Blade Structure, Types of Blades, Teeth Shape

Blade Structure

For non--ferrous metals, it is common to use circular saws with brazed hard metal HM cutting edge, consisting of a disc made of alloy tool steel (71Cr1) on which the shape of the teeth and the seats for the cutting edges are made of Widia K10. These saws have shown excellent wear resistance but low resistance to impact, which is in any case a minor problem with non- ferrous materials.

Figure 14

”BW” TYPE SHARPENING DIN 1838--UNI 4014

Coarse toothing with teeth alternately raked to the right and left.

Toothing generally used on cutting-off machines for cutting ferrous and alloy materials with tubular and profiled sections.

Table 2

Types of Blades

The blades fitted to the FK350 and FK350-2SX have dimensions 350 x 32 x 2.5 mm and are of HM hard steel type since the machine is to be used for cutting non-ferrous materials. In addition to the size and pitch of the teeth, however, the blades also have different geometric characteristics in accordance with their particular use:

tooth cutting angle – may be negative or positive

tooth sharpening –may be BW with an alternate raked tooth or C with a roughing tooth raked on both sides and a non--raked finishing tooth

tooth pitch – the distance between the crest of one tooth and the crest of the next tooth (tooth pitch = T)

Teeth Shape

”C” TYPE SHARPENING (HZ)

Coarse toothing with roughing tooth raked on both sides and non--raked finishing tooth. The roughing tooth is about 0.3 mm higher.

Coarse toothing with roughing tooth and finishing tooth. Used in saws with pitch greater than or equal to 5 mm for cutting ferrous and non-ferrous materials with solid or solid-profiled

sections.

Figure 15

POSITIVE AND NEGATIVE CUTTING ANGLES

The cutting angle may vary from positive to negative depending on the cutting speed, the profile and the type of material to be cut.

Figure 16

A positive angle determines better penetration of the tool and hence lower shear stress and greater ease of sliding for the swarf over the cutting edge. On the other hand, the cutting edge has lower mechanical resistance, so as the breaking load of the material to be cut increases, the cutting angle decreases from positive until it becomes negative so as to offer a cutting edge with a larger resistant section.