How a TIJ printer puts a code on a pack

In a TIJ printer, a tiny heater in each nozzle heats the ink until a bubble forms and pushes a drop out. The nozzles are part of the ink cartridge, so every new cartridge also brings new nozzles. The cartridge sits 1–2 mm from the surface on the GT-100E and 1–5 mm on the ST-210S printers, and the drops build the text, barcode or logo as the pack passes.

The code is formed as the print head and the surface move past each other. On a conveyor line, the print head stays fixed while the pack moves past at a set distance. With the GT-100E in handheld use, you hold the printer flat against the box, pipe or part and move it across the surface. The print builds up column by column; the encoder built into the GT-100E counts the travel, so the stroke does not have to be at an exact speed, but the printer must stay flat on the surface.

The distance between the cartridge and the surface matters because the drops of ink travel through the air. If the gap is too large, the drops spread out and the edges of the code become soft or blurred. On a line, guide plates keep every pack at a distance of 1–5 mm from the nozzle. If a box drifts away from the guide, or if the surface is uneven, the code can be faint or broken. In handheld use, the printer must stay flat on the surface all along the print, so the nozzle keeps its 1–2 mm.

Without an encoder, the printer uses a fixed line speed set on its screen. If the conveyor slows down or stops, the code stretches or shrinks, and the bars of a barcode can become unreadable. An encoder measures the real travel of the goods, so the code keeps its length even if the speed changes. For goods pushed by hand or lines that stop and start, the encoder is needed to keep every code the right size.

The photo eye is mounted before the print head and tells the printer when a pack is coming. A delay set on the printer decides how far from the front edge of the pack the code starts. If two packs touch as they pass the photo eye, the printer sees them as one long pack and only one code is printed. Every pack needs a clear gap before and after it.

On the ST-210S printers, inputs let you reverse the print or turn it upside down, so the code reads correctly if the head is mounted on the other side of the line or if the line runs in the opposite direction. When printing on film or metal, the fresh code needs a moment to dry, so nothing should touch it right after the head.

Choosing a handheld inkjet printer or a fixed model

The GT-100E is a handheld inkjet printer with a battery, suitable for marking boxes, pipes or parts by hand. It can also be fixed on a line for automatic printing. The ST-210S-H1 and ST-210S-H2 are fixed on the conveyor, with one or two print heads and a separate controller.

The GT-100E has a 5-inch touch screen and works from a battery, while fixed models offer a 7-inch screen, a network port and more inputs and outputs. The ST-210S-H2 has two heads, printing up to 25.4 mm in one block or marking two sides at once. As a carton printer on a packing line, a fixed model prints every box as it passes, without anyone holding the printer.

A handheld printer such as the GT-100E is used where goods do not travel on a conveyor. For example, large pipes, metal profiles or panels stored on racks are marked while they stand still. Boxes that are already stacked on a pallet or stored on the floor can be coded without moving them to a line. The printer is brought to each item, so there is no need for a conveyor or a fixed coding point.

Handheld use also fits small batches or situations where many different products are coded in a day. You type the text on the screen, print the code on the product, and move on to the next one. There is no need to set up a line or adjust guide plates. One printer can serve several workstations, such as goods receipt and dispatch, by moving it between them as needed.

When using the GT-100E by hand, hold it flat against the surface and pull it across in one steady stroke, so the nozzle stays 1–2 mm from the surface. On a pipe, you move the printer along the length of the pipe, where the distance stays the same. If the printer tilts or lifts, the code can become slanted or broken.

A fixed printer such as the ST-210S-H1 or ST-210S-H2 is used when every pack passes the same point on a conveyor. The code lands in the same place on every pack and nobody needs to hold the printer. The ST-210S printers can take data from your own system over the network port, so the text does not have to be typed on the screen.

The GT-100E can also be mounted on a line with an external photo eye and encoder, which suits a small line or a line that is still being built. Compared with the ST-210S printers, it does not have 600 DPI, the network port, the 7-inch screen or a second head. The removable battery of the GT-100E allows a charged spare battery to replace an empty one during a shift.

The main questions are whether the goods move on a conveyor or stand still, how many packs are coded per day, whether the code changes from pack to pack and where its data comes from, and whether the code goes in one place or two.

GT-100E, ST-210S-H1 and ST-210S-H2: key differences

The table below compares the three thermal inkjet printers: GT-100E, ST-210S-H1 and ST-210S-H2. It lists type and number of heads, print height, resolution, speed, printing distance, screen, data ports, power, cartridge, size and warranty.

