1、Designation: E618 07 (Reapproved 2013)Standard Test Method forEvaluating Machining Performance of Ferrous Metals Usingan Automatic Screw/Bar Machine1This standard is issued under the fixed designation E618; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method was written to fill a requirement for a standard test for determi
3、ning themachinability of ferrous metals using automatic screw/bar machines. (Hereafter, these machines willbe referred to as automatic screw machines.) Although a variety of short-time laboratory tests havedemonstrated different machining characteristics among ferrous metals, it has been difficult t
4、o applythe resulting data to commercial automatic screw machine practice.In this test method a standard test piece is machined using tools and machining operations typicalof automatic screw machine practice.Through the use of this test method, the relative machining performance of a metal can be eva
5、luatedeven though different automatic screw machines are used. Further, comparisons can be made amongdifferent lots of the same grade or different grades to determine relative machining performance.1. Scope1.1 This test method covers a production-type test forevaluating the machining performance of
6、ferrous metals asthey are used in single-spindle or multiple-spindle automaticscrew machines. It is based on producing parts of a standarddesign in such machines to uniform levels of quality withrespect to surface roughness and size variation. The standardtest piece, designed for this test, is machi
7、ned from bars usinga specified number of tools in a specified sequence. Nothing inthis test method should be construed as defining or establishinglimits of acceptability for any grade or type of metal.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parent
8、heses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate
9、 safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 American National Standard: B46.1 Surface Texture23. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 average surface roughness (per set of samples)forea
10、ch surface (the major and minor diameter formed surfaces)the surface roughness per set of samples is the average of theroughnesses recorded as in 3.1.5.1 for the six test pieces perset. A test set is described in 9.3.3.1.2 calculated hourly production rate (in pieces perhour)3600 s/h divided by the
11、cycle time in seconds per piece.(Unit: pieces per hour.)3.1.3 cycle timethe time in seconds per piece from barfeed-out to bar feed-out, or from cutoff to cutoff, duringuninterrupted operation of the machine. It includes all stock,machine, and tool movements.3.1.4 surface speedthe product of the orig
12、inal bar circum-ference (in feet or metres) and the spindle speed in revolutionsper minute. (Unit: ft/min or m/min.)3.1.5 surface-roughness average value (Ra)the surface-roughness average value is the mean reading around which theneedle tends to dwell or fluctuate under small amplitude when1This tes
13、t method is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.15 on Bars.Current edition approved June 1, 2013. Published June 2013. Originallyapproved in 1977. Last previous edition approved in 2007 as E618 0
14、7. DOI:10.1520/E0618-07R13.2Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1a continuously averaging meter i
15、s used. (Refer to 3.8.1.1 inANSI B46.1). The surface-roughness value obtained by acontinuously averaging digital readout meter is acceptable.3.1.5.1 The surface-roughness recorded for each surface onthe test piece is the maximum of the surface-roughness averagevalues measured on that surface at a mi
16、nimum of four placesequispaced around the circumference and measured as de-scribed in 3.1.5.3.1.6 surface-roughness range (per set of samples)thelowest and highest values of the surface roughnesses recordedfor each surface as in 3.1.5.1for each set.3.1.7 surface-roughness range (per test)the lowest
17、andhighest values of surface roughnesses recorded for each surfaceas in 3.1.5.1 during the test.3.1.8 theoretical hourly production rate (in pieces perhour)3600 s/h divided by the cycle time in seconds per piecediminished by: (1) the indexing time or high-speed time inseconds per piece for a multipl
18、e-spindle machine, or (2) thetime in seconds per piece when no tools are cutting for asingle-spindle machine.3.1.9 tool feed ratethe distance traveled by the tool at auniform rate divided by the number of spindle revolutionsduring which this travel occurs. (Units: decimal inch ordecimal millimetre p
19、er revolution.)3.1.10 tool life (for a form tool)the hours of machine timedetermined from the calculated hourly production rate and thetotal number of test pieces produced from the start of the testto the earliest point at which the average of the recordedsurface-roughness average values or the aver
