Injectable manufacturers often fill several vial sizes on the same line, from small 2 ml vials to larger 20 ml or 30 ml vials. Each size has a different diameter, and each diameter changes how the label wraps around the vial. When the line changes from one vial size to another, the labelling machine must be reconfigured: guides, spacing, wrap components, sensors, label roll and coding all need attention.
A poorly managed labeller changeover can take longer than the filler changeover and lead to a slow start-up with skewed, wrinkled or overlapping labels. A well-managed one is quick, repeatable and right first time.
This article explains how to handle different vial diameters on a vial sticker labeling machine efficiently. It covers what changes with diameter, a step-by-step changeover procedure, machine features that help, label design considerations, verification and troubleshooting.
For a refresher on how vial labellers work, see our article on the vial sticker labeling machine working principle.
How a Vial Sticker Labeller Applies a Label
A typical vertical vial sticker labeller works as follows:
- Vials arrive upright on a conveyor.
- A separating device, such as a screw or star wheel, spaces them evenly.
- A product sensor detects each vial.
- The labelling head dispenses a label onto the vial as it passes.
- The vial is rolled through a wrap station, typically between a moving belt and a fixed or padded plate, wrapping the label around its circumference.
- A coder prints batch and expiry details on the label, usually before it is dispensed.
Machines such as an automatic vial sticker labeling machine or a vertical vial sticker labeller follow this principle.
What Changes When the Vial Diameter Changes
| Element | Why It Changes | What to Adjust |
|---|---|---|
| Label size | Larger diameters need longer labels to wrap fully | Load correct label roll |
| Conveyor guides | Must hold the vial upright and centred | Guide width |
| Separating screw or star wheel | Pitch and pocket size match the vial | Change part |
| Wrap station | Gap between belt and plate must suit the diameter | Wrap station position |
| Labelling head | Label must meet the vial at the correct point | Head position and distance |
| Label height on vial | Taller or shorter vials may need different positioning | Head height |
| Product sensor | Detection position may shift with diameter | Sensor position or timing |
| Label speed | Must match vial surface speed in the wrap | Speed or synchronisation settings |
| Coder position | Code must fall in the correct area of the new label | Coder position or settings |
| Hold-down or top guide | Vial height may differ | Height setting |
Label Length and Wrap
The label length needed depends on the vial’s circumference:
Circumference = π × diameter
Illustrative examples (not specific vial or label specifications):
- a vial with a 16 mm diameter has a circumference of about 50 mm
- a vial with a 22 mm diameter has a circumference of about 69 mm
- a vial with a 30 mm diameter has a circumference of about 94 mm
Labels may be designed to wrap only part of the way around, leaving a viewing window to inspect the contents, or to wrap fully with a small overlap. Either way, each vial diameter needs its own label design and roll. The label design should be agreed during packaging development, considering:
- whether a viewing window is required
- the overlap length, if the label wraps fully
- the area for batch and expiry coding
- the label material’s flexibility for small diameters
Step-by-Step Changeover Procedure
Before the Line Stops (Preparation)
- Confirm the next format: vial size, label code, coding data.
- Prepare change parts: separating screw or star wheel, and any other format parts, on a changeover trolley.
- Prepare the label roll: correct label, checked against the batch record.
- Prepare coding data: batch number, manufacturing and expiry dates.
- Check the setup sheet or recipe for the new format.
During the Changeover
- Clear the line: remove all vials and labels from the previous batch. Reconcile and remove remaining labels.
- Change format parts: fit the separating screw or star wheel for the new vial.
- Adjust conveyor guides to the new diameter using scales or set points.
- Set the wrap station gap for the new diameter.
- Set labelling head height and distance to recorded values.
- Load the new label roll and thread it through the web path.
- Calibrate the label sensor for the new label and backing.
- Set the product sensor position or timing for the new diameter.
- Adjust label speed or confirm synchronisation with the conveyor.
- Set coder position and load batch data.
- Adjust any hold-down or top guide for the vial height.
Verification
- Run test vials at low speed and check label position, wrap, overlap, skew and coding.
- Increase to production speed and check again.
- Second-person check of line clearance, label identity and coding.
- Record settings and release the labeller for production.
Machine Features That Speed Up Diameter Changes
Scales and Set Points
Graduated scales or digital counters on guides, wrap station and labelling head allow operators to set recorded values instead of adjusting by eye.
Centralised Guide Adjustment
Mechanisms that move both conveyor guides together with one handwheel save time and keep vials centred.
Tool-Less Change Parts
Separating screws and star wheels that fit with quick-release knobs and locating pins can be changed in minutes.
Recipe Storage
On labellers with programmable controls, label length, dispense position, speed and sensor settings can be stored for each format and recalled from the operator panel.
Encoder Synchronisation
An encoder on the conveyor allows label speed to follow vial speed automatically, so labels wrap smoothly without manual speed matching.
Marked Parts
Colour-coded or engraved change parts prevent the wrong part from being fitted.
