Two labels, one on the lid and one on the underside, applied while the pack is moving and never turned over. Getting the label onto the bottom of a pack without stopping it is the whole trick, and it is why the top and bottom labeling machine exists as a format of its own.
Anyone can label the top of a tray. Labeling the bottom means the pack has to be unsupported for the moment the label goes on, which means the conveyor has to open and close underneath it, which means the conveyor is the machine.
Marapack Services specifies, supplies, installs, commissions and services top and bottom labeling machines from a base in the Pacific Northwest. We are the Pacific Northwest distributor for Altech labeling systems, importing direct from the factory in Bareggio, Italy. Fresh produce and fresh food packers ask for this format often, because a clamshell with a top label and a bottom label is the standard retail presentation for berries, cherries, tomatoes, herbs and fresh cut product.
Bring the pack, full, the way your line runs it: book an equipment audit and we size the gap, the heads and the sensing on site.
What is a top and bottom labeling machine?
A top and bottom labeling machine applies one label to the lid and one to the base of a pack in a single pass, without turning the pack over. It runs the pack across a two section belt conveyor with a controlled gap, and a lower applicator labels the base through that gap while an upper applicator labels the top.
The trade also calls it a top and bottom labeler, a top and bottom label applicator, or a clamshell or tray labeling machine, depending on the pack. It is a different machine from a front and back labeler, which labels two opposite side faces of a standing container.
How does a top and bottom labeling machine label the underside?
A top and bottom labeling machine labels the underside through the gap in a two section belt conveyor. Two independently driven belt sections leave a controlled gap; the pack bridges it for a fraction of a second, and the bottom applicator applies upward through it. Gap width, belt speed match and head timing decide whether it works.
Everything else about the machine follows from that gap.
- Gap width has to be small enough that the pack does not tip into it and large enough that the applicator can reach through. That is a function of pack length, not of preference.
- Belt speed match between the two sections has to be exact, because a pack that is half on each belt at different speeds skews.
- Belt width is chosen for the pack.
- Timing between the two heads has to hold, so that the top and bottom labels land in the same relative position.
The two section conveyor we build these on is the ALbelt two section; its configuration is on our ALbelt two section system page. Where only the top of the pack needs a label, the single belt version does the job, and it is covered on the Altech ALbelt conveyor page.
Which labeling heads go on a top and bottom machine?
A top and bottom machine carries two labeling heads, one above and one below, matched to label length and line speed: ALstep S or M for compact and lower speed lines, ALritma S or L for volume, and the ALritma X S where an integrated rewinder saves operator stops. The lower head needs the most protection.
- ALstep S, labels to 100 mm (about 3.9 in) at up to 30 m/min (about 98 ft/min)
- ALstep M, labels to 200 mm (about 7.9 in) at up to 20 m/min (about 66 ft/min)
- ALritma S, labels to 100 mm at up to 50 m/min (about 164 ft/min), IP54 rated, color touchscreen, 40 stored label formats, and in a 200 mm label version
- ALritma L, labels to 300 mm (about 11.8 in) at up to 40 m/min (about 131 ft/min)
- ALritma X S, up to 40 m/min, adding an integrated 250 mm (about 9.8 in) backing web rewinder
The volume heads are compared on our ALritma S and L page.
Environmental protection matters more on a bottom head than anywhere else on the line, because the head under the conveyor catches everything that falls through the gap. Be precise about what the rating buys you: the ALritma S is IP54, which is splash-rated and not a washdown rating. Where the line is hosed down, the answer is the harsh environment kit, a protected mounting position, or a different layout, and we will tell you which. If somebody tells you a splash-rated machine will survive your sanitation cycle, ask them which rating they are quoting.
At the smaller end, where the pack rate does not justify an automatic line, we service Tach-It top and bottom applicators and stock Tach-It parts, and for hand fed work there are semi automatic label dispensers.
Which application method suits the bottom label?
The bottom label is applied upward onto a surface that is rarely flat or clean, so the method matters more here than anywhere. Tamp suits a flat, consistent tray base; tamp blow suits light packs that shift; air blow suits filled, deformable clamshells; soft touch suits mixed pack sizes; vacuum belt suits long labels.
Tamp, where the pack presents a flat, consistent underside. A thermoformed tray with a flat base is the good case.
Tamp blow, where the pack position varies slightly or the base is delicate. This is the common choice on light packs, because the applicator does not have to push against something that will move.
Air blow with a fixed tamp, non contact, for unstable or deformable packs. A filled berry clamshell is not a rigid object, and pushing a pad into its base has a cost.
Multi format soft touch, where the same line runs several pack sizes and the application has to be gentle across all of them.
Vacuum belt, where the label is long relative to the pack and needs to be laid down rather than thrown.
Every method, and the rules for choosing one, is on our full range of label applicators page.
How do you stop clear labels being missed on clear packs?
