THE UN IV ER SIT Y OF MI CHI GAN COLLEGE OF ENGINEERING Department of Mechanical Engineering Progress Report A COMPARATIVE EVALUATION OF A MODIFIED MEDIUM, CARBON GRADE, FREE-MACHINING STEEL AND TWO SIMILAR STANDARD GRADES J. CO Mazur ORA Project 01197 under contract with: THE BETHLEHEM STEEL COMPANY BETHLEHEM, PENNSYLVANIA administered through: OFFICE OF RESEARCH ADMINISTRATION ANN ARBOR July 1965

TABLE OF CONTENTS Page LIST OF TABLES v LIST OF FIGURES vii ABSTRACT ix INTRODUCTION 1 TEST RESULTS 3 Chip Formation 3 Tool Life 3 Surface Finish 8 CONCLUSIONS 10 Chip Formation 10 Tool Life 10 Surface Finish 10 iii1

LIST OF TABLES Table Page I. Test Material Composition and Properties 1 II. Effect of Tool Shape on Tool Life —HR Steel 3 III. Hot-Rolled Steels-Tool Life and Surface Roughness Data 4 IV. Cold-Drawn Steels-Summary of HSS Tool Life and Surface Roughness Data V. Hot-Rolled Steels-Summary of Carbide Tool Life and Surface Roughness Data 6

LIST OF FIGURES Figure 1. Chip formation vs. feed. 2. Chip formation vso cutting time, 3. Tool life curves for hot-rolled and cold-drawn steels as plotted from HSS results in Tables III and IV, respectively. 4. Carbide tool life curves on hot-rolled materials as plotted from results in Table V. 5. Axial surface roughness vs. feed and tool shape at 100 and 200 fpm on H.R. steels. 6. Peripheral roughness of same surfaces represented in Fig. 5. 7. Fax film reproductionsof some of the surfaces whose roughness values are shown in Figs. 5 and 6. 8. Surface roughness vso time on hot-rolled steels with HSS tools at various velocities. 9. Fax film reproductions of surfaces produced at a velocity of 150 fpm with cutting conditions listed in Fig. 8. 10. Fax film reproductions of surfaces produced at 258 fpm with cutting conditions listed in Fig-. 8. 11. Comparison of surface roughness of hot-rolled and cold-drawn steels at a velocity of 258 fpm under cutting conditions listed in Fig. 8. 12. Fax film reproductions of surfaces produced on cold-drawn steels at 258 fpm under cutting conditions listed in Fig. 8. 13. Surface roughness vs. time on hot-rolled and cold-drawn steels based on velocities which gave comparable tool life. 14, Surface roughness vs. time on hot-rolled materials with carbide tools. 15. FaX film reproductions of surfaces of the Cl144 steels under conditions and values represented in Fig. 14co 16, Fax film reproductions of surfaces on hot-rolled materials under conditions and values represented in Fig. 14b. vii

ABSTRACT This investigation, initiated by the Bethlehem Steel Company, was a comparative study of the turning qualities of a modified analysis C1144 and two standard grades with very similar properties, C1144 and C1141. Chip formation, tool life, and surface finish were the machinability criteria for the evaluation. Viewing the results of this investigation as a whole, the standard and the modified C1144 steels are both rated higher than the C1141 in all machinability criteria. The differences between the two C1144 steels, however, did not show any consistent trend in favor of either. The relative behaviors are sensitive to cutting conditions, cutting time, evaluation techniques, and interpretation. Differences in chip formation and surface finish are erratic and are of more academic than practical significance. On the other hand, tool-life results warrant more consideration, for the materials go through a complete reversal of tool-life behavior. The standard C1144 holds an edge with high-speed steel cutting tools, particularly at lower rates. With carbide cutting tools, however, the modified C1144 steel can run as much as 50% faster with comparable tool wear and surface-finish results. ix

INTRODUCTION The bulk of the work material used in this investigation was in the hotrolled condition. A very small sampling of cold-drawn bars of each grade was also made available. The chemical analyses and properties of these materials, as furnished by the Bethlehem Steel Company, are listed in Table I. TABLE I TEST MATERIAL COMPOSITION AND PROPERTIES* 'Grade Composition C Mn P S Si C1144 0.43 1.50 0.016 0.31 0.22 C1144 modified 0.45 1.22 0.015 0.20 0.13 C1141 0.41 1.43 0.017 0.11 o.o8 Bar Grade and Mechanical Properties Diameter, Condition Y.S.,** T.S., El.,*** R.A., BHN in. psi psi. % C1144 3-7/16 H.R. 52,500 98,400 19.0 35.0 201 3-3/8 C.D. 98,600 107,000 14.5 38.4 217 C1144 Modified 3-1/2 H.R. 50,200 96,300 21.5 41.9 201 3-7/16 C.D. 99,500 108,100 15.5 36.6 223 C1141 3-9/16 H.R. 50,500 98,100 19.0 37.8 201 3-1/2 C.D. 98,300 105,400 14.5 42.3 217 *Supplied by Bethlehem Steel Company. **0.2% offset. ***2-in. gage length. The test program was limited to conventional turning with high-speed steel (HSS) and carbide cutting tools at what were considered to be representative cutting conditions. All tests were conducted dry on a 15 hp, 14x30 American "Pacemaker" lathe equipped with a variable speed drive and capable of a top speed of 2000 rpm. The HSS tools were standard 1/2 in. square tool bits of a single grade, Latrobe's "Electrite No. 1," a T-1 high-speed steel.

