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  • Writer's pictureSusanne Nordman

Chuck Repairs - An Economical Way to Keep Production Going

Updated: May 7

Proper care of your electromagnetic chuck is a necessity. As quoted straight from the Mattison Machine Works grinder operator’s manual, “The magnetic chuck is one of the most essential parts of grinder equipment. The character of work turned out from your grinder depends to a very large extent upon the condition of the chuck. It must run true, it must be accurately flat and it must hold the work to the full limit of its magnetic power. For these reasons considerable detail is given regarding its construction, mounting and use.”

Mattison grinder with magna-lock usa chuck
Magna-Lock Electromagnetic Chuck on Mattison Grinder

Knowing this information, let’s discuss electrical connections in electromagnetic chucks. Solid wire connections are essential for electromagnetic chucks to function properly. Loose wires, frail connections and poor electrical wiring can cause your chuck to malfunction. A malfunctioning chuck is a safety hazard to the operator and means downtime for your production.

One the biggest problems we see with electromagnetic chucks is wearing and lack of maintenance of the terminal box. Attaching fluid hoses, over bending cords, breaking the seal on the box, bending the cord grip and quick patch fixes are the most common types of problems that occur with terminal boxes that eventually allow fluid inside the chuck. When fluid gets inside, there will be electrical shorts and burned-out coils that result in poor holding of the chuck which presents a safety issue.

Prevent all of these problems by maintaining a clean, solid seal at the terminal box location. If your terminal box seal should become broken, contacting a trained service technician for assistance in resealing the box to prevent any further damage to the chuck and any safety problems for the operator is strongly advised.

Damaged collector ring in rotary magnet that took on fluid.
Damaged collector ring in rotary magnet that took on fluid.

Is there a section of your chuck not holding well?

Is the chuck control blowing fuses?

Do you have “hot spots” is your magnet?

These are all signs that your magnet may have taken on fluid.

Poor holding performance from your chuck is a safety factor that needs immediate attention. Sometimes fluid leaks can be slow and corrosion inside takes its toll. If your chuck is not holding as well as it once did, take notice of the signs that there is a problem. Gathering a few electrical readings and a phone call to a trained service technician can help most diagnose a problem immediately and assist them in making a plan of action to correct the problem.

An ohmmeter is an electrical instrument that measures electrical resistance.

If your electromagnetic chuck is not responding to available DC power, an ohmmeter can be the best tool you have. To check for faulty internal wiring or coils, check the resistance with an ohmmeter. Minimum resistance to ground should be above 100,000 ohms. Also check resistance between power leads. Note the electrical rating on the chuck name plate or chuck body. To calculate resistance, use the following formula. Resistance (OHMS) = volts/amperage. Measure the actual resistance by connecting an ohmmeter across the leads. If the resistance differs by more than 10% from the calculated value, the chuck will require factory repair.

There is a lot involved with an electromagnetic chuck repair and most of it is unseen by our customers because it happens inside the chuck. Waterproofing, new coils, proper potting compound material for electric conductivity and solid wire connections are a few of the many things that go on inside a chuck. Each of those things (and more) are included with every Magna-Lock USA chuck repair we complete!

electromagnetic chuck repair
Most of the work of a chuck repair is unseen by our customers because it happens inside the chuck.

When we repair an electromagnetic chuck, we strip it down complete. Opening the chuck disturbs the electromagnetic field so most re-wires or one coil replacements are only temporary fixes. The properties of electromagnetism require an electrical circuit that is solid and dependable with many variables. Magna-Lock USA electromagnetic chuck repair services include new electrical wiring—we never reuse wire. The only way we can offer our industry leading two-year warranty on our chuck repairs is to replace all wiring while the chuck is unsealed and open.

chuck repair
We repair all brands of electromagnetic chucks.

If your chuck needs maintenance, Magna-Lock USA trained technicians are available for troubleshooting the problem via phone or email. We repair all makes, models, sizes and shapes of electromagnetic chucks and our repair services include interior waterproofing, an industry leading two-year warranty and quick turnarounds.

In closing, there are many factors that can lead to an electromagnetic chuck failing and needing repair. We have discussed a few here but there may be others that are unique to your circumstances. Please contact our trained service technicians with any questions you may have about keeping your chuck running in tip-top shape remembering that to keep your machine turning out exceptional parts and material, your chuck needs to be always running it’s best.

obsidianmfg logo

Obsidian Manufacturing Industries, Inc. is a Rockford, Ill. manufacturing company and is the OEM for Magna-Lock USA workholding, MagnaLift & Power-Grip lift magnets, and Arter Precision Grinding Machines as well providing surface grinding services. They are located at 5015 28th Ave. in Rockford, Ill. with a phone number of 815-962-8700. Check out more at


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