Режущие и зажимные инструменты Hoffmann Group 2026 - страница 374

GBP 57 Band-saw blades Clamping of the material Clamp the material so that the band saw blade cuts with as little vibration as possible. When cutting material bundles, tack weld the ends together if necessary. This increases the cutting performance and the blade life. Running in new blades At normal feed rates the sharp teeth of a new blade dig very aggressively into the material. Therefore reduce the feed rate by 50 % and the cutting speed by 70 % for the first cuts. After the blade has cut an area of about 400 cm², slowly increase the feed rate to the optimum value. The working life of a band-saw blade is to a large extent dependant on controlled running in! Coolant The coolant helps to prevent the saw tooth and workpiece from overheating and to take the chips away from the cutting point. Coolant is normally applied when sawing all steels. Cast iron on the other hand is usually sawn dry. Cutting oil gives good results when sawing case-hardening steels, higher alloyed tool steels, heat-treatable steels, stainless steels and titanium. Micro-spray systems give good results when sawing pipes and profiles. In this connection, note the need for a good chip clearance brush. Cutting speed and feed rate The cutting speed (blade speed) depends on the tensile strength, type and cross-section of the material to be sawn. The greater the tensile strength, the lower the cutting speed should be. Smaller cross-sections can be sawn at higher speeds than larger cross-sections. Thin-walled pipes and profiles, and sharp edges, are sawn at low feed rates; the feed rate (pressure) should be kept as constant as possible. Material Cutting speed in m/min bi-alfa-cobalt (M42) General purpose steels / machining steels 80 − 90 Case-hardening steels / heat-treatable steels 45 − 75 If vibration occurs adjust the cutting speed (m/min) Unalloyed tool steels / roller bearing steels 40 − 60 to marginally faster or slower. Alloyed tool steels / high speed steels 30 − 40 As the blade becomes more blunt increase the feed rate Stainless steels 20 − 35 somewhat. Heat resistant steels 15 − 25 High-temperature alloys Assessing a cracked weld on the blade Straight rupturing of the weld after a short period of use indicates a manufacturing fault. Breaking of the weld after longer term use, the crack propagating as a zigzag, is an overload fracture. Tooth pitches Tooth pitch recommendations for solid material: Tooth pitch recommendations for pipes: Recommendation: also state the rake angle. For Wall thickness Pipe outside⌀ D (mm) Variable pitch teeth Rake angle 17 material thickness < 25 mm 10/14 0° S (mm) 20 40 60 80 Tooth pitch Z (tpi) 100 120 150 200 300 500 15 − 40 mm 8/12 0° 2 14 10/14 10/14 10/14 10/14 8/12 8/12 8/12 8/12 5/8 25 − 50 mm 6/10 0° 3 14 10/14 10/14 8/12 8/12 8/12 8/12 6/10 6/10 5/8 35 − 70 mm 5/8 0° 4 10/14 10/14 8/12 8/12 8/12 6/10 6/10 5/8 5/8 4/6 40 − 90 mm 5/6 10° 5 10/14 10/14 8/12 8/12 6/10 6/10 5/8 4/6 4/6 4/6 50 − 120 mm 4/6 0° / 10° 6 10/14 8/12 8/12 6/10 6/10 5/8 5/8 4/6 4/6 4/6 50 − 150 mm 4/5 10° 8 10/14 8/12 8/12 6/10 5/8 5/8 4/6 4/6 4/6 4/6 80 − 180 mm 3/4 0° / 10° 10 8/12 6/10 5/8 4/6 4/6 4/6 4/6 4/6 4/5 130 − 350 mm 2/3 10° 12 8/12 6/10 4/6 4/6 4/6 4/6 4/6 4/6 4/5 150 − 400 mm 1.5/2 10° 15 8/12 6/10 4/6 4/6 4/6 4/5 4/5 4/5 4/5 200 − 600 mm 1.1/1.6 10° 20 4/6 4/6 4/6 4/6 4/5 4/5 4/5 3/4 > 500 mm 0.75/1.25 10° 30 4/6 4/6 4/5 4/5 4/5 4/5 2/3 50 4/5 3/4 2/3 2/3 Variable pitch teeth 3/4 0° and 4/6 0° are suitable only for pipes, profiles and girders, not for solid material. Variable pitch teeth 10° and the band qualities 80 3/4 2/3 2/3 Bi-Alfa Master No. 174050 are recommended for sawing solid material of > 100 2/3 1.5/2 high-alloy and long-chipping materials. For thin-walled pipes (up to approx. 8 mm wall thickness) use preferably tooth pitches with 0° rake. Rule of thumb: There should be at least 3 teeth in contact with the component. Blade width The largest blade width permissible on the machine should be selected, in order to achieve sufficient stability at higher feed rate forces. Radius (mm) 3 8 15 30 38 65 100 140 When sawing curves, the blade width depends on the smallest radius to be cut (see table). Blade width (mm) 3 5 6 8 10 13 16 20 374