How
to choose a magnetic chuck
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Five Main factors to consider
before selection of Magnetic Chucks |
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Contact Area |
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The ideal condition is minimum
air gap, which offers highest resistance to machining force
and larger contact area. The poorest results are obtained
where large airgaps and limited (line) contact. |
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Surface Finish |
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A lapped finish which has no air
gaps present the best magnetic workholding condition, a
coarsce surface with many air gaps the worst. |
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Lapped
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Ground
finish |
Rough
finish |
Rough
planned |
As Cast |
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100% |
85% |
65% |
45% |
25% |
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Workpiece Materials |
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Maximum induction of flux is
done in Pure Iron and minimum in Stainless Steel for practical
purpose. |
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Cobalt Iron |
Best possible grip 26 kg/cm2 |
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Mild Steel (C-<0.25%) |
Best practical grip 17 kg/cm2 |
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Carbon Steel (0.9%) |
Best possible grip 12 kg/cm2 |
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Cast Iron |
Best possible grip 8 kg/cm2 |
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Nickel (SS 410/420) |
Best possible grip 2 kg/cm2 |
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Condition of Material |
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Heat Treatment of materials
effects its physical structure and its ability to absorb
Magnetic Flux. Annealed materials absorbs Maximum induction of
flux and do not retain any residual magnetism.
Hardened materials do not absorb as much Magnetic Flux but
tend to retain after the Chuck is switched Off. |
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Workpiece Thickness |
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The Magnetic Flux path within a
work-piece is a semi-circle path from the center of one Chuck
Pole to the Center of the next Pole.
So if the work-piece is
thinner than its radius path, it cannot absorb all the flux
and some passes out in Air. Thus the resultant pull is lower
than that when all the flux is absorbed by a Thick job. |
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Different types of magnetic
chucks For work holding |
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1. Permanent Magnetic Chuck |
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2. Electro Magnetic Chuck |
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3. Electro Permanent Magnetic
Chuck |
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From the above it is found that
the main consideration for choosing the correct type of
Magnetic Chuck is determined by the above 5 factors.
Further
type of Grinding Machine and the directional force of the
Wheel is also to be considered.
(direction on which the grinding or cutting force is
applied). |
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Generally the maximum grip is
generated where force is applied at right angle to the pole
direction. Downward force is 4-5 times the magnitude of the
sliding force so that the greater the downward grip the less
likely is the job to slide. |
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Availability of various type of
SARDA magnetic chuck |
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Rectangular Permanent Magnetic
Chuck |
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Model – Kalyani : Standard Pole - Art No. 11101 |
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This is a Standard Pole
configuration of Steel and Aluminium and is suitable for
holding fairly medium/ thick material for general purpose
work. Maximum grip is achieved when thickness of job is 20 mm
and length 30-40 mm or bigger. Magnets are in the Center Body
and such the Top Plates can be machined / drilled/ grooved
upto 12 mm from top. Usually gives about 6Kg/ Cm Sq
on pole area. |
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Model – Permafine : Fine Pole – Art No. 11103
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These are truly Universal Highly
Powerful Magnetic Chuck having Full width Steel and Brass fine
pole using Double Magnetic Pack i.e Magnet in Top Plate as
well as inside. Thus they generate very High Magnetic Pull
upto 10-12 Kgs/ Cm Sq. Being filled with Magnet
on Top Plate, these chucks cannot machined but have working
life of Top Plate upto 6 mm wear & tear and regrinding in
normal use. Having apprx. 6.25 mm Pole Pitch they can hold
small component from 6 x 10 x 3 mm to thick and large size.
Light Milling operation can be also done using these Chucks |
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Model – Microfine : Microfine Pole – Art No. 11104
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These are Fine Pole Magnetic Chuck having Full width 2 mm
Steel and 1 mm Brass Spacing of Fine pole using Single
Magnetic Pack . These are mainly suitable for thin components
even upto 0.5 mm for Grninding application which is not
possible in other chucks due to Pole Distance.
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Circular Permanent Magnetic
Chuck
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Model – Udayan :
Standard Pole - Art No. 11201 |
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This is a Standard
Pole configuration of Steel and Aluminium and is suitable for
holding fairly medium/ thick material for general purpose work.
Maximum grip is achieved when thickness of job is 20 mm and
length 30-40 mm or bigger. Magnets are in the Center Body and
such the Top Plates can be machined / drilled/ grooved upto 12
mm from top. Usually gives about 6Kg/ Cm Sq on pole
area |
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Model – Permafine
: Fine Pole – Art No. 11203 |
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These are Fine
Pole Magnetic Chuck having Full width 2 mm Steel and 1 mm Brass
Spacing of Fine pole using Single Magnetic Pack . These are
mainly suitable for thin components even upto 0.5 mm for
Grinding application which is not possible in other chucks due
to Pole Distance.
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Model - Radial :
Radial Pole - Art No. 11206 |
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High Powerful all
Metal Body Radial Pole Magnetic chucks are having Universal Pole
segments using latest NdFEB Technology. These are most suitable
for Ring type components for both Grinding and Lathe
application. Chucks are Standard with Through Bore which gives
location of spigots and for use for through coolant. Center Plug
for extending Magnetic power to the Center is available as
optional.
Most suitable for
Gears and Hobs for Internal Grinding operation.
This is only
the circular chuck and gives excellent grip on ring type
components when chuck is revolving. This keeps grip force
roughly at right angle to the poles. |
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Rectangular
Electro Magnetic Chuck |
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Model – Emax
: Standard Pole - Art No. 12101 |
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This is a Standard
Pole configuration of Steel and Aluminium and is suitable for
holding fairly medium/ thick material for general purpose work.
