Workshop practice
Replace the consumable without losing the setup
On a machine with printheads, every head replacement can mean setting up from scratch. Or it need not. The difference is whether the design separates the part that wears out from the part that locates it.
Some machine parts wear out: printheads, blades, nozzles, punches, suction cups. They are replaced frequently, sometimes several times a week.
Other parts provide positioning: they determine where that tool sits relative to the product.
When both functions belong to the same part, every consumable replacement requires a new setup. The operator removes the worn head, installs the new one and starts testing: one print, one adjustment, another print, another adjustment. Ten minutes, twenty, half an hour. And material consumed by trials.
When the design separates those functions, replacing the consumable is just that: replacing it.
The case
A machine that encodes and personalises RFID tickets on a reel, with inkjet printheads on both sides.
Because of intensive use, head replacement is routine. It is a normal operation, not a breakdown. Precisely for that reason, it had to be quick and leave everything else undisturbed.
The solution was to design the mounts so the head can be replaced without losing its position. The setup lives in the mount. The head fits into it, and the mount remains untouched when the head is changed.
Separating consumable replacement from setup allows the printing configuration to be maintained throughout production.
A mount that had to evolve
This mount did not emerge fully formed. It changed as the jobs changed:
- Three fixed heads per side. The initial configuration.
- Five fixed heads per side. New messages required greater coverage of the ticket. The commercial mount could no longer provide that, so a custom mount was designed.
- Three fixed central heads and two adjustable outer heads. Later, message positions across the ticket needed to vary. The outer heads became independently adjustable.
- Adjustable and compact. A final evolution made it more compact to coexist with the machine's adjustable encoding boxes.
At each stage, the mount gained adjustment options. Precisely because more adjustment was possible, it became more important not to lose that setup when changing a head.
A mount with many adjustment options but no references creates a machine every operator sets differently, and which never produces the same result twice.
References: recovering what already worked
The other half of the problem is not changing heads, but changing jobs.
When moving from one order to another, head positions change. When that order returns a month later, ideally nobody should have to rediscover those positions.
That is why the mounts have position references: marks that allow a known setting to be restored. Operators record the configurations for each job and apply them again on later runs. Once the job is set up, the machine maintains that setting throughout long production runs.
Head adjustments are still manual. And that is fine. Manual does not mean imprecise when the adjustment has references. A manual setting with references is repeated; one without references is guessed.
Even the adjustment knobs are custom turned. It seems like a cosmetic detail, and partly it is, but a knob that is easy to grip and turn with control makes adjustment easier to perform well.
The principle, for any machine
This is not just about printheads. It applies to any machine with a tool that wears out.
1. Identify what wears out and what provides positioning. If they are the same part, every consumable replacement means a setup. Separate them if you can.
2. Locate the consumable against a reference that remains untouched. The mount retains the position; the consumable locates against it. How this is achieved depends on the application — stops, seats, pins, defined supports — but the idea is always the same: the new consumable must sit where the old one was, without anyone measuring it.
3. Give the adjustment visible references. Scales, marks, numbered positions. Whatever operators need to record each job's settings and return to them.
4. Design for the most frequent replacement. If a consumable is replaced every week, it should be the easiest part of the machine to access. Do not hide it behind a cover with six screws.
5. Ask the person who replaces it. The operator knows how long it takes, what is difficult and what forces them to readjust. That information is not on any drawing.
Why it matters so much
Because replacement time does not appear on the machine's specification sheet, but it does affect its actual output.
A fast machine that loses half an hour at every consumable change can produce less than a slower machine that changes it in two minutes. On long runs, with consumables that wear frequently, that difference accumulates every week.
Every readjustment is also an opportunity for error. An incorrectly refitted head prints out of position, and if nobody notices in time, that means defective product. The best way to avoid a setup error is to avoid having to set up again.
At 7Axis Industrial, we design machines and assemblies with maintenance in mind too: what needs replacing, how often, and how to leave everything set as it was.
See the full CCPB7 case study → Machinery modifications and upgrades →