Size check & sourcing guide
Start with the 12.7 × 1.5875 mm disc: estimate mass, compare sourced N42/N52 pull references and prepare an RFQ. Results update as you type.
1/2 Inch Disc Quick Check
Default: 1/2 in × 1/16 in. Change size, grade or contact for instant screening results.
Popular 1/2" Disc Presets:
Dimensions: diameter 1–200 mm; thickness 0.5–100 mm (or inch equivalents). Use decimals, e.g. 0.5 and 0.0625. All fields are required.
Whole pieces, from 1 to 1,000,000.
Target size: 1/2" × 1/16" (12.7 × 1.5875 mm), t/D = 0.125. Thermal limits require grade-specific B-H curves and the actual magnetic circuit. Protect thin edges during assembly.
K&J catalog pull reference
3.10 lbf
13.8 N, catalog test on thick, flat steel
Single magnet weight
1.528 g
Batch weight
1.53 kg
Aspect ratio (t/D)
0.125
Est. surface field
~1,576 Gauss
Volume
0.2011 cm³
12.7 × 1.5875 mm
0.500 × 0.0625 in; t/D = 0.125. Axial magnetization is the tool assumption; specify it on the drawing.
1.528 g each
Volume × assumed density of 7.6 g/cm³. Use this for lot planning; obtain actual packed weight for freight.
Circuit review required
Thickness alone cannot set a safe temperature. Review load line and B-H curves with the supplier.
| Parameter | Value / decision |
|---|---|
| Diameter | 1/2 in = 0.500 in = 12.7 mm |
| Thickness | 1/16 in = 0.0625 in = 1.5875 mm |
| Volume | 0.20110 cm³ (ideal cylinder) |
| Magnetization | Axial assumed; specify north/south face if needed |
| Tolerance & coating | Unknown until agreed; specify finished, coated dimensions |
Specify pocket clearance and adhesive allowance against the agreed maximum coated size. “12.7 × 1.59 mm” is a rounded description, not a finished tolerance specification.
Catalog pull is a lookup, not a force calculation or a guarantee for a custom magnet. Mass uses the same geometry method as the tool. N/A means no verified row in this dataset.
| Thickness (in) | Thickness (mm) | t/D | Mass (g, est.) | N42 pull (lbf) | N52 pull (lbf) | K&J part |
|---|---|---|---|---|---|---|
| 1/32 | 0.79375 | 0.063 | 0.764 | 1.15 | 1.42 | D801 / D801-N52 |
| 1/16 | 1.5875 | 0.125 | 1.528 | 3.10 | 3.84 | D81 / D81-N52 |
| 3/32 | 2.38125 | 0.188 | 2.293 | 4.16 | N/A — unverified | D803 (N42 only) |
| 1/8 | 3.175 | 0.250 | 3.057 | 6.44 | 7.97 | D82 / D82-N52 |
| 3/16 | 4.7625 | 0.375 | 4.585 | 9.14 | 11.32 | D83 / D83-N52 |
| 1/4 | 6.35 | 0.500 | 6.113 | 10.88 | N/A — unverified | D84 (N42 only) |
Source: K&J Magnet Finder. Pull references apply to those catalog parts; no interpolation is made for other dimensions or grades. A thicker candidate consumes more pocket depth and material; compare assembled retention before choosing it.
K&J defines Case 1 as separation of one magnet from thick, ground, flat steel. A coated, thin or uneven target can give a different result. Read the supplier test method.
The tool withholds force for paint, an air gap or thin steel. It also withholds shear: friction and mechanical retention are unspecified. Record the total separation from plastic walls, paint, adhesive and assembly clearance.
| Assembly | Known here | Minimum next step |
|---|---|---|
| Clean thick steel, direct normal pull | Matching catalog benchmark only | Agree target alloy, finish and test method; measure samples |
| Paint/plastic/adhesive gap | Gap correction unknown | Measure total gap and test worst-case tolerance stack |
| Thin sheet or small steel target | Target saturation/leakage not modeled | Test the actual sheet size, alloy and thickness |
| Vertical or sliding load | No shear rating | Measure slip and consider a retaining pocket or stop |
| Two magnets or a steel cup | Different magnetic circuit | Test the complete paired/cup assembly |
Dimensions are converted with 1 in = 25.4 mm. For diameter D and thickness t in mm: V = π(D/2)²t / 1000 in cm³; mass = V × 7.6 g/cm³. The density is a planning assumption, so results exclude coating and production variation.
This ideal-cylinder estimate assumes uniform axial magnetization, no nearby steel and room temperature. The tool uses assumed Br values of 11,950 / 13,000 / 13,500 / 14,000 / 14,500 G for N35 / N42 / N45 / N48 / N52. At the target size it gives about 1,576 G for N42 and 1,758 G for N52. These are estimates, separate from a supplier’s published field values.
K&J explains the center-axis field model and measurement location; Arnold provides cylinder field equations. K&J grade specifications show Br ranges, so a grade name alone does not fix an exact field.
Aspect ratio t/D is reported as geometry only. It is not Pc and cannot determine thermal safety. Neither surface field nor mass is converted into a force prediction.