The carbide tools were square, positive rake, throw-away inserts held in a standard 6~ positive rake ':Carboloy"v holder with a 15~ side cutting edge angle. Two grades were used; Carboloy grade 350, 3/4 in. square x 1/16 in. nose radius9 and Carboloy grade 370, 1/2 in. square x 1/32 in. nose radius. Primary emphasis was placed upon tool life and surface finish, with secondary emphasis upon chip formation. Tool failure criteria were established as total failure for HSS tools and 0.015 in, flank wear for carbide tools. Sarface roughness was measured with a Micrometrical Manufacturing Company "Profilometer at the beginning and end of a test run, and at varioLus intervals in between. Chips were collected whenever chip form changes occurred. Because of a limited supply of material, the majority of the tests were confined to HSS applications with a tool shape of 8, 14, 6, 6, 6, 15, 3/64, at a depth of cut of 0.070 in. (constant for all tests) and a feed of o00oo65 ipr. However, shorter test series, including some sharp tool tests, were conducted to find the effects of tool shape and feed upon the test criteria. Carbide cutting speeds onthe Cl14)4 steels were mutich higher than articipated, and required speeds could not be reached on thle r.acchine with the given bar diameters arid keep tool lives within bouxnds of the quantity of material available. Therefore, it was necessary to stop a rumber of tests short of the preferred flank wear at failure.

TEST RESULTS CHIP FORMATION Chip formation characteristics were noted with respect to four variables: tool shape, cutting velocity, feed, and cutting time. In each case, the C1144 materials demonstrated a greater inherent ability to produce small, broken chips than did the Cl141. The C1144 is rated slightly higher than the modified grade, particularly at light feeds and low velocities. At heavy feeds, or high velocities, the two gave very similar results. Typical behavior is illustrated in Figs. 1 and 2 for tool shape 8, 14, 6, 6, 6, 15, 3/64, which was the basic shape for tool life tests. Sharp tool tests, similar to those represented in Fig. l,were repeated with tool shapes 8, 14, 6, 6, 6, 15, 1/8 and 8, 8, 6, 6, 6, 0, 0.020. The larger nose-radius tool gave larger chips and accented even more the differences between the two grades of steels. The more severe shape of the 0.020 nose-radius tool reduced the differences. At higher velocities, regardless of tool shape, all three materials produced similar, undesirable chips when sharp tools were used, as may be noted for zero time in Fig. 2. However, with continuous cutting short chips were produced from each material after the initial stages of tool wear. The C1144 steels hold the advantage in that shorter time intervals are required. Cold drawing did not materially affect chip formation characteristics. TOOL LIFE Tool-life results gave the most distinguishable differences among the three work materials, and yet were more affected by cutting conditions, leading to a positive and complete reversal of behavior of the two C1144 steels with HSS and carbide cutting tools. The results of all tests are tabulated in Tables II, III, IV, and V. Many of these results have been plotted in Fi'gs. 3 and 4. TABLE II EFFECT OF TOOL SHAPE ON TOOL LIFE-HR STEEL Operation: Turning Velocity: 250 fpm Tool Material: T-l, HSS Depth of Cut: 0.070 in. Tool Shape: As indicated Feed: 0.0065 ipr Tool Life, min Tool Shape C1144 C1144 Cll4l Modified 8, 14, 6, 6, 6, 15, 3/64 27.57 12.62 6.32 8, 8, 6, 6, 6, 15, 0.020 20.26 7.45 1.70 8, 8, 6, 6, 6, 0, 0.020 5.49 1.32 0.65

TABLE III HOT-ROLLED STEELS-TOOL LIFE AND SURFACE ROUGHNESS DATA Operation: Turning Tool Material: T-l, HSS Fluid: Dry Tool Shape: 8, 14, 6, 6, 6, 15, 3/64 Depth of Cut: 0.070 in. Velocity, Tool Life, min Axial Surface Roughness, in. rms fpm C1144 C1144 C1141 C1144 C1144 C1141 Modified Modified Feed: 0.0065 ipr 357 0.13 305 2.53 60-90* 302 1.45 60-85 300 3.47 60-130 294 6.13 0.79 0.97 80-150 110-145 80-95 5.42 0.99 70-140 120-140 8.10 90-135 285 2.70 1.45 80-110 70-80 281 11.43 4.00 1.42 75-190 70-85 11.07 4.39 70-95 276 8.91 70-130 270 5.05 90-120 265 14.80 6.34 2.60 90-110 75-125 100-150 260 20.28 258 22.57 7.26 0.81 See Fig. 8 11.70 251 27.57 12.62 6.32 75-230 100-125 90-115 244 14.61 80-110 240 N.F.** 19.70 6.21 See Fig. 7 230 50.67 16.15 12.05 95-110 90-130 90-130 215 31.90 30.76 100-140 90-120 205 97.25 79.75 95-140 80-375 200 N.F.** N N.F N.F.** See Fig. 7 150 N.F.** N.F.** N.F.** See Fig. 7 Feed: 0.0208 ipr 450 170 0.35 45 (75)*** 130 4.1 3.42 169 -400o 300-500 240-300 (40-go90) 60-go90) (80-80) 200-300 400-500 150-300 (70-110) (55-70) (80-150) *Initial roughness —roughness just before failure. Peripheral roughness not recorded on most tests. **No failure. Surface finish test. Stopped at 25 min. ***Peripheral roughness in parentheses. 1,

