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Ningbo Xinfeng Magnet Industry Co., Ltd.
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Technical Support
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Five Main factors to consider before selection of Magnetic Chucks
Contact Area
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.
Surface Finish
A lapped finish which has no air gaps present the best magnetic workholding condition, a coarsce surface with many air gaps the worst.
Lapped | Ground finish | Rough finish | Rough planned | As Cast |
100% | 85% | 65% | 45% | 25% |
Workpiece Materials
Maximum induction of flux is done in Pure Iron and minimum in Stainless Steel for practical purpose.
Cobalt Iron | Best possible grip 26 kg/cm2 |
Mild Steel (C-<0.25%) | Best practical grip 17 kg/cm2 |
Carbon Steel (0.9%) | Best possible grip 12 kg/cm2 |
Cast Iron | Best possible grip 8 kg/cm2 |
Nickel (SS 410/420) | Best possible grip 2 kg/cm2 |
Condition of Material
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.
Workpiece Thickness
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.
Different types of magnetic chucks For work holding
Permanent Magnetic Chuck
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).
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.
Availability of various type of SARDA magnetic chuck
Rectangular Permanent Magnetic Chuck
Model ?Kalyani : Standard Pole - Art No. 11101
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.
Model ?Permafine : Fine Pole ?Art No. 11103
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
Model ?Microfine : Microfine Pole ?Art No. 11104
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.
Circular Permanent Magnetic Chuck
Model ?Udayan : Standard Pole - Art No. 11201
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
Model ?Permafine : Fine Pole ?Art No. 11203
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.
Model - Radial : Radial Pole - Art No. 11206
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.
