Ι What Are Ferrite Compounds?

Injection molded magnets are a type of bonded magnets produced by embedding magnetic powder in thermoplastic binders such as PA6 (Nylon 6), PA12 (Nylon 12), or PPS (Polyphenylene Sulfide). These magnets can be classified into different categories based on various criteria, one being the type of basic magnetic material. The majority of magnetic materials for all types of permanent magnets is still made up of ferrites, comprising approximately 80 percent of worldwide production by weight. This trend holds for injection molded magnets, though their monetary contribution is about 50 percent due to higher raw material costs of rare earth-based magnetic alloys, including NdFeB, SmCo, and SmFeN.

Hard magnetic compounds serve as an intermediate material for manufacturing injection molded magnets, with their quality significantly influencing the final magnets’ performance. Hard magnetic compounds based on ferrite, which are used to manufacture injection ferrite magnets, are commonly known as ferrite compounds or ferrite pellets.

Ferrite Compound: Process and Role in Injection Magnet Production

Ferrite compounds are manufactured by kneading components in double or single screw extruders following coupling treatment and mixing, with subsequent shaping into pellets with sizes of a few millimeters. As these compounds can absorb moisture, which may impact the quality of the final magnet, they are dried to a specific moisture level before being fed into injection molding machines and are subsequently molded into complex, dedicated structures akin to plastic. As anisotropic magnets, injection ferrite magnets are primarily oriented and magnetized within the mold, requiring sophisticated tools equipped with magnetic inserts, such as assemblies of strong permanent magnets or current-carrying coils.

Magnetic Properties of Ferrite Compounds

The ratio between ferrite magnetic powder and binder is virtually endless, resulting in numerous grades of ferrite compounds that vary based on magnetic properties, mechanical properties, temperature resistance, and moisture absorption.

The grade of ferrite compounds is typically denoted by a combination of the letter F, followed by letters A, B, or C, and a number, sometimes with additional letters or numbers. The letter F serves as an abbreviation for ferrite magnets, indicating the material base. The subsequent letters A, B, or C signify the thermoplastic binder type, corresponding to PA6, PA12, or PPS, respectively. The number that follows represents ten times the typical value of the maximum energy product (BH)max for ferrite compounds, measured in CGS units of Mega-Gauss Oersted (MGOe), with extra codes stemming from R&D and retained post-mass production.

PA6 type

Grade	Remanence Br		Coercivity Hcb		Intrinsic Coercivity Hcj		Max. Energy Product (BH)max		Density	Melt Flow Rate	IZOD Impact Strength	Tensile Strength	Flexural Strength
Grade	mT	Gs	kA/m	Oe	kA/m	Oe	kJ/m³	MGOe	g/cm³	g/10min	kJ/m²	MPa	MPa
FA11	213	2130	162	2040	279	3500	8.8	1.1	3.03	100	50	85	160
FA15	245	2450	183	2300	251	3150	11.9	1.5	3.32	80	35	85	165
FA18	276	2760	191	2400	239	3000	14.9	1.87	3.55	230	23	90	170
FA19	284	2840	195	2450	235	2950	15.6	1.96	3.6	120	19	90	170
FA19RD5	285	2850	197	2470	243	3050	15.9	2	3.6	140	25	60	120
FA20T	293	2930	193	2420	223	2800	16.6	2.08	3.7	80	15	85	160
FA22T	305	3050	191	2400	229	2870	18.1	2.27	3.85	50	11	80	145

PA12 type

Grade	Remanence Br		Coercivity Hcb		Intrinsic Coercivity Hcj		Max. Energy Product (BH)max		Density	Melt Flow Rate	IZOD Impact Strength	Tensile Strength	Flexural Strength
Grade	mT	Gs	kA/m	Oe	kA/m	Oe	kJ/m³	MGOe	g/cm³	g/10min	kJ/m²	MPa	MPa
FB12	227	2270	171	2150	279	3500	10	1.26	3.1	150	45	57	108
FB16	258	2580	193	2430	255	3200	13.1	1.64	3.3	110	40	62	110
FB19R	283	2830	205	2570	255	3200	15.5	1.95	3.58	100	26	56	110
FB19RT	286	2860	204	2560	255	3200	16.1	2.02	3.59	180	24	56	110
FB20RT	294	2940	203	2550	247	3100	16.7	2.1	3.7	90	22	54	105
FB22T	303	3030	187	2350	215	2700	17.8	2.23	3.8	100	18	50	100
FB23R	306	3060	209	2620	253	3180	18	2.26	3.83	50	15	50	100

PPS type

Grade	Remanence Br		Coercivity Hcb		Intrinsic Coercivity Hcj		Max. Energy Product (BH)max		Density	Melt Flow Rate	IZOD Impact Strength	Tensile Strength	Flexural Strength
Grade	mT	Gs	kA/m	Oe	kA/m	Oe	kJ/m³	MGOe	g/cm³	g/10min	kJ/m²	MPa	MPa
FC14	242	2420	175	2200	271	3400	11.3	1.42	3.35	150	13	70	130
FC15	250	2500	179	2250	247	3100	12.1	1.52	3.44	270	9	55	110
FC15A	248	2480	175	2200	239	3000	11.9	1.5	3.42	190	12	55	100
FC16B	256	2560	178	2230	227	2850	12.9	1.62	3.54	260	9	55	110
FC17	267	2670	177	2200	219	2750	13.7	1.72	3.6	220	8	50	100
FC18	272	2720	171	2150	215	2700	14.3	1.8	3.66	180	7	45	105

Intriguing Applications of Ferrite Compounds

The use of ferrite compounds to promote plant growth unveils an unexpected and intriguing application, surprising those who view them only as intermediates in magnet production. Ferrite compounds may enhance root absorption, activate plants, and accelerate growth—potentially boosting fruit quality—through their magnetic influence, which could stimulate plant vitality. In ikebana vases or with kenzan, they extend water freshness, reduce odor, and prevent rust, with their activated carbon content possibly amplifying these effects alongside the magnetic influence.

As permanent magnets in this unique scenario, ferrite compounds are reusable and economical, washable with detergent and dryable for repeated use. While the authenticity of these benefits requires further study, their untapped potential in floral and agricultural innovation captivates interest.

Intriguing Applications-Ferrite Compounds

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Ι What Are Ferrite Compounds?

Ferrite Compound: Process and Role in Injection Magnet Production

Weighing

Coupling treatment

Mixing

Granulation

Injection molding

Magnetization

Packaging and shipping

Magnetic Properties of Ferrite Compounds

PA6 type

PA12 type

PPS type

PA6 type

PA12 type

PPS type

Intriguing Applications of Ferrite Compounds