For magnets inside plastic housings, review the distance between the working pole faces, not only whether the outer surfaces touch. Ordinary nonmagnetic plastic does not form the flux path that ferromagnetic material can, but its thickness still separates the poles. Validate the final attachment with the complete construction.
Closed housing faces do not mean touching pole faces
Two magnets mounted behind separate housing walls can remain apart by both wall thicknesses and an assembly gap even when the product closes. Magnet dimensions or external appearance alone may not reveal that spacing.
Draw a section along the working direction and identify the magnets, pole faces, walls and clearance. For a magnet-to-metal arrangement, identify the metal location, material and thickness. Different mating arrangements are not automatically equivalent.
Break spacing into identifiable parts
The simplified illustration includes a left wall, central clearance and right wall between the pole faces. Count other nonmagnetic layers only if they actually lie between those faces. An adhesive layer behind a magnet should not automatically be added to that same distance.
Principle only: opposite working poles face each other. The figure describes positions and spacing, not actual scale, force or every possible assembly layer.
| Item | Illustrative value | Meaning |
|---|---|---|
| Left wall | 0.8 mm | Between the left pole face and housing interface |
| Central clearance | 0.2 mm | Between the two housing interfaces |
| Right wall | 0.8 mm | Between the right interface and pole face |
| Pole-face spacing | 1.8 mm | Sum of these three example layers, not a product specification |
Review the range, not just the nominal gap
Production and use can involve dimension variation, offsets, warpage and changing contact. Ideal closure may not cover a larger-gap or misaligned condition. Describe the nominal arrangement and the boundary conditions relevant to the product.
For closure, removal or location, also describe motion and permitted displacement. When spacers represent a gap, verify their thickness and position against the real construction and record the test method. An arbitrary sheet is not a defined distance.
Keep the comparison conditions consistent
Options may involve magnet volume, spacing, pole arrangement, mating parts or retention. State what changes in each comparison so the cause of a difference remains identifiable. A grade change alone is not a guaranteed remedy for every structural issue.
Check model scope before using calculations. The website field estimator supports its stated axial field model; it does not calculate the complete plastic-housing assembly’s pull force or automatically include two magnets and surrounding components. Validate the function with the intended structure.
Share the section and the intended function
Provide magnet and mating-part dimensions, mounting positions, pole directions, wall/gap ranges and the intended attachment, locating or removal action. If a sample was tested, identify whether the final housing and assembly method were used.
The 1.8 mm stack is only an illustration of distance recording and has no attached force claim. Complete conditions support a useful sample and validation discussion more effectively than a request for one universal allowable plastic thickness.