Frameless BLDC Motor: The Compact Powerhouse for Precision Automation & Robotics

"High torque density frameless motor" – if you’re searching for a motion solution that packs maximum power into minimal space, look no further than frameless brushless DC (BLDC) motors. Unlike traditional housed motors, these innovative components eliminate bulky casings, bearings, and shafts, delivering unrivaled design flexibility for custom mechanical systems. Whether you’re engineering a collaborative robot arm, a high-speed CNC machine, or a precision medical device, frameless BLDC motors redefine what’s possible in compact, high-performance motion control.

"Compact brushless DC motor for precision automation" isn’t just a keyword – it’s the backbone of modern manufacturing. From semiconductor equipment to 3D printers, today’s machines require motors that balance small size with exceptional precision. Frameless BLDC motors deliver exactly that: with low cogging torque (as low as 69 mN·m in standard models) and high dynamic responsiveness, they enable sub-millimeter positioning accuracy even at high speeds. This series – available in 56mm, 60mm, 76mm, 89mm, and 95mm diameters – has become a staple in industries where every millimeter and millisecond counts.

"Frameless motor for robotic joints" is one of the fastest-growing search terms in industrial automation – and for good reason. Humanoid robots, cobots, and industrial manipulators demand motors that fit inside joints, not around them. Frameless BLDC motors answer this need by integrating directly into mechanical structures: their stator mounts to the joint housing, while the rotor attaches to the moving shaft, creating a "zero-backlash" direct-drive system. This design cuts weight by 40% and reduces footprint by 30-50% compared to housed alternatives, enabling smoother, more agile robotic movement.

We’ve compiled the most common questions about frameless BLDC motors to help you decide if they’re the right fit for your project.

Q1: What is a frameless BLDC motor, and how does it differ from traditional motors?

A frameless BLDC motor consists only of a stator (copper windings + steel laminations) and a rotor (permanent magnets + steel core) – no integrated housing, bearings, or output shaft. Traditional housed motors include these components as a single, enclosed unit, limiting how they can be integrated into custom systems.

Frameless motors shift this paradigm: you design the "frame" around the motor, embedding the stator and rotor into your mechanical structure. This means the motor uses your system’s bearings, shaft, and housing, reducing overall weight, size, and component count. For example, a 60mm frameless motor can replace a 80mm housed motor while delivering 20% higher torque – a game-changer for space-constrained applications like robotic joints or medical device actuators.

Q2: What are the key advantages of frameless BLDC motors?

The benefits of frameless BLDC motors align with the most pressing needs of modern engineering:

· Exceptional torque density: By eliminating non-essential components, these motors deliver 3-5x the torque per unit volume of traditional motors (e.g., a 76mm frameless model offers 4.4 N·m continuous torque in a package smaller than a coffee mug).

· Precise motion control: Direct integration into your system eliminates backlash from gears or couplings, enabling sub-arcsecond positioning accuracy – critical for CNC machining, optical alignment, and surgical robotics.

· Compact, lightweight design: Sizes from 56mm to 95mm (with stack heights customizable to your needs) let you fit power into tight spaces, while weight reductions of 40%+ optimize payload capacity for robots and drones.

· Design flexibility: Choose from standard diameters (56/60/76/89/95mm) or customize windings, voltage, and feedback options (encoders, hall sensors) to match your system’s exact requirements.

· Durability & low maintenance: With fewer moving parts, frameless motors reduce wear and tear – ideal for 24/7 industrial automation or extreme environments (e.g., high-vacuum aerospace systems or washdown food processing equipment).

·

Q3: Which applications benefit most from frameless BLDC motors?

Frameless BLDC motors are the go-to choice for industries where precision, space, and power intersect:

· Advanced robotics: Humanoid robots (shoulder/elbow/knee joints), collaborative cobots, and AGVs rely on frameless motors for compact, high-torque actuation. A 95mm model, for example, powers heavy-lift robotic arms while fitting inside the joint housing.

· CNC & industrial automation: High-speed milling machines, 3D printers, and pick-and-place systems use frameless motors for fast, accurate positioning – reducing cycle times by up to 25%.

· Medical devices: Surgical robots, diagnostic equipment, and prosthetics demand sterile, compact motion solutions; frameless motors integrate seamlessly into sealed, space-saving designs.

Q4: How do I choose the right frameless BLDC motor size (56mm, 60mm, 76mm, 89mm, 95mm)?

Selecting the correct diameter depends on your torque, space, and speed requirements:

· 56mm: Ideal for small, low-torque applications (e.g., robotic grippers, medical pumps) .

· 60mm: A versatile mid-size option for cobot joints or 3D printer extruders.

· 89mm: Suited for heavy-lift robotic arms or industrial conveyors.

· 95mm: The largest in this series, designed for high-power applications like large CNC machine axes.

Our engineering team can help you match stack height (customizable for each diameter) to your exact torque-speed needs – no over-engineering, no wasted space.

Q5: Are frameless BLDC motors difficult to integrate?

While frameless motors require more upfront design work than housed motors, the payoff in performance and flexibility is unmatched – and we’re here to simplify the process. Our kits include detailed documentation, CAD models, and technical support to help you:

1. Mount the stator to your system’s housing (using our pre-drilled mounting holes).

2. Attach the rotor to your shaft (via press-fit or keyway).

3. Integrate feedback devices (encoders/hall sensors) for precise motion control.

For turnkey solutions, we also offer integrated packages with brakes, gearboxes, and torque sensors – perfect for high-torque robotic joints or safety-critical applications.

Why Frameless BLDC Motors Are the Future of Motion Control?

The global frameless BLDC motor market is projected to grow to $3.6 billion by 2035 – and for good reason. As industries push for smaller, smarter, and more efficient machines, traditional housed motors can’t keep up. Frameless BLDC motors don’t just fit into modern designs – they enable them: from humanoid robots that mimic human movement to CNC machines that produce parts with micron-level precision.

This series (56mm, 60mm, 76mm, 89mm, 95mm) has become a favorite among engineers because it balances performance, flexibility, and affordability. Whether you’re designing a prototype or scaling production, these motors deliver the power, precision, and compactness your system needs to stand out.