milling report (indexing)

8/16/2019 milling report (indexing)

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INTRODUCTION

Milling is the machining process of using rotary cutters to remove

material from a workpiece by advancing (or feeding) in a direction

at an angle with the axis of the tool. It covers a wide variety ofdierent operations and machines, on scales from small individual

parts to large, heavyduty gang milling operations. It is one of the

most commonly used processes in industry and machine shops

today for machining parts to precise si!es and shapes.

Milling can be done with a wide range of machine tools. "he

original class of machine tools for milling was the milling machine

(often called a mill). #fter the advent of computer numericalcontrol ($%$), milling machines evolved into machining centers

(milling machines with automatic tool changers, tool maga!ines

or carousels, $%$ control, coolant systems, and enclosures),

generally classi&ed as vertical machining centers ('M$s) and

hori!ontal machining centers (M$s). "he integration of milling

into turning environments and of turning into milling

environments, begun with live tooling for lathes and the

occasional use of mills for turning operations, led to a new class of

machine tools, multitasking machines (M"Ms), which are purposebuilt to provide for a default machining strategy of using any

combination of milling and turning within the same work

envelope.



Types of Milling Machines

"here are several types of milling machines, but usually they are

classi&ed by the orientation of their spindles, which are positioned

either hori!ontal or vertical. ach type of mill has its own

attributes depending on what type of work one is doing, so it is

essential to familiari!e oneself with the dierences between these

two before purchasing one for use.

Horizontal Millingori!ontal milling machines have a spindle or cutters mounted on

a hori!ontal arbor above an *+ table. ome hori!ontal mills have

a table, known as universal table, that features a rotary function

for machining at dierent angles. ori!ontal mills are optimal for

machining heavier pieces because the cutters have support from

the arbor, as well as a bigger crosssection area than a vertical

mill. "he design of the hori!ontal milling machine allows for the

rapid removal of material o of the piece one is machining. "hesetypes of milling machines can range in si!e from something small

enough to &t on a tabletop to roomsi!ed machines.

Vertical Milling

'ertical milling machines have a spindle that moves in a vertical

orientation over the table, working on the top and bottom sides of

the ob-ect being machined. 'ertical milling machines lend

themselves to standing machinists and detailed work. "hese

machines tend to be taller than they are wide since their

operation is vertical, which works well when dealing with die

sinking. ie sinking is when a cavity of a particular si!e and shape

is machined into a steel block. "he opening can then be used for



molding plastic or for forging, coining, or diecasting. /elow are

the two types of vertical milling machines most commonly used.

Turret

"urret milling machines are classi&ed as vertical milling machines

because the spindle is positioned vertically0 it is considered a

versatile machine since it can create a wide selection of shapes.

1ike a drill press, this milling machine features a 2uill that when

lowered or raised can create dierent cutting depths0 the 2uillworks in con-unction with a part under the table called a 3knee3 to

machine a piece. "he table on this machine moves both parallel

and perpendicular to allow the machinist to make easier cuts, but

this maneuverability can add stress on the table. "urret milling

machines also tend to be smaller since it is di4cult to move a

2uill on a larger machine.

Bed Mill

5ith bed milling machines, the table moves against the axis of

the spindle. "his machine does not create as much 6exibility in

shape cutting like a turret milling machine, but this type of

con&guration is often used on larger machines.

Milling Machine u!ricants

ince machining solid materials, especially metal, can create a lot

of friction, it is extremely important for milling machines to be

properly lubricated. 1ubricants help reduce friction and cool the

machine while it performs its intended functions, which prevents

failure and damage to the mill and the piece it is machining. ach



milling machine comes with a builtin lubrication system, but it is

up to the user to maintain the lubricant for it to function correctly.

Most mill manufacturers indicate what kind of lubricant to use, but

if one is unsure, it is a good idea to try and &nd a manual online

or ask a professional to make sure what the proper lubricant isneeded for the particular machine being used.

