Last updated: April 2026
How to Choose a Welding Robot: Payload, Reach & Welding Process Matching Guide
Choosing the right welding robot requires matching three core specifications to your application: payload capacity for your torch and tooling, reach to cover your largest workpiece, and axis configuration for your joint access requirements. This guide walks through each selection criterion with practical sizing methods, then maps EVST’s welding robot lineup to common application profiles.
Step 1: Define Your Welding Process Requirements
The welding process determines nearly every downstream specification — torch weight (which sets payload), heat management requirements, travel speed expectations, and power source compatibility. Start here before evaluating any robot specifications.
MIG/MAG welding is the right choice for 70% of robotic welding applications. It offers the best combination of speed (800–1500 mm/min), penetration, and cost per meter of weld. If your primary materials are carbon steel, stainless steel, or aluminum in thicknesses above 1 mm, MIG is almost certainly your process.
TIG welding is required when weld appearance, metallurgical integrity, or thin-material control (under 1.5 mm) takes priority over speed. Aerospace components, pharmaceutical equipment, food-grade stainless fabrication, and precision thin-sheet assemblies typically demand TIG.
Spot welding dominates sheet metal assembly, particularly in automotive body-in-white production. Spot welding robots require higher payloads (50–200+ kg) to carry the welding gun and transformer assembly.
The process you select directly constrains your robot choices. Use the table below to narrow the field.
| Welding Process | Required Robot Payload | Typical Reach | Speed Expectation | EVST Series |
|---|---|---|---|---|
| MIG/MAG (standard) | 6–10 kg | 1400–1800 mm | 800–1500 mm/min | QJAR 6 / QJAR 10 |
| MIG/MAG (heavy torch) | 10–20 kg | 1600–2000 mm | 600–1200 mm/min | QJAR 20 / EVS 20 |
| TIG (precision) | 6–10 kg | 1400–1600 mm | 200–500 mm/min | QJAR 6 / QJAR 10 |
| Spot welding | 80–210 kg | 2000–2800 mm | 1–3 sec/spot | QJAR 165 / QJAR 210 |
| Laser welding (remote) | 20–50 kg | 2000–2500 mm | 3000–8000 mm/min | EVS 50 |
Step 2: Calculate Payload Requirements
Payload sizing errors are the most common and costly mistakes in welding robot selection. Oversizing wastes capital; undersizing causes premature joint wear and performance degradation.
Payload calculation formula:
Required Payload = (Torch weight + Wire feeder weight + Sensor/camera weight) × 1.3 safety factor
Typical component weights for reference:
| Component | Weight Range | Notes |
|---|---|---|
| MIG torch (air-cooled) | 2.5–4.0 kg | Up to 350A rating |
| MIG torch (water-cooled) | 3.5–6.0 kg | 350–500A rating |
| TIG torch | 1.5–3.5 kg | Including gas lens |
| Wrist-mounted wire feeder | 2.0–4.0 kg | If not using push-pull system |
| Seam tracking sensor | 0.5–2.0 kg | Laser or tactile |
| Vision camera | 0.3–1.5 kg | For adaptive welding |
Example: A standard MIG welding application with water-cooled torch (5 kg) + wrist-mounted wire feeder (3 kg) + laser seam tracker (1.5 kg) = 9.5 kg × 1.3 = 12.4 kg. Select a robot with ≥12 kg payload capacity — the EVST QJAR 20 (20 kg payload, 1668 mm reach) provides comfortable margin for this configuration.
For straightforward MIG welding with an air-cooled torch and no additional sensors, total payload is typically 4–5 kg including safety margin. The EVST QJAR 6 (6 kg payload, 924 mm reach) or QJAR 10 (10 kg payload, 1450 mm reach) handles this comfortably.
Step 3: Determine Reach Requirements
Reach defines the robot’s maximum working envelope — the 3D space within which the torch can access all weld joints. Insufficient reach means inaccessible joints; excessive reach wastes money and reduces stiffness.
Reach calculation method:
- Measure the maximum distance from your intended robot base mounting point to the farthest weld joint on your largest workpiece, accounting for positioner position.
- Add the torch length (typically 200–350 mm from the wrist faceplate to the contact tip).
- Subtract this from the robot’s maximum reach specification.
- Ensure at least 15–20% reach margin remains for approach angles and clearance.
Practical reach guidelines:
| Application Size | Workpiece Envelope | Recommended Reach | EVST Model |
|---|---|---|---|
| Small parts (brackets, frames) | < 600 × 600 mm | 1200–1500 mm | QJAR 6 (924mm) + positioner |
| Medium parts (chassis, furniture) | 600–1200 mm | 1400–1800 mm | QJAR 10 (1450mm) |
| Large parts (beams, tanks) | 1200–2000 mm | 1800–2500 mm | EVS 20 (1850mm) |
| Extra-large weldments | > 2000 mm | 2000mm + linear track | QJAR 10/20 + EVST track |
Important: If your workpiece exceeds the robot’s reach from a fixed base, adding a linear track (7th axis) is usually more cost-effective than selecting a larger robot. EVST offers floor-mounted and wall-mounted linear tracks in lengths from 2 to 20 meters, compatible with all QJAR and EVS series robots.
Step 4: Evaluate Precision and Speed Requirements
Repeatability determines weld placement accuracy. For most arc welding applications, ±0.05–0.08 mm repeatability is sufficient — this is standard across all EVST QJAR series models. For precision TIG welding of thin-walled parts or laser welding, look for ±0.03–0.05 mm.
