Injection molded magnets are widely used as high-grade magnetic materials in the field of small electrical appliances due to their ability to be processed into complex shapes and high dimensional accuracy, such as injection molded magnets used in the steering wheels of intelligent floor sweeping robots. This is a kind of multi-pole ring magnet applied to the left and right wheel motors of the sweeping robots, and its main function is to control the motion speed and direction of sweeping robots.
Most of the magnets used for the steering wheels of sweeping robots are injection molded magnets, such as injection molded ferrite magnets and neodymium magnets.
Image source: Grandviewresearch & Techhive & Couragemagnet
Production Process of Injection Molded Magnets
In the molding process, the injection molded magnet material, with the highest concentration, is completely filled with the mold space under strong injection pressure, plus the material contains thermoplastic binder, so that the injection molded magnets obtain good physical and mechanical properties.
Image source: Brisotech & Couragemagnet
Operating Temperature of Injection Molded Magnets
The maximum operating temperature depends on the magnetic powder and binder used.
Magnetic Powder | As an example, if NdFeB powder, which has a high magnetic energy product, has an intrinsic coercivity is 9500 Oersteds (760 kA/m), the magnetic properties of the material will show a significant and irreversible loss of magnetic properties above 120°C, regardless of the type of binder used. Magnet manufacturers will list the maximum operating temperature for injection molded magnets in their product performance tables.
Binder | Ferrite powder combined with Nylon 6 or PPS can pass the 180℃ test. Nylon 12, however, melts at 170°C or higher, so if the magnet is designed for use at temperatures above 150°C, Nylon 12 is not recommended.
Common Specifications of Injection Molded Magnets Used in Sweeping Robots
The specifications of mass-produced sweeper magnet rings on the market are listed below.
| Outer Diameter(mm) | Inner Diameter(mm) | Height(mm) | |
| TY125 | 18 | 2.25 | 3.6 |
| TY126 | 18 | 1.96 | 3.6 |
| TY127 | 18 | 2.25 | 3 |
| TY128 | 18 | 2.25 | 3.2 |
The Tolerance of Injection Molded Magnets
The dimensional accuracy of the injection molded magnets used in sweeping robot steering wheels could be controlled relatively high, since the injection molded product is dimensionally consistent with the injection mold space. However, shrinkage of the binder during cooling can also cause changes in product dimensions, and the degree of shrinkage depends on the thickness and shape of the product. The dimensional tolerance of injection molded magnets for sweeping robots is generally: ±0.08mm.
The Magnetization Direction of Magnets Used in Sweeeping Robots
The magnetization direction is mostly axial multi-pole magnetization, mainly axial magnetization 8-pole, axial magnetization 16-pole, axial magnetization 24-pole, and axial magnetization 32-pole.
Image source: Couragemagnet & Web
Magnetic Properties
| Magnetic Property List of Injection Molded Magnets (NdFeB Magnets) | ||||||||
