Spec sheets vs shop-floor reality
On paper everything looks precise. In production you face tolerances, scrap risk, manual tweaks, and material variability. The honest question is:
“Will the robot actually be more accurate than what we do today?”
Accuracy vs repeatability
Repeatability
The robot’s ability to return to the same point over and over.
- Typical modern values: ±0.02 to ±0.1 mm, depending on model and size.
- Defined by manufacturers and verifiable.
Accuracy
How close the position is to the ideal (nominal). Driven by:
- Calibration (robot + TCP)
- Tooling (mounting, offset, stiffness)
- Part fixturing and references
- Environment (temperature, vibration)
- Process (paths, speeds, force control)
👉 A robot can be very repeatable, but final accuracy is a system property.
The human factor: “I always tweak it a bit”
Operators often compensate with eyesight, experience, and constant micro-tweaks. This creates a perception of accuracy that:
- Varies by person
- Lacks traceability
- Degrades over time
Robots remove improvisation and expose the true state of the process.
What truly drives accuracy on the floor
- The robot doesn’t work alone
- Poor tool mounting → repeatable error
- Weak fixturing → systematic error
- Bad references → constant offset
- System stiffness
In deburring, light milling, polishing: stiffness of tool/fixture/robot often matters more than nominal repeatability. - Material variability
Plastics, aluminium, castings, composites behave differently. You may need:
- Compensation
- Force control
- Adaptive strategies (vision/tracking)
Can a robot be “more accurate” than a manual process?
Yes—but differently.
- It doesn’t “intuitively correct”; it executes as taught.
- It removes human variability → less spread, less scrap, less rework, more stability.
- Not necessarily tighter tolerance, but more consistent quality.
Sensors & software: where real accuracy is won
To go beyond repeatability:
- Force/torque sensing → controlled contact
- Vision → real position adjustment
- Software → path correction and online compensation
This turns the robot from “mechanical” into a process system.
Robots vs CNC: a calm comparison
- CNC: micrometric absolute accuracy.
- Robot: outstanding repeatability and flexibility where extreme tolerance isn’t the main driver.
Robots don’t replace CNCs; they complement them where CNC is not economically or operationally viable.
Human and business impact
- Less dependency on who’s on shift
- Fewer subjective tweaks
- More data for decisions
Accuracy shifts from opinion to a measurable parameter.
The question that truly matters
Before “How accurate is the robot?” ask:
What stability and repeatability does my process need to be profitable and sustainable?
In industrial automation, real accuracy is engineered, not promised.
🎥 Related video: https://www.youtube.com/watch?v=Lxz3k3yIeJk
✅ Checklist: Validating real accuracy on the shop floor
- Define critical tolerances per operation
- Select rigid fixturing for part and tool
- Calibrate robot, tool (TCP) and references
- Verify repeatability (go/return tests on known points)
- Measure accuracy with gauges/vision on real parts
- Force control for contact / variable materials
- Trajectory compensation for thermal drift or wear
- MSA (Gage R&R) and CP/CPK for the cell
- Maintenance plan (backlash, play, torque checks)
- Data logging (traceability) + periodic review
❓ FAQs
1) What repeatability can I expect from an industrial robot?
Typically ±0.02 to ±0.1 mm, depending on model/size.
2) Why doesn’t accuracy match the spec sheet?
Because accuracy is governed by the entire system (calibration, fixtures, references, environment, process), not just the arm.
3) How can I improve accuracy without changing the robot?
Upgrade fixturing, TCP calibration, references, stiffness, and add vision/force control.
4) Can a robot replace a CNC for fine finishing?
Usually no for micrometric tolerances; yes where flexibility/cost outweigh extreme tolerance.
5) How do I prove accuracy to a customer?
With a test plan, MSA, CP/CPK studies, and traceable measurements.
6) What if the robot “repeats poorly”?
Check tool mounting, part fixturing, calibration, backlash; run a repeatability test and apply compensations.