Printing machines: register, tension and dryers at higher speed

Register drifts on faster webs and thinner materials

What happens. On a press the colours must land on each other. At higher speed and with thin film or paper, the web stretches and wanders between the print units, and the register marks drift. The operator corrects, and the result is lagging behind the web.

What it costs. Waste in every start-up and after every speed change, and a lower speed whenever the job is critical. Thin materials make the waste worse, because they are less forgiving.

Why the usual fix fails. A register controller tuned for the old material and speed reacts too late or too hard on the new one. Corrections by the operator follow the error instead of preventing it.

How a fixed-price remote diagnosis checks it. From press logs (register errors, web speed, tension, temperatures, job data) I check how the register error develops and whether a model that predicts web behaviour could act earlier. The fixed-price remote diagnosis tells you what a redesign could gain.

Background: Control that adapts to drift and wear

Web tension swings at every roll change

What happens. When a reel is almost empty and the next one is spliced in, the tension in the web jumps. The roll diameter changes continuously, and the drives have to follow. After the splice the web may flutter, wrinkle or even break.

What it costs. Web breaks stop the machine and bring waste, clean-up time and sometimes damaged rollers. Wrinkles end in rejected rolls, and operators run slower around the splice.

Why the usual fix fails. A tension sensor can only measure what has already happened. Re-tuning the drive for one roll size does not hold for the others, and for another material it needs doing again.

How a fixed-price remote diagnosis checks it. From drive logs (speeds, torques, tension signals, roll data) I check whether the diameter and the tension can be computed continuously and which part of the swing a better control could remove. The fixed-price remote diagnosis answers that for your machine.

Background: Computed measurements

Wider and faster machines change the web dynamics

What happens. A new machine generation runs wider and faster, and the control that worked on the previous one no longer fits. Longer free web spans, more drive axes and higher speeds give different oscillations, with the same settings as before.

What it costs. The commissioning of the first machines takes longer than planned, and the customers see waste they did not have with the old model. The builder has to choose between slower rated speed and long tuning on site.

Why the usual fix fails. Scaling up the old settings carries over what worked for a narrower web. Tuning each machine on site once built is slow, and the lessons stay with the commissioning engineer.

How a fixed-price remote diagnosis checks it. From the drive data of existing machines, material tests and the layout of the new one, I check how tension and register behave over width and speed and whether the control can be designed on a model. The fixed-price remote diagnosis tells you what that would involve.

Background: Predictive control of process plants

Ink density is corrected by the operator's eye

What happens. Colour drifts during a run with temperature, ink and speed. The operator looks at the print, compares it with the sample and turns the ink keys. Different shifts and different people give different results.

What it costs. Waste until the colour is right, customer complaints when a job leaves with colour off the target, and time spent on measuring strips and checking.

Why the usual fix fails. A colour measuring system in the press helps, but reacts only to what it measures and often takes the settings of the last job as given. Corrections made with a feeling for the press do not carry over to other people.

How a fixed-price remote diagnosis checks it. From colour measurements, ink-key positions and job data, I check how the colour responds to the settings and whether an estimate could steer the ink before the error is visible. The fixed-price remote diagnosis tells you if that is realistic for your press.

Background: Computed measurements

Printing dryers run for the worst case

What happens. The dryer is set to dry the heaviest ink coverage on the least absorbent material at top speed. Most jobs need less. The air stays hot and the fans run at full power, because nobody sees how wet the web still is.

What it costs. Gas or electricity for drying that was not needed, and a web that is over-dried, which brings curl and brittle material. Solvent residues and odour are a risk when the dryer is set too low.

Why the usual fix fails. Cutting the setpoint by hand works for easy jobs and fails on the next demanding one. A dew-point or solvent sensor at the dryer exit gives one value, late.

How a fixed-price remote diagnosis checks it. From dryer logs (air temperatures, fan speeds, web speed, exhaust humidity) and job data, I estimate the remaining moisture or solvent and check how much heat each job needs. The fixed-price remote diagnosis tells you whether a computed value can lead the dryer.

Background: Computed measurements

Tension zones in converting machines interact

What happens. A converting line has several tension zones between unwind, process stations and rewind. When the operator corrects one zone, the neighbours react. The web then swings between sections, and each section is tuned separately.

What it costs. Wrinkles, breaks and rejects, especially at speed changes and with elastic materials. Staff spend commissioning time chasing interactions from one zone to the next.

Why the usual fix fails. Loops tuned one by one cannot solve a problem that is a property of the whole line. Detuning them to stop the interaction makes every zone slow.

How a fixed-price remote diagnosis checks it. From drive and tension logs of a line, I identify how the zones influence each other and check whether one multivariable control could replace the separate loops. The fixed-price remote diagnosis tells you what that would take.

Background: Predictive control of process plants

Adhesive weight varies in laminating

What happens. In laminating, the adhesive layer has to be uniform. The coat weight is checked now and then by weighing samples, while the web runs on. Between checks, the weight drifts with viscosity, temperature and speed.