History of Milling Machines "he milling machine performs a variety of operations, so it has

numerous historical predecessors, from the drill to the lathe. "he

&rst milling machines were developed to shape wood in the 78th

century, and as technology and the knowledge of metallurgy

advanced, these wood mills were modi&ed to cut and shape

metal. "hese machines helped fuel the pace of the Industrial

9evolution, when precise machining became increasingly

important. ince so many machinists were making ad-ustments

and developments in their own shops, it is di4cult to credit one

person with the invention of the mill. # mill of note, however, is

one built in the 7:;<s by =ames %asmyth0 his milling machine

could mill the six sides of a hex nut. >ver time, milling machines

have become synonymous with industry and manufacturing.

Modern mills employ the use of computer numerical control ($%$)

for even more ease of use and precision.



OB"#CTIV#$

7."o understand the function and feature provided by the indexing

milling machine.

?."o learn the tool and e2uipment needed while operating the

machine.

;."o understand the safety precaution when operate and handling

of indexing milling machine.

@. Introduction and working principle of milling machine,

A. ierent type of milling operations,

B. ierent type of milling machine and their main parts,

C. peci&cations of milling machines



%&'#T( RU#%

7.afety glasses worn at all times,by everyone in the shop.

?.%o long sleeves,no gloves,no open toe shoes,and no -ewelry or

watches.

;.1ong hair must be secred behind your head.

@./ecome thoroughly familiar with the machine before operating

it.

A.5hen in doubt,always ask a supervisor or shop manager.

B.%ever use the mill (or any other e2uipment) when tired or

rushed for time.

C.>nly attempt work that you have been approved to do and are

comfortable doing.

:.Det additional training,refresher courses and approval as

necessary. #E F>9 1G.

8.%ever reach anywhere over,around or near any rotating cutter.

7<.top the machine every time the cutter is not cutting,not being

used , or you are changing toolsHparts.



77.>nly remove chips using gentle air blasts or chip brushes, be

aware of cutting tools.

7?.se a chip shield to keep chips from hitting you and other in

the area.

7;.Eeep #11 rags and tools away from the machine and o

machine table during use.

7@./e sure the holding device and workpiece are both securely

clamped.

7A.#lways make sure that the cutting tool is sharp,at the correct

height and has the proper clearance.

7B.o not be distracted or talk to other when operating the

machines.

7C.o not walk way from running machines."urn them o every

time.

Conclusion

Milling machines are important for cutting and shaping wood and

metal, among other solid materials. "hese machines are aninvaluable resource for any business or individual seeking to

create precision pieces in a work or personal shop environment.

"here are several dierent types of milling machines, but the two

main types are classi&ed by the orientation of their spindleJ

hori!ontal and vertical. ince milling machines are a big

investment, it is best to research which kind best &ts oneKs budget

and needs before purchasing one particular kind of mill over

another. Milling machines can be purchased at machinery shops

or dealers. "hey can also be bought second hand and at reducedprices from warehouse li2uidation sales or previous owners,

although it is important to check the working condition of a used

mill before purchasing it. Mills can also be found online through

any authori!ed dealer or on auction sites like e/ay. Milling

machines are an integral part of the industrial world, so owning



one can be a valuable asset to oneKs business or home workshop0

it is only a matter of &nding the right mill for the right machining

-ob, and determining the right orientation is a step in the right

direction

)OR*IN+ ,RINCI,# O' MIIN+ M&CHIN#

5orking of a milling machine is based on the fact that milling

cutter is fed against workpiece. "his is achieved by developing

relative motion with precise control between workpiece and

rotating milling cutter. Feed motion is generally given to the

workpiece through its holding device. $utting mechanism of the

workpiece in milling operations is Milling cutter work piece

$onventional Gartial Face Milling nd Milling 5ork piece Milling

cutter 5ork piece Feed direction Gro&le Milling work piece Milling

cutter 5ork piece Gocket Milling cutter Gocket Milling Milling cutter

5ork piece same as that in turning operation on lathe. "his

cutting takes place due to plastic deformation of metal by the

cutting tool. Milling machine can also hold more than one cutter

at a time. "he holding device is supported by mechanism that can



oer a selective portion of the workpiece to milling cutter for its

processing. Indexing is one of the examples of this type of

processing.

