    Single-point tools for turning the austenitic chromium-nickel grades
 must have adequate clearance to avoid work hardening of freshly cut
 surfaces.  The back rake angle should be as large as permissible, to aid in
 breaking of chips.  Chip breakers are helpful, but their design must be such
 that the cutting edges will not be weakened.  Improperly designed chip
 curlers can cause chip crowding and tool damage.  (Example 6, in the article
 "Turning", shows the design of a chip-curler groove in a box tool used for
 turning type 304 stainless).
    In Table 3, the design of single-point tools (made of high speed steel,
 cast alloy and carbide) for turning stainless steels is compared with
 designs for turning plain carbon, alloy and ultra-high-strength steels.
    The use of a cutting fluid is more desirable for machining stainless
 steels than for machining carbon or alloy steels for two reasons:  (a)
 stainless steels are generally less machinable than carbon or alloy steels,
 and (b) the lower heat conductivity of stainless steels increases the need
 for cooling.
    Water-soluble oils (usually in proportions of 1 part oil to 12 to 20
 parts water) and sulfochlorinated cutting oils (having a viscosity of 300
 SUS maximum at 100 F) are the cutting fluids most widely used in machining
 stainless steels.
 ===========================================================================

             Nominal Speeds and Feeds for Turning Stainless Steels
                        With Single-Point and Box Tools

                                   Rough turning (c)        Finish turning(d)
                                   (.150-in. depth)         (.025-in. depth)

                                   Speed (sfm) of:          Speed (sfm) of:

Type of   Condi-      Brinell      HSS    Carbide tools     HSS   Carbide tools
steel     tion(b)     hardness     tools  Brazed   Dispos.  tools  Braz.  Disp.


FM Fer    Ann         135 to 185    150     500     575     170     560     640
FM Mar    Ann         135 to 185    150     500     575     170     560     640
          Ann or CD   185 to 240    140     450     515     160     500     575
          Q & T       275 to 325     70     325     375      80     375     425
          Q & T (e)   375 to 425     40     150     170      50     200     225
FM Aus    Ann         135 to 185     95     400     460     115     450     515
          CD          225 to 275     90     350     400     110     400     460
Ferritic  Ann         135 to 185    110     450     515     130     500     575
Mar(410)  Ann         135 to 185    110     450     515     130     500     575
          Ann         175 to 225    100     400     460     120     450     520
          Q & T       275 to 325     60     250     285      75     300     345
          Q & T       375 to 425     40     150     175      50     175     200
Mar(431)  Ann         225 to 275     70     300     350      85     350     400
          Q & T       275 to 325     55     225     260      80     275     315
          Q & T (f)   375 to 425     40     150     175      50     175     200
Mar(440)  Ann         225 to 275     60     275     315      75     335     385
          Q & T       275 to 325     50     200     230      60     240     275
          Q & T (f)   375 to 425     40     150     175      50     175     200
          Q & T (e)  Rc48 to 52      20     100     115      30     125     140
          Q & T (g)  Rc54 to 56              55      65              70      80
Aus(304)  Ann         135 to 185     80     275     315     100     335     385
          CD          225 to 275     75     250     285      95     300     345
Aus(316)  Ann         135 to 185     70     250     285      90     300     345


 (b) Ann = Annealed   CD = Cold Drawn    Q & T = Quenched and tempered
     Hard = Hardened  N & T = Normalized & tempered
 (c) Feed,.015 ipr
 (d) Feed, .007ipr
 (e) Feed, high speed steel and carbide, .010 ipr for roughing, .005 ipr for
       finishing
 (f) Feed, high speed steel only, .010 ipr for roughing, .005 ipr for
finishing
 (g)  Feed, carbide only, .005 ipr for roughing and finishing