What it costs. Too little adhesive gives delamination, which often shows up at the customer. Too much wastes adhesive and energy for drying and curing, and can cause bleed-through.

Why the usual fix fails. More frequent sampling takes staff time and still shows only a spot. Aiming high on the coat weight as a safety margin is the common choice and costs material every day.

How a fixed-price remote diagnosis checks it. From machine data (roller speeds, nip pressure, adhesive temperature and viscosity, web speed) and the lab values, I check whether the coat weight can be computed continuously and which settings move it. The fixed-price remote diagnosis tells you how much margin a computed value could release.

Background: Computed measurements

Roll hardness and telescoping at slitting and winding

What happens. Finished rolls come off the winder too hard in the core or too soft at the edge. A roll that is wound too loosely telescopes; one wound too tight crushes the core or leaves marks. The operator only sees the result after the roll is off.

What it costs. Rejected rolls, complaints from the customer’s machine and the working time of staff handling them. The material that was already slit and wound is lost.

Why the usual fix fails. Winding with a fixed taper tension for every material and every diameter is a rule of thumb that holds in a narrow range. Checking hardness by hand after winding is too late to correct the roll.

How a fixed-price remote diagnosis checks it. From winder logs (tension, nip or contact pressure, speeds, roll size) and reject records, I check how the winding parameters relate to the faults and whether a winding model could set them. The fixed-price remote diagnosis tells you if that would work on your winder.

Background: Control that adapts to drift and wear

Job changes take long because settings come from experience

What happens. At a job change the machine is made ready: tension, register, dryer, pressure. The operator takes the settings from the last similar job and corrects them on the first metres. A new combination of material and format needs several rounds.

What it costs. Downtime and make-ready waste on every change, more so with short runs. The more jobs a day, the larger the share of non-productive time.

Why the usual fix fails. A recipe database of past jobs helps for known combinations only. Hand-corrected values drift from the recipe over time, and nobody knows which one is right.

How a fixed-price remote diagnosis checks it. From job histories, settings and waste records, I check how well a model can predict the starting settings for a new combination. The fixed-price remote diagnosis shows how much make-ready time and waste it could save and what data you would need to log.

Background: Replacing hand-tuned parameter tables by a model

Digital presses: drying and media handling limit quality

What happens. Inkjet and other digital presses print on many media without plates, but each medium dries and moves differently. Paper that takes up too much water curls, coated stock may smear, and a thin sheet wanders in the transport path.

What it costs. Quality varies between media, jobs need test prints, and speed is cut for the difficult stock. The press cannot always print what its resolution promises.

Why the usual fix fails. A profile per medium helps with the known stock only. Fixing the dryer power high wastes energy and damages the sensitive media.

How a fixed-price remote diagnosis checks it. From press data (dryer settings, ink coverage, humidity, transport speed, print results) I check how drying and handling depend on the medium and whether a model-based control could adapt itself. The fixed-price remote diagnosis tells you what to expect.

Background: Control that adapts to drift and wear

Presses and dryers idle hot between jobs

What happens. Between jobs, at shift change and during breaks, the press stands ready and the dryers stay at temperature, because heating up again takes too long and nobody knows exactly when the next job starts.

What it costs. Gas or power for a machine that produces nothing. Over a year the idle hours add up to a substantial share of the energy bill.

Why the usual fix fails. Switching off by hand risks long warm-up times and bad first metres. A fixed standby timer does not know the order book.

How a fixed-price remote diagnosis checks it. From machine data, shift plans and job schedules, I estimate how long each unit needs to be ready and when it can safely drop to standby. The fixed-price remote diagnosis tells you how much energy a standby plan could save.

Background: Economic predictive control

Many machines abroad, and every fault means a trip

What happens. Machine builders sell all over the world. When a press runs badly in another country, the service engineer travels there, often just to find that the cause was a setting or a worn part that the data could have shown.

What it costs. Travel costs, days of lost production for the customer and service engineers who are away instead of working on the next case. Time zones and language slow the first answer.

Why the usual fix fails. Remote access to the screen helps, but only if someone knows what to look for in the data. A hotline reads the manual to the operator and cannot tell a control problem from a worn mechanical part.

How a fixed-price remote diagnosis checks it. From logs the machines already record (drive currents, tensions, register errors, alarms), I check what a remote analysis can find and what still needs a visit. The fixed-price remote diagnosis shows how such a service would work for your fleet.

Background: Computed measurements

Control algorithms limited by the drive hardware

What happens. The drives of a modern machine have their own processors, but the vendor’s firmware offers only simple control blocks. Better algorithms are known, yet they run too slowly or do not fit the memory.

What it costs. The machine stays with simple control that needs tuning and wastes speed. Additional hardware costs money and space in the cabinet.

Why the usual fix fails. Moving to a more powerful controller adds cost and a new software platform. Simplifying a better algorithm by hand loses what made it better.

How a fixed-price remote diagnosis checks it. From your drive specifications, the cycle times and the present control, I check which algorithm can run on the hardware you have, in real time. The fixed-price remote diagnosis tells you what could be gained without changing the drives.

Background: Predictive control on embedded hardware