Formwork magnets use a magnetic field to hold steel shutters in position on a casting table. Inside the housing, permanent magnets create a strong pull toward the steel surface. A switch or release mechanism changes the magnetic circuit, allowing workers to secure or remove the unit. That matters. When engaged, the magnet presses the formwork down and helps resist movement during concrete placement. Its actual holding force depends on the steel surface, contact area, and setup. Dust, dried concrete, or a slight gap can reduce contact and weaken the hold. A magnet may look firmly seated but still perform below its rated capacity.

On a casting table, check that the steel is flat and clean before positioning the magnet. Align it with the formwork, then engage the mechanism fully. Do not judge performance by appearance alone; follow the stated force rating and the setup guidance for the specific application. Small gaps count. Keep magnets clear of loose debris, and check that the formwork does not shift when pressure is applied. Release the unit using its intended mechanism rather than prying against the table. After use, inspect the housing and contact face for damage or buildup. Even careful crews can miss a thin layer of residue, so cleaning deserves a second look.

Before selecting formwork magnets, examine the formwork system they must hold. Is it a steel casting bed, a modular table, or a setup with uneven contact surfaces? Check the bed’s thickness, flatness, and condition. Small gaps matter. Dust, dried concrete, or a slight bend can reduce contact and weaken holding performance.

Then assess the project itself. Record panel height, concrete pressure, pour rate, and vibration levels. These factors affect how much force the magnets must resist. Note where each magnet will sit, especially near corners and joints, where forms may shift. Use the technical data for the specific magnet and confirm that its rated capacity suits the actual setup. A rating alone is not a complete design check.

Walk the site, too. Check access for positioning and removal, and consider whether crews can keep contact surfaces clean during repeated pours. Test the arrangement on the real bed when practical. I have seen a layout look adequate on paper, then struggle because the steel surface was rougher than expected. That detail is easy to miss. Recheck magnet spacing after changes to panel size, concrete mix, or placement method, and involve a qualified engineer when loads or support conditions are uncertain.

How to Choose the Right Formwork Magnets?

Match the magnet’s dimensions and fixing system to your formwork panel. Check the steel thickness, contact area, and available space around the mounting point. A magnet suited to a thick steel table may hold less reliably on a thinner panel. Concrete pressure, vibration, and panel alignment also affect performance. A label can look reassuring, but it cannot replace a trial on your actual setup.

Durability matters across repeated casting cycles. Look for a sealed housing and corrosion-resistant surfaces, especially if panels are cleaned with water. Inspect the switch, welds, and contact face for cracks, rust, or concrete buildup. Small debris can create a gap and reduce holding strength. In practice, this check is easy to skip when production is busy. That is worth reconsidering.

Choosing a formwork magnet starts with the form system, not the magnet’s advertised holding force. Check the steel table’s surface, panel thickness, magnet footprint, and expected concrete pressure. Dust, dried slurry, paint, or a slight gap can reduce contact. A small mismatch matters.

Test it on the actual setup. Clean the steel, place the magnet where it will work, and check that it seats flat. Mark its position with chalk. Apply a controlled sideways push, then inspect for movement or rocking. Follow the supplier’s instructions and keep clear of pinch points. Don’t rely on a hand test as proof of capacity. A clean calculation can still miss a rough surface or vibration.

Run a trial before the pour, using the same panel arrangement and release method planned for the job. Watch for shifting during placement, and check that the magnet can be removed without bending the form. If the setup changes, test again. I’ve found that this step can feel fussy, especially on a familiar table, but assumptions are easy to make. Record the magnet location, surface condition, and any movement. Small notes help explain a poor result later.