NMB PG Permanent-Magnet Stepping Motors with Gearboxes Review: Specs, Price and Applications
Updated: 4 days ago
NMB PG permanent-magnet geared stepping motors combine a PM rotor motor with a reduction gearbox for compact OEM motion mechanisms. The range includes miniature K-series configurations and several larger J, D and C arrangements. These PM products are distinct from the PG20 and PG25 hybrid geared families, even though their names share the PG letters.
Quick Verdict
Consider the PM geared range when a compact low-speed output and a defined reduction ratio fit a valve, appliance or adjustment mechanism. Keep the complete motor-and-gearhead identity, torque units and ratio in the specification. Large reduction and a small nominal output step do not establish zero backlash, high accuracy or safe load holding.
NMB PG Permanent-Magnet Stepping Motors with Gearboxes at a Glance
Specification | Details |
Current miniature families | PG6-K20 / PG6L-K20 / PG8-K20 / PG8L-K20 / PG10-K20; each has its own ratio and length table |
PG6-K20 ratios | 4 / 16 / 64 / 256 / 1024; nominal output-step entries 4.5 / 1.125 / 0.281 / 0.070 / 0.018° |
PG6-K20 rated / instantaneous torque | Ratio 4: 0.010 / 0.020 Nm; ratio 16: 0.020 / 0.030 Nm; ratios 64 / 256 / 1024: 0.040 / 0.060 Nm |
PG6-K20 full length | 19.25 / 21.85 / 24.45 / 27.05 / 29.65 mm across those ratios |
PG15S-K20 ratios | 4 / 16 / 24 / 64 / 96 / 144; rated torque 0.049 / 0.0735 / 0.0735 / 0.098 / 0.098 / 0.098 Nm |
PG25L-K24 ratios | 4 / 16 / 24 / 64 / 96 / 144; output-step entries 3.750 / 0.938 / 0.625 / 0.234 / 0.156 / 0.104° |
PG15S-J20 / PG15S-D20 | Ratio 50 / 102.5; output step 0.360 / 0.175°; 15 mm diameter and 22.5 mm catalog body length |
Other current geometry examples | PG20S-D20: 20 mm diameter, 27.5 mm long; PG25S-D48: 25 mm, 24.5 mm; PG35L-D48: 35 mm, 45 mm |
Reference drive scope | PG6 example: 3 V bipolar constant-voltage; PG15S J20/D20 examples: 5 V bipolar constant-voltage; other windings require their own driver data |
System scope | Motor and reduction gearbox; external driver/controller; application-specific sensing and load support |
Price | Request a quote for exact motor, ratio, winding, shaft and permissible duty |
Design and Engineering Assessment
The gearbox reduces output speed and nominal movement per motor step while adding its own loss, clearance and load limits. A designer must check the permissible output torque independently of the motor torque multiplied by ratio. Higher reduction does not imply a proportionate increase in useful continuous output.
PG6-K20 demonstrates that limit directly. Its rated-torque entry reaches 40 mN m, or 0.040 N m, at ratio 64 and remains at that value at ratios 256 and 1024. The nominal output step continues to shrink, but the torque ceiling does not keep rising. The higher ratios also increase full assembly length from 24.45 to 29.65 mm across those three selections.
The same PG prefix appears in both PM and hybrid geared products. PG15S-K20 and PG25L-K24 are PM geared references, while PG0043-08M000 and PG0043-10M100 belong to current hybrid geared configurations. Their motor architecture and torque limits must not be mixed merely because the size or prefix looks similar.
In an open-loop system, the controller counts commanded motor steps rather than independently measuring the gearbox output. Gear clearance, elastic deflection, an obstruction or a missed motor step can affect the load position. If the process requires position assurance, specify the measurement point and fault behavior as part of the complete mechanism.
K20 and K24: retain the motor step count
PG15S-K20 and PG25L-K24 have different rotor step counts. At ratio 16, their listed output steps are 1.125 and 0.938 degrees respectively. At ratio 144, they are 0.125 and 0.104 degrees. Equal reduction does not produce equal output travel per command when the motor step count differs.
Use the current model-specific step entries and controller convention. Microstepping introduces another command subdivision, but does not remove gear backlash or guarantee equal physical movement for every command. Calibrate and test the process at the output, especially for repeated reversals.
J20 and D20: distinct reduction arrangements
PG15S-J20 and PG15S-D20 share a 15 mm diameter and 22.5 mm catalog body length, but use ratios 50 and 102.5. Their nominal output steps are 0.360 and 0.175 degrees. The reference catalog uses a 5 V bipolar constant-voltage arrangement for these examples.
Do not substitute a K20 ratio table or the phase setting of a different motor. Confirm the complete winding, drive circuit and output drawing, and use the torque curve belonging to that exact assembly.
Torque units and transient capability
The manufacturer’s geared PM tables use mN m. A 98 mN m rated entry is 0.098 N m, while 147 mN m maximum instantaneous torque is 0.147 N m. These are different limits, and neither should be converted into a continuous motor rating without the documented operating conditions.
Select the output torque at the intended speed and duty, including acceleration and externally applied loads. A gearhead’s transient limit is not an allowance for repetitive overload without a defined duty qualification.
Packaging, support and service
Use the full assembly length and actual output shaft drawing. Gearhead length alone excludes part of the motor package, and ratios can change the number of gear stages and overall length. Include the mounting structure, coupling and wiring clearances in the mechanism.
Provide suitable radial and axial support for the applied load. Reduction does not automatically make the output a load-bearing rotary stage, and a compact geared motor should not be assumed to self-lock under gravity or spring force. Engineer the required holding and power-loss behavior separately.
Applications and current ordering scope
NMB identifies appliance, printer and related compact motion applications for PM geared selections. Match the exact mechanism’s load cycle, acoustic requirements and service expectations to the supplied assembly. A generic family example does not establish a quantified noise level or lifetime.
Older listings include PG5 references and short forms that are not all reproduced in the current family table. Confirm supply and replacement support for the exact old code instead of assuming it is either currently stocked or discontinued. Preserve the full manufacturer reference and approved drawing for maintenance.
Commissioning and alternatives
Verify ratio, direction, output travel per command and limit behavior at controlled speed. Evaluate loaded reversals, starting reliability and temperatures through the complete duty cycle. Test a blocked mechanism and power interruption using the machine’s defined fault strategy.
Compare against a hybrid geared stepper or another miniature gearmotor at the same output torque, speed, backlash and installation envelope. A closed-loop alternative changes the control and feedback scope. Quote the full mechanism requirements, not only diameter and the largest available ratio.
Applications and Selection
Manufacturer application examples include appliance mechanisms, printer or office-automation motion and related compact OEM drives. Select the exact PM geared configuration by output torque-speed duty, travel scale, reversal behavior and mechanical integration.
For NMB PG Permanent-Magnet Stepping Motors with Gearboxes, define the actual machine duty before selecting an ordering configuration. Include the required operating point, available installation space, environment and control interfaces. The specification table describes the product or family; the surrounding machine determines which of those features matters for the intended job.
Price and Value
Price: Request a quote for the exact configuration. Compare the product, compatible control equipment, required mechanical parts, cabling and commissioning as one installed system. A component price alone does not represent the cost of a working automation axis.
Evaluate an alternative against the same duty and acceptance criteria. Match the continuous operating requirement first, then compare transient capability, feedback, mechanical fit and support. This avoids choosing between superficially similar products whose ratings describe different operating conditions.
Pros and Cons
Advantages
Miniature geared configurations combine reduction with a compact motor
Several ratios and rotor step counts provide different output command scales
Model-specific rated and instantaneous torque tables support selection
Current drawings and length entries distinguish installation requirements
Limitations
Higher ratio does not guarantee higher rated torque
Gear clearance and compliance affect actual output positioning
PM PG names must be distinguished from hybrid PG products
External control, sensing, load support and holding provisions remain necessary
Who Should Consider NMB PG Permanent-Magnet Stepping Motors with Gearboxes?
Consider the PM geared range when a compact mechanism needs reduction and can use an external stepper-control architecture. Define the actual ratio, permissible output duty, shaft loads, reference strategy and power-loss behavior before ordering.
NMB PG Permanent-Magnet Stepping Motors with Gearboxes FAQ
Are all NMB motors with PG in the name PM motors?
No. The current product range also includes PG hybrid geared references. Identify the complete motor code and product class before transferring winding, torque or mechanical data.
Does PG6 ratio 1024 have sixteen times the rated torque of ratio 64?
No. The current table lists 40 mN m, or 0.040 N m, rated torque for both, while their nominal output step and assembly length differ. Check the actual gearhead ceiling.
Why do K20 and K24 have different output steps at the same ratio?
Their rotor step counts differ. For example, PG15S-K20 and PG25L-K24 at ratio 16 list 1.125 and 0.938 degrees per output step. Keep the motor count and controller convention with the ratio.
Is 98 mN m equal to 98 N m?
No. It is 0.098 N m. Preserve the table’s units, and distinguish rated torque from maximum instantaneous torque.
Does a small output step eliminate backlash?
No. The step entry is a nominal command increment. Gear clearance, elastic deflection and load changes still affect bidirectional output positioning.
Can a gearbox be used as a holding brake?
Do not assume that reduction safely prevents backdriving. Specify the required holding and power-loss response for the actual mechanism and external loads.
Are old PG5 references currently available?
An older listing does not establish current availability or discontinuation. Request confirmation of the exact code, drawing, replacement support and delivery terms.
What is the price?
Request a quote for the full PM motor and gearhead configuration, ratio, winding and shaft. Include the driver, control, load support and any required feedback or holding mechanism.
Prices are indicative and may change. Confirm the final configuration, commercial terms and delivery schedule before ordering.