Maximum TCP speed affects cycle time but is rarely the bottleneck in welding applications — the welding process speed itself limits travel speed. However, fast air-move speed (the speed between welds) directly impacts cycle time in multi-weld parts. EVST robots achieve joint speeds up to 460°/s, ensuring rapid positioning between weld segments.
Path accuracy is more critical than repeatability for welding. A robot may have excellent repeatability (returning to the same point) but poor path accuracy (deviation from the programmed path during motion). For weaving or circular weld paths, request path accuracy specifications — not just repeatability.
Step 5: Match the Complete Welding Cell Configuration
The robot arm is one component of a complete welding system. Your selection should account for the full cell configuration.
Positioner selection: Match positioner payload to your heaviest workpiece plus fixture weight. Add a 50% safety margin for dynamic loads during rotation. EVST offers single-axis turntables and dual-axis positioners from 100 kg to 5,000 kg capacity, with coordinated motion control for seamless robot-positioner synchronization.
Controller compatibility: Verify that the robot controller supports your welding power source brand through a certified interface. EVST controllers offer pre-configured interfaces for Fronius, Lincoln, Miller, Panasonic, and Megmeet digital welding power sources.
Safety enclosure: Budget for safety fencing, interlocked gates, arc flash curtains, and fume extraction. For collaborative welding robot applications, standard safety fencing may be reduced or eliminated — see our welding workstation setup guide for detailed configuration guidance.
EVST Welding Robot Product Map
The following table maps EVST’s welding robot lineup to application profiles. All EVST robots are CE-marked and manufactured under IATF16949 quality management. International buyers receive English-language documentation, remote technical support, on-site engineer dispatch, and factory training programs.
| Model | Payload | Reach | Repeatability | Best Welding Applications | Key Features |
|---|---|---|---|---|---|
| QJAR 6 (QJR6S-1) | 6 kg | 924 mm | ±0.05 mm | Small-part MIG/TIG, cobot welding | Compact, drag-and-teach, no fencing needed |
| QJAR 10 (QJR10-1) | 10 kg | 1450 mm | ±0.05 mm | General MIG welding, medium fabrication | High speed, wide reach, versatile |
| QJAR 20 | 20 kg | 1668 mm | ±0.05 mm | Heavy-torch MIG, multi-sensor setups | High payload for complex torch configs |
| EVS 20 | 20 kg | 1850 mm | ±0.05 mm | Large-part welding, extended reach | Long reach for structural fabrication |
| QJAR 50 | 50 kg | 2050 mm | ±0.06 mm | Laser welding head, heavy tooling | Stiff wrist for laser applications |
| QJAR 165 | 165 kg | 2650 mm | ±0.08 mm | Spot welding (automotive) | High moment/inertia capacity |
| QJAR 210 | 210 kg | 2800 mm | ±0.08 mm | Heavy spot welding, handling + welding | Maximum payload in QJAR range |
Not sure which model fits your application? Contact our welding automation team with your workpiece dimensions, material type, welding process, and target cycle time — we will recommend the optimal configuration within 24 hours.
Common Selection Mistakes to Avoid
Mistake 1: Selecting on payload alone. A 20 kg robot with 1450 mm reach may not cover your workpiece, while a 10 kg robot with 1850 mm reach might. Always evaluate payload and reach as a pair.
Mistake 2: Ignoring wrist moment and inertia ratings. Heavy or long torches create significant moment loads on the wrist joints. Check that the combined torch + wire feeder mass at the actual mounting distance does not exceed the wrist moment rating — even if total weight is within payload capacity.
Mistake 3: Specifying maximum reach too tightly. Operating consistently at 95%+ of maximum reach reduces accuracy and increases vibration. Budget 15–20% reach margin for reliable production quality.
Mistake 4: Buying the robot arm without specifying the full cell. The robot is 30–40% of system cost. Positioner, fixtures, power source, safety, and integration engineering make up the remainder. Budget for the complete system from the start.
Frequently Asked Questions
What payload capacity do I need for a welding robot?
Calculate total payload as welding torch weight plus wire feeder (if wrist-mounted) plus any sensors or cameras. Most MIG welding torches weigh 3–6 kg, and TIG torches weigh 1.5–4 kg. Add a 30% safety margin above the calculated total. For standard MIG welding applications, a 6–10 kg payload robot is sufficient. For heavy-duty torches with integrated wire feeders or multi-process capability, consider 12–20 kg payload models.
How do I determine the right reach for a welding robot?
Measure the maximum distance from the robot base mounting point to the farthest weld joint on your largest workpiece, including the positioner offset. Add 15–20% margin for approach angles and torch clearance. Standard welding applications typically require 1400–1800 mm reach. Large weldments may require 2000+ mm reach or a linear track.
Can one welding robot handle both MIG and TIG welding?
Yes, with a torch changeover system. Automatic tool changers allow a single robot to switch between MIG and TIG torches within 15–30 seconds. However, in most production environments, dedicated single-process cells deliver better utilization and simpler maintenance.
Next Steps
Ready to specify your welding robot? Here is how to move forward:
- Download our welding robot specification worksheet (coming soon) to organize your requirements.
- Review our welding workstation setup guide for complete system configuration details.
- Request a quote with your workpiece details — our engineering team provides model recommendations and budgetary pricing within 24 hours.
For broader industry context on robotic welding technologies and ROI, see our Complete Guide to Robotic Welding (2026) on our brand site.
Last updated: April 2026. Product specifications referenced in this article are based on current EVST product data. Contact sales for the latest specifications and pricing.