Specify magnetic tubes by powder flow, contaminant characteristics, rod geometry, mounting, temperature and cleaning method. A gauss value alone does not establish removal performance. Confirm the assembly dimensions and evaluate separation with representative material before selecting a replacement rod or grate.
Separate the rod dimensions from the opening between rods
A replacement rod must fit its mounting points, but the completed grate must also allow the powder to pass through. Record the rod outside diameter, working length, end fittings and mounting centres. For an existing assembly, supply a drawing rather than measuring only the hopper opening.
Published grate dimensions are useful references, not universal design rules. For example, Eriez lists a configuration with 25 mm tubes on 51 mm centres. For parallel round tubes of those nominal dimensions, the nominal gap is 26 mm. That calculation does not determine whether your powder will bridge or whether the assembly will meet a removal target.
Changing diameter while retaining the same centres changes the gap. Changing rod spacing changes both the flow opening and the material’s proximity to the rods. JINHONG can vary magnetic rod dimensions and magnetic strength to the application; agree the complete geometry before manufacture.
Compare complete configurations rather than the highest gauss number
| Published example | Geometry or specification | What still needs confirmation |
|---|---|---|
| JINHONG custom magnetic rods and grates | Rod dimensions and magnetic strength can be specified for the assembly | Approved drawing, operating temperature, measurement location and cleaning arrangement |
| Bunting general-purpose grates | 25 mm round cartridges; round or rectangular arrays | Selected model, powder flow and installation dimensions |
| Eriez easy-to-clean grate-in-housing example | 25 mm tubes on 51 mm centres; one or multiple rows listed | Selected configuration, operating temperature and cleaning procedure |
This is a comparison of published configurations, not a controlled performance test. Sources: JINHONG magnetic rods, Bunting grate magnets and Eriez grate magnets, checked 26 October 2026. Manufacturers’ rounded dimensions are retained as published.
When comparing magnetic readings, agree the measuring instrument, probe location, distance and temperature. A surface reading and a measurement taken away from the surface are different conditions. Neither value alone establishes a plant’s iron-removal rate.
Define the contaminant separately from the powder
The powder particle size and the iron-contaminant size answer different questions. Provide both, together with contaminant shape, approximate loading and whether it is loose or associated with powder agglomerates. State the acceptance method before comparing suppliers.
JINHONG’s approximately 80 μm iron-contaminant capability statement applies to the JH-LX machine under the relevant evaluation conditions. It is not a guarantee for every loose rod, every grate or every powder. Do not transfer a complete machine’s removal claim to a replacement component.
Likewise, the confirmed 1.3-times comparison concerns JH-LX whole-machine iron-removal rate under matched conditions. It does not mean a magnetic rod captures 1.3 times as much material, and it does not mean a 130% improvement. If this comparison matters to your process, agree the baseline machine, sampling method and matched operating conditions.
Evaluate cleaning and powder flow as separate requirements
A grate can be easy to clean yet still restrict a cohesive powder. Record the feed arrangement, powder behaviour and required throughput. Where bridging is a concern, compare the flow path with a rotary magnetic separator and verify the proposed arrangement with representative material.
For cleaning, specify whether production can stop, how far rods can be withdrawn, where collected contamination will discharge and how it will be prevented from re-entering the product. An easy-clean sleeve does not automatically provide automatic or continuous cleaning. See the JH-LX self-cleaning powder separator when automatic cleaning is part of the project.
Prepare a drawing and a process specification for quotation
Include the hopper or housing drawing, rod dimensions, end connections, quantity, material-contact requirements, operating temperature, powder properties, throughput and cleaning method. For a replacement, identify which dimensions must remain interchangeable and which may be redesigned.
Ask for the proposed configuration and its inspection conditions to be stated in the quotation. An agreed drawing establishes fit; a representative-material evaluation establishes whether the selected arrangement meets the process requirement. They are separate checks.
Review JH-B rare earth magnetic rods, compare custom magnetic grates, or send your hopper drawing and process conditions for a quotation.
Frequently asked questions
What magnetic tube diameter should I use in a powder hopper?
There is no single diameter for all powders. Match rod diameter, mounting centres and the available flow opening to the powder and throughput. Use the existing drawing when replacing a rod; evaluate the complete grate when changing its geometry.
Does a higher gauss value guarantee better iron removal from powder?
No. Field measurement conditions, contaminant properties, material flow, rod geometry and accumulated material affect the result. Compare readings under the same conditions and use a representative-material test for the removal target.
Can I replace one manufacturer’s magnetic rod with a custom rod?
Custom manufacture is possible, but interchangeability must be checked. Supply dimensions, end connections, contact-material requirements, temperature and the intended inspection conditions. Do not assume compatibility from the outside diameter alone.
Does the JH-LX 80 μm statement apply to a standalone magnetic tube?
No. It concerns iron-contaminant diameter for the JH-LX machine under its relevant evaluation conditions. A standalone rod or different assembly needs its own specification and process evaluation.
Should a cohesive powder use a grate magnet or a rotary separator?
Compare the flow behaviour and available space. A rotary configuration may help address bridging, but it does not guarantee unrestricted flow for every powder. Check the selected design using the proposed material and throughput.