Direct answer: List what each existing machine can and cannot do, how the part changes shape and clamping between operations, and how parts move and buffer between them. Only then choose robots. In practice the constraints change at every step, so grippers and fixtures rarely carry across, and a proposal built on one concept for the whole chain usually stalls at the second operation.
Who this is for: Written for engineers and owners planning to automate sheet and tube fabrication that currently runs across several standalone machines.
Scope: This EVST guide covers how constraints change from operation to operation and why transfer between them usually decides the result. It does not quote throughput, cycle times or payback figures.
Three machines, three operations
The reference footage shows three separate machines: plate measured and formed, a shell worked further on a second machine, and tube joints welded on a third.
They are shown together to make one point. A retrofit here faces a chain, not a station, and nothing in the footage implies one continuous line.
The constraints change at every step
A flat sheet locates from an edge and a feed. Once rolled into a shell the part clamps in a completely different way, and nothing about the first fixture carries across.
By the time the work reaches tube joints, the constraint has become port position and the intersection line, which is a different problem again.
Why a fan manufacturing automation retrofit stalls at step two
Proposals that assume one gripper and one fixture concept across the whole chain usually run into trouble at the second operation, because the part is no longer the same shape.
Treating each operation as its own constraint set is slower to write and much faster to build.
Transfer between operations decides the result
Each operation on its own is usually automatable. What decides whether the chain runs is transfer: how parts move between machines, where they wait, and whether cycle times match.
When an upstream operation runs faster than the one after it, something has to buffer. When the buffer is full, the upstream machine stops, and the throughput gain disappears.
According to ISO 12100:2010, the assessment covers the installation as a whole, which for a chain means the transfer between machines and not only the machines themselves.
What to list before choosing hardware
The product range and its variants; what each existing machine can and cannot do; how the part shape and clamping change at each step; and the current order of operations with transfer method.
That list is the input a supplier needs. Without it, a proposal is a guess dressed as a specification.
| Operation | What the part is | Constraint that dominates |
|---|---|---|
| Plate forming | Flat sheet | Locating from an edge and a feed |
| Shell working | Rolled shell | Clamping a curved body without distortion |
| Tube joint welding | Tube and branch | Port position and the intersection line |
| Transfer between them | Part in motion | Buffering and cycle matching |
Safety follows the layout, not the machine list
Once parts move between machines automatically, the safeguarded space covers the transfer as well as the machines. ISO 12100:2010 and ISO 10218-2:2025 apply to the cell as integrated.
Welded joints in the chain also carry their own acceptance and records requirements under ISO 3834-2:2021.
According to ISO 10218-2:2025, an integrated cell is assessed as integrated, so automatic transfer between operations brings the transfer inside the safeguarded space.
According to ISO 3834-2:2021, welded joints in the chain carry their own acceptance criteria and record requirements, which do not change because the handling around them was automated.
In practice an application review lists the project inputs before any hardware: product range, machine capability and the current order of operations. Selection follows from that evidence, and acceptance is agreed operation by operation.
Frequently asked questions
Can we automate one operation at a time?
Yes, and it is often the right order. What matters is that the transfer to and from the automated step is designed at the same time, otherwise the gain is absorbed by handling.
Does one gripper concept work across the chain?
Rarely. The part changes shape between operations, so clamping and gripping usually change with it.
What usually limits throughput after a retrofit?
Transfer and buffering between operations, more often than any single machine’s cycle.
What should we send to get a useful answer?
The product range, what each existing machine can do, and the current order of operations with how parts move between them.
Project inputs for an application review
To have the chain reviewed rather than a single station, send:
- product range and variant mix
- existing machine list with capability and age
- current order of operations and transfer method
- target throughput and available floor space
Send the part range and the current process order and the chain can be reviewed against it. Related reading: sheet fabrication automation, cylindrical part welding boundaries.