G3-251S SCARA Robotic Arm (Manipulator)
SCARA Robot · Load capacity 3 kg · Arm length 250 mm
G3-251S specifications
About 10 years ago, Epson began using our E Series production line to produce compact SCARA robots. Today, after two generations, the G3 SCARA arm still leads the compact SCARA market. Although the G3 arm is small in size, it includes all high-performance components and design concepts. Other G-series robots, such as the high-rigidity arm and PowerDrive servo technology, also deliver high performance, enabling a more compact and lower-cost model.
Model introduction
About 10 years ago, Epson began using our E Series production line to produce compact SCARA robots. Today, after two generations, the G3 SCARA arm still leads the compact SCARA market. Although the G3 arm is small in size, it includes all high-performance components and design concepts. Other G-series robots, such as the high-rigidity arm and PowerDrive servo technology, also deliver high performance, enabling a more compact and lower-cost model. High performance: Excellent range of motion with high efficiency; 0.41 seconds cycle time, improving overall component throughput; Excellent acceleration/deceleration speed, enabling smooth start/stop movements; A high speed of 4400mm/second enables component movement faster and more precise; Unique high-rigidity arm design enables low vibration; High-altitude ratio enables rapid 24-hour cycle all day Diverse arm types and configurations: selectable arm lengths of 250, 300, and 350mm, allowing users to choose the optimal length according to their needs; Desktop and multifunctional installation (ceiling/wall-mounted) models; ISO Clean (ISO14644-1:2015) & ESD certified models, targeting electrostatic-sensitive applications such as semiconductor and hard drive assemblies; The unique left-right bending arm model allows users to purchase G3 arms that bend left or right, maximizing workspace utilization while occupying very small workspaces. The G3 arm offers optional arm lengths of 250, 300, and 350mm, with a Z-axis length of 150mm (120 clean). It also offers tabletop, sidewall, ceiling mount configurations, as well as Clean/ESD configurations, giving you more choices. Powerful controllers and development software: Epson RC+ leads the industry in ease of use, saving development time; With the G3 robot, the two-stage controller product offers higher performance and a low-cost solution; Integrated options can significantly improve system performance and reduce overall development time; High-performance processing capabilities are faster than similar Epson models
Exclusive highlights of the G3-251S
Excellent range of motion with high efficiency; 0.41 seconds cycle time, improving overall component throughput; Excellent acceleration/deceleration speed, enabling smooth start/stop movements; A high speed of 4400mm/second enables component movement faster and more precise; Unique high-rigidity arm design enables low vibration; High-altitude occupancy enables rapid 24-hour cycles all day long
Available arm lengths are 250, 300, and 350mm, allowing users to choose the optimal length according to their needs; Desktop and multifunctional installation (ceiling/wall-mounted) models; ISO Clean (ISO14644-1:2015) & ESD certified models, targeting electrostatic-sensitive applications such as semiconductor and hard drive assemblies; The unique left-right bending arm model allows users to purchase G3 arms that bend left or right, maximizing workspace utilization while occupying very small workspaces. The G3 arm offers optional arm lengths of 250, 300, and 350mm, with a Z-axis length of 150mm (120 clean), and also offers tabletop, sidewall, and ceiling mount configurations
Epson RC+ leads the industry in ease of use, saving development time; With the G3 robot, the two-stage controller product offers higher performance and a low-cost solution; Integrated options can significantly improve system performance and reduce overall development time; High-performance processing capabilities are faster than similar Epson models
Automotive—mirror/glass assembly, ignition module assembly, headlight and taillight assembly and testing, clutch assembly, fuel injector assembly, dashboard assembly; Hard drives — cover parts, hard drive polishing, cassette tape assembly, high-precision driver assembly; Medical products — surgical blade processing, dental instrument insertion and molding, pacemaker battery assembly, wire quota laser welding, hearing aid assembly; Laboratory automation — pipette encapsulation, DNA sequence testing, blood analysis, tube capping, tube handling; Consumer products — paint brush assembly, electric toothbrush assembly, chainsaw assembly, connector assembly; Industrial products—smoke detector assembly, fiber optic connector assembly, light bulb assembly, hydraulic valve testing
G Series SCARA · Classic High Reliability · Series technical features
The G Series is Epson's classic SCARA product line, covering loads ranging from G1 to G20 weighing 0.5-20kg, known for its PowerDrive servo technology and high-rigidity arm design, and has long dominated precision manufacturing production lines.
