Bottling star wheels: how to tell they are worn and what to do next
Paschalis KosmidisMSc Mechanical Engineer, AUTh5 min read
You don't pick a star wheel from a catalogue. It is made for your machine and your bottle. So the question is rarely "which one should I buy". The question is "when does it need replacing".
In this guide
Wear does not happen overnight. It starts with a bottle that knocks a little more than it should. Then comes a sudden jam. Then a bottle that falls. By the time you get there, the line stops more often than it should.
In this guide you will see where a star wheel wears, how to spot it and what to do next.
- Check the corners of the star wheel and the entry edges of the guides.
- When wear reaches 2 mm on the radius, it is time to replace it.
- Don't patch up the machine. Temporary fixes become permanent.
Where a star wheel wears
Wear almost always follows the same order:
- the corners of the star wheel,
- the ends of the guide, mainly the entry edges, on both sides,
- the pocket of the star wheel, where the bottle sits.
The star wheel wears first, then the guide.
If the machine has an infeed screw, it wears too. A worn screw cannot hold the pitch, or it leaves large gaps between the bottles.
Breakage comes last, in star wheels and guides. If you see a broken piece, the wear is already advanced.
What wear looks like
In the first stage the star wheel and the guide get rubbed. The surface looks as if someone went over it with sandpaper.
As it goes on, material is lost and the pocket opens up. When wear reaches 2 mm on the radius, the star wheel needs replacing.
A close-up photo of the pocket says a lot. If you are not sure what you are looking at, send us the photo.
What it does to your line
- bottles fall,
- bottles suddenly jam,
- bottles knock hard and wobble left and right as they pass,
- the movements lose their consistency and are not the same for every bottle.
Every jam means stopping, clearing and starting again. And the longer you leave it, the more the machine itself wears.
Be careful, though. A star wheel that is not set correctly on its shaft, or an infeed screw out of sync with the star wheels, gives similar symptoms. So before you replace anything, do the check in the next step.
What to do next
Step 1Check
Put your phone in slow motion. Film the problem spot for 10-15 seconds, long enough for 6-7 bottles to pass. Watch it back slowly, bottle by bottle.
Two times out of three, that is enough to find the cause yourself. If it is a setting, you do not need a new star wheel.
Then look at the star wheel and the guide themselves: corners, entry edges, pocket.
Step 2No "temporary fixes"
I want to be clear here. Do not butcher the machine just to get the production out.
Temporary fixes end up permanent. At first you run them carefully. Then you trust them and raise the speed. That is when the really big damage happens, and by then it is no longer just a star wheel.
If you really have to keep running until the new one arrives, it may be possible. Before you do, contact me so we can confirm it on a video call.
Step 3Replacement or reproduction
You have two options here.
Original replacement
You order it from the machine manufacturer. If it is easy to find and the price is reasonable, this is the simple route.
Reproduction by us
We make the part from the real dimensions of your machine. It also works for machines that no longer have spare parts, as long as we can get access to the machine to measure it. What exactly we need depends on the case, and we work it out together.
Factory star wheels are usually made of acetal or PTFE. Ours are polycarbonate (PC). The properties are similar, so nothing essential changes in terms of wear.
If you already have a Bottleneck base, you do not replace the whole star wheel. You replace only the grippers. And because every set comes with extra spare parts from the start, a damaged part does not stop your line.
When it is not worth it
It is not always worth having us make it.
- If the original is easy to find and costs little, buy the original.
- If the problem is a setting or the screw, a new star wheel will not fix anything.
- If you do not plan a large production, in other words you want to do one bottling run and that's it.
How long you wait
A new set of grippers is delivered in 3-5 working days from our own workshop. For reproducing a whole star wheel, the time depends on the case, and we agree it before we start.
Frequently asked questions
How do I know a star wheel is worn?
Its corners and the entry edges of the guides look rubbed, as if with sandpaper. On the line, bottles knock, wobble left and right, jam or fall. When wear reaches 2 mm on the radius, the star wheel needs replacing.
Is it always the star wheel when the line jams?
No. A star wheel set wrong on its shaft or an infeed screw out of sync gives similar symptoms. I can't tell without seeing it. Send us a video or a photo and we will tell you what it looks like.
Can I keep running with a worn star wheel until the new one arrives?
Do not rely on temporary fixes. They end up permanent, the speed goes up, and that is when the big damage to the machine happens. It may be possible for a short time, but contact us first so we can confirm it on a video call.
Do you make star wheels for machines that no longer have spare parts?
Yes, as long as we can get access to the machine to measure it.
How long does it take?
A new set of grippers in 3-5 working days. For a whole star wheel, the time depends on the case.
Want us to look at your own line?
Book a free 30-minute call, or send us a message. There is no commitment.