ABB IRB 6720 vs Nachi SRA166: Robot Comparison
Updated: 3 hours ago
IN A NUTSHELL
🔎 THE KEY DIFFERENCE ABB IRB 6720 170 kg / 3100 mm has the higher stated load capacity and longer stated reach. Those figures help shortlist it for heavier loads or wider layouts, but do not prove a faster production cycle. |
→ CONSIDER ABB IRB 6720 170 kg / 3100 mm Consider it when additional load capacity and reach matter. This article compares 170 kg with a published reach of 3,100 mm; include the gripper and part in the load. |
→ CONSIDER Nachi SRA166 Consider it when its stated load and reach already cover your task and its controls fit your equipment. This article compares 166 kg with a published reach of 2,654 mm; include the gripper and part in the load. |
💡 THE TAKEAWAY Choose the robot that handles your actual tool and part through the required path, with controls and support your team can use. Compare complete installation quotes, rather than arm-only prices. |
ABB IRB 6720 vs Nachi SRA166 is a choice about heavy handling and tooling. ABB IRB 6720 170 kg / 3100 mm and Nachi SRA166 differ in their working envelope, loading assumptions and engineering ecosystem. A useful decision starts with the exact mechanism and process, then checks whether either robot can execute the required path with the real tool attached. This comparison separates documented specifications from application-level engineering judgments.
ABB IRB 6720 vs Nachi SRA166: quick verdict
Shortlist ABB IRB 6720 for 170 kg tooling capacity within the selected 3100 mm ABB envelope and an established RAPID workflow. Shortlist Nachi SRA166 for the documented Nachi payload/reach combination. Neither is a universal winner: a robot that can carry the load may still fail the fixture-access, controller or maintenance requirements.
The numerical comparison below uses ABB IRB 6720 170 kg / 3100 mm against Nachi SRA166. The ABB configuration is a worked example chosen from documented family combinations, not a claim that every family member has those specifications. Other variants can change the conclusion. Published repeatability describes return to a taught position under specified conditions; it does not establish complete-cell accuracy or prove a faster production cycle.
Specifications and exact configuration scope
Criterion | ABB IRB 6720 | Nachi SRA166 |
|---|---|---|
Comparison configuration | ABB IRB 6720 170 kg / 3100 mm | Nachi SRA166 |
Payload used for comparison | 170 kg | 166 kg |
Reach / motion-area reference | 3100 mm | 2654 mm |
Axes | 6 | 6 |
Repeatability for this scope | ±0.06 mm | ±0.06 mm |
Controller reference | ABB OmniCore | FD11 / FD18 |
Historical ATC review starting reference | From USD 84,000 | From USD 43,200 |
Purchase pricing | From $84,000 (arm list price) | From $43,200 (arm list price) |
Read the reach row together with the geometric notes below. Manufacturers may specify an arm-link sum, a wrist-centre motion area or reach to the flange; those dimensions are not interchangeable. The table does not establish access to every point at every tool angle. Controller references identify reviewed packages, and actual compatibility must be confirmed by model, software version and region.
ABB IRB 6720: design and configuration
Standard IRB 6720 examples include 240 kg/2650 mm, 210 kg/2800 mm and 170 kg/3100 mm, with different repeatability values. LeanID or other variants require their own load limits. The longer arm should be selected because the fixture requires that geometry, rather than by combining the highest family payload with the longest reach.
ABB documented configuration | Payload / reach | Repeatability scope |
|---|---|---|
ABB IRB 6720 240/2.65 | 240 kg / 2650 mm | ±0.04 mm |
ABB IRB 6720 210/2.8 | 210 kg / 2800 mm | ±0.05 mm |
ABB IRB 6720 170/3.1 | 170 kg / 3100 mm | ±0.06 mm |
The selected example is ABB IRB 6720 170 kg / 3100 mm. Standard and internally dressed versions must not be blended into one specification. Obtain a load diagram and current technical sheet for the actual order code, including any reduced payload or different protection package. A family starting price is not a quotation for the chosen variant.
Nachi SRA166: design and configuration
The Nachi SRA166 is a 6-axis spot welding robot with a 166 kg payload, a reach of 2654 mm and a position repeatability of ±0.06 mm. It is built for spot welding on automotive body lines and also handles material handling, machine tending and palletizing work. The arm weighs 960 kg and is designed for floor mounting, and it runs on the Nachi FD11 or FD18 controller. This is a heavy six-axis welding and handling platform. A spot-welding gun, transformer and service bundle must be included in wrist mass, moment and inertia. Confirm the specific FD controller and process options; a payload rating is not a weld-quality or installed-cycle specification.
