Slotless BLDC Motor

28 mm Slotless Brushless DC Motor

Compact 28 mm slotless (ironless-winding) brushless DC motor designed for high-torque-density rotary motion applications requiring Hall sensor feedback, low cogging, and smooth, low-noise output in robotics, laboratory automation, medical devices, AGV/AMR systems, and industrial automation.

Available in five voltage and duty-cycle configurations, the 28ZWWC52 slotless BLDC motor delivers 30–37 W rated power, 32–50 mN·m rated torque, and no-load speeds up to 9,680 RPM, with optional precision planetary gearbox configurations available for precision motion applications.

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Motor Characteristics

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Specification	Unit	28ZWWC52
Specification	Unit	12V	24V (S2)	36V	48V	24V (S1, 2-Pole)
Pole Pairs	-	1				2
Terminal Resistance, Phase-Phase	Ω	0.52	1.7	4.3	6.6	1.6
Terminal Inductance, Phase-Phase	mH	0.0495	0.178	0.42	0.77	0.13
Winding Connection Method	-	Star Connection
Insulation Class	-	B
Duty Type	-	S2				S1
Feedback Method	-	Hall Sensor
Commutation Angle	-	120°
Insulation Strength (Withstand Voltage)	-	500VAC/1KHz/1mA/1s
Insulation Resistance	-	100MΩ/500VDC
Weight	g	170
Rated Voltage	V	12	24	36	48	24
Rated Power	W	30	34	35		37
Rated Torque	mN·m	32			34	50
Rated Speed	RPM	6970	8430	8370	8340	7000
Rated Current	A	3.13	1.69	1.17	0.86	2
No Load Speed	RPM	9270	9680	9500	9400	8500
No Load Current	A	0.2	0.11	0.084	0.061	0.12
Motor Efficiency	%	80	84	83	85	81.5
Noise (Ambient 20dB, Test Distance 1m)	dB	<50
Thermal Resistance	K/W	8.9	8.2	8.17	7.76	8.96
Thermal Time Constant	S	1200		1080	1100	1000
Ambient Temperature	℃	24				21.2
Max Winding Temperature	℃	80				46.7
Torque Constant	mN·m/A	10.24	18.97	27.32	39.63	25
Back-EMF Constant, Peak Value	V/Krpm	1.52	2.81	4.04	5.87	3.7
Back-EMF Constant, Effective Value	V/Krpm	1.07	1.99	2.86	4.15	2.62
Peak Torque	mN·m	236.31	267.87	228.72	288.25	375
Peak Current	A	23	14	8	7	15
Rotor Inertia	g·cm²	10.2
Mechanical Time Constant	ms	5.06	4.82	5.88	4.29	2.61
End Bell	-	Stainless Steel
Bearing	-	Deep Groove Ball Bearing
Magnet	-	Sinter NdFeB
Rotation Shaft	-	Carbon Steel

Dimensional Drawing

Outline and dimensions shown below apply to the 28ZWWC52 motor at a constant 28 mm diameter.

28 mm slotless BLDC motor dimensional drawing

Torque Performance Curves

28ZWWC52 (1 pole pair) torque performance curve

28ZWWC52 (2 pole pairs) torque performance curve

Customization Options

The 28 mm Slotless Brushless DC Motor can be paired with a precision planetary gearbox to increase output torque and reduce output speed. Contact our engineering team for shaft, cable, and connector customization requests for this series.

Precision Planetary Gearbox

The 28 mm Slotless BLDC motor ships standard with the 28 mm gearbox below. DINGS' offers 10 precision planetary gearbox sizes from 6 mm to 42 mm — browse any size for reference.