TABLE IV COLD-DRAWN STEELS-SUMMARY OF HSS TOOL LIFE AND SURFACE ROUGHNESS DATA Operation: Turning, dry Tool Material: T-l, HSS Depth of Cut: 0.070 in. Tool Shape: 8, 14, 6, 6, 6, 15, 3/64 Feed: 0.0065 ipr Surface Roughness vs. Time,,lin. rpm Velocity, Life, 1144 C1144 Modified C1141 fpm I11 C l 1 4 9 16 1 4 9 16 1 4 9 16 fpm c1144 M14 dfidC1141 Begin i 4 9 i Failure Begin i 9 Failure Begin 9Failure Modified mi min min min min min min min min min min min 40 50 60 330 1.34 4 50 6 (25)* (30) (30) 300 4.56 60 70 80 100 (25) (25) (35) (40) 55 65 70 289 2.73 (25) (25) (35) 65 75 80 95 (25) (25) (40) (30) 80 85 o100 110 (70) (65) (90) (100) 270.98 2.2 0.70 95 95 90 90 90 70 70 110 (50) (35) (45) (50) (55) (35) (40) (35) 68.56 100 100 110 110 110 70 70 100 120 (50) (60) (80) (80) (85) (30) (25) (55) (60) 257 17.25 8 70 75 90 11o 130 140 60 70 75 95 90 (50) (45) (60) (70) (90) (95) (30) (25) (25) (30) (40) 65 80 90 oo100 110 100 110 120 (35) (35) (60) (70) (75) (40) (40) (80) 245 23.22 50 55 70 80 110 120 (3o) (30) (40) (45) (50) (60) 120 150 160 235 1.92 (95) (80) (90) 70 90 100 100 233 8.(35) (50) (60) (45) 80 90 100oo 100 115 231 15.29 (40) (45) (60) (65) (55) 60 65 lO0 1lO ll O l O1 (30) (35) (45) (55) (65) (65) *Numbers in parentheses represent surface roughness around the periphery. Others represent axial roughness perpendicular to feed marks.

TABLE V HOT-ROLLED STEELSmSUMMARY OF CARBIDE TOOL LIFE AND SURFACE ROUGHNESS DATA Operation: Turning, dry Depth of Cut: 0.070 in. Carboloy Grade 350 Carboloy Grade 370. 0t 6~ 11t ~ 15~ 15, 1/16 0, 6, 11! 5, 15, 15~ 1/32 Feed: 0.006~ ipr Feed: 0.0168 ipr Feed: 0.006~ ipr Cl144 Cl144 Cl141 Cl144 01144 Cll41 Cl144 Cl144 Cll41 Modified Modified Modified Velocity, 1495 912 1725 1460 1425 905 1700 1530 1310 l190 l140 995 900 840 775 900 900 1310 900 1300 1400 605 912 900 910 905 900 900 f~m: Total Cutting 6.10 ll.30 11.50 2.92 12.27 10.87 3.21 2.86 3.50 5.50 6.10 6.68 10.30 7.50 14.50 6.56 7.20 3.67 6.30 2.84 2.00 20.18 14.32 18.84 11.65 19.62 20.53 6.97 Time~ rain: Flank Wear, in.:.016.0046.0154.0158.0038.0052.0041.0153 Tool Life, 10.70......... 2.00 2.50 3.40 5.40 5.90 6.90 9.50 7.40 13.70...... 3.40 6.20 2.40 1.9 --- 13.95 18.20......... 6.2 rain: 5.40 --- Oh ~egin 55 85 140 70 105 100 85 70 90 50 140 75 70 65 60 220 170 180 200 100 200 60 40 -- 50.... 40 (15) (~) (40) (14) (15) (~) (8) (9) (8) (~) (25) (20) (15) (30) (50) (15) (~) (8) (18) (35) (8) (25) (35) -- (~).... (10) i min 50 75 200 95 95 90 95 90 95 40 120 95 65 65 60 210 250 200 190 120 170 90 50 -- 65.... 70 (12) (40) (30) (8) (15) (58) (18) (20) (lO) (15) (25) (25) (32) (50) (30) (20) (16) (10) (~) (55) (15) (20) (45) -- (25).... (15) 4 rain 60 100 105 -- 100 75...... 65 95 80 75 80 70 190 220 -- 200.... 120 65 -- 95.... 95 (15) (40) (25) -- (20) (68)...... (32) (20) (20) (45) (35) (50) (15) (50) -- (15).... (25) (40) -- (35).... (28) rain 100 -- 150 -- 90 ll0............ 95 -- 95............ 155 75 -- 140...... -- (20) (50) -- (35) (35)............ (35) -- (50)............ (28) (~) -- (35)...... 16 rain........................................ 145...................................................... (~0)............ Failure 85.... llO -- 95 -- 50 100 80 80 110 ll0 l10 100.... 210 150 120 200 -- 140........ ll0 (38).... (28) -- (42) -- (50) (14) (38) (25) (20) (35) (40) (50).... (28) (40) (50) (~) _. (45)........ (35)