,RINCI,& ,&RT% O' & MIIN+ M&CHIN#

Denerally columns and knee type milling machine is considered

as typical milling

machine. Grincipal parts of a typical milling machine are described

as below.

/ase

It provides rest for all parts of milling machine including column. It

is made of



grey iron by casting.

$olumn

It is a type of rigid vertical long box. It houses driving mechanism

of spindle, table

knee is also &xed to the guide ways of column.

Enee

Enee can be ad-usted at a height on the column. It houses the

feed mechanism of

the table and other controls.

addle

addle is placed at the top of the knee. addle provides guide

ways for the

movement of the table.

"able

"able rests on the saddle. It consists of L" shaped slots for

clamping the

workpiece. Movements of the table (feed motions) are given in

very controlled

manner be lead screw.

>verhanging #rm



>verhanging arm is mounted on the column and serves a bearing

support for the

arbor. "his arm is ad-ustable so that the bearing support may be

provided near to

the milling cutter. "here can be more than one bearing supports

to the arbor.

#rbor

It holds rotating milling cutters rigidly and mounted on the

spindle. ometimes

arbor is supported at maximum distance from support of

overhanging arm like a

cantilever, it is called stub arbor. 1ocking provisions are provided

in the arbor

assembly to ensure its reliability.

Front /race MillingFront base is used to ad-ust the relative position of knee and

overhanging arm. It is also an extra support &xed between the

knee and overhanging arm for rigidity.

pindle

pindle is pro-ected from the column face and provided with atapered hole to

accommodate the arbor. Gerformance of a milling machine

depends on the



accuracy, strength and rigidity of the spindle. pindle also

transfer the motive

power to arbor through belt or gear from column

MI11I%D M#$I%



U%IN+ TH# M&CHN#

7 Tra--ing the Head with the help of a upervisor or hopManager.

"he head of a vertical milling machine can be tilted from side to

side and from front to back. "his allows for versatility of the

machine,but these ad-ustments can drift. >ccasionally, one

should check and ad-ust the head so that the spindle will be

normal to the plane of the table."o check, install a dial indicator

into the tramming bar,and install the dial indicator on the other

end of the bar. "he indicator face should be facing up and the

probe at @A degree to the table. 1ower the spindle until the dial

indicator contacts the table then registers about one half of a

revolution. et the dial indicator is toward you and set the be!el

to !ero. 9otate the spindle by hand 7:< degrees. If the dial

indicator still reads !ero, the spindle is aligned front to back. If

not, ad-ust the head until the dial reads half of the original

reading and iterate the entire process until the error falls within

acceptable limits. 9epeat the process with the dial displaced leftand right to alight the head side to side.

?.%.uaring the Vise. $heck before every -ob, donNt assume itNs

aligned or tightened

5ork on a milling machine is most often held in a vise clamped

onto the bed. "o make sure the parts we make are s2uare and

parallel, the vice must be aligned with the * travels of the

machine. "o do this, mount the vise on the bed and secure it with

"bolts, but only lightly so as to permit ad-ustment of the

orientation of the vise. Mount a dial indicator in the spindle of the

machine with the probe facing away from you. 1ower the spindle

and run the bed of the table back until the &xed (back) -aw of the

vise is in contact with the indicator and further until the indicator



registers one half of a revolution. et the be!el to !ero. se the

manual cross feed to run the indicator across the face of the vise.

If the vise is s2uared, the indictor will remain at !ero. If the dial

indicator does not read !ero, tap lightly with a soft hammer to

realign the vise. 9epeat this procedure until the dial indicatorreads !ero through the full travel across the face of the vise -aw.