Specify a label tracing sensor built for transparent product. A standard gap sensor reads the difference between label and liner, and a clear label on a clear liner gives it nothing to see. On top and bottom lines, where clear clamshells and clear labels are normal, this sensor belongs on the first quote, not the retrofit.
Many top and bottom applications involve a clear pack: a clear clamshell, a clear lidding film, a clear label, or all three. This is not an edge case on a produce line. It is the normal case, and a common cause of a new machine that "runs fine in the demo and misses in the shed".
Retrofitting the right sensor after a season of intermittent misses costs more than the sensor and a great deal more than the downtime.
Beyond label detection, Altech lists a label presence check, laser scanner, mark reader and camera vision as orderable options, with a product ejector where a pack missing a label must not leave the machine. On a top and bottom line these are worth more than usual, because a pack missing its bottom label looks perfect on the conveyor and is discovered by a customer.
What is a top and bottom labeler used for?
A top and bottom labeler is used for fresh produce clamshells and punnets, trays and thermoformed packs, tubs and lidded containers, and flat products and cartons. The top label usually carries brand and retail barcode; the bottom label carries date, lot and traceability data, which is why the format is common on produce lines.
Fresh produce clamshells and punnets
Berries, cherries, cherry tomatoes, herbs, grapes, fresh cut fruit. Top label carries brand, commodity, count or weight and the retail barcode. Bottom label carries the pack date, the lot code, grower or packer information, and increasingly the traceability data a buyer asks for. Produce clamshell lines are the core of our work on this format.
Trays and thermoformed packs
Fresh meat, prepared food, ready meals, bakery. Frequently a sealed film lid, which changes the top label surface and sometimes rules out a tamp.
Tubs and lidded containers
Dairy, dips, deli, cannabis edibles. Often a lid label plus a base label with variable data.
Flat products and cartons
Cards, blister packs, folding cartons, printed matter. The bottom label is often a compliance or logistics label rather than a retail one.
Where the format meets traceability
If your buyer is asking for case level traceability data, the pack label is only half of it. The case those packs go into needs a PTI harmonized case label carrying a GS1-128 barcode with the GTIN and the batch or lot, and the pallet needs its own SSCC. That is print and apply work rather than labeling head work, because the data is variable. A produce line frequently ends up with both: a top and bottom machine on the retail pack, and a print and apply head on the case downstream.
How much does a top and bottom labeling machine cost?
A top and bottom labeling machine costs what the two section conveyor, two heads, application methods, sensing and any wet-area protection add up to. The conveyor and the lower head's protection are the parts buyers underestimate. We quote after measuring the full pack, its base surface and the line rate, not from a list price.
The cheaper alternatives are real and we will name them when they fit: a single top head on your existing conveyor if the base label can be dropped, or a smaller applicator at the low end. For side-face labels on standing containers, the equivalent machine is covered on our opposite-face labeling page, and every other format is on our labeler machines hub.
Frequently asked questions
Do we have to flip the pack to label the bottom? No, and you should not want to. A two section conveyor applies the bottom label through the gap between the belts while the pack is moving. Flipping adds a mechanism, a failure mode and a place for product to spill.
Will it handle more than one pack size? With changeover, yes, and the practical question is how much of that changeover is mechanical. Belt gap, guides and head height are the parts that take time. Label formats are stored in the head, up to 40 of them on the ALritma S.
Our bottom labels are lifting. Usually surface, not machine. A clamshell base is often textured, sometimes dusty, and on a produce line frequently damp from condensation. Adhesive selection and wipe down length matter more than applicator force, and forcing the applicator harder into a filled clamshell is how packs get crushed.
Can we put a date and lot code on the bottom label? Yes, three ways. Preprint everything except the code and add it with a coder, print the whole label at the moment of application with a print and apply head, or mark the pack directly. Which is cheapest depends on how much of the label is variable.
Our clear labels keep getting missed by the sensor. That is the transparent product problem described above. The standard gap sensor cannot see a clear label on a clear liner. The label tracing sensor for transparent product exists for this and it is a normal specification item on this format, not an exotic one.
Can this run in a wet environment? The ALritma S is IP54 rated, which is splash-rated and not a washdown rating, and there is a harsh environment kit available. Whether that is enough depends on how your line is washed down and whether the lower head can be protected. We will tell you honestly when the answer is a different layout rather than a different rating.
Can you service a top and bottom machine you did not sell us? Yes. Altech, Label-Aire 3100 applicators and 5100 systems, PackLeader, CTM and Tach-It are all in our service scope.
Bring us the pack, full
An empty clamshell and a filled clamshell are different objects. The one that matters is the one your line actually runs, at the temperature it runs at, wet if it comes out wet. We measure pack dimensions, base surface, stability, rate and label size and tell you the gap, the belt width, the heads and the sensing. Call 253-709-5566 or request a top and bottom line assessment.