The majority of HSS tests were made with a standard tool shape of 8, 14, 6, 6, 6, 15, 3/64 at a constant depth of 0.070 in. and a feed of 0.0065 ipr on both the hot-rolled and cold-drawn materials. A few tests at a feed of 0.0208 ipr were conducted on the hot-rolled materials only. The results of tests on the hot-rolled steels, as plotted in Fig. 3a, show that there is a definite separation of the three materials at a feed of 0.0065 ipr, with the C1144 showing a 15% and 8% higher velocity at a 30-min tool life than the C1141 or C1144 modified, respectively. These same relative positions were held with two other tool shapes as indicated in Table II. At a feed of 0.0208 ipr, however, the two C1144 steels gave almost identical results within the limited number of tests run. It may be noted, also, that the tool-life curve for the C1144 material is the only one showing a tendency for a double slope, with greater sensitivity at higher velocities. Tests on the cold-drawn materials were to be in the nature of spot checks only, and tool lives had to be short because very little material was availableo However, the results, as plotted in Fig. 3b, are rather interesting, for cold drawing has affected the slopes of the tool life curves of the two C1144 steels, causing them to converge at a tool life of about 30 min, thus erasing the differences that existed on the hot-rolled materials. Carbide tests were also to be in the nature of spot checks, and the results achieved were somewhat unexpected, However, the results were consistent with. two carbide grades, two feeds, and over a range of cutting velocities. Repeat tests with HSS and carbide tools on the same bars of steel verified earlier results, Bar samples were even sent to the Bethlehem Steel Company for confirmation of identification, Typical of the behavior are the partial results plotted in Fig, 4 for a Carboloy grade 350 at a feed of 0.006p' ipr, we note that the tool life (0.015 in. flank wear) is twice as long on the modified C1144 as it is on the standard (10.7 min to 5.4 min), even though the velocity is 15% higher (1725 fpm to 1495 fpm). Comparing the two materials on the basis of the partial wear results for the same carbide (Table V), at a velocity of 900 fpm and feeds of either 0.0065 ipr or 0.0168 ipr, the standard material gave more than twice the flank wear in approximately the same time interval. Similar results were achieved with the 370 grade carbide, With this grade, wear and cutting time on the two steels correlated very well when the cutting velocity on the standard steel was reduced from 900 to 600 fpm. In other words, the modified steel could run at a 50% higher speed for the same tool wear in a given time. In all instances, the C01141 is rated well below the other two steels, We did not make special attempts during this investigation to seek the causes of the unexpected behavior. Tools were examined, however, Even though the amount of wear was greater, the C1144 tools usually had more uniform flank wear with less notching at the peripheral point of contact, Crater wear was quite similar, although there was evidence that the C1144 had more unstable

"smear" characteristics. Light smear was found in the crater as well as on the "lip" around the cutting edge. On the C1144 modified tools, the smear, perhaps even smaller, was confined to the lip. The fax-film reproductions shown in Fig. 15 also illustrate the greater smear tendencies of the standard C1144. If the smear with the modified steel is more stable, this could have some influence in reducing wear. Smear was found in the craters of both tools when flank wear was carried to 0.015 in. In any event, the amount of smear was small. SURFACE FINISH Surface-roughness measurements with a Profilometer consist of two main groups: (1) sharp tool results versus feed and tool shape with ESS tools on hot-rolled materials, and (2) roughness versus cutting time at various velocities with HSS tools on hot-rolled and cold-drawn steels, and carbide tools on hot-rolled materials. In the beginning, these measurements were made in the usual manner by traversing the feed marks, parallel to the axis of the workpiece. However, the values did not always separate the surfaces in accord with visual interpretations. Therefore, readings were added in a second direction parallel to the feed marks around the periphery of the workpiece. The peripheral values seemed to better reflect the smearing and tearing tendencies of the material, and in many instances, surfaces which had lower axial values had much higher peripheral values. Figures 5 and 6 show the axial and peripheral surface-roughness results of sharp tool tests. These results carry more meaning when they are compared with the fax-film reproductions of the surfaces shown in Fig. 7. Built-up edge and tear marks are evident in all materials in varying degrees of texture as influenced by cutting conditions. At low velocities, cutting tools with larger nose radii were effective at lower feeds, but produced badly torn surfaces at higher feeds. Critical combinations of cutting conditions may be noted for each of the work materials. The inconsistencies in the relative values of surface roughness across the feed marks may be accounted for by the fact that feed marks in the form of ridges were usually much more prominent on the C1144 materials, particularly at higher feed rates. In contrast, it may be noted that the feed marks are much less pronounced on the C1141, but there is more tearing in between. Thus, it is probable that the ridges raised the axial roughness level of the 01144 steels even though the surface as a whole was of finer texture. Although the sharp tool results show, at least to some extent, the inherent characteristics of each material, they do not predict the influence of time and tool wear. Figure 8 shows typical HSS results of the variations in surface quality experienced during continuous tests at given velocities on the hot-rolled steels, with a tool shape of 8, 14, 6, 6, 6, 15, 3/64 and a feed of 0.0065 ipr. On the basis of these results, the modified 01144 steel would