For this pair, Nachi SRA166 offers 166 kg over the stated 2654 mm reference, compared with 170 kg and 3100 mm for the ABB example. ABB IRB 6720 has the larger stated distance by 446 mm, but this difference is only a preliminary layout indicator because reference points and joint envelopes can differ. Locate the actual fixture in each manufacturer model before treating this as usable extra working space.
Payload, tooling and a worked load example
Consider an illustrative total wrist load of 132.8 kg: a 33.2 kg tool and adapter package carrying a 99.6 kg part or product group. This arithmetic leaves 37.2 kg below the ABB IRB 6720 example’s nominal limit and 33.2 kg below Nachi SRA166’s nominal limit. These are mass differences, not safety factors or a validated load approval. A heavy camera, valve block or retained material must be included before recalculating the total.
The example exposes the practical question: is the application limited by mass, by tool offset or by wrist rotation? Nachi SRA166 is the lower-or-equal nominal payload choice in this pair. ABB IRB 6720 offers more or equal headline mass capacity, but that alone cannot approve an eccentric fixture. Moving the same mass farther from the flange increases the moment, and spreading it increases rotational inertia. Manufacturer load diagrams and the actual centre of gravity govern the final allowable motion.
Model the empty, partly loaded and fully loaded tool states separately. A vacuum layer gripper, a weld torch with hoses or an inspection head may change its effective loading during the cycle. Set the controller’s load data for each supported state and validate the transition logic. A payload table cannot predict acceleration derating, cable pull or transient reactions at a machine interface.
Reach, orientation and fixture access
Build the same cell model for both candidates: base height, machine opening, fixture datum, maximum part size, tool extension and access for maintenance. ABB IRB 6720 170 kg / 3100 mm provides a stated 3100 mm reference, while Nachi SRA166 provides 2654 mm. Check the deepest production pose and the return path with the loaded tool. An arm that just touches the target at full extension may have little freedom left to turn, retract or avoid a door.
For assembly and machine tending, test the gripper jaws in their open and closed positions. Include feeder replenishment, rejected-part disposal and tool changes. Check wrist flips and singularity avoidance along the whole path. A compact robot can fit a small fixture well, while a longer arm can simplify station placement; neither geometric benefit can be assumed without the actual model.
Precision and throughput: compare the same task
The comparison uses ±0.06 mm for ABB IRB 6720 and ±0.06 mm for Nachi SRA166. These figures should be read in their documented configuration scope. Repeatability is not absolute accuracy, camera calibration accuracy or finished-part capability. Fixture variation, TCP calibration, thermal conditions and tool compliance can dominate the error at the process point, especially when the tool extends far from the flange.
Ask each integrator to execute the same representative path with the same payload model, tool length, process dwell and stop conditions. Report transfer time, settling time, process time and waiting time separately. Published standard cycles often use different loads and distances; dividing one catalogue cycle by another would not establish the production advantage of ABB IRB 6720 over Nachi SRA166. Use a measured or validated application cycle before assigning a throughput benefit.
Programming, controls and production integration
ABB installations use the RAPID and RobotStudio engineering workflow, with the quoted controller and software determining the available functions. The reviewed DENSO platform requires its own controller, programming tools and compatible software package; match the exact robot generation before selecting interfaces. Existing staff skills, reusable code, spare parts and local service can therefore matter as much as the arm’s dimensional specifications.
Specify the PLC handshakes before ordering: cycle request, ready, busy, complete, fault, part present and recovery authorization. Define how an interrupted operation resumes without repeating a dangerous or quality-critical action. Vision, force sensing, fieldbus communication and external-axis coordination must be checked as explicit included or optional functions. An Ethernet connector does not by itself prove that a particular industrial protocol or software interface is licensed and supported.
Protection, installation and maintenance
Match the precise protection package to the process. Standard, protected, cleanroom, foundry and washing configurations can have different seals, services and maintenance requirements. Do not transfer the best optional IP or cleanroom rating to an unprotected base model. Check the controller location, cable bend radius, available lifting access and base reactions with the installer.
Plan for tooling changes and fault recovery as normal operating tasks. A gripper that can only be removed after dismantling guarding creates a maintenance cost that the robot purchase price will not show. Include access to connectors, lubrication points, mastering references and spare cables. Use a task-specific risk assessment and validated safeguarding for the whole installation; these industrial-arm specifications do not authorize unguarded collaborative operation.
Price and lifecycle value
The source reviews list starting references of USD 84,000 for ABB IRB 6720 and USD 43,200 for Nachi SRA166. These are historical editorial starting references, not current sales offers, confirmed stock or matched quotations. The ABB reference covers a family and must not be assigned automatically to the worked configuration. Request a written quotation naming the arm, controller, pendant, cables, software options, warranty and commissioning scope.