6 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3
Gear Ratio	X : 1	3.9	15	57
Max. backlash	°	1.8	2.0	2.2
Max. continuous output power	W	0.65	0.4	0.2
Max. peak output power	W	0.8	0.5	0.25
Max. continuous input speed	rpm	20000
Max. peak input speed	rpm	25000
Max. continuous torque	N·m	0.002	0.005	0.01
Max. peak torque	N·m	0.005	0.01	0.02
Max. efficiency	%	88	77	68
Weight	g	1.6	2	2.4
Gearbox length L	mm	4.7	7.2	9.7

8 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3
Gear Ratio	X : 1	4	16	64
Max. backlash	°	1.8	2.0	2.2
Max. continuous output power	W	0.84	0.52	0.4
Max. peak output power	W	1.05	0.65	0.5
Max. continuous input speed	rpm	14000
Max. peak input speed	rpm	20000
Max. continuous torque	N·m	0.01	0.02	0.06
Max. peak torque	N·m	0.015	0.03	0.09
Max. efficiency	%	90	81	72
Weight	g	2.6	3.2	3.8
Gearbox length L	mm	5.5	8.1	10.7

10 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3	Stage 4
Gear Ratio	X : 1	4.25	18	77	326
Max. backlash	°	1.5	1.8	2.0	2.2
Max. continuous output power	W	1.6	1.2	1.0	0.4
Max. peak output power	W	2	1.5	1.3	0.5
Max. continuous input speed	rpm	14000
Max. peak input speed	rpm	18000
Max. continuous torque	N·m	0.01	0.03	0.10	0.15
Max. peak torque	N·m	0.02	0.05	0.15	0.2
Max. efficiency	%	90	81	73	65
Weight	g	6.8	7.3	7.8	8.3
Gearbox length L	mm	10.1	13.6	17.1	20.6

12 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3	Stage 4
Gear Ratio	X : 1	4.3	18.4	79	337
Max. backlash	°	1.2	1.5	1.8	2.1
Max. continuous output power	W	2.0	1	0.5	0.25
Max. peak output power	W	2.5	1.25	0.65	0.3
Max. continuous input speed	rpm	16000
Max. peak input speed	rpm	20000
Max. continuous torque	N·m	0.08	0.11	0.14	0.17
Max. peak torque	N·m	0.1	0.14	0.18	0.21
Max. efficiency	%	90	80	75	65
Weight	g	9	12	15	18
Gearbox length L	mm	11.3	15.1	18.9	22.7

14 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3	Stage 4
Gear Ratio	X : 1	4.3	18.4	79	337
Max. backlash	°	1.1	1.3	1.45	1.7
Max. continuous output power	W	4.0	2.0	1.0	0.4
Max. peak output power	W	5.0	2.5	1.25	0.5
Max. continuous input speed	rpm	14000	16000
Max. peak input speed	rpm	18000	20000
Max. continuous torque	N·m	0.16	0.2	0.25	0.3
Max. peak torque	N·m	0.2	0.25	0.31	0.38
Max. efficiency	%	90	80	75	65
Weight	g	11	15	19	23
Gearbox length L	mm	11.8	16.1	20.4	24.7

16 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3	Stage 4
Gear Ratio	X : 1	3.9, 5.3	16, 21, 28	62, 83, 111, 150	243, 326, 439, 590, 794
Max. backlash	°	1.0	1.2	1.3	1.4
Max. continuous output power	W	6.5	3.2	1.6	0.6
Max. peak output power	W	8.0	4.0	2.0	0.75
Max. continuous input speed	rpm	12000	14000
Max. peak input speed	rpm	15000	18000
Max. continuous torque	N·m	0.2	0.25	0.35	0.45
Max. peak torque	N·m	0.25	0.35	0.45	0.55
Max. efficiency	%	90	80	75	65
Weight	g	25	31	37	42
Gearbox length L	mm	18.7	25.5	30.2	35