"ighten down the "bolts be careful not to change the vise

orientation.

;. %etting %pindle %peed / High0o1 +earing

pindle speed is set by turning the speed crank on the right side

of the spindle. "he spindle must be on and rotating to ad-ust thespeed. "here is a manual display (dial) on the head of the

machine that shows the speed in rpm. "he spindle speed dial has

two scales, one for low range, and one for high range. "he

machine is switched between ranges with OG 9#%DP lever

on the right side of the machine head. witching this lever must

be done with the spindle not runningQ ometimes, the spindle

must be rotated slightly (by hand) to allow the

23 Using an #dge 'inder

/efore doing precise work on a milling machine, one must locate

the edges of a part accurately. #n edge&nder is designed to do



this on edges with 6at vertical surfaces. #n edge&nder is

composed of two concentric cylinders, spring loaded together. "o

use it you must &rst insert it into the machine with the

appropriate collet. "he big end of the edge&nder is held in the

collet at least R way in. tart the spindle and set the speed toapproximately 7,<<<rpm. Flick the bottom of the edge&nder to

induce a wobble in the smaller diameter. "he smaller diameter is

usually .?<<P diameter. "hen, move the part into the tool very

slowly. "he edge &nder will center up, then break out of

concentricity suddenly. #t that point, reset the dial indicator or

digital readout for that axis of the machine to a value e2ual the

radius of the edge&nder. 9epeat the process at least twice to

make sure your edge &nding was correct.

A. Using the Digital ReadOuts commonly known as 9>s

"he mills are e2uipped with electronic display for accurate

positioning. "hese 9>s have a @ place display (.<<<?Paccuracy)

for the * and + axes. "he S axes is still read o the mechanical

dial on the Saxis handle with a .<<7P accuracy. "here are two

systems of measurement that the 9>s can supply, Incrementaland #bsolute. #bsolute should be used for the O!eroP corner of

your part and not be changed during the -ob. "he incremental

setting can be O!eroedP as necessary for use between any two

locations, features, holes, etcT.



B. $utting Fluids and their applications.

ierent applications andHor materials re2uire slightly dierent

cutting 6uids. "hese 6uids are designed to provide the correct

amount of lubricity, cooling, better surface &nish, increased tool

life and more. #ll cutting 6uids (especially 577) should be

thoroughly cleaned H removed from the machine when &nishedQ

"he machine should be dry and a light OmistingP of 5@< applied

to the entire vice, tables and machine ways to prevent corrosion.

U%IN+ ,&R&#% in a Eurt vice.

Garallels are used to raise the work above the vice -aws for

machining, drilling or other operations. "hey can set the part

height so the vice -aws will not be hit by your cutting tools and

that any drilling operations will not cut into the bottom of the

vice. Make sure you use a matching (height) set. #lso be aware of

running into the parallels, and constantly check to see that theyhave not moved unintentionally. It is a good idea to always check

that no chips have fallen on toip of or underneath the parallels, as

this will greatly eect the accuracy of your parts.

%4U&RIN+ %TOC* / '&C# MIIN+ First step in accurate parts

"o create a s2uare corner on a part, &rst orient an already &nished

edge vertically in the vise and clamp lightly onto the part. et a

machinistKs s2uare against the &nished edge and the bottom of

the vise. 1ightly tap the part with a plastic hammer to align it withthe s2uare. $lamp the vise down securely. %ow the top edge of

the part is ready to be milled to hori!ontal. It is often necessary to

create a 6at face on a large part. "his is called face milling. elect

a sharp, 6at bottom, end mill cutter a little wider than the

workpiece so that the facing can be accomplished in one pass.