When you read the comparison table, start with the type of printer and the print height. If you need a code taller than 12.7 mm or codes in two places on one pack, only the ST-210S-H2 fits. Next, check the resolution: small barcodes and 2D codes such as DataMatrix need fine dots, which the ST-210S printers provide with up to 600 × 600 DPI. For data connections, data from your own system over the network port requires an ST-210S printer. The GT-100E takes data over USB and RS232. It is also the only one that runs from a battery.

What a date coder prints on your packaging

All three print text, the time and the date, a shift mark, serial numbers and a logo, so each one also works as an expiry date printer. Barcodes include CODE39, CODE128, EAN13, EAN14 and UPCA; 2D codes include QR code, GS1 DataMatrix, MicroQR and PDF417.

Fields can be filled from a database, so the inkjet date coder prints batch data or product information that changes from pack to pack.

The date and time printed on each pack come from the printer’s clock. This means that a date field changes automatically at midnight, so there is no need to enter the date by hand each day. If the clock is set incorrectly, the wrong date will be printed on every pack. After setting up the printer, check both the clock and the date format to make sure they match what is needed on your packaging.

A shift mark changes with the time of day, so the code shows which shift packed the goods. Counters can be set up to add one with every print, creating a unique serial number for each pack or counting the number of packs in a batch. The ST-210S printers can keep more than 20 independent counters, for example one per product or one per shift.

EAN13 and UPCA are used on retail packs for consumer scanning, while EAN14 marks outer cartons. CODE128 is common in logistics, and NVE18, the German name of the SSCC, numbers shipping units such as pallets. A 2D code like a QR code can carry a web address or a batch record, and GS1 DataMatrix is used where one small code must carry the product number, batch and expiry date together.

Within the 12.7 mm print height of a head you can set up several lines, for example a best-before date, a batch number and the time in two or three lines.

How an industrial inkjet printer works on a conveyor

On a line, the print head sits on a bracket beside the conveyor, 1–5 mm from the pack. Guide plates keep the goods aligned and prevent contact with the nozzle. The photo eye detects each pack, and the encoder tracks the line speed for accurate code length.

The print head can mark either the side or the top of each pack. For side printing, the pack runs along a guide rail, which keeps it at a constant distance within 1–5 mm from the print head. For printing from above, all packs must have the same height, because a lower pack passes too far from the head and its code comes out faint.

Guide plates before the print head bring each pack into line and stand 0.5–2.5 mm from it, so a bulging or badly closed box touches the plate and not the nozzle. The heads of the ST-210S printers can also be fitted with anti-collision parts, for lines where packs vary in shape.

At 600 DPI, the ST-210S printers print up to 60 m/min, so a packing line running slower than this can use full resolution for sharp codes. If your line runs faster, you must use a lower resolution: 300 DPI allows 120 m/min.

The alarm light output connects to a lamp or sends a signal to the line control, so a fault is noticed at once and not after a whole pallet of packs without a code. External text selection lets the line control pick which stored text the printer uses, which is useful when one line packs several products. The serial number output passes the printed number on to the line.

With the ST-210S-H2, the two heads can be stacked to print one block up to 25.4 mm, for example a large date with a batch line, or set apart so one head marks the top and the other the side of a pack in one pass.

Thermal inkjet printer or another coder

Thermal inkjet is one of several ways to code a pack. Its sealed cartridges carry their own nozzles, so an inkjet coding machine of this type needs little upkeep; its limit is the short distance of 1–5 mm between the cartridge and the pack. Continuous inkjet printers fire a constant stream of drops and recirculate the ink they do not print. They print from a greater distance and on curved surfaces, but use make-up fluid besides the ink and need more maintenance.

A laser coder marks the pack by burning or removing a thin layer, without ink. A label is the better choice when the text is long, when the surface cannot take ink, or when the code must be ready before packing; a labeling machine applies pre-printed labels. The thermal inkjet printers here fit where you need direct marking on packaging, with codes up to 25.4 mm high and options for handheld or fixed use.

In daily use, a thermal inkjet printer needs none of the start-up and shut-down sequence of a continuous inkjet printer: there is no ink system to flush, and changing a cartridge takes about a minute. Each new cartridge brings new nozzles, so print quality stays consistent. In contrast, a continuous inkjet printer circulates ink through pumps and filters that require regular maintenance, including cleaning and replacing filters and managing make-up fluid.

The main limits of this technology are the print height and the distance to the pack. The print heads here cover 12.7 mm each, so large characters on big outer cartons need two heads or a different technology. The short distance to the pack means that deep recesses or strongly curved surfaces are hard to mark. Coding inside a deep tray or around a small round bottle is therefore difficult.

Continuous inkjet is the usual choice for very fast lines and for round products such as cans and bottles, because it prints from further away and can mark a curved surface.

