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A magnetic chuck is a piece of equipment designed to hold ferrous parts firmly in place so a machinist can work on them. It is a type of work holding device that allows the machinist to grind, drill or otherwise manipulate the iron-based part in question with greater ease and precision. The term can also be used in reference to an attractor that fixates a work holder, for example a vise, to work equipment. Various industrial applications utilize these mechanisms on a regular basis, but the device is also commonly seen in hobbyists’ shops.
A magnetic chuck can be permanent, electromagnetic or electro-permanent in design and functionality. The permanent version of the device latches onto the ferrous part indefinitely, thanks to several attractor inserts that are continuously polarized and lock the part into position. The concept can be compared to that of a refrigerator magnet sticking a piece of paper to the refrigerator door until it is forcefully removed.
The electromagnetic version uses electricity to activate and deactivate the attractor. This means that with the flip of a switch, a surge of electricity engages the mechanism. Conversely, a lack of electricity leaves the attractor idle. This system has the advantage of engaging and releasing the work piece quickly and easily, with minimal effort on the machinist’s part.
The electro-permanent magnetic chuck combines the features of the previously mentioned versions. Although jolts of electric current are used to both lock and unlock the attractor, the work piece is held in place safely and securely even in the event of a power outage. This on-off functionality is achieved through an electric coil wrapped around the attractor, which allows it to switch polarity instantly by sending a current through the device in the desired direction. This version has the added advantage of not requiring a continuous power source.
A magnetic chuck used in industrial applications is likely made of a rare metal called neodymium, which is at a minimum five times more powerful than a regular attractor used around the household. Some models feature a clamping force of up to 12 tons per square foot, making them ideal candidates for purposes such as heavy stock removal. The device is frequently implemented as part of a manual or robotic machining process.
The obvious drawback to this type of device is, of course, its limited application with iron-based metals. For machinists or factories working with ferrous metals, however, there is rarely a better option when it comes to strength, accuracy of positioning, and ease of handling.
For non-ferrous materials, those that are not iron-based, a vacuum chuck may work well. This type of device, as the name implies, creates a vacuum to “suck” the work piece into place. This method works well on materials such as titanium, plastic, stone and bronze, as well as aluminum.
Another product suitable for some non-ferrous materials is the electrostatic chuck. Frequently applied in lithography, this device successfully anchors silicon pieces with electrostatic force.
Certainly, vacuum or electrostatic versions would not possess sufficient strength to secure ferrous metal pieces. In addition, the use of a magnetic chuck has become a popular work holding device because it offers ease of access and relatively simple setup.
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