"his can work for end mills up to .CA<P diameter in si!e. /eyond

that si!e, you will have to make multiple passes or use a

6ycutter.Fly cutting, which is also called single point milling, is

one of the most versatile milling operations. It is done with a

singlepoint cutting tool shaped like a lathe tool bit. It is held androtated by a 6y cutter arbor. +ou can grind this cutter to almost

any form that you need. It is more economical to grind the desired

form on a lathetype tool bit than to buy a preground form cutter,

which is very expensive and usually suitable only for one

particular -ob. For milling slots, end mills are an idea tool. "hey

will produce a slot to within two onethousandths of an inch in one

pass. If greater accuracy is re2uired, use an end mill a little

smaller than the desired slot. Measure the slot you produced and

then open it to the desired dimension with a second pass. %otethat the depth of cut should not exceed three times the diameter

of the cutter.

DRIIN+5 BORIN+ / R#&MIN+ Much more accurate than a

drill press

"he milling machine may be used eectively for drilling, since

accurate location of the hole may be secured by means of table

positioning. pacing holes in a circular path, such as the holes in

an index plate, may be accomplished by indexing with the index

head positioned vertically. "wist drills may be supported in drill

chucks fastened in the milling machine spindle or mounted

directly in milling machine collets or adapters. "he workpiece to

be drilled is fastened to the milling machine table by clamps,

vises, or angle plates. For boring, there are various types ofboring tool holders may be used for boring on the milling

machine, the boring tools being provided with either straight

shanks to be held in chucks and holders or taper shanks to &t

collets and adapters. "he two attachments most commonly used

for boring is the oset boring head, also known as the O$riterion

/oring eadP "he singleedge cutting tool used for boring on the



milling machine is the same as a lathe cutter bit. $utting speeds,

feeds, and depth of cut should be the same as that prescribed for

lathe operations. /oring is usually used for holes bigger than .

A<<P diameter. "he most accurate way to &nish a hole smaller

than .A<<P diameter is the process of reaming. 9eaming is aprocess which slightly enlarges a preexisting hole to a tightly

toleranced diameter. # reamer is similar to a mill bit in that it has

several cutting edges arranged around a central shaft. 9eaming is

always done after hole drilling. If the hole is drill crooked, the

reamer will follow the crooked hole. 9eaming should not be relied

upon to correct the location or alignment of a hole. 9eamed holes

should not intersect with drilled holes. Its primary purpose is to

&netune the diameter of the hole. 9eaming is most accurate for

axially symmetric parts produced and reamed on a mill. 9eamerscome in a multitude of si!es.

Maintenance and ser6icing of -illing

-achines

1ike any other machine, milling machines are sub-ect to wear and

tear. "he physical wear is a result of the use of the machines and

of the abrasion caused by friction during use. uch wear can be

reduced by regular maintenance and servicing of the milling

machine by the operatorJ

"he degree of wear depends onJ



maintenance and servicing of the milling machine,

properties of coolants and lubricants,

environmental conditions (dust, temperature variations, etc.)

operating conditions (single or multishift operation, volume of

metal removed, proper operation).

&d6antages

7. "he metal is removed at a faster rate as the cutter has got

multiple cutting edges and rotates at a higher speed.

?. It is possible to perform machining by mounting more than onecutter at a time.

;. "he table of the machine can be moved to an accuracy of

<.<?mm.

@. It is very useful since various cutters and precise tools can be

machined.



A. pecial attachments can be mounted on the machine to

perform operations that are performed in other machine tools.

B. "he 2uality of the shop is enhanced with the presence of this

machine.

Disad6antages

7. "he cost of the milling machine is high.

?. #s milling cutters cost high, the investment for procuring tools

is more.

;. "he production cost will increase if we carry out the operations

performed in a shaper or a drilling machine with a milling

machine.

Inde7ing heads

$rosssection of an indexing head

# dividing head mounted on the table of a small milling machine.

"he direct indexing plate and center are visible facing the camera.

#n interchangeable indexing plate is visible on the left side.

