Getting clean, durable expiration dates onto moving products should not slow your line. This guide walks you through how to print expiry date on products across common substrates, what to watch for with adhesion, and where contact reciprocating coders shine compared with non-contact options. You will see practical mounting tips, quick changeover methods, and a short troubleshooting workflow for non-porous plastics so you can get codes live in minutes and keep them from smearing.
The fastest path: how to print expiry date on products
Start by deciding on the code content and placement, then match the coder to the substrate and line constraints.
- Define your text: date format (MM/DD/YYYY or JULIAN), shift or lot, or lot+date combos for traceability.
- Pick character height for readability at inspection distance, often 1.5 mm to 6 mm.
- Choose the marking location that stays flat enough for legibility and is reachable on the conveyor or indexer.
For curved bottles, cans, vials, and tight machine spaces, a contact reciprocating coder is a proven approach. The marking head advances, touches the part for a controlled instant, transfers quick-drying ink, then retracts. With a sealed ink system and a quick-change reservoir, startup is fast and maintenance stays low.
If you run wide cartons, films, or need long multi-line text or 2D codes, evaluate non-contact options at a high level. Continuous inkjet and thermal inkjet deliver flexible message content. These systems can be excellent for cartons and porous packaging. They can struggle during cold starts or viscosity swings, which is why many plants keep a mechanical contact station on the line for mission-critical date and lot codes.
If you are comparing technologies, you will see two core groups when people ask what are the different types of date coders. Contact systems such as reciprocating coders and dot/spot markers; non-contact systems such as continuous inkjet, thermal inkjet, laser, or TTO for films. For food processors wondering what are the two types of date coding food, the practical split on most lines is simple human-readable characters versus machine-readable barcodes or 2D codes. Many lines use both, with a short human-readable date and lot plus an optional 2D symbol on a label or carton.
For a broad overview of equipment options, you can review date coders or code date printers to see configuration ranges that fit different environments.
Printing on plastic: adhesion, ink choice, and setup
Teams often ask how to print expiration date on plastic and, more specifically, what ink will stick to plastic or how to get ink to stick to plastic. Non-porous plastics such as PP, PE, PET, and PVC can be slick. The keys are solvent compatibility, surface energy, and time to set.
- Use quick-drying ink formulated for non-porous plastics. Solvent-based, fast-evaporating blends bite into the surface and resist smearing during handling and case packing.
- Choose a sealed ink system to keep solvents stable and to reduce contamination that causes viscosity drift.
- Prep the surface when needed. Light wiping to remove mold release or oils improves wetting and bond. In some cases, a quick alcohol wipe or corona treatment improves adhesion.
- Control dwell and pressure. A reciprocating head that contacts and retracts cleanly leaves crisp characters with minimal wet spread.
If you need to review formulations and selection, see ink for plastic for quick-drying options that balance open time with fast set on slippery substrates.
Metals and glass: crisp characters with minimal dwell
Metal cans, glass bottles, and vials accept sharp imprints with contact transfer when you use the right ink. The curved contact point is where reciprocating coders excel. The head rotates slightly on contact and lands square on the arc, so characters are consistent even on small diameters. Quick-dry, pigmented inks add contrast on dark glass or lacquered aluminum and set quickly to avoid smears during accumulation or capper contact.
If your operation is can-heavy, a compact can coder integrated near the seamer often simplifies installation and inspection.
Why contact coders win on curved parts and tight spaces
Contact reciprocating coders are simple, rugged, and low-maintenance. They shine when you have:
- Curved or small-diameter containers that need a clean imprint.
- Tight machine envelopes where a compact frame and any-orientation mounting matter.
- Cold-start conditions and seasonal ramp-ups where you cannot babysit viscosity alarms.
- A need for low operating cost, fast consumable swaps, and minimal downtime.
A sealed ink system keeps solvents where they belong, starts quickly, and resists shop air contamination. Quick-change ink reservoirs reduce changeover time. Removable marking heads let you swap character sets and logos without pulling the entire unit.
For an at-a-glance look at installation choices and models, see lot coding to review reciprocating coders commonly used for date and batch marks on plastics, glass, and metal.
Mounting and orientation options
You can mount contact coders in-line or at benchtop stations. Common setups include:
- Horizontal to hit sidewalls of bottles or jars on a conveyor.
- Vertical for top or bottom panel marks on lids, ends, or closures.
- Angled mounts where guards or frames limit access.
The mechanism runs in any orientation. Use rigid brackets and a fine-adjust slide so you can dial in contact pressure and timing against product sensors or mechanical triggers.
Changeovers: removable heads and character set swaps
For frequent SKU changes, set up a simple routine.
- Keep prebuilt marking heads for each date format you use, such as MM/DD/YYYY or JULIAN.
- Store rubber-type character sets and number wheels by language or customer, including lot+date combos.
- Swap the head and snap in a fresh quick-change ink reservoir. Confirm imprint on a test panel, then go live.
Most teams can switch over in minutes with no software, just a clear kit and a checklist.
Troubleshooting non-porous plastic adhesion
If codes wipe off or smear on PP, PE, PET, or film:
- Ink selection. Move to a quick-drying ink with a solvent blend tuned for your substrate. Consider pigmented inks for contrast if the base color is dark.
- Surface prep. Wipe test pieces to remove mold release. If adhesion improves, integrate a light wipe or an upstream clean.
- Dwell and pressure. Reduce over-inking and spread. Adjust the stroke so the head contacts, transfers, and clears quickly.
- Temperature and humidity. Cold parts slow evaporation. Pre-warm parts slightly or shield from condensation at the coder.
- Test marks. Run a small matrix of inks and settings. Check rub resistance after 30 to 60 seconds and again after case packing simulation.
- Placement. Move the mark away from seams, heavy radii, or oily zones, and ensure the container is stable at impact.
If you need sample prints on your exact substrate, request a demo with your parts to lock in the right ink and character height before full rollout.
Barcode question: can you scan a barcode to get an expiration date
Sometimes. If the barcode encodes the date, your scanner can read it. Many product barcodes carry only the GTIN or internal SKU, while the date and lot remain human-readable nearby. GS1 DataBar and some 2D codes can include expiry, lot, and serial. If automated capture is required, add a small 2D code on a label or carton and keep the human-readable date printed by your contact station on the primary package.
Alternatives at a glance
- Continuous inkjet or thermal inkjet, flexible messaging, strong on cartons and labels, more maintenance sensitivity.
- Laser, permanent on certain substrates and coatings, requires contrast and fume control.
- Thermal transfer overprinter, excellent for films and labels on form-fill-seal lines.
- Contact reciprocating coders, low cost to run, rugged, ideal for curved parts and tight spaces.
If your team is evaluating non-contact for high mix or long messages, explore an inkjet coder to understand capabilities and upkeep alongside your contact station.
Summary: get durable codes live in minutes
For expiration dates on plastic, glass, and metal, contact reciprocating coders paired with quick-drying ink in a sealed ink system deliver crisp, smear-resistant characters with low maintenance and low operating cost. Mount in any orientation to fit tight spaces, use removable heads for fast changeovers, and keep character kits ready for MM/DD/YYYY, JULIAN, or lot+date combinations. When printing on non-porous plastics, focus on the right ink, clean surfaces, and controlled dwell, then verify with quick test marks. Non-contact methods complement these stations for long messages or barcodes, but when you need a dependable date on curved containers day after day, a compact contact coder keeps production moving.
If you want help matching ink to your substrate or setting up mounts, schedule a short application review and have your codes running cleanly on the next shift.