A laser code cannot be rubbed off and does not need ink, but the laser must be matched to the material being marked. Fumes created by the laser must be extracted from the work area, and the initial cost of a laser coder is usually higher than for a thermal inkjet printer. Laser marking is used where permanent codes are needed and the material allows it.

Thermal transfer overprinters use a ribbon to print onto flexible film and are usually built into bagging or flow wrapping machines. For film packs made on such machines, they are the common choice. Where the surface is flat, as on cartons and trays, the code is no taller than 25.4 mm and the line speed allows the resolution the code needs, a thermal inkjet printer is a simple coder to keep running.

Choosing ink for your packaging surface

The ink for a thermal inkjet printer must match the surface. Porous surfaces such as carton, paper and untreated wood absorb water-based ink. Sealed surfaces such as plastic film, metal, glass and coated boxes need a solvent-based ink that dries on the surface.

On a dark surface a light ink such as white stays readable, and invisible ink shows only under UV light. Where the ink can touch food, a food-grade ink is used, so the cartridge is chosen for the product as well as for the surface.

Always test the ink on your own packaging before starting the line. Print a code, wait for it to dry and rub it with your thumb. If the code smears or fades, try another ink type or surface treatment.

Plastic films can vary: some accept ink well, while others have a smooth surface where ink does not hold. Your film supplier can tell you if the surface has been treated for printing.

Wet, cold or oily surfaces take ink badly. Condensation on a pack coming out of a cold room keeps the drops from sticking, so print before the cold room or dry the surface first. Solvent inks dry quickly on film, metal and glass, but also dry quickly in the nozzles, so take the cartridge out and close it whenever the printer stops for longer.

Food-grade ink is needed for codes printed directly on food, such as eggs, or where the ink may touch the product. A code on a closed outer carton does not touch the food, so a standard ink can be used.

Black ink gives the strongest contrast on white or brown carton. Cartridges have a use-by date, so only buy what you will use within that time and store spare cartridges closed, in a cool and dry place.

Inks and cartridges for your inkjet coder

These printers use 42 ml cartridges with a contactless RFID chip. The chip tells the printer what ink is loaded and records usage. Inks are available in food-grade, water-based, oily, weak solvent and solvent types.

You can choose from black, white, red, yellow, blue, green, invisible and UV inks. The maker lists carton, plastic, metal, sheet, pipe, stone, cable, glass, electronic components, auto parts and industrial or food packaging as surfaces these printers mark.

Because the chip records the ink used, the operator can change the cartridge before the code fades on the line.

When changing a cartridge, stop printing, take the old cartridge out at an angle, and insert the new one at the same angle. Wipe the nozzle plate with a lint-free cloth to remove any dust or dried ink, and print a test code to check print quality.

The ST-210S-H2 uses two cartridges, one for each print head. Keep at least one spare cartridge per head at the line, so a change can be made without delay. When ordering a printer, say what you print on and whether the ink can touch food, so the right cartridge is supplied. When a line packs products in different materials, such as carton and film, keep both inks at the line and mark which cartridge goes with which product.

What a code on a pack has to do

A code on a pack has two jobs. A date and a batch code let you trace every pack back to its production run, which is what you need when one batch has to be found again. A serial number or a QR code goes further and identifies every single pack.

When a scanner reads the code further down the line, the code has to be sharp and large enough. Choose the resolution and the code height with the scanner in mind, and test them on your own packaging before the line runs.

Most prepacked food in the EU must carry a best-before or use-by date and a lot mark for traceability. Retailers often require a barcode on outer cartons to help with warehouse and store logistics. A missing or unreadable code means a rejected pack or relabeling by hand.

Place the code on a flat, smooth panel, away from folds, flaps, seams and glue lines, and always in the same place on every pack. This helps both people and scanners find the code quickly. A barcode needs strong contrast: a dark code on a light background, a blank margin around it, and bars that are not smeared. Print at a resolution high enough for the width of the bars you need.

Check the code at the point where it will be read: after stretch wrapping, after cold storage, or after transport. A code that looked sharp at the printer can be rubbed or covered later.

A batch code only helps if it is recorded, so link each batch code to the date, the line, the shift and the batches of raw material. This way, a complaint or recall can be limited to the affected packs. Write the date in the format your market uses and keep it the same for all products. A date that can be read two ways, such as day and month swapped, is a common cause of complaints.

Running cost of a thermal inkjet printer

Ink use depends on the height of the code, the amount of text and the print resolution. The cost of one print is the price of a cartridge divided by the number of codes it prints. The GT-100E shows the printing cost on its screen. The ink cartridge records how much ink has been used, so you can track usage directly on the printer.

