Permanent magnetic chuck (circular) TC-250B

TC series circular permanent magnetic chucks are designed to clamp ferromagnetic workpieces (iron, structural steel, alloy steel, cast iron) during grinding, milling and electrical discharge machining. In the case of materials with high magnetic properties (steels with high iron content), the chucks can be used as holders in turning operations.

The chuck can be mounted using the grooves at its bottom or the four threaded holes (see the attachments). The body of the chuck consists of a single block of steel, while its top plate is made from steel and brass lamellas placed interchangeably. TC series circular chucks use neodymium magnets, so that a maximum magnetic holding force of approx. 100 N/cm² is achieved. The magnetic field can be turned on with the use of a lever (Allen wrench), by turning the lever to the right by 180^o. To turn the field off, the lever should be turned inversely.

The rigid structure of the chuck enables very precise machining, while its tightness allows using the chuck for operations involving coolant or operations in full submersion. The simplicity of the design ensures a long and reliable operation of the device. A lack of electrical power supply makes the chuck completely safe during the operation. The pole pitch (3.0 + 1.0 mm) enables firm clamping at a small height of the magnetic field, so the workpieces clamped can be thin.

Pole pitch diagram:

The clamping force depends on the following parameters:

• type of material (the clamping force increases proportionally to the content of iron in steel):

- Armco iron 100%
- low-carbon steel 90% (St3s)
- high-carbon steel 80% (St45)
- alloy steel 70% (Corrax)
- high-alloy steel 65% (1.2436)
- cast iron 50%

• roughness of the surface of the chuck and the workpiece clamped:

- for Ra up to 0.08 µm 100%
- for Ra up to 0.20 µm 90%
- for Ra up to 1.25 µm 70%
- for Ra up to 6.30 µm 50%
- for Ra up to 25.00 µm 30%

• thickness of the workpiece clamped (the tests were carried out for plates with the size of 20 x 20 mm made of Armco iron):

• contact area - in order to ensure good holding, workpieces cannot be shorter than 3 mm and additionally, in the case of small surfaces, they should be surrounded with auxiliary plates. The maximum clamping force per cm² is obtained for workpieces with an area of approx. 4 cm².
  A further increase in the workpiece area does not translate into a higher clamping force. It is also important that the workpiece clamped is parallel to the chuck, because every roughness, even the smallest, causes a decrease of the clamping force.
  The design of the chuck allows regenerating the working area by grinding it to 5 mm of the thickness.

The circulair permanent magnetic sine chucks available in our offer are presented below: