Planetary Gearbox for Electric Screwdrivers and Fastening Tools¶

Electric screwdrivers, compact nut runners and cordless fastening mechanisms commonly use a high-speed DC or BLDC motor together with a reduction gearbox to obtain lower output speed and higher usable torque.

For SigGear's current planetary gearbox program, these applications are a potential OEM Design-In path. This page does not claim that a specific SigGear gearbox has been validated or mass-produced in a named fastening-tool customer project.

Find Published Gearbox Candidates Compare 8–42 mm Planetary Gearboxes Download Public STEP CAD Start Fastening Tool Project Brief

Compare Published SigGear Gearhead Models¶

For cordless screwdrivers and compact fastening tools, the model comparison starts from fastening torque, loaded motor speed, output speed and jam conditions; diameter alone is not sufficient.

Frame and specification page	Example mechanism for evaluation	Engineering checks
24P 24 mm Gearhead	Smaller fastening mechanisms	Check normal fastening torque, gearbox ratio and duty
32P 32 mm Gearhead	Compact tools with greater load demands	Review momentary versus rated torque and stage length
42P 42 mm Gearhead	Higher-load fastening mechanisms	Check stall duration, output bearing loads and tool envelope

These are potential candidates for initial engineering comparison, not claims of suitability, certification or production deployment. Consult each model's rated torque, stage-dependent ratio and length, output load limit, motor interface and simplified 4-stage STEP reference before design freeze.

Browse All 12 Precision Planetary Gearheads

Where to Start by Gearbox Size¶

Use the gearbox diameter only as a first packaging filter. The exact model must still be checked for ratio, stage count, rated torque, length, motor interface and duty cycle.

Starting frame group	Typical tool direction	First engineering checks
10P–20P — Micro / small precision tools	precision electric screwdrivers, electronics assembly tools and compact adjustment mechanisms	low output torque, speed, diameter, noise, repeatability and motor shaft size
20P–28P — Compact OEM tools	cordless screwdrivers, moderate-torque fastening mechanisms and compact service tools	continuous torque, peak torque, loaded motor speed, duty cycle and available axial length
32P–42P — High-Torque Compact	higher-torque fastening tools, compact nut-runner mechanisms and larger motors	rated torque, peak / jam duration, shock load, motor power, bearing load and thermal behavior

See the 3 Planetary Application Families

The Main Engineering Questions¶

1. What torque is required at the fastener?¶

Define the normal fastening torque and any higher peak or stall condition separately. The gearbox should not be selected from maximum momentary torque alone.

For controlled fastening, also define whether the final torque is limited by:

motor current
clutch
electronic torque control
external torque sensor
shut-off logic
operator input

The gearbox provides mechanical reduction; final screw torque accuracy depends on the complete motor, driver, controller, tooling and fastening process.

2. What output speed is required?¶

Provide target output rpm or fastening cycle time. A preliminary reduction ratio can be estimated from:

loaded motor speed / target output speed

The actual available ratio and stage count then need to be checked against gearbox length, torque capacity and efficiency.

3. What motor is already selected?¶

If the motor is fixed, send:

motor manufacturer and model
motor drawing
shaft diameter and length
pilot diameter
mounting-hole pattern
loaded motor speed
voltage
motor power
current limit

SigGear can evaluate a gearbox-only route around that motor.

4. What happens during a jam or hard stop?¶

A fastening tool may see sudden torque rise at seating, stall or a blocked mechanism. Define:

peak torque
peak duration
stall strategy
current limit
hard-stop frequency
reverse / release behavior

These conditions influence gearbox life and should be reproduced during sample validation.

Application Segments¶

Precision Electric Screwdrivers¶

Typical priorities:

small diameter and low mass
controlled low-speed motion
smooth start and stop
repeatable fastening behavior
low vibration
compact output interface

Cordless Screwdrivers and Service Tools¶

Typical priorities:

higher intermittent torque
battery efficiency
compact packaging
repeated start-stop duty
reasonable acoustic behavior
scalable OEM cost

Compact Fastening and Nut-Runner Mechanisms¶

Typical priorities:

rated torque margin
peak-load capability
rigid output interface
stable thermal behavior
cycle life
motor / gearbox alignment

Gearbox-Only or Complete Drive¶

Keep Your Existing Motor¶

SigGear can review:

input pinion or motor interface
reduction ratio
stage count
gearbox length
custom output shaft
mounting flange
housing adaptation

Motor + Gearbox Integration

Need a Motor + Gearbox Assembly¶

If the motor is not fixed, provide:

required output torque
required output speed
available diameter and total length
operating voltage
duty cycle
control method
prototype and annual volume

SigGear can review a motor-matched planetary gearbox configuration.

What to Send for an Engineering Review¶

tool type
normal fastening torque
peak / stall torque
target output rpm
motor model and drawing
voltage and current limit
maximum gearbox diameter
maximum gearbox or total drive length
output shaft / chuck / coupling requirement
normal cycle and rest time
jam / hard-stop condition
backlash or repeatability target
acoustic target
prototype quantity
expected annual volume

Sample Validation Path¶

A useful sample plan is:

no-load run -> representative fastening cycle -> repeated start / stop -> temperature review -> stall / jam review -> endurance cycles -> output-interface inspection -> design freeze

Sample Validation Workflow Design-In Checklist

Start a Fastening Tool Project¶

Wanrong Wang
International Sales, SigGear
wangwanrong@siggear.com

Start Fastening Tool Project Brief