Tool-less Changeover on Packaging Lines Running High SKU Counts
Every time a secondary packaging line changes from one format to another, production stops. The product may be a different size, the carton may need to change or the count inside the carton may be different, but the effect is the same because the line cannot produce saleable packs while the machine is being reset. That period between the last good pack of one SKU and the first good pack of the next is the changeover time, and on a line running several different formats during the same shift it can take a surprising amount of production time out of the day.
Tool-less changeover is designed to reduce that lost time by making the machine easier and quicker to reset. Instead of operators undoing bolts, moving parts by judgement and then making repeated corrections once the machine starts again, the main adjustment points are designed around known positions for each format. Depending on the machine, that can mean quick-release parts, indexed scales, mechanical stops or electronically stored settings. A change that might take around ninety minutes on a conventionally adjusted machine can, on a well-specified tool-less system, be reduced to around fifteen or twenty minutes. If that happens several times in one day, the difference becomes several hours of production time rather than a small saving at each change.
What tool-less changeover actually means
The name can make it sound as though the main benefit is simply that the operator no longer needs a spanner, but the bigger advantage is repeatability. On a conventional machine, an experienced operator may know that a guide needs to move slightly further than the drawing suggests, or that one part needs a small correction before a particular carton runs properly. That knowledge can make the difference between a quick restart and half an hour of adjustments, but it also means the quality of the changeover depends heavily on who is carrying it out.
A tool-less system tries to remove as much of that judgement as possible. The correct position for a known format is already established, so the operator moves the relevant part to that position rather than trying to find it again each time. That can be done with a scale, a stop, a coded format part or a stored electronic setting, depending on the machine and the type of adjustment involved.
On a cartoning machine, a format change can affect several parts of the machine because the carton has to be fed, opened, loaded and closed correctly. The magazine may need to move to suit a different carton size, the infeed and collation guides may need to change, and the loading or closing section may need a different setting. When each of those adjustments has to be measured and checked manually, the time adds up quickly. When the positions are already known and repeatable, the operator has a much clearer route from one format to the next.
The real test comes after the mechanical work is finished because a machine is not properly changed over until it is producing acceptable packs again. If the first cartons jam, the product does not enter cleanly or the closing section is slightly out, the operator has to stop and make another correction. That is why a changeover time quoted only for the physical adjustment can give a misleading picture of how long the line will actually be unavailable.
Why high SKU counts make changeover more important
Many packaging lines now have to handle more product variations than they did in the past. A manufacturer may run different carton counts for different customers, promotional packs alongside standard packs or several versions of the same product for different markets. Range expansion can make good commercial sense, but every additional format has to fit into the production schedule somewhere.
This is where changeover time starts to have a much bigger effect on output. If a line takes ninety minutes to move from one format to another and there are three changes during the day, four and a half hours have disappeared before machine faults or planned stops are taken into account. The line may still have an impressive rated speed, but that figure becomes less useful if the machine spends a large part of the shift being reset instead of producing.
This is especially relevant on high-speed packaging operations, where increasing the rated machine speed is not always the most useful way to gain more output. If a machine already runs quickly when it is producing, reducing the amount of time it spends stopped can give a better result than trying to squeeze a few more packs per minute out of it.
The same applies to shorter production runs. If a manufacturer makes one product all day, a long changeover may only happen occasionally. If the same line runs several SKUs with shorter batches, the changeover becomes part of the normal working day and the design of the machine has to reflect that.
Where the time goes during a conventional changeover
A lot of changeover time disappears in small tasks rather than one large operation. An operator may loosen a fixing, move a guide, tighten it again and then repeat the same process somewhere else on the machine. If a setting is slightly wrong, the adjustment has to be revisited, and even a few minutes at each point can become a substantial delay once the full machine has been reset.
The first production run after the change is often where more time is lost. Product has to be fed through the machine so the operator can check that cartons are opening correctly and that the product is loading without resistance. The closing section also has to run properly, and if glue is being used the finished carton needs to leave the machine in an acceptable condition. A small error at one adjustment point may only become obvious once product starts moving through the line.
Glue systems can add more delay if the machine has been stopped long enough for operating conditions to change. On automatic cartoning lines using hot-melt glue, the system has to be ready when production restarts, and the original draft notes that recovery can add around ten to fifteen minutes to the effective changeover time in some situations. The mechanical settings may therefore be complete while the line is still not producing acceptable cartons.
