A case coder puts the date, the lot and the plant code on the outside of the case, so the pallet can be traced even when the product inside cannot be seen. It is a small machine with a short list of things that make it work.
A case coder is a printer mounted on a conveyor that marks each corrugated case, carton or tray as it passes. For most food, produce and packaged goods plants it is the last place a lot and date can be added before the case becomes anonymous on a pallet. This page covers thermal inkjet case coders for the commercial buyer: what they print, what the case surface and the ink have to agree on, and when a printed label is the better answer.
Marapack Services is the Pacific Northwest distributor for Altech labeling systems. On the coding side we supply thermal inkjet printers under our own label, and the ink under our own part numbers, to plants anywhere in the United States. We also take on the case line around the coder: labels, pallet labels and field service for labeling equipment.
Not sure what your cases need? Book an equipment audit and we look at the case, the conveyor and the room before anything is specified.
What is a case coder?
A case coder is an in-line printer that codes the side of a case, carton or tray as it travels past on a conveyor. It prints a date, lot, batch, shift or plant code directly onto the surface, triggered by a product sensor, without a label. Thermal inkjet is the usual technology for it in a packhouse.
A case coder is also called a case coding printer, a carton coder or a box coder. The last phrase is shared with unrelated software, so we use "case coder" on this page, and we mean the printer.
The core of the machine is the same in every case: a printer, a bracket that holds it a steady, short distance from the case, a sensor that tells it a case has arrived, and a source for the data it prints. How well those four work together decides whether the code is readable, far more than the badge on the printer.
Should you code the case or put a label on it?
Code the case directly when the data is a date, lot, batch or plant code and the case face is clean, dry and printable. Put a label on it when a customer or retailer requires a scannable barcode to a stated grade, when the case will not take a good mark, or when the data will not fit.
The case is where the two answers meet, and plants often end up using both. A thermal inkjet coder prints the date and lot on the case. A label carries the barcode that a retailer's scanner reads.
Code the case when:
- The variable information is a date, lot, batch, shift or plant code
- The case is corrugated board with a dry, reasonably clean printable face
- Anything fixed (brand, product description, barcode) is already preprinted on the case
- You want the lowest cost per case marked
Label the case when:
- The data includes a GS1-128 or other barcode that a customer's fixed scanner has to read to a grade
- The case face is dusty, wet, waxed, deeply textured or chilled and will not hold a mark
- The information is long enough to need the room of a label
- A customer specification calls for a label
Produce is the usual example. A produce buyer working to the Produce Traceability Initiative expects a scannable case label, and we cover the equipment on our PTI labeling systems page and the packhouse side in produce packing line labeling. A coder does not replace that label; it adds the plain text date and lot.
Which ink does a case need?
The case surface decides the ink. Uncoated corrugated board and kraft paper absorb ink, so water based ink is right and is the lowest cost per code. Coated, waxed or glossy case faces and plastic wrap do not absorb ink, so they need solvent based ink, and a water based ink on them will smear.
Ink choice is where most case coding installations succeed or fail, so settle it by printing on your actual case before you buy.
| Marapack SKU | Chemistry | Color | Typical use |
|---|---|---|---|
| MPT-WB1-BK | Water based | Black | Uncoated corrugate, kraft, absorbent board |
| MPT-SB1-BK | Solvent based | Black | Coated cartons, plastics, films |
| MPT-SB2-BK | Solvent based | Black | Second solvent black formulation for different substrate and dry time needs |
| MPT-SB3-WH | Solvent based | White | Dark and brown surfaces where black will not read |
| MPT-SB4-RD | Solvent based | Red | Color coding, alerts, allergen and grade marking |
| MPT-SB5-YL | Solvent based | Yellow | Color coding on dark surfaces |
| MPT-SB6-BL | Solvent based | Blue | Color coding, shift or line differentiation |
| MPT-SB7-GR | Solvent based | Green | Color coding, shift or line differentiation |
| MPT-SB8-IV | Solvent based | Invisible | Covert marking where a visible code is not wanted |
On a dark or brown case, white solvent ink is the usual answer, because black will not read on it. For a case that is partly coated and partly bare, test both areas.
How do you mount a case coder so the code reads?
Mount the printer on a rigid bracket close to the case face, with a guide rail that holds the case at a constant distance, and a product sensor placed so the code starts in the same place on every case. Thermal inkjet prints at close range, so a case that wanders gives a code that fades on one side.
