pros man ii handout 02 turning 1

8/16/2019 Pros Man II Handout 02 Turning 1

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Turning ProcessProses Manufaktur II

Sumber:Manufacturing Engineering & Technology

Oleh: Serope Kalpakjian


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Mesin Bubut ( lathe )

Mesin bubut merupakanmesin serba guna(general purposemachine ), karenamampu mengerjakan

berbagai jenispekerjaan.

Bagian utama mesinbubut adalah: (1) thebed, (2) the headstock,(3) the carriage, (4) thetailstock, and (5) thegearbox.


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Engine Lathe (1600x12000) American

Salah satu cara u/ melihat dimensi benda kerja yg bisa

diproses di mesin bubut adalah dengan melihat swing dan distance between center dari mesin bubut.

Swing menunjukkan diametermaksimum benda kerja yang bisadiproses di mesin bubut tersebut.

http://www.techmaksintl.com/images/product_images/Engine_Lathe_1600x12000_American-872217.jpghttp://www.techmaksintl.com/images/product_images/Engine_Lathe_1600x12000_American.jpg


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Beberapa contoh mesin bubut (1)


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Big engine lathe (www.osun.org)


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Big engine lathe, 60 ft c - c (www.osun.org)


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Bagian-bagian mesin bubut


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Lathe Construction & Description


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Figure 2 - Lathe Parts Descriptions

Headstock

The headstock houses thespindle and the componentswhich drive the spindle and thefeed gears.

Spindle SpeedSelector

The spindle speed selectorallows the operator to adjustthe spindle speed of themachine.

Emergency StopButton

The emergency stop buttonturns off the power to themachine.

Motor StartButton

The motor start button starts the electric drive motor for the machine. Themotor start button does not control the spindle; however, it does supply the

power.

Spindle Clutchand Brake Lever

This lever controls the spindle rotation. Through the use of this lever, theoperator controls the spindle direction, spindle on, and spindle off. On somemachines, when the spindle is turned off, a magnetic spindle brake isapplied. The other type of spindle brake is the foot pedal. The foot pedaltype of brake is found on many other types of machines.


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LatheCutting

Operations

Figure 23.1 Miscellaneous cuttingoperations that can be performedon a lathe. Note that all parts arecircular – a property known as axi-symmetry. The tools used, theirshape, and the processingparameters are describedthroughout this chapter.


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Lathe

Figure 23.2 General view of a typical lathe, showing various components.Source: Courtesy of Heidenreich & Harbeck.


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Turning Operation

Figure 23.3 Schematic illustration of the basic turning operation, showing depth-of-cut, d ; feed, f ; and spindle rotational speed, N in rev/min. Cutting speed is the surfacespeed of the workpiece at the tool tip.


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Designations for a Right-HandCutting Tool

Figure 23.4 Designations for a right-hand cutting tool. Right-hand means the tooltravels form right to left, as shown in Fig. 23.3.


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General Recommendations for Tool Angles in Turning


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Forces Acting on a Cutting Tool inTurning

Figure 23.5 Forces acting on a cuttin tool in turning, F c is the cutting force , F t is the thrust of feed force (in the direction of feed), and F r is the radial forcethat tends to push the tool away from the workpiece being machined.


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Range of Applicable Cutting Speeds andFeeds for Tool Materials

Figure 23.6 The range ofapplicable cutting speeds andfeeds for a variety of toolmaterials.


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General Recommendations for Turning Operations


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General Recommendations for Turning Operations, con’t

G l R d i f C i Fl id f


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General Recommendations for Cutting Fluids forMachining


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Typical Capacities and Maximum WorkpieceDimensions for Machine Tools


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Collets

Figure 23.7 (a) and (b) Schematic illustrations of a draw-in type collet. Theworkpiece is placed in the collet hole, and the conical surfaces of the collet areforced inwards by pulling it with a draw bar into the sleeve. (c) A push-out typecollet. (d) Workholding of a workpiece on a face plate.


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Mandrels to Hold Work-pieces for Turning

Figure 23.8 Various types of mandrels to hold workpieces for turning. These mandrelsusually are mounted between centers on a lathe. Note that in (a), both the cylindricaland the end faces of the workpiece can be machined, whereas in (b) and (c), only thecylindrical surfaces can be machined.

Mandrel berfunggi u/ memegang b-kerja yang didalamnya berlubang ( hollowwork-piece ), agar b-kerja bisa diproses ( machining ) di mesin bubut.


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Turret Lathe

Figure 23.9 Schematic illustration of the components of a turret lathe.Note the two turrets: square and hexagonal (main).


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Numerical Control Lathe and Turret

Figure 23.10 (a) A computer numerical-control lathe. Note the two turrets onthis machine. These machines have higher power and spindle speed than otherlathes in order to take advantage of new cutting tools with enhanced properties.(b) A typical turret equipped with ten tools, some of which are powered.


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Parts Made on CNC Lathes

Figure 23.11 Typical parts made on CNC lathes.


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TypicalProductionRates forVarious

MachiningOperations


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Range of SurfaceRoughness in

MachiningProcesses

Figure 23.13 The range ofsurface roughnesses obtainedin various machiningprocesses. Note the widerange within each group,especially in turning and boring.


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Range ofDimensional

Tolerances inMachining as a

Function of

Work-piece Size

Figure 23.14 Range ofdimensional tolerances obtained

in various machining processesas a function of workpiece size.Note that there is an order osmagnitude difference betweensmall and large workpieces.


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Troubleshooting Guide for Turning


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CuttingScrewThreads

Figure 23.15 (a) Cutting screw threads on a lathe with a single-point cutting tool. (b) Cutting screwthreads with a single-point tool in several passes, normally utilized for large threads. The small arrows inthe figures show the direction of the feed, and the broken lines show the position of the cutting tool as timeprogresses. Note that in radial cutting , the tool is fed directly into the workpiece. In flank cutting , the tool isfed inot the piece along the right face of the thread. In incremental cutting , the tool is first fed directly intothe piece at the center of the thread, then at its sides, and finally into the root. (c) A typical coated-carbideinsert in the process of cutting screw threads on a round shaft. (d) Cutting internal screw threads with acarbide insert. Source : (c): Courtesy of Iscar Metals Inc.


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Chasers and Die for Thread Cutting

Figure 23.16 (a) Straight chasers for cutting threads on alathe. (b) Circular chasers. (c) A solid threading die.


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T b l S ifi C tti E


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Tabel Specific Cutting Energy


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Parameter dan Perhitungan Dasar ProsesPemesinan ( Turning )

Waktu permesinan

Laju pembuangangeram

Daya pemotongan

Daya motor

nl t

w

wm f

ad na Z pmw pw f

Z p P w sm

m

m

e

P P


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Parameter dan Perhitungan Dasar ProsesPemesinan ( Turning )

Daya pemotongan

Torsi

T adalah torsi yang dibutuhkan, ω adalah kecepatan sudut = 2 N dimana N adalah putaran spindle(benda kerja), F

c adalah gaya pemotongan (cutting

force), d avg adalah diameter rata-rata b-kerja, (d w +d m )/2

T P m

)2/( avg c d F T

pros man ii handout 02 turning 1

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