Turning.docx

8/20/2019 Turning.docx

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TURNING

A lathe is a machine tool which rotates the workpiece on its axis to perform

various operations such as cutting, sanding, knurling, drilling,

or deformation, facing, turning, with tools that are applied to the

workpiece to create an object which has symmetry about an axis of

rotation.

A lathe may or may not have legs which sit on the foor and elevate the lathe bed to a

working height. A lathe may be small and sit on a workbench or table, and not reqire a

stand. Almost all lathes have a bed, which is !almost always" a hori#ontal beam

!althogh $N$ lathes commonly have an inclined or vertical beam %or a bed to ensre

that swar% , or chi&s, %alls %ree o% the bed". At one end o% the bed !almost always the le%t, as

the o&erator %aces the lathe" is a headstock. The headstock contains high'&recision s&inning

bearings. Rotating within the bearings is a hori#ontal a(le, with an a(is &arallel to the bed,called the s&indle. )&indles are o%ten hollow, and have e(terior threads and*or an

interior +orse ta&er on the inboard !i.e., %acing to the right * towards the bed" by which

work'holding accessories may be monted to the s&indle. )&indles may also have e(terior

threads and*or an interior ta&er at their otboard !i.e., %acing away %rom the bed" end,

and*or may have a hand'wheel or other accessory mechanism on their otboard end.

)&indles are &owered, and im&art motion to the work&iece.

The s&indle is driven either by %oot &ower %rom a treadle and fywheel or by a belt or gear

drive to a &ower sorce. In most modern lathes this &ower sorce is an integral electric

motor, o%ten either in the headstock, to the le%t o% the headstock, or beneath the headstock,

concealed in the stand.

In addition to the s&indle and its bearings, the headstock o%ten contains &arts to convert the

motor s&eed into varios s&indle s&eeds. -arios ty&es o% s&eed'changing mechanism

achieve this, %rom a cone &lley or ste& &lley, to a cone &lley with back gear !which is

essentially a low range, similar in net eect to the two's&eed rear o% a trck", to an entire

gear train similar to that o% a manal'shi%t ato transmission. )ome motors have electronic

rheostat'ty&e s&eed controls, which obviates cone &lleys or gears.

The conter&oint to the headstock is the tailstock, sometimes re%erred to as the loose head,

as it can be &ositioned at any convenient &oint on the bed by sliding it to the reqired area.

The tail'stock contains a barrel which does not rotate, bt can slide in and ot &arallel to the

a(is o% the bed, and directly in line with the headstock s&indle. The barrel is hollow, and

sally contains a ta&er to %acilitate the gri&&ing o% varios ty&e o% tooling. Its most commonses are to hold a hardened steel center, which is sed to s&&ort long thin sha%ts while

trning, or to hold drill bits %or drilling a(ial holes in the work &iece. +any other ses are

&ossible./01

+etalworking lathes have a carriage !com&rising a saddle and a&ron" to&&ed with a cross'

slide, which is a fat &iece that sits crosswise on the bed, and can be cranked at right angles

to the bed. )itting ato& the cross slide is sally another slide called a com&ond rest, which

&rovides 0 additional a(es o% motion, rotary and linear. Ato& that sits a tool &ost, which holds

https://en.wikipedia.org/wiki/Swarf

https://en.wikipedia.org/wiki/Lathe#cite_note-2

https://en.wikipedia.org/wiki/Lathe#cite_note-2

https://en.wikipedia.org/wiki/Swarf



a ctting tool which removes material %rom the work&iece. There may or may not be a lead

screw, which moves the cross'slide along the bed.

T23)3 AR3 T23 G3N3RA4 T563) 78 4AT23 +A$2IN3)-

9. 3NGIN3 4AT23)

These are &robably the most &o&lar among the lathe machines. In %act, no machine

sho& is seen withot this ty&e o% lathe. The good thing abot engine lathes is that it

can be sed in varios materials, aside %rom metal. +oreover, the set'& o% these

machines is so sim&le that they are easier to se. Its main com&onents inclde the

bed, headstock, and tailstock. These engine lathes can be ad:sted to variable

s&eeds %or the accommodation o% a wide sco&e o% work. In addition, these lathes

come in varios si#es.