Indexing is an operation of dividing a periphery of a cylindrical

workpiece into e2ual number of divisions by the help of index



crank and index plate. # manual indexing head includes a hand

crank. 9otating the hand crank in turn rotates the spindle and

therefore the workpiece. "he hand crank uses a worm gear drive

to provide precise control of the rotation of the work. "he work

may be rotated and then locked into place before the cutter isapplied, or it may be rotated during cutting depending on the

type of machining being done.

Most dividing heads operate at a @<J7 ratio0 that is @< turns of the

hand crank generates 7 revolution of the spindle or workpiece. In

other words, 7 turn of the hand crank rotates the spindle by 8

degrees. /ecause the operator of the machine may want to rotate

the part to an arbitrary angle indexing plates are used to ensure

the part is accurately positioned.irect indexing plateJ Most dividing heads have an indexing plate

permanently attached to the spindle. "his plate is located at the

end of the spindle, very close to where the work would be

mounted. It is &xed to the spindle and rotates with it. "his plate is

usually e2uipped with a series of holes that enables rapid

indexing to common angles, such as ;<, @A, or 8< degrees. # pin

in the base of the dividing head can be extended into the direct

indexing plate to lock the head 2uickly into one of these

angles."he advantage of the direct indexing plate is that it is fast

and simple and no calculations are re2uired to use it. "he

disadvantage is that it can only be used for a limited number of

angles.

Interchangeable indexing plates are used when the work must be

rotated to an angle not available on the direct indexing plate.

/ecause the hand crank is &xed to the spindle at a known ratio

(commonly @<J7) the dividing plates mounted at the handwheel

can be used to create &ner divisions for precise orientation atarbitrary angles. "hese dividing plates are provided in sets of

several plates. ach plate has rings of holes with dierent

divisions. For example, an indexing plate might have three rows of

holes with ?@, ;<, and ;B holes in each row. # pin on the hand

crank engages these holes. Index plates with up to @<< holes are



available. >nly one such plate can be mounted to the dividing

head at a time. "he plate is selected by the machinist based on

exactly what angle he wishes to index to.

For example, if a machinist wanted to index (rotate) his workpiece

by ??.A degrees then he would turn the hand crank two full

revolutions plus onehalf of a turn. ince each full revolution is 8

degrees and a halfrevolution is @.A degrees, the total is ??.A (8 U

8 U @.A V ??.A). "he onehalf turn can easily be done precisely

using any indexing plate with an even number of holes and

rotating to the halfway point (ole W: on the 7Bhole ring).

/rown and harpe indexing heads include a set of ; indexing

plates. "he plates are marked W7, W? and W;, or 3#3, 3/3 and 3$3.

ach plate contains B rows of holes. Glate W7 or 3#3 has 7A, 7B,7C, 7:, 78, and ?< holes. Glate W? or 3/3 has ?7, ?;, ?C, ?8, ;7,

and ;; holes. Glate W; or 3$3 has ;C, ;8, @7, @;, @C, and @8 holes.

Xcitation neededY

niversal ividing headsJ some manual indexing heads are

e2uipped with a power drive provision. "his allows the rotation of

the dividing head to be connected to the table feed of the milling

machine instead of using a hand crank. # set of change gears is

provided to select the ratio between the table feed and rotation. "his setup allows the machining of spiral or helical features such

as spiral gears, worms, or screw type parts because the part is

simultaneously rotated at the same time it is moved in the

hori!ontal direction. "his setup is called a 3G"> dividing head3.



R#'#R#NC#%

httpsJHHen.wikipedia.orgHwikiHIndexingZhead

httpJHHcollections.infocollections.orgHukeduHenHdH=gt!7<@aeH;.html

httpJHHwww.lathes.co.ukHindexH

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

http://collections.infocollections.org/ukedu/en/d/Jgtz104ae/3.html

http://www.lathes.co.uk/index/

http://collections.infocollections.org/ukedu/en/d/Jgtz104ae/3.html

http://www.lathes.co.uk/index/

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

milling report (indexing)

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