Frameless Torque Motors

Frameless torque motor stator and rotor sets for humanoid robot joints where teams need high torque density, low dead weight, and direct integration into a custom mechanical housing.

Target Buyer:For robotics teams designing their own actuator housing or reducer stack but needing a proven motor core class before custom tooling.

Frameless torque motor stator and rotor set for humanoid joints

Reference visual for selection context. Confirm controlled drawings, CAD path, and test records for shortlisted models.

Engineering Asset Status

Reference visuals, controlled records on request

Current site images are reference selection visuals for catalog navigation. They should not be treated as final factory photos, CAD drawings, test records, or lot-specific inspection documents. For shortlisted models, request the controlled packet tied to model code, drawing revision, test condition, and sample lot.

Request model records

Public now

Reference visuals, product-family routes, RFQ class matrices, and validation checklists for early selection.

Request before PO

Controlled datasheet, drawing or CAD path, torque-speed or thermal record, wiring notes, and sample or OQC evidence.

Not claimed publicly

Verified factory-floor photos, teardown images, and lot-specific test reports are not presented as public evidence until real project assets exist.

Capability Highlights

Outrunner and inrunner frameless motor classes for compact humanoid joints
Selection support by OD, ID, stack length, KV, continuous torque, rotor inertia, and thermal path
Useful baseline for QDD joints, low-ratio reducer modules, and custom integrated actuator stacks

Typical Applications

Humanoid hip, knee, shoulder, elbow, and wrist motor cores
Quasi-direct-drive actuator development
Custom joint shells with embedded stator and rotor assemblies

Engineering Focus

OD, ID, active length, mounting datum, magnet grade, winding option, and thermal path through the robot structure
Outrunner versus inrunner inertia tradeoffs for force control, acceleration, and packaging
Continuous torque, thermal time constant, phase resistance, KV, and current limit rather than peak torque alone

Key Evaluation Matrix

Outer diameter

Typical Range: 40-160 mm RFQ classes
Why It Matters: Torque scaling is often driven more efficiently by diameter than by forcing current into a small package.

Continuous torque

Typical Range: Thermal-path dependent
Why It Matters: A frameless motor inside a sealed humanoid joint must be selected from realistic heat rejection assumptions.

Rotor inertia

Typical Range: Architecture dependent
Why It Matters: Low reflected inertia is critical for compliant motion and impact response in humanoid joints.

Metric	Typical Range	Why It Matters
Outer diameter	40-160 mm RFQ classes	Torque scaling is often driven more efficiently by diameter than by forcing current into a small package.
Continuous torque	Thermal-path dependent	A frameless motor inside a sealed humanoid joint must be selected from realistic heat rejection assumptions.
Rotor inertia	Architecture dependent	Low reflected inertia is critical for compliant motion and impact response in humanoid joints.

Related RFQ Classes

Use these representative classes as shortlist anchors. Final quoted samples depend on confirmed drawings, torque-speed duty cycle, thermal assumptions, protocol, brake, encoder, and validation requirements.

HRA-FTM76-O

76 mm frameless outrunner class

Torque Class

<50 Nm class

Form / Joint Fit

Frameless torque motor

QDD wrist, ankle-light, shoulder-light, custom reducer input

Output Window

2.5-8 Nm continuous

10-28 Nm peak

KV and winding dependent

Interface Assumptions

OD 70-85 mm / ID and stack length by design

24-48 V DC

Encoder selected by housing design

Sample Gate

Motor-core shortlist after OD/ID review

Thermal path, winding, rotor inertia, magnet retention, and encoder space.

HRA-FTM110-O

110 mm high-torque frameless class

Torque Class

50-150 Nm class

Form / Joint Fit

Frameless torque motor

Knee, hip-light, shoulder-heavy, low-ratio reducer input

Output Window

10-30 Nm continuous

50-120 Nm peak

KV and thermal-path dependent

Interface Assumptions

OD 100-125 mm / large ID option

48-60 V DC

Absolute encoder or dual feedback

Sample Gate

DFM and thermal assumption review

Continuous torque, heat rejection, rotor inertia, and reducer coupling.

HRA-AF80-SMC

Axial-flux SMC prototype class

Torque Class

50-150 Nm class

Form / Joint Fit

Axial-flux motor prototype path

Hip-light, knee R&D, compact high-torque demonstrator

Output Window

Project-specific torque target

Project-specific overload target

Magnetic design dependent

Interface Assumptions

Short axial package / OD by torque goal

48-72 V DC target range

Resolver or absolute encoder review

Sample Gate

Concept review before tooling commitment

SMC grade, loss model, cooling path, torque density, and manufacturable core geometry.

HRA-SMC-SEG

SMC stator segment and 3D core class

Torque Class

<50 Nm class

Form / Joint Fit

SMC magnetic core component

Advanced motor core validation and material trials

Output Window

Magnetic property target

Validation sample target

Frequency and loss model dependent

Interface Assumptions

Net-shape 3D core geometry

Not applicable

Magnetic validation report

Sample Gate

Material and tooling DFM review

Density, permeability, core loss, insulation, heat treatment, tolerance, and traceability.

Class	Form / Joint Fit	Output Window	Interface Assumptions	Sample Gate
HRA-FTM76-O 76 mm frameless outrunner class <50 Nm class	Frameless torque motor QDD wrist, ankle-light, shoulder-light, custom reducer input	2.5-8 Nm continuous 10-28 Nm peak KV and winding dependent	OD 70-85 mm / ID and stack length by design 24-48 V DC Encoder selected by housing design	Motor-core shortlist after OD/ID review: Thermal path, winding, rotor inertia, magnet retention, and encoder space.
HRA-FTM110-O 110 mm high-torque frameless class 50-150 Nm class	Frameless torque motor Knee, hip-light, shoulder-heavy, low-ratio reducer input	10-30 Nm continuous 50-120 Nm peak KV and thermal-path dependent	OD 100-125 mm / large ID option 48-60 V DC Absolute encoder or dual feedback	DFM and thermal assumption review: Continuous torque, heat rejection, rotor inertia, and reducer coupling.
HRA-AF80-SMC Axial-flux SMC prototype class 50-150 Nm class	Axial-flux motor prototype path Hip-light, knee R&D, compact high-torque demonstrator	Project-specific torque target Project-specific overload target Magnetic design dependent	Short axial package / OD by torque goal 48-72 V DC target range Resolver or absolute encoder review	Concept review before tooling commitment: SMC grade, loss model, cooling path, torque density, and manufacturable core geometry.
HRA-SMC-SEG SMC stator segment and 3D core class <50 Nm class	SMC magnetic core component Advanced motor core validation and material trials	Magnetic property target Validation sample target Frequency and loss model dependent	Net-shape 3D core geometry Not applicable Magnetic validation report	Material and tooling DFM review: Density, permeability, core loss, insulation, heat treatment, tolerance, and traceability.

Evidence Before Sample PO

Product Evidence Path Before Ordering Samples

This product family should be evaluated with practical evidence before a first sample PO. The goal is to confirm fit, duty, control interface, validation target, and repeatability without pretending that every controlled drawing or test record is a public download.

Check model selection

Decisive Evidence for This Family

Rotor / stator geometry, air-gap control, cooling path, encoder strategy, and housing integration boundary.
Torque constant, rated current, thermal path, and assembly tolerance assumptions.
Whether the buyer has the mechanical capability to integrate a frameless kit safely.

Records to Request

Motor summary with rotor / stator envelope and winding assumption.
Thermal, current, encoder, and air-gap assembly notes.
Controlled drawing or CAD path after the integration scope and NDA status are clear.

Sample PO Gate

Use frameless samples only when the buyer can control housing, bearing, air gap, feedback, and heat rejection.

No-Go Signal

Pause if the project needs a drop-in actuator but only asks for a frameless motor kit without integration resources.

01. Fit baseline

Buyer Input: Joint position, robot class, available OD / length / bore, mounting interface, cable exit, and first quantity.
Supplier Evidence: Candidate model family, envelope drawing, accessory boundary, and whether a standard model or OEM interface is required.
Hold Signal: At least one model path can be mapped to the mechanical envelope without inventing unconfirmed dimensions.
No-Go Signal: The inquiry only says "humanoid actuator" or "high torque motor" without joint, envelope, or quantity context.

02. Duty and thermal check

Buyer Input: Continuous output, peak output, peak duration, speed or stroke, cycle profile, current limit, and ambient assumption.
Supplier Evidence: Rated versus peak boundary, torque-speed or force-stroke explanation, temperature-rise note, and current-limit assumption.
Hold Signal: Selection is based on continuous duty and validation cycle, not peak output alone.
No-Go Signal: The sample decision depends on a peak rating while repeated gait, lift, grip, or force-control cycles are undefined.

03. Interface and control check

Buyer Input: Voltage bus, protocol, controller location, encoder, brake, pinout, cable length, and firmware integration boundary.
Supplier Evidence: Wiring / protocol note, controller compatibility, brake / encoder assumption, and connector or harness options.
Hold Signal: Electrical and control interfaces are clear enough for a bench test without late adapter redesign.
No-Go Signal: Mechanical fit is accepted but protocol, feedback, brake, or harness integration is still ambiguous.

04. Sample validation check

Buyer Input: The specific pass / fail test for the first sample: backlash, thermal rise, noise, force response, impact, or stroke repeatability.
Supplier Evidence: Focused inspection note, test record type, revision baseline, and which result should be checked by the buyer after receipt.
Hold Signal: Both sides know what evidence will decide whether the sample can move toward pilot planning.
No-Go Signal: The sample PO is placed without a named acceptance check or revision trace.

05. Pilot continuity check

Buyer Input: Pilot quantity, repeat-order forecast, inspection expectation, packaging / shipping limits, Incoterm, and destination.
Supplier Evidence: Repeat-lot change-control path, outgoing inspection scope, packaging baseline, and commercial delivery assumption.
Hold Signal: The accepted sample can be repeated without silent model, drawing, accessory, or firmware drift.
No-Go Signal: The project treats a one-off sample as proof of supply readiness without defining repeat-order controls.

Gate	Buyer Input	Supplier Evidence	Hold Signal	No-Go Signal
01. Fit baseline	Joint position, robot class, available OD / length / bore, mounting interface, cable exit, and first quantity.	Candidate model family, envelope drawing, accessory boundary, and whether a standard model or OEM interface is required.	At least one model path can be mapped to the mechanical envelope without inventing unconfirmed dimensions.	The inquiry only says "humanoid actuator" or "high torque motor" without joint, envelope, or quantity context.
02. Duty and thermal check	Continuous output, peak output, peak duration, speed or stroke, cycle profile, current limit, and ambient assumption.	Rated versus peak boundary, torque-speed or force-stroke explanation, temperature-rise note, and current-limit assumption.	Selection is based on continuous duty and validation cycle, not peak output alone.	The sample decision depends on a peak rating while repeated gait, lift, grip, or force-control cycles are undefined.
03. Interface and control check	Voltage bus, protocol, controller location, encoder, brake, pinout, cable length, and firmware integration boundary.	Wiring / protocol note, controller compatibility, brake / encoder assumption, and connector or harness options.	Electrical and control interfaces are clear enough for a bench test without late adapter redesign.	Mechanical fit is accepted but protocol, feedback, brake, or harness integration is still ambiguous.
04. Sample validation check	The specific pass / fail test for the first sample: backlash, thermal rise, noise, force response, impact, or stroke repeatability.	Focused inspection note, test record type, revision baseline, and which result should be checked by the buyer after receipt.	Both sides know what evidence will decide whether the sample can move toward pilot planning.	The sample PO is placed without a named acceptance check or revision trace.
05. Pilot continuity check	Pilot quantity, repeat-order forecast, inspection expectation, packaging / shipping limits, Incoterm, and destination.	Repeat-lot change-control path, outgoing inspection scope, packaging baseline, and commercial delivery assumption.	The accepted sample can be repeated without silent model, drawing, accessory, or firmware drift.	The project treats a one-off sample as proof of supply readiness without defining repeat-order controls.