22 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3	Stage 4
Gear Ratio	X : 1	3.9, 5.3	16, 21, 28	62, 83, 111, 150	243, 326, 439, 590, 794
Max. backlash	°	0.85	1.05	1.2	1.35
Max. continuous output power	W	24	12	6.0	1.6
Max. peak output power	W	30	15	7.5	2.0
Max. continuous input speed	rpm	8000	10000
Max. peak input speed	rpm	10000	12500
Max. continuous torque	N·m	0.5	0.7	1.2	1.5
Max. peak torque	N·m	0.6	0.9	1.5	1.9
Max. efficiency	%	90	81	74	66
Weight	g	59	83	97	112
Gearbox length L	mm	22.3	33	39.6	46.3

28 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3	Stage 4
Gear Ratio	X : 1	3.9, 5.3	16, 21, 28	62, 83, 111, 150	243, 326, 439, 590, 794
Max. backlash	°	0.5	0.6	0.7	0.75
Max. continuous output power	W	100	50	25	8.0
Max. peak output power	W	125	62	31	10
Max. continuous input speed	rpm	6000	7000
Max. peak input speed	rpm	7500	8750
Max. continuous torque	N·m	1.25	2.90	5.0
Max. peak torque	N·m	1.6	3.6	6.3
Max. efficiency	%	90	81	72	65
Weight	g	103	150	174	198
Gearbox length L	mm	24.2	36.9	43.5	50.2

36 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3	Stage 4
Gear Ratio	X : 1	3.9, 5.3	16, 21, 28	62, 83, 111, 150	243, 326, 439, 590, 794
Max. backlash	°	0.5	0.6	0.7	0.8
Max. continuous output power	W	185	90	45	15
Max. peak output power	W	230	115	60	19
Max. continuous input speed	rpm	6000
Max. peak input speed	rpm	7500
Max. continuous torque	N·m	2.3	5.4	9.3
Max. peak torque	N·m	2.9	6.8	11.6
Max. efficiency	%	90	80	72	65
Weight	g	156	238	277	315
Gearbox length L	mm	30	44.7	51.3	58

42 mm size planetary gearbox dimensional drawing

Specification	Unit	Stage 1	Stage 2	Stage 3	Stage 4
Gear Ratio	X : 1	3.9, 5.3	16, 21, 28	62, 83, 111, 150	243, 326, 439, 590, 794
Max. backlash	°	0.3	0.4	0.5	0.6
Max. continuous output power	W	480	200	85	20
Max. peak output power	W	600	250	106	25
Max. continuous input speed	rpm	6000
Max. peak input speed	rpm	7500
Max. continuous torque	N·m	3.0	7.5	15
Max. peak torque	N·m	4.5	11.3	22.5
Max. efficiency	%	90	81	72	64
Weight	g	252	405	476	544
Gearbox length L	mm	36.1	54.9	63.6	72.4

Gear ratios shown above reflect standard stock configurations for each size. Additional gear ratios and stage combinations are available upon request — contact our engineering team to configure a custom reduction for your application.

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Downloads

General Resources

↓ General Catalog ↓Slotless BLDC Motor Catalog (PDF) ↓ Manual

Part Number Builder

28 ZWWC 52

28 mm motor diameter

ZWWC

Slotless (ironless-winding) brushless DC motor series

Body length designation, mm

Hall

Hall sensor feedback is standard

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Part Number	Rated Voltage	Duty Type	Rated Power	Rated Torque	Rated Speed
28ZWWC52	12 V	S2	30 W	32 mN·m	6970 RPM
28ZWWC52	24 V	S2	34 W	32 mN·m	8430 RPM
28ZWWC52	36 V	S2	35 W	32 mN·m	8370 RPM
28ZWWC52	48 V	S2	35 W	34 mN·m	8340 RPM
28ZWWC52	24 V (2-Pole)	S1	37 W	50 mN·m	7000 RPM

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28 mm Slotless Brushless DC Motor

Motor Characteristics

Dimensional Drawing

Torque Performance Curves

Customization Options

Precision Planetary Gearbox

Downloads

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