Epson's self-developed servo technology enables high-speed, smooth start/stop and excellent acceleration and deceleration characteristics.
The G Series has large shipments and high inventory, with abundant maintenance documentation and spare parts resources.
Countertop, ceiling, and sidewall mounting models are fully available to suit different production line layouts.
High-performance or economical controllers can be selected as needed, balancing performance and cost.
Applicable industries
Typical applications of this model in the following industries (click to view industry solutions).
Mirror/glass assembly, ignition module assembly, headlight and taillight assembly and testing, clutch assembly, fuel injector assembly, instrument panel assembly
Cover parts, hard drive polishing, cassette tape assembly, high-precision driver assembly
Surgical blade processing, dental instrument insertion and molding, pacemaker battery assembly, wire quota laser welding, hearing aid assembly
Pipette encapsulation, DNA sequence testing, blood analysis, tube capping, and tube handling
Paint brush assembly, electric toothbrush assembly, electric saw assembly, connector assembly
Smoke detector assembly, fiber optic connector assembly, light bulb assembly, hydraulic valve testing
Typical application scenarios
Common application processes for this model (click to view process details):
G Series SCARA · Classic High Reliability · Other models in the same series
Compare load and reach to choose the model that best suits your process.
G3-251S model positioning and working condition adaptation
G3-251S Belongs to the Epson G Series SCARA · The classic highly reliable SCARA horizontal multi-joint robot model has a rated load of 3kg, a motion radius of 250mm, and a repeatability of ±0.008mm. Epson's technological foundation is SCARA's global market leader: RS/GX/LS series with high speed and precision, SPEL+ development efficiency, and mature vision integration; The control platform is RC700-A, and the program ecosystem is SPEL+ language (BASIC style) + Vision Guide visual.
From the perspective of working condition adaptation, typical applications for small load (3kg) positioning are:High-speed sorting, precision assembly, dispensing coating, and inspection/pick-and-place processing。 The short arm (250mm) model has a compact structure, suitable for dense workstations and close-range pick-and-place operations, with a small work unit footprint. ± 0.008mm repeatability is classified as precision-grade, meeting the trajectory requirements for precision assembly, dispensing, and inspection guidance. Although the load is light, it is recommended to keep the total weight of the end and workpiece within 70% of the rated value, leaving ample acceleration margin at high speeds.
| Parameters | Engineering interpretation and usage recommendations |
|---|---|
| Rated load 3kg | It is recommended to reserve a load margin of 20%–30%; Verification is made by combining end self-weight + workpiece + imbalanced load inertia, especially sensitive to high-speed conditions |
| Movement radius: 250mm | Determine the radius of the workcell layout: bins, tooling, and fences are bounded by maximum arm span + safety distance; Verify the accessibility of each pick-and-place point during cross-station service |
| Repeatability: ±0.008mm | Repeatability ≠ absolute accuracy: Precision assembly requires external measurement closed-loop or visual guidance; Long-term accuracy trends rely on annual retest management |
| Main unit weight: 14kg | Installation base and foundation load-bearing check based on weight + dynamic load; Floor slab installation requires structural calculation, with heavy-duty models serving as independent foundations |
| Controller RC700-A | Decide on the process ecosystem, spare parts channels, and second-hand residual value; Currently, spare parts channels are smooth, and repair and upgrade paths are mature |
Control systems and common failure modes
The G3-251S comes with the RC700-A controller, with a programming language and development environment of SPEL+ (BASIC style) + Vision Guide for vision. Maintenance of this generation of control platforms focuses on three basic components: power, storage, and cooling—most "sudden downtime" can be detected in advance when preventive maintenance is in place.