Compare the installed production scope: tool, fixtures, sensing, guarding, machine interface, programming, acceptance and training. For heavy handling, include lifting, foundations, cable routing and fixture load verification. Keep purchase cost and recurring support costs separate. No payback figure is defensible until the actual cycle, yield, utilization and installation quotation are known.
Selection and acceptance plan
Decision gate | ABB IRB 6720 | Nachi SRA166 |
|---|---|---|
Strongest documented fit | 170 kg tooling capacity within the selected 3100 mm ABB envelope and an established RAPID workflow | the documented Nachi payload/reach combination |
Main boundary | Family maxima belong to different variants; the selected example needs a matched quotation. | Confirm exact configuration, controller, wrist loading and installation envelope. |
Required approval | Exact ABB variant, tool load and validated process path | Exact competitor revision, tool load and validated process path |
Acceptance evidence | Agreed parts, path, quality and recovery results | The same agreed parts, path, quality and recovery results |
Advance ABB IRB 6720 when 170 kg tooling capacity within the selected 3100 mm ABB envelope and an established RAPID workflow solves the real constraint and its selected configuration passes the load and access checks. Advance Nachi SRA166 when the documented Nachi payload/reach combination provides the more suitable process arrangement. Reject either candidate if a mandatory pose, protection requirement or controller function cannot be demonstrated. A purchasing shortlist should preserve these conditions instead of converting a single catalogue advantage into a blanket recommendation.
Before acceptance, agree the representative parts, tool states, operating sequence and quality criteria with both suppliers. Demonstrate cold start, normal production, rejected parts, interrupted cycles and controlled recovery. Record the final tool data and software backup. This turns the comparison into a repeatable purchasing decision and helps prevent a later fixture change from invalidating the original robot selection.
Frequently asked questions
Which robot is better for this application?
ABB IRB 6720 is the stronger starting point for 170 kg tooling capacity within the selected 3100 mm ABB envelope and an established RAPID workflow, while Nachi SRA166 is worth shortlisting for the documented Nachi payload/reach combination. The final choice depends on the real loaded path, required protection, controls and acceptance results. Neither a higher payload nor a longer reach establishes a universal winner.
What payload should I use for the comparison?
Use 170 kg for the specified ABB IRB 6720 170 kg / 3100 mm example and 166 kg for Nachi SRA166, subject to all documented load and orientation conditions. Include the tool, adapters, sensors and carried part. Confirm exact configuration, controller, wrist loading and installation envelope.
Does the stated reach guarantee access to my fixture?
No. The comparison gives 3100 mm for ABB IRB 6720 and 2654 mm for Nachi SRA166 using the stated model references. Joint limits, reach reference points, wrist orientation, tool length and collisions determine whether the actual fixture is accessible. Simulate the full approach and exit path.
Can I use the best specifications from every family variant?
No. The ABB family has distinct payload/reach combinations; this comparison uses ABB IRB 6720 170 kg / 3100 mm as a worked example. Match the order code, repeatability and protection package before purchasing. Do not combine one version’s maximum payload with another version’s maximum reach.
Is repeatability the same as finished-part accuracy?
No. The stated values are ±0.06 mm for the ABB scope and ±0.06 mm for the competitor scope. Finished-part results also depend on fixtures, TCP calibration, sensing, thermal conditions and tool compliance. Validate the actual process instead of treating catalogue repeatability as a complete accuracy guarantee.
Are the review starting prices current purchase quotations?
No. From USD 84,000 and USD 43,200 are historical references from the linked ATC reviews. They are not current matched offers and do not establish stock or the installed-cell cost. Obtain configuration-specific quotations with the controller, software, tooling, safety and commissioning scope itemized.
Can these robots operate safely next to people without guarding?
These specifications do not establish a safe unguarded installation. Assess the complete task, tool, load and machine interface, then implement and validate the required safeguarding and operating procedures. Do not infer collaborative operation from a compact arm, limited payload or education setting.
What should an acceptance test compare?
Use the same parts, actual tool load, fixture locations, path and quality criteria for ABB IRB 6720 and Nachi SRA166. Check production timing, settling, interruptions and recovery. Include the most difficult loaded approach and retreat. Approve the exact delivered configuration and preserve its final settings.
Related ATC reviews
Specifications describe the model scope identified above. Prices are indicative historical review references and may change. Confirm current manufacturer documentation, local supply, controller compatibility and the exact configuration before purchase.
