Harmonic Reducer Gear – Precision Gear Set for Robot | DD Gear

Features & Benefits

• High reduction ratio in one stage
  Harmonic reducer gears achieve reduction ratios typically between 1:30 and 1:160, with possible ranges extending up to around 1:320 in some designs—without multi-stage gear trains.

• Near-zero backlash and high accuracy
  Because the flexspline teeth simultaneously engage the circular spline across a broad region and the tooth count difference is small, harmonic reducers provide very low lost motion (nearly zero backlash) and high positioning accuracy, ideal for servo axes and robotic joints.

• High torque density & stiffness
  The load is shared over many teeth in contact, so the torque capacity per unit mass and volume is high, supporting compact, high-torque joints for humanoid and industrial robots.

• Compact, coaxial layout
  Input and output shafts are often coaxial, and the reducer height is small, making harmonic reducers ideal where space is limited but precision and torque are critical—such as robot elbows, wrists, and waist joints.

• Smooth motion and low noise
  DD Gear specializes in small-module gears for emerging industries. Our machining and finishing routes support high tooth accuracy (internal and external), controlled profile/lead, and surface finishes tailored for low backlash and low wear.

• Custom materials and heat treatment for durability
  Gear materials and heat treatments are chosen to handle high contact stresses and reverse torque cycles seen in robotic joints, with attention to tooth root strength, pitting resistance, and fatigue life

• Prototype to series support
  We support you from small prototype batches for actuator development to stable mass production with complete inspection data and traceability.

Technical Specifications

Final data will be defined according to the customer’s drawing and EV duty cycle.

Applications

• Humanoid robot joints
  Harmonic reducer gears used in hip, knee, ankle, shoulder, and wrist joints where compact size and high torque density are essential.

• Collaborative robots (cobots) and 6-axis industrial robots
  Joint actuators in arms that require smooth motion, repeatable positioning, and low backlash for safe human-robot collaboration and precise path control.

• SCARA and pick-and-place robots
  High-ratio joints and rotary axes handling high speed and precise positioning in compact envelopes

• AGV / AMR wheel modules and drive units
  Harmonic reducers integrated into wheel modules to deliver high torque at low speed with precise control and compact size.

• Medical and surgical robots
  Joint and wrist actuators needing very low backlash and smooth motion to support delicate procedures and safe operator interaction

• Precision positioning systems
  Rotary tables, semiconductor handling equipment, and laboratory automation requiring high reduction, high stiffness, and small size.

Gear Manufacturing Process

Every harmonic reducer gear component is produced under a controlled gear manufacturing route designed for precision and durability. A typical process flow is:

1. Blank preparation – forging, ring rolling, or bar cutting of cups and rings

2. Turning – CNC machining of reference diameters, faces, and cup walls

3. Gear cutting – internal gear shaping / hobbing for circular spline; external gear hobbing / shaping for flexspline and related gears

4. Auxiliary machining – drilling, milling of mounting holes, slots, and reference features

5. Heat treatment – carburizing & quenching, nitriding, or Q&T according to tooth load and life requirements

6. Shot peening / stress relief – optional to improve tooth root strength and fatigue resistance

7. Finish machining – grinding of reference surfaces and critical diameters

8. Gear finishing – internal / external gear grinding or honing (where required) for high accuracy and smooth tooth contact

9. Cleaning & anti-rust treatment – for clean assembly in precision actuators

10. Final inspection & packaging – according to agreed control plan

Precision Gear Customization Process

To support custom harmonic reducer gear projects, DD Gear follows a clear, eight-step customization process:

Step 1 – Requirement Collection
Customers provide design requirements, 2D drawings, 3D models, or physical samples, together with basic duty cycle information (torque, speed, life, installation).

Step 2 – Drawing Design & Optimization
Based on the provided drawings or samples, DD Gear prepares or optimizes detailed manufacturing drawings and shares them with the customer for confirmation.

Step 3 – Quotation
After the drawings and technical points are confirmed, we issue a precise quotation covering tooling, piece price, lead time, and quality requirements.

Step 4 – Tooling & Fixture Preparation
Once the price is confirmed, we arrange tooling and fixture production. Any tooling cost is agreed with the customer in advance and can be offset or refunded after mass orders, according to the commercial agreement.