have to be rated about equal to the C1144 at lower speeds, but definitely better at what appears to be a critical speed range for the C1144, from 200 to 260 fpm, The Cli41 is rated consistently below the other two steels. Differences in surface texture may be noted in Figs. 9 and 10 for velocities of 150 and 258 fpm. Tests performed in the cold-drawn steels show the surfaces to be more consistent and more stable at slightly lower roughness levels, as indicated in Figs. 11 and 12. Figure 11 shows a direct comparison between the hotrolled and cold-drawn materials at identical cutting conditions. Both the axial and peripheral surface-roughness values are lowest on the modified C1144 steel. The surface reproductions in Fig, 12 can be compared directly with those in Fig. 10. Less tearing and streaking is noted on the cold-drawn steels. So far, roughness has been compared on the basis of identical cutting conditions, which resulted in different tool-life values between the two C1144 materials, Figure 13 shows surface-roughness values for hot-rolled and cold-drawn steels plotted on the basis of cutting velocities which gave comparable tool life. The modified C1144 shows to advantage at the longer tool lives, with both axial and peripheral roughness of lower magnitude for both steel conditions, At the short tool lives, the relative standings of the two steels are reversed for the cold-drawn condition, particularly with respect to the roughness around the periphery. The results in Table IV show that velocity had a much greater effect on the cold-drawn C1144 than it did on the hot-rolled grade. Typical results of the carbide tests are shown in Figs. 14, 15, and 16. Based on visual appearance, the C1141 material must be rated higher than the other two, and this observation is substantiated, at least in part, by the results shown in Figs. 14 and 16. The surfaces were cleaner, more highly polished, and less subject to streaking than either of the C1144 steels. The C1144 material had more evidence of smearing on the surface and had a tendency to streak more than the modified grade. Lower axial roughness values were recorded with the Profilometer, however, and one reason for this may be seen in Fig. 15. The feed marks on the modified steel are much more prominent. Apparently, the smearing tendency of the C1144 helped. fill in the grooves, presenting a smoother path for the Profilometer. The smearing, however, is reflected in somewhat higher average levels of peripheral roughness. The surfaces for the C1144 at 600 fpm, and the modified C1144 at 900 fpm (Fig. 15) can be compared on the basis of comparable tool wear in a comparable period of time, Both tools had less than 0,005 in.. flank wear after 20 min of cutting. Streaking was not evident at the 600 fpm velocity on the C1144, but the surface was not so good as that of the modified steel.

CON(CLUSIONS The conclusions are based v.pon the results within the range of cutting variables used in. this investigation. It is belie-ved that sufficient numbers of tests were made to place a 'hiAgh reliability on chiDp formation and toollife behavior for the given condi;.ti~ons. However, measured differences in surface quality were often small. in magnitu;de, and in many instances, particularly with -the C1.L441 steel-,, they iwere probably smaller than the variation one would expect in repeat runs on the s.am.e material~ Under these circ'ixnstances, a statistical. approach, involving many more tests, would be required for proper evaluation. There were, however, certain trends which were evident, CHIP FORMATION Of the three work materials, the C1144 had, the greatest inherent ability to produce more desirable chips. They broke n.p more readily and in less time at given cutting conditions. The Cl144. modified steel bhad similar tendencies and is rated just below the CiL44, significantly above the Cl 141, Cold drawing had no effect on the relative behavior, and only a negligible effect in chip form. TOOL LIFE T'nhe C1141 is rated lowest of the three steels at all test. conditions. However, the rel.ative positions of the Ci-iLL and the C1].4L4 mcdifi-ed steels are influenced very strongly tby cutting conditionso With;' HSS cutting tools, the modified C1.144i is rated about 8~0% lower th-an. the standard C1144 at a feed of 0o0065 ipr, but is rated equal to he C1i.44 at a feed of 0 020 ipr. With carbide tools, at either light or heary feeds,-, te masterials. reverse position and the C1144 modf:ied step<I.is capable of -oroductlcton rates as miuchl as 50% higher than the standard C IA44. Cold drawing does nc-t affect the level of performance of t;he two C1-14,4 stee.ls apprecinab-ly. b'Jlt it does modify the slopes of tthe tool-life cur-ves s o the -two steel-s have comparable behavior at tool liv-es of 30 ra-in or more. SURFACE FINISH The C1141. steel. ia3 rated below the other steels with HSS tools, but is rated at least equial to the C' '1144 mataeias.s with carbide tool s Based upon the combined results of ax:ial. and. peri.pheral rou.ghness and vis.ua! inspection, the modi:fied C1L44 is rated ro lees t;har. tLe standard. C.144I with, either HSS or carbide tools at practical speed ranges, Cold drawing redices tPhe smear 10

and tearing tendencies of all steels, and results in a more uniform and stable surface finish. It is particularly effective in reducing the surface roughness of the C1144 steel at high cutting velocities. 11

