Grinding Magnetic Chucks Provide Vibration Dampening

Magnetic work holders overcome the intrinsic limitations of mechanical work holders.

Surface grinding is one of the most common machining operations. A work holder anchors the work piece to the grinding table so the material can be worked on. Due to the friction between the abrasive wheel and the work piece, the work holder is integral in providing a rigid support so the piece stays in place, otherwise, excessive vibrations are generated, which creates the risk of workpiece deformation. Mechanical work holders, such as clamps, vises, and screws, hold at their point of anchoring, hence, do not provide full and rigid support a work piece. This can cause excessive vibrations and limit work speed as well as productivity. Magnetic work holders overcome the intrinsic limitations of mechanical work holders.

Overview of Grinding Magnetic Chucks

Grinding magnetic chucks are an effective work holder for grinding operations because they provide a uniform holding force over the entire surface area of the workpiece. Additionally, they are easily integrated with pallet changing and tombstone systems used in production cells. They can be designed for a wide variety of work piece sizes and can be fitted with accessories such as riser blocks, v-blocks and double magnet modules to adapt to irregular work pieces.

Their ability to reliably hold ferrous-material depends on a variety of factors including, type of magnetic chuck, magnetic pole design, material, thickness, area, dimensions and work piece roughness. They are constructed with longitudinal, transverse and radial pole configurations. Radial pole types are used for holding circular work pieces such as rings and discs. A configuration can be fitted with fine pole or standard poles. Fine poles create the strongest magnetic field and are ideal for thin work pieces. The chuck's top plate is sealed to prevent contamination from coolant.

Magnetic Control Types

Grinding magnetic chucks are primarily controlled by two types of technologies: Permanent and Electro-Permanent. When permanent magnet technology controls the chuck, the operator energizes or de-energizes the chuck manually with an actuator located on the side of the unit. No external controls or electrical power is required. This gives them two important features: portability and a failsafe operation.

Electro-permanent magnetic technology, on the other hand, requires a chuck controller, which provides a D.C. excitation voltage to coils embedded in the magnetic chuck. When the controller applies power to the coils, the chuck's magnetic force is energized. Power is only needed to energize or de-energize the chuck's holding force. This gives electro-permanent magnetic chucks the same advantages as the permanent magnetic types, portability and failsafe operation, with one additional advantage: variable holding power. Since the chuck controller can vary the magnetic field of the chuck, the holding force can be varied and adapted to both thin and thick work pieces.

The Vibration Dampening Advantage

Since grinding magnetic chucks provide uniform and full support of the work piece, chatter, harmonics and vibrations are dampened. The intrinsic dampening feature not only improves the surface finish of the workpiece but also can extend tool life.

DocMagnet Inc. designs and supplies workholding magnets. DocMagnet magnetic chucks have all metal surfaces and are built and tested to the highest quality.