A useful magnet drawing explains more than length, width and thickness. It identifies how the part fits, which face works and how polarity relates to the structure. The aim is a common reference for machining, magnetization and assembly, with tighter control where the function needs it.
Separate overall geometry from critical interfaces
Overall dimensions describe the magnet; interface dimensions determine fit and location. A hole position, slot width or assembled working-face height can be more important than a non-contact outer contour. Identify which features are critical and why.
Show units and dimension directions. Holes, steps, notches and arcs need suitable views or sections and identifiable reference features. A group of numbers without an order is ambiguous. A 3D model also needs the dimensions and notes that establish the acceptance requirements.
Identify the axis and the working face
Axial and diametric magnetization, or different block axes, produce different pole-face relationships. A “through thickness” note should refer to an identifiable dimension axis. If an assembly face must be north or south, mark that face on the relevant view.
The sectional illustrations use t, L and W for thickness, length and width. Review orientation, magnetization and feasibility against the material and geometry; do not infer the axis from the longest or shortest side.
Specify registration, marking and assembly relationships
Correct polarity on a loose magnet does not by itself define the correct arrangement in an assembly. Describe its orientation relative to the metal part, plastic carrier or locating feature. For multipole designs, also define the pole count, reference position, phase and working face.
If marking is needed, state its position, polarity meaning and any restrictions on appearance or bonding surfaces. A generic request for a mark leaves interpretation to the assembler. Unmagnetized assembly or magnetization after assembly also needs the process and structural constraints to be reviewed.
| Drawing item | Question to resolve |
|---|---|
| References and fit | Which face, hole or feature locates the magnet? |
| Axis and working face | Which face performs the function and which axis is magnetized? |
| Polarity and marking | Which pole is on the designated face, and what does the mark mean? |
| Finished condition | Are dimensions before or after surface treatment? |
| Assembly relationship | Are adhesive space, gaps, orientation and mating parts defined? |
Review tolerances with the finished condition
Do not specify every tolerance as tightly as possible. Consider the fit, processing route, surface treatment and quantities. Critical dimensions need a clear method of acceptance, while non-critical features may not need the same control. Agree the actual values for the project.
Surface treatment can affect finished size and contact conditions. State which dimensions are accepted after finishing or where an intermediate measurement applies. For bonded installation, define adhesive space and location so that separately acceptable parts still assemble correctly.
Use a short ambiguity check
Check units, views, references, critical tolerances, working-face polarity, marking and finished condition. Confirm that mating parts and operating gaps can be understood. A schematic arrow is not a substitute for the required technical parameters.
A notation example is “magnetize through thickness t; designated mating face N; dot-mark that face.” Dimensions, magnetic properties, mark position and inspection still need their own definitions. Keep the drawing revision aligned with the sample record so later changes have a clear baseline.