CHIP FORMATION VS FEED Speed-lOOfpm Tool Mat.-T-l H.S.S. Depth-.070 in. Tool Shape-8,14,6,6,6,15,3/64 Cutting Fluid-DRY I'L-I Work Mat.-1141 Work Mat.-1144 Work Mat.-1144 M ~ 1. ~..:.:: 0021 0021 0021 VA.0 ':'4$' ' 4 ii 0042 0042 0042 0065 0065 0065.:; W \' 0 0 I e:;.x. |:~ ~ r r 0083 0083 0083 ~M:;tl. )::.. 3::l: 0)04 ~0104: 0104 0135.:01350 i:; 1 ~ 0135 0168 0 168:: \ 0168 tool shapes 8, 14, 6, 6, 6 15, 1/8 and 8, 8, 6, 6, 6, 0, 0.020 gave larger and smaller chips respectively, but relative results were the same. At 200 fpm, differences among materials were far less pronounced.

Depth-070 in. (All materials are H.R.) Tool Mat-T-I H.S.S Feed-.0065i.p.r Tool Shape-8,14,6,6,6,15,3/64 Cutting Fluid-DRY Speed-230 f.p.m. Work Mat-1141 Work Mat-1144 Work Mat-1144M 0060.0 0 0 3.0 Q~f3 Uo~~', O 2.8 60 9.0 I QU, I 90; t, d13.0 12.5 TL.=i12.0Omin. TL.=50.7min. TL.= 16.1 min. Speed-280 fp.m. 0.0 0.0 0.0 1.0 0. 9 1.0 6.2 TL. i. 4 m i n. L.9min TL.-89min 2.7min. Fig. 2. Chip formation vs. cutting time. Numbers alongside chips represent time in minutes at which form changes were observed. Note that the Cll41 chips at 230 Ipm changed form, but were long and continuous for 9 min. The others changed abruptly from large, long, helical spirals to broken form at times indicated.

HSS, CUTTING VELOCITY VS TOOL LIFE- HOT ROLLED AND COLD DRAWN STEELS (BASED ON COMPLETE TOOL FAILURE) 400 (a) C1144 H.R. ~~~3002~o~-~~~ t = = 4C1144 Mod H.R 200- (f=. C1141 H.R. C1144 H.R. C1141 H.R. E 1144 Mod H.R. 100,~~ L. I = 7~~~(f=.0208).> 100 1.0 2.0 4.0 6.0 8.0 10.0 20.0 40.0 60.0 80.0 100.0 U o | Operation Turning Depth of Cut:0.070 in Feed:0.0065 ipr HR. & CD z (0 (b) 1144 Mod CD 0.0208 ipr HR. 400- Tool Material: T-l, HSS H I ~ -, _ 1144 CD Tool Shape:8,14,6,6,6,15,3/64 U 300 Cutting Fluid: Dry 200 1141 CD (f=.0065) 100 I I I I I I I I 1.0 2.0 4.0 6.0 8.0 10.0 20.0 40.0 TOOL LIFE -- MIN Fig. 3. Tool life curves for hot-rolled and cold-drawn steels as plotted from HSS results in Tables III and IV, respectively.

CARBIDES,CUTTING VELOCITY VS TOOL LIFE-HOT ROLLED STEELS (BASED ON 0.015" FLANK WEAR) Operation: Turning Depth of Cut:O.070 in cE Feed: 0.0065 and 0.0168 ipr 7I Tool Material: Carboloy Grade 350 0CI 1144 Mod. Tool Shape: 0,6,11,5,15,15,1/16 o 2000 C01144 f=00065 ipr Cutting Fluid: Dry W 1500 z 1000 C1144 Mod - [ H 800 f=0.0168 ipr, 1,41 600 f =0.0168 ipr C1141 f= 0.0065 ipr l II l I i I i lI 2 3 4 5 6 78910 15 TOOL LIFE-MIN Fig. 4. Carbide tool life curves on hot-rolled materials as plotted from results in Table V. Only those points which resulted in 0.015 in. flank wear have been plotted.

TOOL SHAPE: 8,8,6,6,6,0, 0.20 150 150 p 120 120 150F90 TOOLS 10-,o60h 30; V= 100 fpm 30 V=200fpm t 0.006.012.018 0.006.012.018 z TOOL SHAPE 8,14,6)6,6,15,3/64 C3= 120 '' -120 0 90 / 90 w, 60 P 60 -< O L I ~I I I I I I x.006.012.018 0.006.012.018 TOOL SHAPE: 8,14,66,6,6,15,1/8 oo 01144 150. - C1144 Mod - C1141 120 -0.006 t012.018.021 mEED- ipr Fig. 5. Axial surface roughness vs. feed and tool shapes at 100 and 200 fpm on H.R. steels. Sharp HSS tool results, cut dry. Depth of cut, 0.070 in. Companion peripheral roughness plotted in Fig. 6. Fax film impressions of surfaces at several feeds reproduced in Fig. 7.