| Failure mode | Typical performance | Disposal recommendations |
|---|---|---|
| SCARA synchronous belt tension attenuation and wear | SCARA Synchronous Belt Tension Attenuation and Wear (Main Cause of Precision Drift) | Included as a mandatory inspection item for annual maintenance, with spare parts stocked in advance |
| The encoder battery is depleted | Encoder battery depleted (loss of origin and calibration data) | Initial interpretation of alarm codes by reference with manuals, remote diagnosis allows for early positioning |
| Driver alarm | Driver alarm (high-speed overcurrent) | Daily inspection coverage, with abnormal trends (abnormal noises/temperature rise/errors) recorded |
| RC controller fan and power supply aging | RC controller fan and power supply aging | Quarterly dust removal maintenance and cabinet temperature monitoring |
| Maintenance projects | Cycle recommendations | Key points |
|---|---|---|
| Timing belt tension adjusted by periodic inspection (SCARA specific item) | By cycle | Timing belt tension adjusted by periodic inspection (SCARA specific item) |
| Annual battery replacement | Year | Battery replacement annually, calibration data backup |
| Guide rails and screw lubrication (LS/GX series) | According to the manufacturer's manual cycle | Guide rails and screw lubrication (LS/GX series) |
| Cable and drag chain inspection | every six months | Insulation, shielding, and bending radius inspection of power and encoder lines, as well as wear of cables inside the drag chain, are the main causes of intermittent faults |
| Zero point and accuracy retest | Every year | Repeatability measured by dial gauges or laser trackers, drift trend digitization—accuracy degradation can be seen six months in advance |
| Control cabinet dust removal and fans | Every quarter | Filter cleaning, fan speed and noise checks, cabinet temperature recording; Dust environments shorten the cycle |
Henghuan's service capabilities for the G3-251S
This site is a third-party robotics technology service provider. The eight major business supports related to the G3-251S are as follows (sorted by service frequency for each model):
- Maintenance and repair: For on-site diagnostics, board-level maintenance, and annual maintenance contracts for the G3-251S—such as periodic inspection and adjustment of synchronous belt tension (SCARA specific item), we implemented brand-exclusive items according to SOPs, and Sichuan-Chongqing responded on the same day.
- Used & in-stock robot sales: SCARA has a large second-hand circulation and is the preferred choice for 3C and electronic assembly conditions; Procurement focuses on inspecting belt and guide rail wear; The G3-251S or equivalent models in the warehouse come with a full-function test report and a 12-month warranty.
- Sales of new industrial robots: When adding new production lines or replacing entire batches, we conduct cross-brand selection comparisons based on process requirements (including models of the same grade as Epson), and provide configuration and pricing plans.
- Applied technology services: Process programming, trajectory optimization, tap time tapping, and formula management for the G3-251S are targeted for high-speed sorting, precision assembly, dispensing and coating, and inspection pick-and-place conditions.
- Research and development of automation equipment: Custom fixture ends, peripheral tooling, and safety barriers for the G3-251S, with interfaces designed according to Epson flange and IO standards.
- Robot rental: For short-term capacity or process validation periods, users can rent G3-251S models in stock at the same level, including transportation, installation, and commissioning, with flexible rental periods and flexible purchase options.
Common issues with this device
Is it easy to find spare parts for the G3-251S?
Epson: The spare parts channel for this generation is smooth; we have in-stock or short-cycle channels for standard parts such as drivers, power modules, batteries, and teach pendant components; It is recommended to allocate consumables for periodic inspection and adjustment of synchronous belt tension (SCARA specific items) according to the annual maintenance contract.
With a rated load of 3kg, how much weight can it actually handle?
The rated load is the static load limit of the flange surface. In actual selection, three factors must be considered: the self-weight of the end fixture (vacuum suction cup groups or grippers often account for 2–5kg), the inertia generated by the workpiece offload (checked according to the inertia ratio when the center of gravity deviates from the flange center), and the dynamic load during high-speed movement. The conventional engineering practice is to keep the "end + workpiece" within 70%–80% of the rated value to ensure cycle time and service life.
If the equipment's accuracy deteriorates after several years of use, how can it be restored?
According to the inspection order: first check whether the zero point is drifting (common after collision or battery depletion), then perform zero calibration; Check the reducer's return error (actual measurement of forward and reverse positioning deviation; if exceeded, disassemble or replace); Then check the installation base fastening and foundation settlement; Finally, trajectory compensation parameter restructuring. Most accuracy issues can be mostly restored after calibration and maintenance, so there is no need to rush into major repairs—we first release the inspection data before deciding on the plan.
Is the used G3-251S worth buying?
SCARA has a large second-hand circulation and is the preferred choice for 3C and electronic assembly applications; Procurement focuses on checking for belt and guide rail wear. Three essential items for second-hand procurement: comprehensive inspection reports (axial accuracy, driver status, insulation and battery), maintenance history and operating hours, controller generation, and software license integrity. Every used machine we sell comes with inspection records and a 12-month warranty, and we can also accept third-party inspections designated by customers.
Need technical support or procurement for this model?
Whether it's model selection comparison, installation and commissioning, or maintenance of in-use equipment, you can contact Henghuan. Tell us about your processes, loads, and equipment status, and we will provide third-party technical support and solution recommendations.
Contact Henghuan Back to the full series