KR 120 R3900-2 K vs NB4
Side-by-side comparison of KR 120 R3900-2 K (KUKA Robotics) and NB4 (Beijing ROKAE Technology Co., Ltd.) — specs, pricing, Robo Index, and verified deployments. Updated daily.
Optimize comparison for buyer
Optimized for Cleaning & Facilities buyers. Priority specs lifted to the top and marked with a target.
Layer 1: Identity & Trust
Manufacturer Country
- KR 120 R3900-2 KGermany
- NB4China
Year First Available
- KR 120 R3900-2 K2015
- NB4—
Verified Deployments
- KR 120 R3900-2 K0 Deployments
- NB40 Deployments
Layer 2: Operational
Price
- KR 120 R3900-2 K$19,000–$84,900 USD
- NB4$14,999–$17,490 USD
Availability Status
- KR 120 R3900-2 KACTIVE
- NB4ACTIVE
Arm Mechanics
Robot Weight
- KR 120 R3900-2 K42 kg
- NB421 kg
Payload
- KR 120 R3900-2 K146 kg
- NB44 kg
Reach
- KR 120 R3900-2 K3,904 mm
- NB4475 mm
Degrees of Freedom
- KR 120 R3900-2 K6
- NB46
Repeatability
- KR 120 R3900-2 K±0.04 mm
- NB4±0.015 mm
IP Rating (Arm)
- KR 120 R3900-2 KIP65
- NB4IP54
IP Rating (Wrist)
- KR 120 R3900-2 KIP67
- NB4—
Controller & Programming
Controller Model
- KR 120 R3900-2 KKR C5, KR C5 micro
- NB4—
End-Effector
Pneumatic Lines
- KR 120 R3900-2 K—
- NB44
Electrical Lines
- KR 120 R3900-2 K—
- NB48
Commercial
Price (USD)
- KR 120 R3900-2 K$19,000–$84,900 USD
- NB4$14,999–$17,490 USD
Warranty
- KR 120 R3900-2 K2 yrs
- NB4—
Service Network
- KR 120 R3900-2 Kglobal
- NB4—
| | |
|---|---|---|
| Layer 1: Identity & Trust | ||
| Manufacturer Country (values differ) | Germany | China |
| Year First Available (values differ) | 2015 | — |
| Verified Deployments | 0 Deployments | 0 Deployments |
| Layer 2: Operational | ||
| Price (values differ) | $19,000–$84,900 USD | $14,999–$17,490 USD |
| Availability Status | ACTIVE | ACTIVE |
| Layer 3: Category Specific | ||
| Arm Mechanics | ||
| Robot Weight (priority for Cleaning & Facilities buyers) (values differ) | 42 kg | 21 kg |
| Payload (priority for Cleaning & Facilities buyers) (values differ) | 146 kg | 4 kg |
| Reach (values differ) | 3,904 mm | 475 mm |
| Degrees of Freedom | 6 | 6 |
| Repeatability (values differ) | ±0.04 mm | ±0.015 mm |
| IP Rating (Arm) (values differ) | IP65 | IP54 |
| IP Rating (Wrist) (values differ) | IP67 | — |
| Controller & Programming | ||
| Controller Model (values differ) | KR C5, KR C5 micro | — |
| End-Effector | ||
| Pneumatic Lines (values differ) | — | 4 |
| Electrical Lines (values differ) | — | 8 |
| Commercial | ||
| Price (USD) (values differ) | $19,000–$84,900 USD | $14,999–$17,490 USD |
| Warranty (values differ) | 2 yrs | — |
| Service Network (values differ) | global | — |
Insufficient data for full comparison
The following fields had no data for any of the selected robots: Battery / Shift Runtime, Path Accuracy, Max TCP Speed, Cycle Time (25/305/25), MTBF, Duty Cycle, Vibration Damping, Safety Category, Dual Check Safety, Safety I/O Pairs, E-Stop Response, Safe Zone Count, Programming Languages, Teach Pendant Type, Offline Programming, Digital Twin Support, Communication Protocols, ROS-Industrial Support, IoT / Cloud Platform, Cybersecurity Certs, Predictive Maintenance, Tool Flange Standard, Tool Changer (ISO), Internal Cable Routing, Spare Parts Lead Time, Expected Service Life
ROI Comparison
Same operating assumptions across every robot — the only difference is price. Set your numbers once to see which pays back fastest.
Annual labor displaced (per robot): $50,000
| Metric | KR 120 R3900-2 K | NB4 |
|---|---|---|
| Investment | $51,950 | $16,245 |
| Payback period | 12.5 mo | 3.9 mo |
| Net savings (5 yr) | $198,050 | $233,756 |
| ROI (5 yr) | +381% | +1439% |
Estimates labor-cost displacement only — not a full total cost of ownership. Actual ROI depends on integration, maintenance, training, downtime, and task fit. Converted currencies are indicative; USD is the price of record.
Trade-offs at a glance
Frequently asked
Who makes KR 120 R3900-2 K and NB4?
KR 120 R3900-2 K is made by KUKA Robotics, based in DE. NB4 is made by Beijing ROKAE Technology Co., Ltd., based in CN.
How do KR 120 R3900-2 K and NB4 compare on the Robo Index?
KR 120 R3900-2 K grades AAA on the Robo Index. NB4 grades A. The Robo Index is a credibility grade (AAA … C) that blends commercial maturity, verified deployments, company standing, and independent coverage — see methodology for the full breakdown.
How does the reach of KR 120 R3900-2 K compare to NB4?
KR 120 R3900-2 K has a reach of 3904 mm. NB4 has a reach of 580 mm.
Are KR 120 R3900-2 K and NB4 in the same category?
Both robots are classified as Industrial Arm on Robolist. Filters and ranking treat them as direct alternatives.
What is the realistic total cost of ownership for Industrial Arm robots?
Hardware cost is one input. Industrial Arm TCO also includes integration, training, downtime, and end-of-life. Our breakdown: TCO of a 6-Axis Arm Cell: Hardware, EOAT, Integration, Programming.
What should a buyer ask vendors when choosing between KR 120 R3900-2 K and NB4?
Spec sheets only show part of the story. Useful vendor questions cover support, lifecycle, integration cost, and references. We have a buyer-focused checklist: Industrial Arm Vendor Selection: Capability Matrices and Proof Points.
Going deeper — picking the right robot
TCO of a 6-Axis Arm Cell: Hardware, EOAT, Integration, Programming
7 min readIndustrial Arms
Industrial Arm Vendor Selection: Capability Matrices and Proof Points
9 min readIndustrial Arms
Programming Approaches: Teach Pendant, Offline, AI-Assisted — What Each Costs You
8 min readIndustrial Arms
Build vs buy vs lease: which model fits a first deployment
8 min readChoosing Your First Robot
The hidden specs vendors hope you'll miss
10 min readReading the Spec Sheet
Want to be notified when specs or pricing change for these robots? Drop your email.
Other comparisons
About this comparison
KR 120 R3900-2 K vs NB4 compares two robots in the industrial-arm category. All data is sourced from manufacturer spec sheets, verified deployments, and third-party filings; see our methodology for how the Robo Index is calculated.