Magnetic chucks are the most flexible type of workholding system for the widest range of machine tools, including horizontal and vertical machine tools, HSM centers, CNC lathes, mills, EDM palletized robotic applications and surface grinders.

They are most flexible because of usage versatility. Using magnetic chucks to affix workpieces to the machining table or surface saves time over mechanical fastening or clamping.

Workpieces are manually attached to the bed, using holding clamps or vises that must be screwed down or secured as part of the machine setup to ensure firm and accurate positioning of the workpiece according to the machine’s CNC program. Magnetic chucks are more flexible or accommodating if a moldmaker wants to machine multiple parts with one setup or several parts of varying dimensions. Each of these scenarios would require much more setup time to prepare for the machining process versus use of magnetic workholding.

They are more flexible, meaning capable, compared to vacuum workholding, because the holding power of the magnet can exceed the suction force created by the vacuum, which is particularly beneficial for machining large-size parts. Furthermore, setting up with vacuum chucks requires a mask to seal any holes that are not directly covered by the mounted workpiece.

Having full support—the uniformed holding of the entire surface of the workpiece—reduces machining-induced vibration. The magnets have a damping effect on the work due to the fact that they are holding the work over a relatively large contact area compared to mechanical vises and clamps. Due to the solid-piece construction of the magnet, it acts as a buffer between the machine bed and workpiece to damp or impede vibration generated by the machine tool, which can affect the outcome of the workpiece. Using magnetic chucks allows the end user to run faster feeds and speeds without chatter.

If a workpiece is held unevenly, or held to the machining bed with mechanical clamps or vises, the machine must be operated to accommodate those conditions, typically requiring multiple stops and starts. This stop/start action can create imperfections in the part surface, which must be corrected in a post-machining operation such as bench cleaning or polishing to remove any imperfections. Additionally, multiple CNC programs may be needed to work around mechanical clamps to achieve a desired surface or part configuration. Finally, faster feed rates are possible due to the magnet’s ability to firmly hold the workpiece in place and precisely positioned while the grinding wheel, milling cutter or drill performs the material removal process.

No longer associated only with surface grinding operations, magnetic workholding is gaining in popularity. More machine tool builders and end users are looking for ways to improve productivity or reduce setup time to improve their machines’ processes and to create a more efficient machine with better ROI.

Advances in technologies and materials make magnets viable holders for all types of machining of ferrous parts. For example, materials such as neodymium magnet (rare earth materials) give magnets the capability to achieve more aggressive holding forces for the parts while keeping the size and weight of the magnet at a manageable size.