A thin disc’s load line depends on the complete magnetic circuit. A free disc and a disc contacting steel may operate at different points. Use the exact grade’s temperature-dependent B-H curve and check the knee; a catalog temperature is not a universal assembly rating. Source: K&J temperature and neodymium magnets.
| Candidate / issue | Tradeoff | Evidence to request |
|---|---|---|
| N42 vs N52 | Compare room-temperature retention and cost on equal geometry | Material certificate plus assembled pull samples |
| Higher-coercivity grade | May improve thermal margin; quote exact grade and availability | Temperature-dependent B-H curves and circuit review |
| High peak temperature or opposing field | Room-temperature pull does not establish retained performance | Hot/cold cycle test with allowed permanent loss |
A coating specification needs a stack and acceptance method. Supplier coating data are specific to that supplier’s process; they do not establish our lot’s corrosion life. See the scope of K&J’s plating data. Finish dimensions after coating should control the pocket drawing.
| Option / requirement | Cost or fit implication | Acceptance request |
|---|---|---|
| Ni-Cu-Ni candidate | Finish and bond compatibility need confirmation | Coating stack, thickness and edge coverage |
| Epoxy or encapsulation candidate | Adds a non-magnetic layer and changes clearance | Environment-specific corrosion and adhesion checks |
| Tighter dimensional tolerance | May increase grinding, sorting and inspection effort | Quote standard vs required limits with inspection records |
| Adhesive mounting | Bondline adds gap; cure temperature affects selection | Validate substrate, surface preparation and cure on samples |
No salt-spray hours, medical suitability, price premium or delivery promise is established here. For a manufacturing quote, ask for the actual slicing/grinding allowance and yield assumptions; a single assumed wire kerf cannot predict unit cost.
Keep magnets separated with spacers, slide them from stacks under control and use an assembly fixture that protects edges. Avoid a press fit or allowing discs to snap together. Agree a visual chip limit and inspect the coating after assembly. These are process recommendations; no universal impact stress or guaranteed cycle life is asserted.
Small strong magnets require controlled handling and retention. Keep loose magnets away from children; use an enclosed assembly when detachment is possible. Follow your application’s magnetic-field restrictions around medical devices.
Illustrative engineering workflows, not measured customer results. Acceptance loads, durability and environmental performance remain to be verified.
Assumption: A 1.6 mm pocket leaves little room for a 1.5875 mm nominal disc plus coating/adhesive.
Process: Check finished thickness and bondline first; prototype the 1/16 inch candidate with its real mating target.
Decision: A fit and pull test decide whether to deepen the pocket or revise the magnet. Catalog pull cannot clear the fit risk.
Assumption: The sensor sees a magnet through a wall with an assembly gap.
Process: Use the exact sensor threshold and worst-case spacing; map field at the sensor position and temperature.
Decision: The displayed face-center field is only a starting reference. Validate the sensor’s switch and release margins.
Assumption: The load acts sideways on painted steel.
Process: Select the gap condition; obtain a drawing review. Compare a retained pocket with a bare magnet using a slip test.
Decision: The tool reports no pull/shear rating for this condition. Choose the retaining feature and magnet from assembled tests.
Use the tool’s email action to carry the current inputs into your draft. For out-of-range or missing references, the drawing-review action supplies a minimum specification checklist. With no mail app, use the contact form and copy the inputs.
It means a 1/2 inch diameter × 1/16 inch thick disc: exactly 12.7 × 1.5875 mm nominally. The fraction describes dimensions; axial magnetization, grade, coating and finished tolerances still need to be specified.
Use the 1/2 × 1/16 preset or enter decimal inches: diameter 0.5 and thickness 0.0625. Choose mm to convert the current dimensions. Empty or invalid inputs show recovery guidance and keep the drawing-review action available.
Nominal equality does not establish clearance. Agree finished, coated OD and thickness limits, pocket limits, adhesive allowance and assembly temperature on the drawing. Request a measured sample before freezing tooling; avoid an interference fit in a brittle thin disc.
K&J catalog parts D81 and D81-N52 list 3.10 and 3.84 lbf respectively for direct pull from thick, flat steel. These are comparison references for those parts, not an acceptance specification or a lifting rating for our supplied magnet. Test the actual assembly.
The catalog condition differs from the selected assembly. There is no validated gap or target-thickness correction in this tool. Send the total non-magnetic gap, target alloy/thickness and direction of load for an application-specific test instead of applying a guessed percentage.
No. The result is an ideal field estimate at the pole-face center of an isolated, axially magnetized cylinder, using the displayed assumed Br. Steel changes the field distribution. Pull, lateral sliding and peeling require separate assembly measurements.
The tool only looks up the verified N42/N52 catalog rows shown in the comparison table. It does not interpolate grades or nearby sizes. Geometry and estimated mass remain available; request a sample pull test for the missing combination.
Choose against the assembled acceptance test. A stronger room-temperature grade may not solve a large gap, lateral sliding, corrosion or thermal loss. Compare N42 and N52 samples at the same finished dimensions and consider a grade with higher coercivity when the temperature/circuit review calls for it.
No universal safe temperature is established here. Give the supplier peak and dwell temperatures, nearby steel, gaps and opposing fields; request the exact grade’s temperature-dependent B-H curves. Verify retained performance after thermal cycling in the intended circuit.
A coating name alone cannot establish service life. Agree the coating stack, edge coverage, humidity or salt exposure, adhesion method and pass/fail criteria. A salt-spray duration is a test condition, not a conversion to years outdoors.
At 12.7 × 1.5875 mm and the planning density assumption of 7.6 g/cm³, calculated magnet mass is about 1.528 g each or 1.528 kg for 1,000 pieces. Packaging, coating and dimensional variation are excluded. Obtain packed gross weight for freight.
Send a finished-dimension drawing, grade or required performance, axial polarity, coating, sample/production quantities, target/gap stack, operating temperature and pull/shear test criteria. Price, MOQ, stock and lead time require a current quotation; this page does not assert them.
Sources checked . Catalog references describe third-party stock parts. The calculations and selection workflows on this page are screening aids; no production test report, inventory or current price is claimed.
Unknowns to resolve: exact production tolerances, grade curve, coating stack, assembly pull/shear, environment, MOQ, price and lead time. Request dated supplier evidence for the specified part and test conditions.
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