Curves and Structure Evidence

What to Request Before Trusting the Sample Data

Public pages can introduce the actuator family, but final sample approval should be based on the records behind the rating. Use this checklist to ask for performance envelopes, duty assumptions, and section-view evidence without treating unverified marketing numbers as engineering proof.

Performance Curve Evidence

Torque-speed or force-speed envelope

Buyer Question: Does the actuator stay inside the usable output window at the target joint speed, not only at stall or no-load speed?
Input to Provide: Target continuous output, peak output, required speed or stroke rate, bus voltage, and controller current limit.
Supplier Record: Torque-speed, force-speed, or model summary with rated and short-duration peak boundaries stated separately.
Decision Signal: Move forward only when continuous output, peak duration, and speed are judged together for the sample duty.

Thermal rise and duty-cycle basis

Buyer Question: Will repeated gait, lift, grip, or force-control cycles push the motor, reducer, driver, or housing into thermal saturation?
Input to Provide: Cycle profile, ambient assumption, cooling path, enclosure condition, duty ratio, and allowable surface or winding temperature.
Supplier Record: Temperature-rise note, duty-cycle assumption, thermal path explanation, or sample test record tied to the selected class.
Decision Signal: Treat peak torque claims as incomplete until the repeated-duty thermal boundary is clear.

Overload duration and recovery limit

Buyer Question: How long can the module tolerate impact, squat recovery, step correction, or grasp overload before derating is required?
Input to Provide: Expected overload multiple, duration, frequency, robot mass or payload, and pass / fail recovery behavior.
Supplier Record: Peak duration note, overload inspection basis, brake behavior, bearing support comment, or derating boundary.
Decision Signal: Use this as a hold gate for hip, knee, ankle, and force-control samples where impact or overload is material.

Control response and feedback loop basis

Buyer Question: Can the motor, encoder, driver, brake, and protocol support the intended torque, position, or impedance-control behavior?
Input to Provide: Control mode, update rate expectation, protocol, encoder requirement, current limit, brake behavior, and bench-test setup.
Supplier Record: Controller compatibility note, encoder and brake assumption, wiring / protocol record, or matched kit recommendation.
Decision Signal: Do not separate mechanical sample approval from control-stack compatibility.

Evidence	Buyer Question	Input to Provide	Supplier Record	Decision Signal
Torque-speed or force-speed envelope	Does the actuator stay inside the usable output window at the target joint speed, not only at stall or no-load speed?	Target continuous output, peak output, required speed or stroke rate, bus voltage, and controller current limit.	Torque-speed, force-speed, or model summary with rated and short-duration peak boundaries stated separately.	Move forward only when continuous output, peak duration, and speed are judged together for the sample duty.
Thermal rise and duty-cycle basis	Will repeated gait, lift, grip, or force-control cycles push the motor, reducer, driver, or housing into thermal saturation?	Cycle profile, ambient assumption, cooling path, enclosure condition, duty ratio, and allowable surface or winding temperature.	Temperature-rise note, duty-cycle assumption, thermal path explanation, or sample test record tied to the selected class.	Treat peak torque claims as incomplete until the repeated-duty thermal boundary is clear.
Overload duration and recovery limit	How long can the module tolerate impact, squat recovery, step correction, or grasp overload before derating is required?	Expected overload multiple, duration, frequency, robot mass or payload, and pass / fail recovery behavior.	Peak duration note, overload inspection basis, brake behavior, bearing support comment, or derating boundary.	Use this as a hold gate for hip, knee, ankle, and force-control samples where impact or overload is material.
Control response and feedback loop basis	Can the motor, encoder, driver, brake, and protocol support the intended torque, position, or impedance-control behavior?	Control mode, update rate expectation, protocol, encoder requirement, current limit, brake behavior, and bench-test setup.	Controller compatibility note, encoder and brake assumption, wiring / protocol record, or matched kit recommendation.	Do not separate mechanical sample approval from control-stack compatibility.