2. TURR3T 4AT23)

These ty&es o% lathes are sed %or machining single work&ieces seqentially. This

means that several o&erations are needed to be &er%ormed on a single work &iece.

;ith the trret lathes, seqential o&erations can be done on the work &iece,

eliminating errors in work alignment. ;ith this set'&, machining is done more

e<ciently. $orres&ondingly, time is saved becase there is no need to remove and

trans%er the work &iece to another machine anymore.

=. )63$IA4 6UR67)3 4AT23)As the name im&lies, these lathes are sed %or s&ecial &r&oses sch as heavy'dty

&rodction o% identical &arts. In addition, these lathes also &er%orm s&eci>c %nctions

that cannot be &er%ormed by the standard lathes. )ome e(am&les o% s&ecial &r&ose

lathes inclde the bench'ty&e :ewelers? lathes, atomatic lathes, cranksha%t lathes,

d&licating lathes, mltis&indle lathes, brake drm lathes, and &rodction lathes

among others.

@. +INI'4AT23 AN +I$R7'4AT23

+ini'lathes and micro'lathes are miniatre versions o% a general'&r&ose center lathe

!engine lathe". They ty&ically have swings in the range o% = to B in !BC to 9BD mm"

diameter !in other words, 9.E to =.E in !=D to DF mm" radis". They are small and

aordable lathes %or the home worksho& or +R7 sho&. The same advantages and

disadvantages a&&ly to these machines as e(&lained earlier regarding ='in'9

machines. As %ond elsewhere in 3nglish'langage orthogra&hy, there is variation in

the styling o% the &re>(es in these machines names. They are alternately styled

as mini lathe, minilathe, and mini-lathe and as micro lathe,

microlathe, and micro-lathe.



E. $N$ 4AT23

These are ra&idly re&lacing the older &rodction lathes !mltis&indle, etc." de to

their ease o% setting, o&eration, re&eatability and accracy. They are designed to se

modern carbide tooling and %lly se modern &rocesses. The &art may be designed

and the tool &aths &rogrammed by the $A*$A+ &rocess or manally by the

&rogrammer, and the reslting >le &loaded to the machine, and once set and trialedthe machine will contine to trn ot &arts nder the occasional s&ervision o% an

o&erator. The machine is controlled electronically via a com&ter men style

inter%ace, the &rogram may be modi>ed and dis&layed at the machine, along with a

simlated view o% the &rocess. The setter*o&erator needs a high level o% skill to

&er%orm the &rocess, however the knowledge base is broader com&ared to the older

&rodction machines where intimate knowledge o% each machine was considered

essential. These machines are o%ten set and o&erated by the same &erson, where the

o&erator will s&ervise a small nmber o% machines !cell".

2+T N2'00+A3 IN INIA

3NGIN3 4AT23 +A$2IN3



Features of a Lathe achine

• Rigid rectanglar section wide bed.

• )hort s&indle and sha%ts %or ma(imm drive rigidity.• )traight bed and ga& version with removable bridge &iece.

• All drive gears in headstock are case hardened and grond.

• ry sm& lbrication %or minimm thermal de%ormation.

• Indction hardened integral gide ways on bed.

!"#$%F%$A&%'(!)2eight o% centers

00H mm

)wing over ed

EHH mm

)wing over cross slide

0BH mm

)wing in ga& B0H

mm

istance between centers

9HHH*9EHH*0HHH*=HHH mm

)&indle Nose*one A0'

CJ*E= mm

)&indle )&eed Range!r&m" @H'0H@H %orward!9C",

CH'9@=H reverse !B"

)&indle 6ower

99 k;

8eed range !longitdinal" CH%rom

H.H@'0.0@ mm*rev

8eed range !cross" CH %rom H.H0'9.90

mm*rev



4ead screw &itch

C mm

+etric threads @D

%rom H.E'0D mm

+odle threads @H %romH.0E'9@ mm

iametric &itch !o&tional" @=

%rom 990'0 mm

Tailstock sleeve travel

0HH mm

+ain motor &ower B.E

k;

7 T23R +A$2IN3 IN T23 TURNING )3$TI7N'

2+T N2'0C+A3 IN INIA

3NGIN3 4AT23 +A$2IN3

23IG2T 78 $3NTR3)'0CH ++

);ING 7-3R 3 EBE ++

)6IN43 67;3R 99K ;

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Turning.docx