How To Evaluate Machining Applications For Magnetic Chuck Work Holding

By Author: JASON CHEN
Total Articles: 41
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While selecting the type of magnetic chuck for a machining application there a variety of factors that you need to consider.

As an alternative to mechanical clamping of work-pieces, for holding ferromagnetic work-pieces together magnetic chucks is an ideal one. In spark erosion, grinding, milling, and pallet-loading applications they are commonly used.

Magnetic chucks are designed in such a way so that they can hold Ferro-metallic work pieces with a strong, uniform holding force. They consist of an accurately centered permanent magnetic face that with an operator actuated permanent or electromagnet in conjunction.

Magnetic chucks contain an accurately centered permanent magnet face. With electromagnets or permanent magnets, fixed pole pieces are brought into contact. The magnetic loop or path is closed by the workpiece, onto those fixed plates and gives a secure anchor for the work-piece. You will find many magnetic manufacturers in the market.

To get maximum benefits, a number of factors need to be considered to properly marry ...
... the magnetic chuck to the application.

Magnetic Chuck Application Considerations

Different factors that need to be considered include:
Type of Machining: For the selection of a magnetic chuck, machines and type of machining are important considerations. Factors that need to be considered are the size of the cutter, horsepower, spindle speed, and or tool.

Surface Area: To surface area magnetic holding force is directly proportional. To overcome the forces of the machine smaller parts that have less available contact area may require positive stops. To securely hold the work-piece irregularly shaped parts may require a magnetic fixture.

Type of Material: Materials that have the ability to be magnetized are the only one with which magnetic chucks work. Paramagnetic or diamagnetic materials do not magnetize well at all and for magnetic chuck, work holding they are not good candidates. In the evaluation process of materials, material hardness, shape, and flatness of the work-piece material are an integral part.

Type of Magnet: With magnetic chucks, there are three types of magnetic circuits that are used: permanent-magnetic, electromagnetic, and electro-permanent. Permanent-magnetic chucks have a non-variable clamping force and are mechanically actuated via a lever. To generate the magnetic field electromagnetic chucks use DC voltage in a coil surrounding mild-steel pole pieces. Electro-permanent chucks are a permanent/electromagnet hybrid. In this design, the material is charged and becomes magnetic when DC voltage is applied to the coil that surrounds the permanent magnet.

Chip Control: For magnetic work holding chips are generally not a problem because the chuck's magnetic field does not cause chips to adhere to the work-piece. In case chip problems occur then by using variable control options, they can be alleviated, and then to keep the magnetic circuit away from the machining area it reduces the amount of force applied or by using riser blocks. In other words, to limit the depth of the magnetic field the chuck can be designed, preventing the force from pulling chips into the work-piece.