Structure and Interface Evidence

Envelope drawing and CAD revision

Inspect For: OD, ID, axial length, flange, mounting bolt circle, output plane, cable exit, connector sweep, and assembly clearance.
Input to Provide: Robot joint envelope, CAD revision, mounting constraint, cable direction, and any forbidden volume.
Supplier Record: 2D envelope, controlled CAD path, drawing revision note, and interface boundary for the candidate class.
Boundary: Public pages can show selection context; precise CAD should stay controlled until the model and project stage are clear.

Internal stack or section-view review

Inspect For: Motor, reducer, encoder, brake, bearing support, hollow routing, sealing surface, and structural heat path.
Input to Provide: Target joint, load path, shock expectation, harness route, brake need, and feedback architecture.
Supplier Record: Exploded-view reference, section-view note, component boundary, or engineering review comment for the selected sample path.
Boundary: Use this to identify integration risks without implying that every supplier drawing can be published openly.

Backlash, stiffness, and bearing support basis

Inspect For: Reducer type, output bearing support, moment-load path, backlash target, compliance behavior, and repeatability risk.
Input to Provide: Joint position, expected moment load, precision need, force-control target, and test that will decide sample acceptance.
Supplier Record: Backlash record, stiffness note, bearing support statement, or application-specific inspection scope.
Boundary: Especially important for leg modules, hollow-shaft modules, and compact arm joints where package size hides mechanical risk.

Harness, connector, and serviceability path

Inspect For: Cable bend radius, connector orientation, pinout, strain relief, service loop, and whether the joint can be assembled repeatedly.
Input to Provide: Cable bundle, connector preference, controller location, service access limit, and repeat-order accessory expectation.
Supplier Record: Wiring / protocol note, pinout baseline, harness option, accessory revision, or OEM interface recommendation.
Boundary: A sample that fits mechanically can still fail the project if harness and connector assumptions are late.

Evidence	Inspect For	Input to Provide	Supplier Record	Boundary
Envelope drawing and CAD revision	OD, ID, axial length, flange, mounting bolt circle, output plane, cable exit, connector sweep, and assembly clearance.	Robot joint envelope, CAD revision, mounting constraint, cable direction, and any forbidden volume.	2D envelope, controlled CAD path, drawing revision note, and interface boundary for the candidate class.	Public pages can show selection context; precise CAD should stay controlled until the model and project stage are clear.
Internal stack or section-view review	Motor, reducer, encoder, brake, bearing support, hollow routing, sealing surface, and structural heat path.	Target joint, load path, shock expectation, harness route, brake need, and feedback architecture.	Exploded-view reference, section-view note, component boundary, or engineering review comment for the selected sample path.	Use this to identify integration risks without implying that every supplier drawing can be published openly.
Backlash, stiffness, and bearing support basis	Reducer type, output bearing support, moment-load path, backlash target, compliance behavior, and repeatability risk.	Joint position, expected moment load, precision need, force-control target, and test that will decide sample acceptance.	Backlash record, stiffness note, bearing support statement, or application-specific inspection scope.	Especially important for leg modules, hollow-shaft modules, and compact arm joints where package size hides mechanical risk.
Harness, connector, and serviceability path	Cable bend radius, connector orientation, pinout, strain relief, service loop, and whether the joint can be assembled repeatedly.	Cable bundle, connector preference, controller location, service access limit, and repeat-order accessory expectation.	Wiring / protocol note, pinout baseline, harness option, accessory revision, or OEM interface recommendation.	A sample that fits mechanically can still fail the project if harness and connector assumptions are late.

RFQ Checklist

Available OD, ID, axial length, and rotor/stator mounting constraints
Target continuous torque, peak torque duration, KV or speed range, and bus voltage
Cooling assumption, ambient temperature, duty cycle, and controller current limit
Prototype quantity, drawing revision, and whether the motor will be paired with a reducer

Risk Controls

Motor core is selected before the housing thermal path is known: Quote continuous torque against housing material, contact area, ambient temperature, and controller current limit.
The selected rotor architecture conflicts with the reducer or cable path: Review OD, ID, rotor clearance, encoder space, and harness routing before freezing the mechanical stack.