Maximum grip is achieved when thickness of job is 20 mm and
length 50 mm or bigger. Coils are provided under each and every
pole thus these Chucks are suitable for both Horizontal and
Vertical Surface Grinding Machines for medium and large
components. |
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Model –
Efine : Fine Pole - Art No. 12103 |
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This is a Fine
Pole configuration of 5 mm Steel and 1 mm Brass full width
extended and is suitable for holding fairly thin /medium and
thick material for general purpose work – thus these are ALL
ROUNDER Chucks for large Grinding Machines.. Coils are provided
alternately at apprx. 45 mm Pitch and magnetic power is induced
through each and every pole thus these Chucks holds both thin
and thick jobs. |
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Controller for
Electro Magnetic Chuck |
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Generally
Transformer Rectifier Set to operate the Chucks from Mains
Supply of 230 or 415 Volts AC is supplied to deliver 110 or 220
Volts DC Power to the Chuck with Manual Spring Return
Demagnetising Switch. However Electronic Variable Modules are
also available with Push MAG/DEMAG facility. |
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Circular
Electro Magnetic Chuck |
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Model –
Econcentric : Concentric Pole - Art No. 12201 |
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This is a Standard
Pole configuration of Steel and Brass and is suitable for
holding fairly medium/ thick material for general purpose work.
Maximum grip is achieved when thickness of job is 20 mm and
length 100 mm or bigger. These chucks are most Rugged Chucks
are they are made by machining from Solid Blocks. Coils are
protected under steel body such they have long life. These
Chucks are suitable for both Horizontal and Vertical Surface
Grinding Machines for medium and large components. These Chucks
can be manufactured and supplied upto 3000 mm Diameter. |
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Model –
Efine : Fine Pole - Art No. 12203 |
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This is a Fine
Pole configuration of 5 mm Steel and 1 mm Brass full width
extended and is suitable for holding fairly thin /medium and
thick material for general purpose work – thus these are ALL
ROUNDER Chucks for large Grinding Machines.. Coils are provided
alternately at apprx. 45 mm Pitch and magnetic power is induced
through each and every pole thus these Chucks holds both thin
and thick jobs. These Chucks can be supplied upto 750 mm
Diameter. |
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Model –
Eradial : Radial Pole - Art No. 12202 |
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This is a Standard
Pole configuration of Steel and Epoxy resign filled gaps and is
suitable for holding Annular type of thin/thick material for
general purpose work where. Maximum grip is achieved when
thickness of job is above 20 mm and big diameter. These chucks
are mainly suitable for machining Rings using raised Blocks for
OD and ID machining. These Chucks are suitable for both
Horizontal and Vertical Surface Grinding Machines for medium and
large components. Sizes available upto 2500 mm Diameter |
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Controller for
Electro Magnetic Chuck |
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Generally
Transformer Rectifier Set to operate the Chucks from Mains
Supply of 230 or 415 Volts AC is supplied to deliver 110 or 220
Volts DC Power to the Chuck with Manual Spring Return
Demagnetising Switch. However Electronic Variable Modules are
also available with Push MAG/DEMAG facility.
Power Supply is
provided through Brass Collector Slipring and Carbon Brush
Holder. |
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Electro
Permanent Magnetic Chuck |
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These are new
Generation Ultimate Magnetic Chucks suitable for Milling /
Turning Application.
EPM Chucks needs
momentary Electric Pulse to Switch On and OFF and such remains
Cold and no Heat is generated during continuous use. |
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Model – EPSquare : 47 x 47 mm - Art No. 13102 |
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This is a Cubic
Pole configuration of Steel and Epoxy Gap and is suitable for
holding fairly thin/medium material for general purpose Milling
work in conventional and CNC Machines. Maximum grip is achieved
when thickness of job less than 20 mm and length 250 mm or
bigger. Each Poles are having tapped holes for mounting Add On
Blocks and generates Magnetic Pull upto 16-18 Kgs/ Cm2. |
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Model – EPSquare
: 70 x 70 mm - Art No. 13101 |
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This is a Cubic
Pole configuration of Steel and Epoxy Gap and is suitable for
holding fairly medium/ thick material for general purpose
Milling work in conventional and CNC Machines. Maximum grip is
achieved when thickness of job is more than 20 mm and length 250
mm or bigger. Each Poles are having tapped holes for mounting
Add On Blocks and generates Magnetic Pull upto 18-20 Kgs/ Cm2 |
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Model – EPMill: Long Pole
: Art No. 13104 |
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This is a
Longitudinal Pole configuration of Steel and Brass/Epoxy Gap
and is suitable for holding fairly thin/medium material for
general purpose Milling work in conventional and CNC Machines.
Maximum grip is achieved when thickness of job less than 20 mm
and length 250 mm or bigger. Tapped Holes can be done on Poles
as per customers requirement. Generates Magnetic Pull upto 14-16
Kgs/ Cm2. |
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Circular EPM
Chuck |
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Model – EPRadial: Radial
Pole : Art No. 13201 |
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This is a Radial
Pole configuration of Steel and Epoxy Gap and is suitable for
holding Annular/ Ring type of component fairly thin/medium
material for general purpose Lathe/ work in conventional and CNC
Vertical Turret Lathe Machines. Each Poles are having tapped
holes for mounting Add On Blocks and generates Magnetic Pull
upto 18-20 Kgs/ Cm2. These Chucks are suitable for
machining ID/ OD and Face in one setting which is not possible
in any other conventional holding chuck. |
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