Step 5 – First Sample Approval
After tooling and fixtures are ready, we manufacture the first sample batch—typically within about 30 days—and ship it to the customer for testing.The customer inspects and validates the samples in their gearbox or test bench and provides feedback on dimensions, performance, and any required adjustments.

Step 6 – Mass Production
When the sample is approved, we start mass production according to the agreed production plan and quality standards.

Step 7 – Finished Product Inspection
After production, we inspect hardness, dimensions, runout, tooth accuracy, and other critical characteristics to ensure full compliance with the drawing and standards.

Step 8 – Shipping Arrangement
Once inspection is passed and shipment is approved by the customer, we arrange booking, packaging, and delivery to the specified destination.

Quality Assurance & Inspection

DD Gear applies the same quality philosophy to harmonic reducer gear and all precision gears:

• Quality management systems based on ISO 9001 and IATF 16949

• Process control from incoming material to final inspection, including:

  • Material certification and chemical composition checks

  • Hardness and case depth verification after heat treatment

  • Gear measurement for profile, lead, pitch, and runout

  • Surface roughness testing on gear flanks and journals

  • Dimensional inspection with calibrated gauges and CMMs

• Traceability for each batch with inspection records and reports

• Optional documentation such as PPAP/FAIR packs on request

Packaging

Usage & Installation Notes

• Ensure that flexspline and circular spline gear components are assembled according to your harmonic reducer design to avoid over-straining the flexspline cup or misaligning the tooth mesh. 

• Follow the specified preload and backlash settings at reducer level; improper preloading may increase friction, temperature, or wear. 

• Use the recommended lubricant type (grease/oil) and fill level for the harmonic reducer; insufficient lubrication can accelerate pitting and wear on fine-pitch teeth. 

• Avoid using the reducer to absorb external shock beyond its rated capacity. In robot joints, external bumpers, torque sensors, or compliant elements may be used to protect the reducer. 

• During maintenance, inspect teeth for wear, pitting, micro-cracking, or deformation, especially in high-load joints such as robot bases and knees. 

• Store finished gears in dry, clean conditions with anti-rust protection and avoid impacts that might damage thin-walled flexspline cups or finely finished internal teeth.

Company Strength – DD Gear

• Specialized in small module, high-precision gears and shafts for EVs, humanoid robots, AGVs, and intelligent automation.

• Integrated manufacturing from forging and machining to heat treatment and gear grinding.

• Quality systems aligned with automotive standards, with experience supporting OEM and Tier 1 projects.

• Engineering support covering concept feasibility, DFM reviews, and failure analysis feedback.

• Global export capability with experience serving customers in multiple countries.

Q1: What information do you need for a harmonic reducer gear quotation?
We normally need 2D drawings (PDF), 3D models (STEP/IGES if available), material and heat treatment requirements, expected annual volume, and basic application data such as robot type, joint torque, reduction ratio, and backlash / stiffness targets.

Q2: Do you supply the complete harmonic reducer, or only gears?
DD Gear primarily supplies gear components such as flexspline and circular spline gears, and related precision gears or shafts. Complete harmonic reducer gearboxes and actuators are usually assembled by the customer or their system partners.

Q3: Can you help optimize tooth geometry for lower backlash or longer life?
Yes. Within the constraints of your standard, we can discuss module selection, tooth count, tooth root fillets, and heat treatment windows to support low backlash, high torque density, and fatigue life.

Q4: What accuracy levels can you achieve on harmonic reducer gears?
We manufacture internal and external gears to high precision per ISO / DIN / JIS standards. Specific grade, runout, and roughness limits are defined together with you according to robot joint accuracy and stiffness requirements.

Q5: What is your typical lead time for samples and mass production?
Prototype harmonic reducer gear sets are usually available in about 2–3 weeks after drawing confirmation and tooling readiness. Mass production lead time depends on quantity and process route and will be confirmed during quotation.

Q6: What is your typical MOQ?
MOQ depends on complexity and tooling. We support flexible MOQ for joint development and pilot runs, then align batch sizes with your robotics program’s series production plan.

Q7: Can you provide inspection reports with each batch?
Yes. We can provide dimensional inspection reports, gear measurement charts (profile/lead/pitch), hardness and case-depth records, and other documents as required.