120| TOOL SHAPE: 8,8,6,6,6,0,0.020 90.006.012.018 0.006.012.018TOOLS 30t- 30 FAILED L, TOOL SHAPE:8,14,6,6,6,15,3/64 Im9 V= 200 fpm:1: 90 0 o 60 o 30' LL _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ I I I oo 0.006.012.018 0.006.012.018 210 kTOOL SHAPE: 8,14,6,6,6,15,1/8 FEED- ipr I 180 V= 100fpm Ix150 120 - o-o C1144 o ---a C1144 Mod 90 _ 01141 60 -....I --- 30 u_,u 30 0 0.006.012.018 FEED- ipr Fig. 6. Peripheral roughness of same surfaces represented in Fig. 5.

C1144 C1144 MOD C1141 nt cm 0 0 (a) V = 100 fpm; tool shape 8, 8, 6, 6, 6, 0, 0.020. Fig. 7. Fax film reproductions of some of the surfaces whose roughness values are shown in Figs. 5 and 6.

~020.. 0 M5.0065 ii~~~~~~~~~~~~~~~~w F-J 0 O..........~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.......... H - 7~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -f O0 c —, * C12 PI ~ 't, a 01\ 01\ Ff F~~~~~~... co.o_ ct '. OD H

C1144 C1144 MOD C1141 mmm 'iT 0ffiwX QI~~:i i?:i i o.g i:;~~~~~~~~~~~~~,:!i'!,~~~~~~~~~~~~~~~~~~~~~~~i aa r 'ii 0 (c) V = 100 fpm; tool shape 8, 14, 6, 6, 6, 15, 1/16. Fig. 7. (Continued)

'0208 '0135 '0065 '0021 IPR 2 C) II IN) P0 o 00 ~~~~~~~~zj ~~~~~~~~~~ ~O C) '. ~~4 Gq H o o,.C p. -5- -<1 --- —- CD 'C 0\ 0\1 H VI ---') ~................ ~;~::...~.~. ~ ~.!.~;-.~..:..- 01, F-J ~~~~~~~~~~~~~fiber HON~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.....

180.15C'1141 PERIPHERAL SURFACE ROUGHNESS 2 C 11440Mod 01141 U<- 120 d,, 120 120 -Cr 1__-~~"'44 Mod 01144 ') 90 90 1144 90 1 _ CL l Cr o — 30f V =150 fpm 30 V=200fpm 30 V=240fpm UJ0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 202 '300 -,,./CII41 AXIAL SURFACE ROUGHNESS z270 - ~240A V=200fpm V=240 fpm g,.C C1144 0 1141 Z210 210 C41 210 CH o 150@t / > / CII44 Mod I.O (3 "- C1144:180 180fpm 180 - C)9C1144 Mod < 90g 90o-/ 90 C 1144 Mod / 60/ 0 510 152025 10 15 20 25 0 5 10 5 2025 CUTTING TIME- MIN. Fig. 8. Surface roughness vs. time on hot-rolled steels with HSS tools at various velocities. Tool shape 8, 14, 6, 6, 6, 15, 3/64; f = o.oo65 ipr; d = 0.070 in. cut dry.

I-Jo~ ~~~25 MIN 16MIN 9MIN 4MIN IMIN BEGIN \. p'x '''j~"~~~~~ ~'''~1 ~~ '~:~...................................'.............'......~~~~~~ I-3C~: ' ':~~~ -.~.L.~.~ ci-~~...... (.D~..~~ __ I~...... — q 0'-" '~~'~..... 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~': ''7 ci~ ~ ~ ~ ~ ~~ ~~~~~~~~~~~~~~~~~'"~~ ~~ -~i. '-e'-~~':-:~" "-"'' ' Pi'~ J ~;~-,:~' '"-~ '~-~ ---~"" ~~,... ~.,'~~, ~ ~~<~,,~:.-:~.,~ 1.~;\~::~'.~/_~:;~.:? ~......~~~~~~~~~~~~~~~~~~~~~~ai FJ-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ '" '~:-~~"i=[:'L''"i Ct. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ ~~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~~~~~~~~'''...''" " ": - i* i.~ U).W77.~.~... F-J~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:~' ~ *~~".~!~~:~~ —~"~-~~' *;': ~~ FJ-~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~'.....:~~ CD ~ ~ ~ ~ ~ ~ ~ ~ ~ (D~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~/~~ _. W.~ ~.:. -:~"''~~":~".... i;j Pi~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. ~ - ~~;. ~. _-~ ~.; -. ~,-~:=.~....~ O'I ('D....11,PI- ~~ ~ ~ — ~~~~~- ' ~~~~ <~.-....... ~ ~.,~~ ~ ~:~~..I:,._.~~!~~~: VD~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~,~ ~'~~~..~~_ ~.,-~ -,,.....,................,-~ ~-,'~-~~ ~'~~ i:~'~..~..... C~-..4