| Material Grade | Remanence | Coercivity | Max. Magnetic Energy Product | Density | Rev. Temp Coeff of Br | Max. Operating Temperature | ||
| Grade | Br/min | Hcb/min | Hcj/min | (BH) max | D/typ. | a(Br) | Tw | |
| mT | kA/m | kA/m | MGOe | KJ/m3 | g/cm3 | %/°C (for reference) | °C (for reference) | |
| ZN 27/73 PA12 | 390 | 275 | 735 | 3.38 | 27 | 4.05 | -0.13 | -40~125 |
| ZN 35/69 PA12 | 454 | 305 | 690 | 4.38 | 35 | 4.69 | -0.13 | -40~125 |
| ZN 43/69 PA12 | 506 | 338 | 692 | 5.38 | 43 | 5.01 | -0.13 | -40~125 |
| ZN 47/77 PA12 | 536 | 350 | 770 | 5.88 | 47 | 5.02 | -0.13 | -40~125 |
| ZN 50/72 PA12 | 555 | 362 | 715 | 6.25 | 50 | 5.37 | -0.13 | -40~125 |
| ZN 55/72 PA12 | 580 | 380 | 718 | 6.86 | 54.9 | 5.57 | -0.13 | -40~125 |
| ZN 62/74 PA12 | 614 | 405 | 745 | 7.76 | 62.1 | 5.53 | -0.13 | -40~1 25 |
| ZN 63/71 PA12 | 625 | 399 | 710 | 7.94 | 63.5 | 5.56 | -0.13 | -40~125 |
| ZN 66/53 PA12 | 675 | 363 | 528 | 8.25 | 66 | 5.59 | -0.13 | -40~125 |
| ZN 35/67 PPS | 450 | 300 | 670 | 4.38 | 35 | 4.61 | -0.13 | -40~1 60 |
| ZN 40/69 PPS | 492 | 322 | 690 | 4.98 | 39.8 | 4.80 | -0.13 | -40~1 60 |
| ZN 47/90 PPS | 525 | 360 | 900 | 5.93 | 47.4 | 5.25 | -0.13 | -40~1 60 |
| ZN 47/69 PPS | 533 | 345 | 689 | 5.86 | 46.9 | 5.08 | -0.13 | -40~1 60 |
| Note: The maximum operating temperature depends on the magnet dimension and the specific application. Please contact our application engineers for more information. | ||||||||
| Magnetic Property List of Injection Molded Magnets (Ferrite Magnets) | ||||||||
| Material Grade | Remanence | Coercivity | Max. Magnetic Energy Product | Density | Rev. Temp Coeff of Br | Max. Operating Temperature | ||
| Grade | Br/min | Hcb/min | Hcj/min | (BH) max | D/typ. | a(Br) | Tw | |
| mT | kA/m | kA/m | MGOe | KJ/m3 | g/cm3 | %/°C (for reference) | °C (for reference) | |
| ZF 12/25 PA6 | 240 | 180 | 250 | 1.5 | 12 | 3.44 | -0.19 | -40~140 |
| ZF 10/21 PA6 | 270 | 167 | 200 | 1.8 | 14.4 | 3.55 | -0.19 | -40~140 |
| ZF 14/22 PA6 | 270 | 190 | 225 | 1.8 | 14.4 | 3.55 | -0.19 | -40~140 |
| ZF 15/22 PA6 | 273 | 190 | 225 | 1.88 | 15 | 3.56 | -0.19 | -40~140 |
| ZF 16/23 PA6 | 280 | 195 | 235 | 1.95 | 15.6 | 3.67 | -0.19 | -40~140 |
| ZF 17/23 PA6 | 290 | 190 | 230 | 2.13 | 17 | 3.74 | -0.19 | -40~140 |
| ZF 15/26 PA12 | 281 | 202 | 258 | 1.93 | 15.4 | 3.65 | -0.19 | -40~125 |
| ZF 16/25 PA12 | 286 | 205 | 250 | 2.03 | 16.2 | 3.70 | -0.19 | -40~125 |
| ZF 17/24 PA12 | 295 | 205 | 245 | 2.14 | 17.1 | 3.80 | -0.19 | -40~125 |
| ZF 11/25 PPS | 240 | 178 | 252 | 1. .40 | 11.2 | 3.40 | -0.13 | -40~180 |
| ZF 13/24 PPS | 260 | 1 83 | 238 | 1 .60 | 12.8 | 3.60 | -0.13 | -40~180 |
| Note: The maximum operating temperature depends on the magnet dimension and the specific application. Please contact our application engineers for more information. | ||||||||
Injection Molded Magnets Provider: Tengye
At Tengye, we empower tech companies and product designers with premium magnets. Backed by ISO 9001 and IATF 16949 certifications, we guarantee the highest quality standards. We’re thrilled to be early participants in your new projects. Our passion for magnets extends from material selection and design optimization to providing magnetic solutions. Contact us to explore comprehensive solutions and push your projects forward.
