EB-450 plates are typically cut to size with
flame cutting or plasma cutting. these cutting procedures leave a hardened edge, which in plates 3 inches and over will be considerably harder than the bulk of the plate. If machining at or within about 3/8 inch of these flame cut edges is planned, some shops prefer to allow a larger positive cutting tolerance, e.g. 1/2" over nominal size rather than 1/4" over so that deeper cuts can be taken on the edge miller to get underneath the hardened edge. On flame cut beveled cutting edges, the hardened zone of the flame cut edge is used to great advantage in service. Cutting blade customers typically use
only a light hand grinding to sharpen the beveled edge.
Details on specific machining processes are
given below:
Milling
For optimum metal removal in interrupted machining (i.e.
milling), best results are also accomplished using negative rake,
mechanically clamped, tungsten carbide inserts. Recommended feed rate is 0.003" per tooth. Total cutting rate therefore, equal 0.003 time number of inserts in cutter times rpm. Uniform distribution of feed is working beyond the zone work hardened by the preceding insert.
For plates at hardness of 350 BHN or less, 150 sfm is
reasonable, with slower speeds for higher hardness and higher speeds for lower hardness.
For cutting keyways in material less than 350 BHN hardness,
use a three or four fluted high-speed cobalt end mill. Run at 12 to sfm with 0.003 chip load. Use a good coolant to keep the cutter and steel cool. The great majority of fatigue failures in shafting made from any steel can be traced
back to sharp corners and notches like those found at the base of a square cornered keyway. To greatly increase your shafting life, put a small radius at the corners of the keyway and put a corresponding radius at the corners of the keyway. To greatly increase your shafting life, put a small radius at the
corners of the keyway and put a corresponding radius on the matching corners of the key. Suggested minimum radius is 1/16"
EB-450 is commonly drilled at full hardness following the
general guidelines suggested below:
- Apply positive power feed to produce continuous chip and
avoid work hardening.
- Use a full flow of heavy duty coolant to dissipate heat and lubricate cutting edges.
- Use high speed steel drills modified with cobalt. AWT has had good experience with Cleveland Twist Drill Premium Steel Cobalt (List No. 2440 for taper shank bits and List No. 2013 for chuck mounted bits). Drill bits should be ground so that the included point angle is 140-150 degree, taking care to ensure that the point angle has exact centering. The flute lip should be ground to a 5 degree positive rake with an approximate land width of 1/32 inch. The web should be thinned to approximately 3/32 inch to reduce drill pressure and to minimize work hardening at the drill center.
- For material 444 BHN and harder, cutting speed should be in the range of 6-8 surface feet per minute with a feed rate of 0.004" per revolution. For material 320 to 370 BHN, used 12 to 15 sfm with a feed rate of 0.004" per revolution.
- Drill rigidity is important to successful drilling. Drill rigidity can be enhanced by using
secure set-up and shortened drill bits.
If you have any questions, or need further information
concerning machining of EB-450, please contact Inside Sales, Technical Services or the Machine Shop Supervisor at Astralloy Wear Technology.
Product Information
Product Specifications
Welding Guidelines
Forming
Heat Treating
Cutting
Printable Specs Sheet
