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How to Select Robot Based on Stroke?
2026-05-14
How to Select Robot Based on Stroke?
In automated production lines—especially for injection molding, parts handling, assembly, and machine tending—strokeis one of the most critical parameters when choosing a robotic arm. Selecting the right stroke directly affects whether the Robot Can reach all required positions, work efficiently, and avoid costly over-investment or insufficient motion range.
This guide walks you through clear, practical steps to choose the right robot stroke for your application.
What Is Robot Stroke?
Stroke refers to the maximum linear or rotational distance a robot can move along each axis (X, Y, Z, or horizontal/vertical/forward). It defines the working range of the robotic arm.
For Cartesian, three-axis, and five-axis robots commonly used in automation:
- Horizontal stroke: Forward/backward or left/right movement
- Vertical stroke: Up/down lifting distance
- Traverse stroke: Side-to-side transfer span
Insufficient stroke means the robot cannot reach pickup or placement points. Excessively large stroke increases cost, weight, and footprint while reducing speed and rigidity.
Key Factors to Determine Required Stroke
1. Measure Actual Working Distance
Start with real-world layout:
- Distance from pickup point to placement point
- Vertical height needed for lifting products or molds
- Safety clearance above obstacles, fixtures, or machine gates
- Extra margin for jigs, grippers, and end-of-arm tools
Rule of thumb: Add 50–100 mm safety margin to your measured distance to avoid jams or insufficient reach.
2. Match Machine and Layout Size
- Injection molding machine size (tonnage)
- Distance between machine and conveyor
- Height of mold or product
- Position of cooling tables, assembly stations, or packing lines
Larger machines and heavier products almost always require longer vertical and horizontal strokes.
3. Consider Load and Speed
Heavier payloads may require shorter, stiffer strokes to maintain precision and speed. High-speed applications often benefit from optimized moderate strokes rather than maximum available length.
4. Future Production Expansion
If you plan to:
- Upgrade to larger machines
- Add downstream processes
- Handle bigger or higher products choose a slightly longer stroke to avoid early replacement.
How to Calculate Correct Stroke (Step-by-Step)
- Measure horizontal moving distance (from pick to place)
- Measure vertical lifting height
- Add safety clearance (50–100 mm)
- Confirm traverse width for side movement
- Match to standard robot stroke models
Example: If your horizontal distance = 850 mm, vertical height = 650 mm Recommended:
- Horizontal stroke ≥ 950 mm
- Vertical stroke ≥ 750 mm
Common Stroke Ranges and Typical Applications
| Robot Type | Typical Horizontal Stroke | Typical Vertical Stroke | Suitable Application |
|---|---|---|---|
| Small 3-axis robot | 500–800 mm | 300–600 mm | Small injection molding, small parts pick & place |
| Medium 3-axis/5-axis | 800–1200 mm | 600–1000 mm | Standard injection molding, general assembly |
| Large high-load robot | 1200–1800 mm | 1000–1400 mm | Large molds, big products, heavy payloads |
Common Mistakes to Avoid
- Underestimating stroke: Robot cannot reach target positions, causing downtime
- Over-sizing stroke: Wastes budget, reduces speed, increases footprint
- Ignoring tool length: Grippers or jigs reduce effective reach
- Forgetting safety clearance: Risk of collision with machines or fixtures
- Not planning for upgrades: Robot becomes unsuitable for future products
Practical Tips for Buyers
- Always measure on-site before selecting a model
- Prioritize standard stroke models for better availability and cost efficiency
- Confirm effective stroke (not just nominal) with your supplier
- Test motion range with actual product and tooling if possible
- Balance stroke, load, speed, and precision for total performance
Conclusion
Choosing the right robot stroke is not about selecting the longest available—it is about precision matching to your working environment, product size, and production flow. Correctly sized stroke improves efficiency, stability, and return on investment.