Document Request Path for This Product Family

Treat this page as the selection context for datasheets, drawings, CAD access, wiring notes, and sample records. Controlled files should be requested with a candidate model, integration stage, and revision baseline.

Public selection packet

Best Timing: Early shortlist
Documents: Datasheet, model summary, basic envelope image, and application fit notes.
Input to Include: Target joint, output window, voltage / protocol assumption, and quantity direction.
Boundary: Used for selection only; it is not a controlled drawing or final project guarantee.

RFQ-qualified engineering packet

Best Timing: Before sample quote
Documents: 2D envelope, interface notes, wiring / protocol note, accessory list, and sample gate.
Input to Include: Drawing revision, mechanical envelope, controller stack, and validation priority.
Boundary: Provided after the model path is clear; it may still exclude editable CAD or supplier-controlled internals.

NDA-controlled CAD packet

Best Timing: Before mechanical freeze
Documents: STEP / CAD path, pinout details, revision-controlled drawings, and customization notes.
Input to Include: Confirmed candidate model, buyer entity, project scope, and NDA path if needed.
Boundary: Not an automatic website download; controlled files depend on model, OEM scope, and permission.

Sample validation packet

Best Timing: Before pilot decision
Documents: Inspection note, focused test result, revision record, and packing / shipment baseline.
Input to Include: Accepted sample scope, test fixture context, pass / fail priority, and pilot quantity.
Boundary: Generic records may not answer the application risk; request the exact test that matters.

Packet	Best Timing	Documents	Input to Include	Boundary
Public selection packet	Early shortlist	Datasheet, model summary, basic envelope image, and application fit notes.	Target joint, output window, voltage / protocol assumption, and quantity direction.	Used for selection only; it is not a controlled drawing or final project guarantee.
RFQ-qualified engineering packet	Before sample quote	2D envelope, interface notes, wiring / protocol note, accessory list, and sample gate.	Drawing revision, mechanical envelope, controller stack, and validation priority.	Provided after the model path is clear; it may still exclude editable CAD or supplier-controlled internals.
NDA-controlled CAD packet	Before mechanical freeze	STEP / CAD path, pinout details, revision-controlled drawings, and customization notes.	Confirmed candidate model, buyer entity, project scope, and NDA path if needed.	Not an automatic website download; controlled files depend on model, OEM scope, and permission.
Sample validation packet	Before pilot decision	Inspection note, focused test result, revision record, and packing / shipment baseline.	Accepted sample scope, test fixture context, pass / fail priority, and pilot quantity.	Generic records may not answer the application risk; request the exact test that matters.

Request matching documents

Product Gallery

Reference visual: Frameless BLDC stator winding reference for actuator integration

Reference visual: Frameless motor rotor magnet reference for torque motor sourcing

Buyer FAQ

Can frameless motors be quoted without a final joint shell?

Yes, but the first response should be treated as a shortlist. Final sample release needs the available OD, ID, axial length, thermal path, and controller assumptions.

Procurement guide

Read Before Finalizing the Product Shortlist

Use the procurement guide when this product family is entering comparison, RFQ, or sample review. It translates page-level claims into torque-speed, interface, evidence, and supplier-readiness questions.

Open guide

Sourcing Humanoid Robot Actuators in 2026

A buyer-side guide for pre-modular humanoid actuator sourcing: selection risk, evidence requests, sample readiness, and pilot supply controls.

Use it to check

Torque-speed, force-stroke, or actuator-envelope assumptions
Datasheet, CAD, wiring, and validation-record request scope
Sample PO hold signals before controlled files are released

Next sourcing step

01 Catalog shortlist

Then validate the application fit

After a product family is shortlisted, validate the joint load case, sample gate, and evidence boundary before custom files or pilot timing enter the discussion.

Open validation plan Send catalog RFQ

Related Resources

Inquiry Email

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Subject: RFQ Inquiry - Frameless Torque Motors

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This inquiry started from a product family page. Keep the request anchored to model-family fit, interface assumptions, and sample evidence. Source context: Frameless Torque Motors.

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