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V) z HOT ROLLED STEELS COLD DRAWN STEELS 8 120 HC1141 U '/ 90; 90 C1141 CI1144 LO6 0 -O 60 J _/ C1144 Mod < i <d 30 - " ---'0'CII1144 Mod o_ 0 5 10 15 20 25 0 5 10 15 20 ') C 240t HOT ROLLED STEELS COLD DRAWN STEELS 210 C111144 Mo44 _ 180 150 C1141 I I I I 1141 0 5 10 15 20 25 0 5 10 120 C11CUTTING44 ModTIME- MIN X 90 90(),- o Or) ~ —"=' CII 44 Mod j 60- 60 x 30 30 0 5 I0 15 20 25 0 5 I0 15 20 CUTTING TIME - MIN Fig. 11. Comparison of surface roughness of hot-rolled and cold-drawn steels at a velocity of 258 fpm under cutting conditions listed in Fig. 8.

C1144 C1144 MOD C1141 Z bJ a3 Z 3E Fig. 12. Fax film reproductions of surfaces produced on cold-dirawn steels at 258 fpm under cutting conditions listed in Fig. 8. May be compared with hotrolled steel results in Fig. 10. ~~~~~~~~~~~~~~~~~~iS~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ O3 ~0 2.58 i'pm under cutt,,ng: conc-[tions ]_~sted ~n Fig. 8. Hay be compared wit~h bot,~'o].3ec steel resu3_ts ~n Fig. lO.

HOT ROLLED T L. -- 75 M in. 210 1144:V=294fpm 1144 (Axial) C1144 Mod:V=258 fpm Un 180 z 150 C1144 = 120 (Axial)C1144(Per) L)O01144 Mod C1144(Axial) W 90 01144 0 60 F 4 (Per) 1144 Mod (Per) o C1144 Mod PTL-r20 Min 30 C01144:V=258 fpm C1144 Mod:V= 240 fpm I 0 I I I! I _05 Cr 5 10 0 5 10 15 20 D -J TL. — 5 Min COLD DRAWN TL.10.5Min < 150 1144:V=300fpm C1144:V= 270fpm I, CC1144 Mod:V=275 fpm 01144 Mod: V= 257 fpm ai 120 C1144 Mod (Axiol) a. 90 -- CI 144 Mod - (Axiol) o (Per) z 60 C1144 (Axial) C1144 Mod oCI44 < 30 — C1144(Per) (Per) 5X 01144 Mod 5 0 5 10 15 20 CUTTING TIME- MIN. Fig. 13. Surface roughness vs. time on hot-rolled and cold-drawn steels based on velocities which gave comparable tool life. Size of cut and tool shape as listed in Fig. 8.

GRADE 350 CARBIDE GRADE 370 CARBIDE 0,6,11,5,15,15, 1/16 0,6,11,5,15,15,1/32 (a) (b) (c) r240 240 240 240; ff =.0065ipr f 0168ipr 20 f =.0065ipr - 0 220 21140 Mod -200C 200 200 LLJ I180 180 \C1141 180 ~I160 160 160 C1144(V=600) u 140 140 Axial 140 / U:: 1144 C1144 Mod, 1144 0120 120 120 P" Mod C1144 -J / C1144 100 100 100 / 01141 < C1141 o 80 80 80 A z Axial xial tj 60 C1144Mod 60 6C01 < CI41144 J40, 400C1144 Mod 40 C44 1144 Uj40 40 Mod I: C1141 1 C1141 C1144 fro20 CiC1144 200 P a 20 C1141 c) gPeriapheral werimeral Periher. 0 5 10 0 5 0 5 10 15 CUTTING TIME- MIN. Fig. 14. Surface roughness vs. time on hot-rolled materials with carbide tools. V = 900 fpm (except as indicated for C1144 in (c)). Depth of cut, 0.070 in.; feed, carbide grade; and tool shape as indicated. Curves plotted from results in Table V. C1144 at 6oo00 fpm and Cl144 modified at 900 fpm in (c) gave comparable tool wear in same time interval.

16MIN 9MIN 4MIN IMIN BEGIN Ad a - X _i ( (Do I-0'"0.~-?:. (D _ I,,,_ A; =, =, _ A == _ (D =0 ( 1: ci-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --- —----- ----- (D~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --- —--—....... (D~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.....W H~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..... U)~~~~~~~~~~~~~~~~~~~~~~~~~~~Wl o

C1144 C1144 MOD C1141 iiij!..-'r'1.1'... '11 I '::;ll I (l: * I l ' ']:i~I II ~I I i: I!~~~~~~~~~~~~~I ~[: J II~~~~~~~~~~~~~~~~~~~~JIII Fig. i6. Fax film reproductions of surfaces on hot rolled materials under conditions and values represented in Fig. 14b,

UNIVERSITY OF MICHIGAN 11111 03483 7636111 111111111111111111111 3 9015 03483 7636