Five things decide whether a case coder installation works, in the order they cause problems.
1. Presentation. The case must pass the head at a steady distance. A guide rail is cheaper than a technology change and fixes most fading.
2. The trigger. A poorly placed product sensor causes faults that look exactly like printer faults: codes that start late, double print or skip.
3. Print height against line speed. A taller image at speed needs more printhead width, which is why stitched multi head configurations exist, up to 4 inches of print height. Tell us the case, the code you need and the speed the line actually runs at.
4. Which side. A printer codes one face. To code two sides of a case you need a printer on each, so decide which faces carry the code before the mounting is designed.
5. The data. A date typed in at shift start is a different system from a date and lot pulled from your ERP or line controller. That is a process decision before it is an equipment one.
Add the room: a chilled case pulled into a warm packhouse grows condensation in seconds, and no ink dries on water.
Which case coders do we supply?
We supply thermal inkjet printers, with the Titan family on half inch printheads under our own label; SJ Freedom and SJ Infinity are available on request. For a case line the fixed mount configurations apply, and the handheld units cover marking away from the line. We do not sell continuous inkjet, laser marking or large character case printers.
For most case lines, the fixed mount Titan printer is where a conversation starts. It is the configuration we standardize on, with a single half inch printhead. Where the code needs more height, the stitched and multi head configurations take over. The full range is on our coding and marking equipment page.
We would rather be plain about what we do not sell. Where a case line needs a very large character mark or a long throw distance, another technology may be right, and we will say so. The mechanics are set out in our thermal inkjet versus continuous inkjet comparison.
Request a line assessment and we will match a printer, an ink and a mounting to your case and your line.
How do you keep a case coder supplied through the season?
Order ink ahead of the season, not during it. We supply the ink under our own part numbers and set up standing pre-season orders, because private-label ink is made to order rather than pulled off a shelf. A case line that runs out of ink stops as surely as one with a failed printer.
Produce packhouses run their case coders hardest in the weeks when nothing can wait. In June 2026 alone we shipped 144 ink cartridges and one printer to five customers. Specify the chemistry once and hold it, because changing ink mid season changes dry time and adhesion. We would rather build the order with you in spring than take the call in July.
Frequently asked questions
What is the difference between a case coder and a label applicator? A case coder prints the code directly on the case. A label applicator puts a printed label on it. The coder is cheaper per case and suits dates and lots. The label suits barcodes that have to scan to a grade, and surfaces that will not take a direct mark.
Can a case coder print a barcode? It can. Whether the printed symbol holds up depends on the surface, print height, speed and ink, and it should be tested on your case. Where a customer requires a barcode to meet a stated grade, a printed label is usually the safer answer.
Will a case coder print on waxed or coated cartons? Sometimes, with a solvent based ink, but waxed and heavily coated faces are the hardest case surfaces to mark. Print on your actual case and check it an hour later. If the code lifts or smears, a label is usually the answer.
How many printers do we need per line? One per face you want coded. A line that codes one side of each case needs one printer; two sides need two. Two heads on one line is normal.
Can one printer code both cases and retail packs? Not usually from one head. The surfaces, print heights and mounting positions differ. The ink can often be the same if both surfaces share a porosity class.
How much does a case coder cost? It depends on the printhead configuration, whether it is fixed or handheld, the ink the case needs and the mounting the line requires. We quote after we know the case, the code and the line speed, because a price before that is a price for a different machine.
How much maintenance does a thermal inkjet case coder need? Very little. The printhead is part of the cartridge, so there is no printhead to clean and no solvent system to run. What it needs is a clean, steadily presented case and a reliable trigger.
Do you sell continuous inkjet or large character case printers? No. We supply thermal inkjet under our own label, plus thermal transfer and hot foil coders through the Altech price list, and we say so where another technology would suit you better.
Can you service a case coder we already have? We support the printers we supply. For other coding equipment, bring us what is on the line and we will tell you whether to keep, retrofit or replace it. For the labeling machines on the same line, see our labeler repair and service work.
Test the code on your own case
The hour that settles a case coding project is the one where a code is printed on your actual case, at your actual line speed, in your actual room, and somebody looks at it an hour later. We walk the line, look at the case face, and tell you which printer, which ink and which mounting, including when the answer is a label. Call 253-709-5566 or book a coding line audit.