20、age of sizes of thetest pieces in a sample set consistently exceed either thesurface-roughness limits or the size limits specified in 9.7.1,9.7.2, and 9.7.3 for the piece diameter produced by that tool.3.2 Machining performance in this test method is evaluatedby the following criteria:3.2.1 Tool lif
21、e as described in 3.1.10.3.2.2 Cutting speed and tool-feed rate as described in 3.1.4and 3.1.9.3.2.3 Hourly rate of production as described in 3.1.2 or3.1.8.3.2.4 A test sample set is described in 9.3.4. Summary of Test Method4.1 A standard test piece, shown in Fig. 1, is machined frombar stock in a
22、n automatic screw machine.FIG. 1 Details of the ASTM Machinability Test Specimen and the Relative Positions of Form ToolsE618 07 (2013)24.2 Specified tools are used in a standard sequence to shapethe test piece. Drills and form tools are used simultaneously toprovide a typical machining condition du
23、ring the test.4.3 Cutting speed and tool feed rate for the metal beingtested are varied from one test run to another to determine themaximum rate at which test pieces can be produced for thespecified length of time without exceeding the specified limitsfor surface roughness and size dimensions.4.4 W
24、hen measured as specified, the level of and changes insurface roughness and the size of pieces produced are used toevaluate the machining performance of the metal being tested.5. Significance and Use5.1 This test method can be used to evaluate the machiningperformance of a single grade or type of me
25、tal or to compareone grade or type with another.5.1.1 The machining performance of the test metal ismeasured by the maximum rate at which test pieces can beproduced within specified surface roughness and dimensionallimits for a specified length of time and also by the cuttingspeed and tool feed empl
26、oyed to attain that rate.5.1.2 The relative machining performance of the variousmetals tested using this test method may be evaluated only atoperating conditions that produce test pieces of like qualitywith respect to surface roughness and dimensional limits forcomparable periods of machining time.6
27、. Apparatus6.1 Automatic Screw Machine:6.1.1 A single-spindle automatic screw machine with a six-or eight-hole turret, with adequate spindle capacity, and withsufficient feed, speed, and power to machine a 1-in. round barof free-machining, alloy or high-strength steel, or6.1.2 A multiple-spindle aut
28、omatic screw machine with aspindle capacity and with sufficient feed, speed, and power tomachine 1-in. round bars of free-machining, alloy or high-strength steel simultaneously at all spindles.6.2 Metal-Cutting ToolsOn the basis of current use forgeneral applications for automatic screw-machine prod
29、uction,two tool-steel grades (M7 for drills and M2 for form tools) aresuggested in 6.2.1 through 6.2.5. This is not intended topreclude the use of other grades. This test method does requirethat the use of tool materials, other than those suggested, berecorded and reported together with the reason(s
30、) for thechange.6.2.1 A34-in. (19.05-mm) diameter or larger spot drill witha 90 included point angle may be used.6.2.2 Two38-in. (9.52-mm) diameter and one58-in. (15.88-mm) diameter drills ground as specified in 8.6.6.2.3 Either a dovetail or a circular rough-form tool of M2steel designed as shown i
31、n Fig. 2.6.2.4 A flat, circular, or dovetail finish-form tool at least916in. (14.29 mm) wide made from M2 steel as shown in Fig. 3.6.2.5 A cutoff tool as described in 8.5.6.3 Stylus-Type Standard Commercial Surface-Roughness-Measuring Instrument, capable of measuring surface rough-ness in microinche
32、s arithmetic average (AA) and having astroke of at least14 in. (6.35 mm).6.3.1 In all cases an electric cutoff of 0.030 in. (0.8 mm) isused. The stylus and skids of the tracer head must becompatible with a 0.030-in. (0.8-mm) cutoff. (See 3.6.2 inANSI B46.1 for a definition of cutoff.)6.3.2 The lengt
33、h of trace is the maximum possible on thesurface being measured but must be at least 0.150 in. (3.81mm).6.4 Micrometer(s), capable of indicating to 0.0001 in. or0.002 mm.6.5 Toolmakers Microscope or equivalent.6.6 Commercially Available Coolant.7. Test Specimen7.1 The test specimen detailed in Fig.
34、1 shall be machinedfrom 1-in. (25.4-mm) diameter bars.7.2 Different bar sizes may be used to produce a differentsize test piece provided that the material removed and thematerial remaining is in the same cross-sectional proportion asin the test piece shown in Fig. 1. When a different bar size isused
35、 a proportionate change is made in all dimensions, exceptthat both formed surfaces must be at least38 in. (9.5 mm) long.This is to ensure accurate surface-roughness measurements.7.3 When a different size test piece is used the bar size andtest piece dimensions shall be recorded on the test report.8.
