Cobot or Industrial Robot: The Task Draws the Line
Direct answer: Write the task list before comparing robots: the motion, the force it needs, the part weight, the cycle the line imposes, and how close people work and for how long. The configuration follows from that list, and the model follows the configuration. Power and force limiting addresses the collision class only; it does not remove reaction torque, fluid hazards, or the need for a risk assessment.
Who this is for: Written for engineers and buyers deciding whether a station should use a collaborative arm, an industrial robot with guarding, or a monitored combination of the two.
Scope: This EVST guide covers how the choice between collaborative and industrial configurations is actually decided: the task list, the hazards each task introduces, what power and force limiting does and does not cover, and where the cycle window comes from. It does not quote force limits, cycle times or capacity figures; those belong to the risk assessment and the capacity study.
Three stations, one arm type
The reference footage shows three separate stations from one supplier, not one continuous line. One runs vision inspection beside an assembly conveyor, one tightens on an engine oil pan, and one handles automatic oil filling.
All three use the same collaborative arm type, and none of them is fenced. People work within a few steps of each.
Seen together they make a single point: what decided the arrangement was the task, not the robot model. The same arm is doing three jobs whose hazards have almost nothing in common.
How collaborative versus industrial robot selection is actually decided
Start by writing the task down in terms that can be checked: the motion, the force it needs, the mass being handled, the cycle the surrounding process imposes, and whether people have to be within reach while it runs and for how long each shift.
Only then is the configuration a real question. A collaborative arm suits low forces, moderate speeds and frequent human proximity. An industrial robot with guarding suits higher forces, heavier parts and cycles that a speed limit would spoil. A monitored arrangement sits between them, with safety-rated speed and separation.
Mixing configurations along one line is normal and does not need to be rationalised away. Different stations have different tasks, and the correct answer per station is the one that matches its own task list.
The model number comes last. Projects that start there usually end up giving back the floor space they saved, because guarding gets added at acceptance to cover hazards the configuration never addressed.
EVST works through that order station by station rather than settling on one configuration for a whole line.
Open stations buy access and cost cycle freedom
The visible benefit of an unfenced station is space and access: the arm sits at the conveyor, parts arrive on pallets, and people can work in the same area.
The cost is that the working window belongs to the line. When the part arrives and how long it dwells decide how long the arm has, and no amount of arm performance exceeds that window.
That is why the capacity question in these stations usually is not about the robot at all. It is about the window and the handover to the stations either side, and it should be answered before configuration, not after.
| Task characteristics | Usual configuration | What to verify first |
|---|---|---|
| Light handling or inspection, people nearby much of the shift | Collaborative arm, unfenced | Cycle window imposed by the line, and the risk assessment for the task |
| Tightening, pressing or any task with reaction force | Collaborative arm only after the reaction path is assessed | Where the reaction goes and what happens on a fault |
| Heavy parts or speeds a limit would spoil | Industrial robot with guarding | Loading access and how often people need to enter |
| Occasional human access, otherwise full speed | Industrial robot with safety-rated monitoring | Separation distances and the stopping performance they assume |
The hazards do not transfer between tasks
Inspection is mainly a collision and pinch problem, and the pinch may be between the part and the conveyor rather than with the arm. Tightening introduces reaction torque, which is a different mechanism entirely. Filling introduces fluid, pipework and whatever the fluid does when it escapes.
According to ISO/TS 15066:2016, power and force limiting is applied to contact between the robot system and a person, with limits set for the body areas involved. It is a supplement to ISO 10218 for collaborative operation, not a self-certifying property of an arm.
According to ISO 12100:2010, the risk assessment is made for the machine in its application, which means the tool, the part and the surrounding equipment are inside the assessment rather than outside it.
So choosing a collaborative arm never closes the assessment. It changes which hazards need which measures, and it leaves reaction torque, fluids and trapped-part hazards exactly where they were.
What the footage cannot show
Force and speed limits, the conclusions of a risk assessment, real cycle time and capacity are not visible in any of these stations. They come from the assessment file and the capacity study.
Whether an unfenced station is genuinely safe to approach is also not a judgement that can be made from the absence of a fence. It follows from how the assessment was carried out and what it concluded.
According to ISO 10218-2:2025, the integrated system defines the safeguarded space, so the conveyor, the fixture and the part belong to the same assessment as the arm.
In practice an EVST application review starts from the task list, part weights and the human traffic pattern around the station, and the configuration follows from that evidence.
Every application review opens from the same project inputs – drawing, standard and current method – so selection rests on evidence and acceptance is agreed against your own parts rather than a datasheet.
Frequently asked questions
Is a collaborative robot always the safer choice?
No. It changes which hazards are covered by which measures. Power and force limiting addresses contact between the robot system and a person; reaction torque, fluid hazards and pinch points between the part and surrounding equipment still have to be assessed and controlled.
Can one line mix collaborative and industrial stations?
Yes, and it is common. Each station has its own task list, and the correct configuration is the one that matches it. There is no requirement for a line to be uniform.
Why is the cycle usually the limiting factor at an open station?
Because the working window is set by the surrounding process. If the part dwells for a fixed time, the arm cannot use more than that, regardless of its own speed.
What should we send to get a useful answer?
A task list per station with motion, force, part weight and cycle, plus how close people work, how often and for how long.
Project inputs for an application review
To have the configuration checked against your own stations, send:
- a task list per station: motion, force, part weight, cycle
- how close people work, how often and for how long
- the surrounding process and the window it imposes
- any existing risk assessment or safety concept
Send the task list and the part weights and the configuration choice can be worked through against them. Related reading: industrial and collaborative robots, robot welding workstation.