Countersunk ring magnets sit at the crossing of two published shapes: the countersunk shape family, with its hole range, and the ring shape family, with its inner diameter. Buyers often merge the two, asking for a ring with a countersunk hole as if one table covered both. This guide keeps the two tables apart, explains what each figure means, and shows what a combined inquiry should contain so that neither figure is borrowed from the wrong table.
Two different hole figures
The countersunk shape range publishes a countersunk hole of M1 to M10, with round and rectangular outer forms listed as customized, standard tolerance ±0.05 mm and minimum ±0.01 mm, and directions axial and through thickness. The ring range publishes an inner diameter of 1.5–150 mm, an outer diameter of 3.0–200 mm and a height of 0.5–50 mm, with directions axial, diametrical and radial. A countersunk hole is a recessed hole shaped to let a screw head sit flush; a ring inner diameter is the through opening of a ring. They are different geometric features, measured differently, and an inquiry should say which one it means rather than writing hole and leaving the reader to guess.
The practical error is easy to picture: a buyer writes hole 10 mm, meaning a ring inner diameter, and the reader takes it as a countersunk hole size, or the reverse. The safeguard is to name the shape first and then the figure in that shape's terms: for a countersunk magnet, form plus hole size in the M range; for a ring, outer diameter plus inner diameter plus height. If the part genuinely needs both — a ring whose face also carries a countersunk recess — say so explicitly with both sets of figures, and ask whether the combination can be made, rather than assuming one table covers it.
Forms: round and rectangular, both customized
The countersunk outer form, round or rectangular, is listed as customized, which means the outer dimensions are supplied by the buyer rather than selected from a published table. That has a consequence for hole inquiries: a hole size without an outer form does not describe a countersunk magnet, and an outer form without a hole size does not describe one either. Both are needed, together with the grade series and the direction — axial or through thickness for countersunk shapes. A rectangular countersunk magnet also needs its length, width and thickness stated, not just a single size word, because a rectangle has three edges and a hole.
Fixing is the reason for the countersunk shape: the recess lets a screw head sit flush with the magnet face, so the magnet can be fixed flat without a protruding head. The screw itself, its material and its length beyond the published hole range are matters for the inquiry, not assumptions. If the fixing must sit in a particular housing, give the mating dimensions as well, because a countersunk magnet that matches its own table but not its housing will still need a second round of questions.
When a ring is the right starting point instead
If the part's defining feature is a through opening that something passes through — a shaft, a cable, a rod — the ring table is usually the right starting point, and the inner diameter should be stated as an inner diameter, not as a hole size in the countersunk sense. Ring directions include diametrical and radial alongside axial, and the direction should be copied from the ring list, not from the countersunk list, because the two lists differ. A ring inquiry that borrows through thickness from the countersunk list, or a countersunk inquiry that borrows radial from the ring list, has mixed two tables, and the review will need to ask which shape was actually meant.
The shape comparison guide places all six ranges side by side for exactly this kind of decision, and the magnetization directions guide collects the six direction lists. Checking a combined inquiry against both before sending it is a small step that prevents the most common countersunk-ring error, which is not a wrong dimension but a dimension quoted from the wrong table.
Questions to send with a countersunk or ring inquiry
A specification that can be answered names four items together: the shape family, dimensions inside that family's published range, the grade temperature series, and the magnetization direction exactly as listed for that shape. Add the operating temperature and the fixing method where they affect the choice, and ask coating and warranty as open questions. Please confirm minimum order quantity and lead time before ordering. Warranty terms are unavailable on the published pages — please confirm warranty terms before ordering. Certificates are available upon request; no certificate number or issuing body is published here.
An inquiry that names only a grade, or only a size, will be answered with questions rather than a confirmation, because neither item alone is a complete specification. The extra sentence that states the direction in plain words, or that gives the mating dimension for a fixing, is often the sentence that prevents a second round of correspondence, and it costs nothing to include at the start.
Frequently asked questions
Which grade series should I discuss for countersunk ring magnets guide?
Discuss the grade series against the shared grade maximum working temperature table, using the temperature the magnet will actually see in service, including heat from neighbouring parts. The series run from N35–N52 at 80°C through the M series at 100°C, the H series at 120°C, the SH series at 150°C and the UH series at 180°C to the EH series at 200°C. State the operating temperature as a figure in the inquiry, because a grade name without its temperature row has not been specified for a warm environment, and the review needs the temperature to confirm the series discussion rather than infer it from a name alone.
How exactly should I state the magnetization direction?
Copy the direction exactly as listed for the shape named in the inquiry, and do not substitute a synonym that feels equivalent, because the same word can describe a different arrangement on a different shape. Where a drawing uses a different convention, add a plain-words description of the pole positions alongside the listed term, so the review can reconcile the two without guessing. A direction that is assumed rather than confirmed is a common source of a magnet that is dimensionally correct and magnetically wrong for its fixing, so the extra sentence describing the poles is worth writing even in a short inquiry.
What should I ask about coating, warranty and certificates?
Please confirm coating requirements before ordering, because coating type names were not transcribed from the company illustration and no coating type is named on this site; state the operating environment with the coating question so the answer can be specific. Warranty terms are unavailable on the published pages, so please confirm warranty terms before ordering rather than assuming a term. Certificates are available upon request: name the certificate required and its purpose in the inquiry, because no certificate number, issuing body, scope or validity period is published here, and a named request can be matched to the order it belongs to.
What if my size or combination is not in the published range?
Ask whether it can be made, and send the dimension as written rather than rounding it into the published range. A value outside a shape range, a direction not listed for that shape, or a combination of features from two shapes should be raised as an explicit question, with a dimensioned sketch where the geometry is curved, holed or otherwise not captured by a single size figure. Please confirm minimum order quantity and lead time before ordering. A question asked before ordering costs one message; a forced fit into the nearest published table can cost the whole part, because a magnet that matches its order and fails its fixing is worse than an extra round of questions.