cut.

Cutoff band sawing of tool steels, reproduced from Table 4 of Sawing, in ASM Handbook, Volume 16, Machining. The source data are based on a 25 mm (1 in.) wide high-speed steel band in regular tooth form, except for hook tooth form on metal thicker than about 250 mm (10 in.), raker set, cutting scale-free solid bar stock up to 460 mm (18 in.) thick with a cutting fluid. D2, D3 and D7 are cut dry. Band life is given for a 3 m (10 ft) band and is proportionate for other band lengths.

The spread across the grades is the whole point of the table. W1 and O1, the low-alloy water and oil hardening grades, saw at 67 to 55 m/min (220 to 180 sfm). D2 and D3 drop to 37 to 27 m/min (120 to 90 sfm) and D7 to 27 to 18 m/min (90 to 60 sfm), and the three of them are cut dry rather than with a fluid. The high-speed grades sit between the two ends, and T15 is the slowest of the whole group at 23 to 15 m/min (75 to 50 sfm).

Band life follows the same order and is quoted for a 3 m (10 ft) band. W1 and O1 return about 1.9 and 1.6 square metres of cut area, D2 and D3 about 1.0, and D7 only 0.55. A shop cutting D7 every day will change bands several times as often as one cutting W1.

Contour band sawing speeds by grade and thickness

Contour sawing follows a shape, and the speed is set by the thickness of the section being cut as well as by the grade. The same grades are listed at three thickness ranges, first with carbon steel bands and then with high-speed steel bands, and the table makes the advantage of the high-speed band clear. On the thin range W1 moves from 45 m/min (150 sfm) to 82 m/min (270 sfm), and O1 from 45 to 80 m/min.

Carbon steel bands are recommended for contour sawing of tool steel only in the softest grades and only where the machine lacks the power and the fluid supply for a high-speed band. On the harder grades the carbon band values fall away, and the D grades are already down to 30 m/min (100 sfm) on the thin range.

Carbon steel bands

Contour band sawing of tool steels by stock thickness, reproduced from Table 7 of Sawing, in ASM Handbook, Volume 16, Machining. Speeds are in m/min with sfm in brackets. The carbon steel band values use regular tooth form at 14 pitch and minimum feed force for the thin range, regular tooth form at 6 to 8 pitch and average feed force for the middle range, and hook tooth form at 3 pitch and maximum feed force for the thick range. The high-speed band values are also suitable for welded-edge high-speed steel bands, and use regular tooth form at 10 pitch and minimum feed force, then regular tooth form at 6 pitch and average feed force, then hook tooth form at 3 pitch and maximum feed force. D2, D3 and D7 are sawed dry, and the footnoted grades in the source run at the heavier feed force for each range.

High-speed steel bands

Band material and blade selection

Bands are carbon steel or bimetallic. The bimetallic, or composite, type carries a high-speed steel cutting edge welded to a high tensile steel back, and these welded-edge bands have replaced both the carbon steel bands and the old solid high-speed steel bands on production machines. The cutting edge of a welded-edge band is usually M2, Matrix 2 or M42 high-speed steel, and the three are chosen by the work rather than by the machine.

Band saw blade composition, reproduced from Table 2 of Sawing, in ASM Handbook, Volume 16, Machining. Heat resistance is the temperature at which the cutting edge retains its hardness. The body of every welded-edge band is a high tensile alloy steel back running at 40 to 47 HRC after the teeth are hardened.

M2 with a tooth tip hardness of 64 HRC is recommended for very thin walled steel tubing below 1.5 mm (0.060 in.) and for very small bar. For carbon and alloy steels the source advises Matrix 2 at 67 HRC, or a variable pitch blade with Matrix 2 edges. For heat treated steels, stainless steels and superalloys an M42 tooth tip at 69 HRC is advised, and M42 bands are the ones to use when sawing diameters of 100 mm (4 in.) or greater. M42 blades for that work should have a positive rake rather than the standard 90 degree rake, for easier penetration. Bands with tungsten carbide edges brazed or welded to an alloy steel back are kept for the hardest work, such as nickel and cobalt base heat resistant alloys and sections thicker than 150 mm (6 in.), because they have low shock resistance but the highest hot hardness.

Band width for a given radius

On a contour machine the band has to follow the radius without binding, and the width of the band sets the smallest radius it can cut. A wider band carries more beam strength and holds a straighter line, so the widest band that will still cut the radius is the one to use. In cutoff work, where every cut is straight, bands 25 to 125 mm (1 to 5 in.) wide are preferred because they take the higher loading.

Recommended band width for the contour sawing of various radii, reproduced from Table 3 of Sawing, in ASM Handbook, Volume 16, Machining.

Grades and stock

The two high carbon high chromium grades in the tables are the ones most shops saw from bar, and the speeds for cutting and machining them are set out on the D2 tool steel machining guide. The air hardening grade and its sawing and machining behaviour are on the A2 tool steel machining and fabrication guide.

For the chromium hot work grades the sawing figures sit alongside the hardening and working hardness on the H13 tool steel machinability page. Where the work moves from the saw to a cutting tool, the per-grade turning, milling and drilling speeds are collected on the tool steel cutting speeds and feeds page.

The finish a saw leaves is well above what a ground surface holds, and the values are listed by process on the surface roughness chart. After heat treatment the same grades are ground rather than sawed, and the wheel choice by grade is on the tool steel grindability and grinding wheel selection page.

Before you use these values

This page is a reference summary of published practice and it is not an Aobo Steel specification. The speeds are reproduced from the source tables, and a different band, tooth form, machine or bar condition will move them. Final conditions are set on the machine against the material as delivered.

Source: ASM Handbook, Volume 16, Machining, ASM International, 1989.