36、 Procedure for Machine Setup8.1 Since there is a difference between automatic screwmachines as to how movement is conveyed to the end and sideworking tools, cams must be designed or selected to provide auniform rate of tool feed for a distance greater than thatnecessary to remove the required metal.
37、 This will ensure auniform feed rate throughout the cut.8.2 Feeds and speeds on the initial test run should beselected on the basis of experience or general guide lines for aferrous metal of similar composition and condition.8.2.1 The positive stop pressure maintained during the testshall be that wh
38、ich is recommended by the machine toolbuilder.8.3 Place the cutting tools so they cut in the followingsequence. The form tools and drills shall cut at the same time.8.3.1 Spot drill (optional).8.3.2 Rough form and drill to depth with58-in. (15.88-mm)diameter drill.8.3.3 Finish form to 0.875-in. (22.
39、22-mm) outside diameterand drill1132 in. (8.73 mm) deep with the first38-in. (9.52-mm)diameter drill.8.3.4 Drill1132 in. (8.73 mm) deep (through the cutoff) withthe second38-in. (9.52-mm) diameter drill.8.3.5 An optional sequence of tooling for a single-spindleautomatic machine uses only three drill
40、s in the turret; namely,one spot drill, one58-in. (15.88-mm) drill, and one38-in.(9.52-mm) drill with double indexing of the turret betweensuccessive drilling operations.8.3.6 Cut off the finished piece.E618 07 (2013)38.4 Form Tool Conditions:8.4.1 Using the most rigid cross-slide, set the rough-for
41、mtool so that the part of the tool forming the 0.615 to 0.620-in.(15.62 to 15.75-mm) or minor diameter will cut on center.8.4.2 Set the finish-form tool to cut the rough-formed 0.900to 0.905-in. (22.86 to 22.99-mm) or major diameter on centerand remove 0.030 in. (0.76 mm) from that diameter to form
42、the0.870 to 0.875-in. (22.10 to 22.22-mm) diameter. When adifferent size test piece is used, proportionately more or lessmetal will be removed by the finish-form tool.8.4.3 Grind and mount all form tools in the machine with aneffective positive top rake angle of 10, a front clearance angleof 5 to 12
43、, and, for the rough-form tool, a side-clearance angleof 2 to 4. Note any deviation from these angles foundnecessary and record the reason. The grinding lay (direction ofdominate linear surface texture) on the rake face of the roughand finish form tools shall run parallel to the leading cuttingedge.
44、 This is coincident with the practice of avoiding a slightnegative lip rake angle.8.4.4 When the side-clearance angle for the rough-formtools is obtained by a tilted tool holder, it is recommended thatthe rough-form tool be reground in a tool holder or fixturehaving an identical angle of tilt.8.4.5
45、All form tools must be hardened to 63 minimum HRC.8.5 Cutoff ToolAn appropriate commercial tool shall beused.8.6 Drills:8.6.1 Use solid two-flute standard length or screw-machinelength high-speed steel twist drills. Note any deviation that isfound necessary to conduct the test and record the reason.
46、8.6.2 Included (point angles) angles shall be 118 for allmetals except stainless steels and high-strength metals, when a135 included angle shall be used.FIG. 2 Details of the Tool Edge for the ASTM Rough-Form ToolE618 07 (2013)48.6.2.1 The lip clearance angles shall be 14 6 2 for the38-in. (9.52-mm)
47、 drill(s) with 118 included angle; 12 6 2 forthe58-in. (15.88-mm) drill with 118 included angle; 12 6 2for the38-in. drill(s) with the 135 included angle; and 10 6 2for the58-in. drill with 135 included angle.8.6.2.2 Web thinning may be necessary when resharpeningdrills with 118 included angle.8.6.2
48、.3 Use a split point on the drills with 135 includedangle.8.6.2.4 All drills shall have the helix angle which is standardfor the manufacturer of the drills.8.7 Direct the coolant to flood the test pieces and the toolcutting edges during machining.9. Test Method9.1 Determine the reliability of machin
49、ing-performancedata to be expected on any given machine by running machine-capability tests prior to a test program to determine thetolerance limits within which the machine is capable ofproducing the test piece. A method for doing this is describedin Appendix X1. Machine-capability tests should be performedeach time a variance pattern of sizes develops which departsfrom the norm previously established.9.1.1 If the machine is not capable of producing pieceswithin the limits specified in 9.7.2 before proceeding with thetest program, ad
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