To find your real running cost, print your actual code on your own packaging for a set period, read from the printer how much ink has been used and count the prints. That tells you how many of your codes one cartridge gives. Ink use falls with lower resolution, fewer characters, smaller text and no logo, so print at the lowest resolution that still gives a readable code and leave out fields that nobody reads.

With this technology there is no make-up fluid, no filter and no pump to service. Ink is wasted when a cartridge stays open in a printer that stands, because the nozzles dry out and then print poorly. Count the cost of a bad code as well: packs that must be coded again or labeled by hand, a batch that cannot be traced, or a complaint from a customer.

What affects the price of a date coding machine

The price of a date coding machine depends on whether it is handheld or fixed, the number of print heads, the print resolution and the maximum code height. A network port for data from your own system also adds to the price.

The current price of each thermal inkjet printer is shown on its product card above. All models come with a 12-month warranty.

A complete coding point on a line includes more than just the printer. You need a bracket, guide plates, a photo eye and, where the speed changes, an encoder. Ask us with the Get offer button which of these parts come with the printer and which must be ordered separately. Ask for the price of spare cartridges with the quote as well, because they decide the running cost over the years.

The ST-210S-H2 can code two places on a pack with one controller and one screen, so one machine is set up and serviced instead of two. To get a quote for a printer with a stock of cartridges, use the Get offer button on the product card. The Add to inquiry button lets you collect several products into one request.

What to check before you order

Before you order a thermal inkjet printer, check the surface and the ink it needs, the code height, the line speed and the resolution. Decide where on the pack the code goes, such as the top, side or both. Make sure there is a firm place for the bracket and 1–5 mm to the goods. Check where the data comes from, either the screen or your own system.

You need a separate socket, grounding and ideally a UPS. The comparison table above shows which printer fits your code height, speed, data connections and number of print heads.

Write down exactly what the code must say, including which date and in which format, the batch, the time or the shift, counters, the barcode type and the number of lines. Check that all this fits into 12.7 mm per head or 25.4 mm with two heads.

Measure your line: its lowest and highest speed, whether it stops and starts (if so, you need an encoder), the gap between packs, and whether the packs run along a rail. Decide which side of the line the code will be printed from. Printing from above needs packs of one height, while printing on the side needs a rail to keep the distance constant. Note the narrowest and the widest pack as well, because the rail has to hold both at the same distance from the head.

Check the room where the printer will stand: these printers work at 0–45 °C and 30–70 % relative humidity. Dust, splashes and condensation from cold rooms need extra care. Decide who will run the printer, who will change cartridges and who will edit the texts. The screen works in more than 40 languages, so you can set it for your team.

Installation and care of a batch coding machine

Install the batch coding machine on its own grounded socket, not shared with other equipment. Use a UPS if possible. Mount the bracket so it does not vibrate, and fit guide plates with 0.5–2.5 mm clearance to prevent goods from hitting the nozzle.

Insert and remove cartridges at an angle, never pull one out while the printer prints, and never plug or unplug cables while it is on.

At the start of each shift, wipe the nozzle plate with a lint-free cloth, print a test code and check the first packs for print quality. At the end of the shift or before any longer stop, take the cartridge out and close it. This keeps the nozzles from drying and helps the next shift start with a clean print.

Use only a lint-free cloth to wipe the nozzle plate. Paper tissue leaves fibers and fingers leave grease, which can block the nozzles. Do not touch the nozzles or the electrical contacts of the cartridge; hold it by its body.

A faint or broken code usually means dried or dusty nozzles or too large a distance to the pack. If the code is too long or too short, check the speed setting or the encoder. A code in the wrong place points to the delay after the photo eye.

Keep the print head and controller away from dust, splashes and vibration, and lay the cable to the head where goods cannot catch it. Keep a short log of cartridge changes and the number of codes each cartridge printed. This gives you the real cost per code and shows if a cartridge runs out sooner than expected.

Questions about thermal inkjet printers

How tall can the code be with these thermal inkjet printers?

The GT-100E and ST-210S-H1 print up to 12.7 mm high. The ST-210S-H2 with two heads can print a single code up to 25.4 mm or mark two places at once.

How fast can the production line run with these printers?

At 90 DPI, all three models print at up to 406 m/min, and at 300 DPI up to 120 m/min. At 600 DPI, which only the ST-210S printers offer, the line can run up to 60 m/min.

Can these printers print QR codes and barcodes?

Yes. All three print barcodes such as CODE39, CODE128, EAN13, EAN14 and UPCA, and 2D codes such as QR code, GS1 DataMatrix, MicroQR and PDF417. The data can come from a counter, the clock or a database.

What temperature and humidity can these printers work in?

The working environment is 0–45 °C and 30–70 % relative humidity. This applies to all three models.