4.4mm diameter micro stepper motor with 20.25 gear ratio planetary gearbox

Short Description:

Model No.: SM044PG

Motor type: 4.4mm stepper motor
Step angle: 22.5 degrees/20.25
No. of phases 2 phases (Bipolar)
Rated voltage 5V DC
Coil resistance 14Ω/phase
Gearbox type Planetary gearbox
Gear ratio 20.25:1

Product Detail

Product Tags


This is a 4.4mm diameter micro stepper motor with a planetary gearbox on top.
The gear ratio of gearbox is 20.25:1, which is a 2 levels gearbox.
Gear ratio of each level is 4.5:1, and total gear ratio is 4.5*4.5=20.25:1
At the early stage of development, we have tried different gear levels and gear ratios, and found out 2 levels, and 20.25:1 is the most suitable range.
Due to restriction of small size, the gearbox can not be designed as multi-levels.

The output connector is a 4 pin FPC, if customer can not find a suitable connector to fit it.
We can also provide customization service, and change output connector into PCB + 4 wires + regular 4-pin connector.


Model No. SM044PG
Motor diameter 4.4 mm
Drive voltage 5V DC
Coil resistance 14Ω±8%/phase
Number of phase 2 phases (bipolar)
Step angle 22.5 degrees/20.25
Gearbox type: Planetary gearbox
Gear ratio 20.25:1

Design Drawing

pro 1

About planetary gearbox (MIM technology)

This planetary gearbox is specifically design drawing micro electronic products such as mobile phone, camera and other small sized products.
It’s a 2 levels gearbox, and the gears and other components inside are made from Metal injection Molding technique (MIM technology).
MIM technology use injection method to produce metallic parts, just like the way we product plastic with injection mold. It can produce high precision metal parts with small size and high precision, which is critical for a mini sized gearbox.
But the equipment of MIM technology is expensive, thus the order quantity of it is higher. Otherwise the cost on each piece of product is too long. So minimum order quantity of MIM is higher, in order to lower average cost.

About geared stepper motors

1.The power input part of the standard stepper motor is available in the form of FPC, FFC, PCB cable, etc.
2.For output shaft, we have two different types of standard shafts:D shaft and screw shaft. If a special axis type is required, we can also customize it, but there is an additional customization cost.
3.8 mm diameter permanent magnet stepper motor with 10*8 mm gear box. The gear box has high precision, high efficiency and low noise, which makes the product have good reliability.


Geared stepper motors, widely used in Smart home, personal care, home appliance equipment, smart medical equipment, smart robot, smart logistics, smart cars, communication equipment, smart wearable devices, consumer electronics, camera equipment, and other industries.

图片 2

Customization Service

pro 3

1. Coil resistance/rated voltage: The coil resistance is adjustable, the higher the resistance, the higher the rated voltage of the motor.
2. Bracket design/slider length: If customers want longer or shorter bracket, there are special design, such as mounting holes, it is adjustable.
3. Slider design: the current slider is brass, it can be replaced with plastic to save cost
4. PCB+cable+connector: PCB design, cable length, connector pitch are adjustable, can be replaced with FPC according to customer's need.

Lead Time and Packaging Information

Lead time for samples:
Standard motors in stock: within 3 days
Standard motors not in stock: within 15 days
Customized products: About 25~30 days (based on complexity of customization)
Lead time for building a new mold: generally about 45 days
Lead time for mass production: based on order quantity
Samples are packed in foam sponge with a paper box, shipped by express
Mass production, motors are packed in corrugated cartons with transparent film outside. (shipping by air)
If shipped by sea, product will be packed on pallets


Shipping Method

On samples and air shipping, we use Fedex/TNT/UPS/DHL. (5~12 days for express service)
For sea shipping, we use our shipping agent, and ship from Shanghai port. (45~70 days for sea shipping)


1.Are you a manufacturer?
Yes, we are a manufacture, and we produces mainly stepper motors.

2.Where is your factory location? Can we visit your factory?
Our factory is located in Changzhou, Jiangsu. Yes, you are very welcome to visit us.

3.Can you provide free samples?
No, we don’t provide free samples. Customers won’t treat free samples fairly.

4.Who pays for shipping cost? Can I use my shipping account?
Customers pay for shipping cost. We will quote you shipping cost.
If you think you have cheaper/more convenient shipping method, we can use you shipping account.

5.What’s you MOQ? Can I order one motor?
We don’t have MOQ, and you can order only one piece sample.
But we recommend you to order a little bit more, just in case the motor is damaged during your testing, and you can have a back-up.

6.We are developing a new project, do you provide customization service? Can we sign a NDA contract?
We have over 20 years of experience in stepper motor industry.
We have developed many projects,  we can provide full set customization from design drawing to production.
We are confident we can give you few advice/suggestions for your stepper motor project.
If you are worrying about confidential issues, yes, we can sign a NDA contract.

7.Do you sell drivers? Do you produce them?
Yes, we do sell drivers. They are only suitable for temporary sample test, not suitable for mass production.
We do not produce drivers, we only produce stepper motors

Frequently Asked Question

1.The difference between reactive stepper motor and hybrid stepper motor?
Different in structure and material, hybrid motors have permanent magnet type material inside, so hybrid stepper motors run relatively smoothly, with high output floating force and low noise.

2.How do stepper motors decelerate?
Stepper motor as a common, widely used drive motor, usually used with reduction equipment to achieve the ideal transmission effect; and stepper motor commonly used reduction equipment and methods, such as reduction gear box, encoder, controller, pulse signal, etc..

3.Stepper motor pulse signal deceleration:
Stepper motor rotation speed, is based on the change of the input pulse signal to change. In theory, give the driver a pulse, the stepper motor rotates a step angle (subdivision for a subdivision step angle). In practice, if the pulse signal changes too quickly, the stepper motor due to the internal damping effect of the reverse electric potential, the magnetic response between the rotor and stator will not follow the change in the electrical signal, will lead to blocking and lost steps.

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