Operator knowledge has an effect as well. On older or manually adjusted machinery, one experienced person can often change a machine much faster than somebody who runs it less frequently. That may work while the experienced operator is available, but it creates a weakness in the production process because the setup lives partly in that person’s memory. Pre-set positions reduce that dependency by putting the correct settings into the machine or the documented format procedure instead.
How the machine is made easier to change
There is no single tool-less system that suits every machine because the adjustment method depends on what needs to move. On a simple guide rail, an indexed scale may be enough. The operator knows that format A runs at one position and format B runs at another, so the guide can be moved directly to the right setting without measuring it again.
Parts that have to be physically exchanged can use quick-release fixings rather than conventional bolts. A lane divider or format plate can then be removed and replaced without tools, which also makes it easier to keep the change parts together as one set. Where a machine runs several regular formats, those sets can be labelled or colour-coded so the operator knows which parts belong together.
More advanced systems can use servo-driven adjustment, where the position is stored electronically. The operator selects the required SKU and the relevant axes move to the stored settings automatically. This does not remove the need for good setup and validation when the format is first created, but it makes repeated changes much easier once the correct positions are known. It can also work alongside vision systems, where the machine checks that the correct setup or product is present before full-speed production begins.
The important point is that the machine should return to the same known setup each time. If one operator changes the machine on Monday and another does the same job on Thursday, the aim is for both of them to reach the same result without relying on personal judgement.
That becomes more useful as the number of SKUs increases because the machine may need to remember or physically accommodate many different format combinations. A tool-less system that handles two regular products very well is not automatically suitable for a business that expects to run twelve formats, so the required range has to be understood when the machine is specified.
Multipacks can make the change more involved
On lines running multipack cartons, the carton itself is only part of the format change because the product group may also change. A snack bar line, for example, might move from a six-count carton to a twelve-count pack, which means the collation section has to create a different group before the carton can even be loaded.
That can require changes to lane width or grouping logic, and the timing between the collation system and the cartoner has to remain correct. If one part of the line is set properly but the transfer into the cartoner is not, products can jam at the handover point even though both machines appear to be correctly adjusted when looked at separately.
This is particularly relevant for snack bar packaging, where manufacturers may run promotional counts as well as normal retail packs. In that type of application, the change in group size can be just as important as the change in carton dimensions, so the whole line needs to be considered rather than treating the cartoner as a separate machine.
What to ask when comparing machines
A quoted changeover time is useful, but only if it is clear what the figure includes. A supplier may state that a machine changes format in fifteen minutes, while the test behind that figure only covers a simple move between two similar cartons. A change that also alters the product count or uses a very different carton may take longer, so buyers need to understand what was actually changed when the time was measured.
It is also worth asking when the timing stops. If the supplier measures only the mechanical adjustment, the figure does not include the time required to run product and make sure the machine is producing acceptable cartons. Where glue is involved, the restart period should be understood as well because a line that has been mechanically reset but is still producing waste is not yet back in production.
The number of formats included in the system should also be clear. If the business expects the line to run several SKUs, the machine needs validated positions or format parts for those products rather than only the two that happened to be present during commissioning.
The same question applies when new products are introduced later. Packaging changes over the life of a machine, so the method for adding another format should be understood before the equipment is purchased. If every new carton requires a specialist engineer to rebuild the format system, the machine may be flexible in theory while being difficult to use in practice.
Documentation is part of this as well. A well-designed tool-less changeover should be easy to follow, with the operator able to identify the correct settings and parts without relying on memory. Clear visual instructions and properly labelled format sets can remove a great deal of uncertainty from a job that may otherwise be carried out differently by different people.
Changeover needs to be considered with the rest of the line
Tool-less changeover works best when it is treated as part of the original machine specification rather than something added at the end. The physical size range capability of the machine still sets the limits on what formats it can run, while modular design can make future changes easier if the line needs to be adapted later.
Format parts also wear over time, so spares and service affect how well the changeover system performs several years after the machine is installed. A damaged guide or worn format part can undo the benefit of a carefully designed setup if the replacement is not available when it is needed.
For manufacturers running a large number of SKUs, the main question is therefore not simply how fast the machine runs once it is up to speed. It is how easily the line moves from one product to the next and how consistently operators can repeat that process throughout the working week. When that change is designed properly, the gain comes from spending less of the shift adjusting machinery and more of it producing finished packs.
