TECHNICAL GUIDE MILLING AND TURNING

Transcription

1 TECHNICAL GUIDE MILLING AND TURNING

2 INTRODUCING OUR NEW PRODUCT NOMENCLATURE BISALLOY has recently introduced a new product nomenclature. The following table details the grade equivalents. Note: Only the designation has changed not the product Previous Name BISPLATE 60 BISPLATE 70 BISPLATE 80 BISPLATE 100 BISPLATE 80PV BISPLATE 320 BISPLATE 400 BISPLATE 450 BISPLATE 500 BISPLATE 600 BISPLATE HIA - Class 2 BISPLATE HIA - Class 1 BISPLATE HTA BISPLATE UHT BISPLATE HHA BISPLATE UHH New Name 60 steel 70 steel 80 steel 100 steel 80 Pressure Vessel steel 320 steel 400 steel 450 steel 500 steel 600 steel BISALLOY Armour RHA300 steel BISALLOY Armour RHA360 steel BISALLOY Armour HTA400 steel BISALLOY Armour UHT440 steel BISALLOY Armour HHA500 steel BISALLOY Armour UHH600 steel 02 BISALLOY is a registered trade mark of Bisalloy Steels Group Limited, ABN

3 MILLING AND TURNING BISALLOY STEEL Milling and Turning recommendations MILLING Milling operations can be performed satisfactorily on all BISALLOY steel grades; utilisation of indexable carbide cutters is recommended. In many situations, the milling operation entails the dressing of a flame cut edge, and then subsequent bulk milling of material to the desired surface finish and dimensional tolerance. Care must be taken to make a first cut sufficiently deep to remove the heat affected zone of the flame cut edge. Cutters must be sufficiently robust to take this heavy loading. In such circumstances it is desirable that, due to the high hardness MILLING adjacent to the flame cut surfaces, cutter speeds and feed rates for initial milling should be reduced to 40-50% of the speed normally used when milling plain carbon steel. The importance of adequate preheating prior to flame cutting and slow cooling after cutting to minimise edge hardening is again emphasised. Speed and feed rates may be increased somewhat for subsequent bulk milling to 50-75% of the settings used for plain carbon steel. MILLING RECOMMENDATIONS Table 1: BISALLOY steel GRADE ISCAR INSERT GRADE SURFACE SPEED Vc m/min FEED/TOOTH Fz 60 steel IC steel IC steel IC steel / 320 steel IC steel IC steel IC steel IC steel IC Notes: These recommendations are given as a guide only, and are based on stable working conditions. It is suggested a 45 deg. Approach angle or a round insert facemill be used. For quick metal removal a very successful cutting method is the use of FF Fast Feed Milling Cutters by ISCAR. Feed rates are dependent on geometry selected TECHNICAL GUIDE - TURNING AND MILLING RECOMMENDATIONS 03

4 TURNING AND MILLING BISALLOY STEEL Milling and Turning recommendations continued... AVOID VIBRATIONS Indexable inserts are sensitive to vibrations. These can be avoided or reduced by observing the following. When turning or milling gas cut edges the cutting depth should be at least 2 mm to cope with the hardness and unevenness of the edge. Figure 1: Figure 2: Undirectional milling milling Normal width Opposed milling Small Small width width Showing the direction of milling Showing the eccentricity milling cutter OTHER MILLING REQUIREMENTS Firm clamping of the workpiece. Use cutters with the smallest possible gap between the teeth. Machine stability permitting, unidirectional milling is preferable, see figure 1. If a large cutter is used for the milling of small areas, place the milling cutter eccentrically to get as many teeth as possible operating, see figure 2. Avoid, if possible, the use of a universal cutterhead which generally causes weakening of the power transmission and the tool holder. 04 BISALLOY is a registered trade mark of Bisalloy Steels Group Limited, ABN

5 TURNING All BISALLOY steel grades, including those with hardness in excess of 400 HB can be turned satisfactorily with carbide tooling, provided spindle speeds and feed rates are reduced from those normally employed when carrying out similar machining operations on plain carbon steel. Reductions of 50-70% in spindle speed and up to 50% in feed rate may be necessary, depending on the hardness of the component being machined. High speed tools are not recommended. As an example, the following settings have been found to give satisfactory results when turning cylindrical workpieces of 25 mm diameter from the various BISALLOY grades. With increases in stock diameter, spindle speeds will obviously need to be decreased. OTHER TURNING REQUIREMENTS Firm clamping of the workpiece. Avoid long overhangs for both workpiece and tool holder. Use correct tip radius: too large a tip radius, combined with insufficient clamping, causes vibrations. Small setting angles also can cause vibrations. Bisalloy Steels wish to thank ISCAR Australia Pty Ltd for information pertaining to milling and turning contained in this publication. TURNING RECOMMENDATIONS Table 2: BISALLOY steel GRADE 60 steel 70 steel 80 steel 100 steel / 320 steel 400 steel 450 steel 500 steel 600 steel ISCAR INSERT GRADE SURFACE SPEED Vc m/min IC IC IC IC8150/IC IC8150/IC IC IC IC Notes: These recommendations are given as a guide only and are based on stable working conditions. The geometry of the inserts used will be dependent on the operation. Insert Geometry, Nose Radius and Chipbreaker will determine the depth of cut and feed rate TECHNICAL GUIDE - TURNING AND MILLING RECOMMENDATIONS 05

6 BIS TECHNICAL GUIDE - TURNING AND MILLING Bisalloy Steels Group Limited BISALLOY is a registered trade mark of Bisalloy Steels Group Limited, ABN