Stellite Saw Blades - Detailed information

The tools affect the result of working with thin cutting frame saws on 99%. If the machine is in a good technical condition, the result is affected by two main factors:

  • preparation of material – it is necessary so that the dimensions of cut wood blocks come up to the kind of guide systems in the machine
  • accurate preparation and choice of saw blades

Choice of a Stellite Saw Blade

Point No.1 – use the shortest possible saw blades for a given wood height (see Table No.1). The shorter saw blades are the high accuracy of cut is ensured. Generally the following Table No.1:

Cutting Height to 80 mm to 120 mm to 150 mm to 200 mm to 250 mm
Saw Blade Length 380 mm 420 mm 455 mm 505 mm 555 mm

Point No.2 – The thickness of body of the saw blade depends on the cuting height. Generally the following Table No.2:

Cutting Height to 80 mm to 120 mm to 150 mm to 200 mm to 250 mm
Body Thickness 0.5 - 0.8 mm 0.6 - 0.9 mm 0.7 - 0.9 mm 0.7 - 0.9 mm 0.7 - 1.0 mm

Point No.3 – The greater cut height = the thicker kerf. Generally the following Table No.3:

Cutting Height to 80 mm to 120 mm to 150 mm to 200 mm to 250 mm
Saw Kerf 0.9 - 1.25 mm 1.00 - 1.4 mm 1.05 - 1.4 mm 1.10 - 1.4 mm 1.15 - 1.4 mm

Point No.4 – Chips, not dust, must be created during cutting. The thickness of a chip can be defined by following formulas:

z = 0,6 * (H + h) / t

  • z = number of teeth
  • H = frame stroke (mm)
  • h = cutting height (mm)
  • t = pitch (mm)

Calculation of chip thickness:

s = u / (n * z)

  • s = chip thickness (mm)
  • u = feed speed (mm/min)
  • n = machine RPM (1/min)
  • z = number of teeth

Orientation values of chip thickness – Table No.4:

Chip Thickness 0.15 - 0.25 mm 0.07 - 0.1 mm 0.03 - 0.05 mm
Surface Roughness rough middle fine

Point No.5 – the element limiting the machine performance is a saw blade. If you intend to work using high feed rates and when a rough machining is sufficient for your requirements, apply saw blades of the body thickness greater by a minimum of 0.1 mm than that as stated in Table No.2.

The edge geometry and micro geometry

Edge is the wedge-shaped part of a tool. The main edge - lip - is formed by the tool's face and flank. Penetration of surfaces of the face and flank is called a lip. Penetration of surfaces of the face and flank forms an ideal edge 1. Actual edge 2 is formed by penetration of uneven surfaces of the tool's face and flank. Tool manufacturer's endeavour is to draw the actual edge nearer to the limit of the ideal edge.

Terminology

  • Face of the tool no. 4 is the surface a chip slips along.
  • Flank of the tool no. 3 is the surface turned to the cutting area.
  • Lateral edges are formed by the tool face and its lateral surfaces.
  • The flank angle α is formed by the face plane and basic plane.
  • The face angle γ is formed by the face plane and basic plane.
  • The edge angle β is formed by the face plane and flank plane.
  • The angle cut δ = α + β
  • The face tapering angle ε releases the tool in the direction perpendicular to its lengthwise axis. It is measured in projection to the basic plane.
  • The face tapering angle ε' releases the tool in the direction of the main cutting movement. It is measured in projection to the cutting plane.

Edge dulling

Edge dulling is a gradual change of the edge micro-geometry under cutting process – edge ceases to have its cutting ability. Cutting edge life is the period for which the edge retains its capability to cut before a change in the edge shape reaches the determined limit. This limit shows up when tolerance ranges of the cut lamellas are exceeded. The cutting edge life depends on hardness of the material to be cut, on its machining, purity, and humidity. The cutting edge life can be shortened substantially when the feed is too slow, that is, slower than the listed values of thickness for finish-machining – see Table No.4 or, on the other hand, when the feed is too fast – faster than a chip thickness for rough machining. When this occurs, the saw blade becomes unstable even with its slightest dulling.

Stellite Saw Blades grinding

For sharpening, we recommend to use our CNC grinding machines. Advantage of this machine consists not only in its accurate guidace of the saw blade but also in efficient cooling the blade during its grinding by water emulsion. The saw blades are ground individually one tooth after another. Face and back edge can be ground in one passage through the machine, however, the best results are achieved by two cycles per tooth. Recommend values of angles – Table No.5:

  γ [°] α [°]
Hard Wood 6 - 10 8 - 12
Soft Wood 10 - 15 12 - 17

Angles of the face edge ε and ε' are not ground. These angles are made during the production of saw blades. The value is 2° - 2.5°, accuracy ranges in ± 10´.

In the course of grinding process the shape and predetermined angles of the face and back edge must be followed. We do not recommend to change the shape and angles. Unskilled changes in geometry can cause serious damage of the tool.

Stellite Saw Blades rolling

The purpose of rolling of the saw blades is to introduce pre-stressing into the rear part of a saw blade body. When saw blades are being stretched, owing to the rolling process, the stress is transferred to the front – tooth part of a blade. Rolling process intensity should be checked using a steel ruler. Due to this rolling process, the rear blade body part is extended so that when the saw blade is put to the ruler, the blade rocks slightly. The oscillation deviation should be in the range of recommended values – see Table No.6:

Saw Blade Length 380 mm 420 mm 455 mm 505 mm 555 mm
Difference Y (mm) 0.3 - 0.5 0.4 - 0.6 0.5 - 0.7 0.7 - 0.9 0.8 - 1.0

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