Building a Setup Sheet for Each Vial Size
A setup sheet, or a recipe on machines that store them, is the single most useful tool for fast, repeatable diameter changes. For each vial size, record:
| Setting | Example Entry |
|---|---|
| Vial size and label code | e.g. 10 ml vial, label code XYZ |
| Separating part | Part number or colour code |
| Conveyor guide setting | Scale reading |
| Wrap station gap | Scale reading |
| Labelling head height | Scale reading |
| Labelling head distance | Scale reading |
| Product sensor position or delay | Value |
| Label speed or synchronisation mode | Value |
| Coder position | Value |
| Top guide height | Scale reading |
| Photo reference | Image of a correctly labelled vial |
Keep the setup sheet at the machine, review it after every change to the machine or label design, and control it as a GMP document.
Measuring and Improving Changeover Time
Time each labeller changeover from the last good labelled vial of one batch to the first good labelled vial of the next. Break the time into preparation, part changes, adjustments and verification. The longest activity is usually adjustment, which is exactly where scales, set points and recipes help most. Review results with operators regularly; they often suggest simple improvements, such as a dedicated trolley position for each change part or a quicker way to thread the label web. Small gains on every changeover add up to significant extra production time over a year, especially on lines that change vial size several times a week.
Training Operators for Diameter Changes
Make sure every operator who performs changeovers understands how diameter affects wrap, spacing and timing, can read and apply the setup sheet, knows how to calibrate sensors and can recognise labelling defects quickly. Cross-train several operators so changeovers do not depend on one person.
Coordinating the Labeller With the Rest of the Line
The labeller is the last major machine on most vial lines. Its changeover should be coordinated with the filler, cap sealer and other machines:
- Prepare the labeller changeover while upstream machines are still being changed over.
- Make sure upstream machines, such as a vial cap sealing machine with 1, 4, 6 or 8 heads, an automatic external vial washing machine and a visual ampoule and vial inspection machine, are set for the same format.
- Clean and dry vials are essential for good label adhesion; residue on vials causes lifting labels.
On an integrated automatic liquid vial filling line, the whole line’s changeover can be planned together. Our article on vial filling machine changeover best practices covers line-wide changeover methods, and our article on vial filling machine flexibility explains how to plan a format range.
Troubleshooting After a Diameter Change
| Problem | Likely Causes | What to Check |
|---|---|---|
| Label skewed | Guides too wide or narrow, vial not upright | Guide width, top guide height |
| Wrinkles | Wrap gap wrong, label speed mismatch | Wrap station gap, synchronisation |
| Label overlap too long or short | Wrong label roll, dispense timing | Label code, product sensor timing |
| Label not wrapping fully | Wrap gap too wide, label too short | Wrap station, label design |
| Flagging (end lifting) | Label too stiff for diameter, wrap pressure low | Label material, wrap pressure |
| Label at wrong height | Head height not reset | Head height setting |
| Missing labels | Label sensor not calibrated for new roll | Sensor calibration |
| Vials jamming | Wrong separating part, guides misaligned | Change parts, guide settings |
| Code in wrong area | Coder position not adjusted | Coder position and label layout |
Common Mistakes to Avoid
- Adjusting guides and heads by eye instead of to recorded values.
- Forgetting to recalibrate the label sensor for the new label.
- Leaving labels from the previous batch on the machine.
- Not checking the wrap station gap for the new diameter.
- Running at full speed before confirming placement at low speed.
- Using label designs that are too stiff for small diameters.
Our article on the top 10 labeling mistakes manufacturers should avoid covers more general pitfalls.
Maintenance Checks During Changeover
Changeovers are a good time for quick condition checks:
- inspect wrap belts and pads for wear
- clean adhesive from the peel plate, rollers and guides
- check label and product sensors for dirt
- check the separating screw or star wheel for wear
Our article on high-speed labeling machine maintenance and components that require regular inspection provides a full maintenance checklist.
Label Roll Preparation
Good changeovers depend on correctly prepared label rolls:
- correct winding direction and core size for the machine
- consistent gaps between labels
- rolls checked against the batch record before issue
- rolls rewound or counted accurately where needed; an automatic label roll winding and counting machine helps with label reconciliation
Vial Labellers Compared With Ampoule Labellers
Ampoules are labelled on similar principles, but their small diameter and shape often call for horizontal or rotary labellers, such as an automatic horizontal ampoule sticker labeling machine or a rotary ampoule sticker labeling machine. Explore our ranges of labeling machines for vials, labeling machines for ampoules and all labeling machines, or browse our labeling machines category.
Frequently Asked Questions
Can one vial labeller handle several vial diameters? Yes, within its specified range and with the correct change parts and settings for each diameter.
How long should a labeller diameter changeover take? It depends on machine design and preparation. Scales, tool-less parts and recipes make changeovers much faster and more repeatable.
Do I need a different label for each vial diameter? Usually yes, because label length must suit the circumference and the design must fit the vial height.
Why do labels wrinkle after a size change? Most often because the wrap station gap or label speed has not been adjusted for the new diameter.
What should be checked before releasing the labeller? Label identity, position, wrap, coding, line clearance and a second-person check.
Make Vial Labelling Changeovers Easy With Harsiddh
Harsiddh Unimach manufactures vial, ampoule, bottle and other sticker labeling machines with features that simplify format changes, including adjustable guides, quick-change parts and programmable settings on suitable models. Our team can recommend the right labeller and change parts for your vial range.
Contact us through our contact page or send your requirements through our inquiry form.