STM42 (Open-Loop) Integrated Stepper Motor

Integrated stepper/servo motors combine the motor, driver, and encoder in one compact unit. They offer a smaller footprint, simpler wiring, reduced installation space, and fewer potential failure points. They also simplify commissioning and maintenance, making them ideal for automated equipment where space and reliability are critical.

A motor housing temperature of 80–90°C is completely normal.** Excessively high temperature demagnetizes the magnetic material and reduces torque; magnetic materials generally demagnetize around 130°C. A rough judgment: if you can keep your hand on it for more than 3 seconds, it is usually < 70°C; if you pull your hand away on contact, it is generally above 80°C. Use a thermometer for precise measurement.

Ball is **point contact** with low friction and high speed, but lower load capacity and rigidity — suitable for general automation, semiconductor and medical. Roller is **line contact** with far higher load capacity and rigidity than a ball guide of the same size, but a slightly lower maximum speed — suitable for heavy-load, high-rigidity applications such as large machine tools, stamping and automotive lines. **Criterion: heavy load and high rigidity → roller; high speed and general use → ball.** --- **Further Reading** - [Planetary Gearbox Working Principle and Selection: Reduction Ratio, Backlash and Inertia Matching](./16_行星减速机原理与选型_en.md) - [Integrated Leadscrew Motor (Leadscrew Stepper Motor) Selection Guide](./18_一体化丝杆电机选型_en.md) - [Servo Motor Selection Step-by-Step: From Load Torque to Inertia Matching](../01_选型对比/02_伺服电机选型步骤详解_en.md)

Both domestic and international players have a presence. International brands focus mainly on low-voltage servo modules; among domestic brands, manufacturers such as Limaisheng NiMotion offer a full range of **integrated low-voltage stepper/servo/brushless** products from 20mm to 86mm frames, covering DC 24V and 48V, supporting CANopen, RS485, and EtherCAT buses, and widely used in AGV, medical, and robotics fields. When selecting, focus on verifying: power range coverage, protection rating, encoder type, bus protocol, and master compatibility.

For ball guides use **L = (C / P)³ × 50 km** (L in km, C is the basic dynamic load rating, P is the equivalent dynamic load); for roller guides the exponent is **10/3**. Key insight: **halving the load increases life 8×** — so underestimating the load by a little causes life to drop off a cliff.