Bin labelling and colour coding that actually holds up

A labelling standard is only as good as the Tuesday morning when nobody who built it is on site. Here is what goes on the card, what stays off it, and how to roll it out without stopping picking.

The real test of a labelling system is a Tuesday morning without you

The honest test of a bin labelling system is not how it looks on the day it is installed. It is what happens on a Tuesday morning when the storekeeper who built it is on leave, the second man has resigned, and a new helper on his third day is asked to pull a part for a line that has stopped. If he can walk to the right shelf, confirm he has the right part and record the issue without phoning anybody, the system works. If he has to ask, or guess, or open three bins to be sure, then what you have is not a system at all. It is one person's habit, written down partially, and it will decay the week that person leaves.

Turnover in Indian stores is the design constraint, not an unfortunate accident to be managed around. Contract loaders change when the contractor changes. Monsoon weeks in Mumbai and Kolkata thin attendance. Festival leave empties a Rajkot or Coimbatore store for a fortnight. The competent storekeeper you rely on is exactly the person who gets moved to planning or leaves for a better plant in Pune. A labelling standard has to assume all of this from the start. Everything the picker needs must be visible on the shelf edge or the bin face, in a form that needs no training beyond a ten-minute walk-through, and it must stay readable for years without anyone deciding to maintain it.

Three properties separate a standard that survives from one that does not. It has to be written down in a single short dated document that a named person owns. It has to be physically durable in the actual environment, which means coolant mist, hand oil, sunlight through a mezzanine window and the occasional wash bay. And it has to be cheap and quick to reproduce, because the moment a replacement label needs an email to IT and a week of waiting, somebody will write on a strip of masking tape with a marker pen. That strip then becomes the real standard by default. Most schemes die of the third failure, not the first two.

First decision: are you labelling the location or the bin?

Before you choose fonts, materials or colours, settle one question, because everything else follows from it. Does the identity belong to the shelf position, or to the container? Location labelling means the address is fixed to the rack, the shelf edge or the louvre panel, and the bin is treated as a holder that can be lifted out, washed, cracked and replaced without anything changing. Bin labelling means the card travels with the plastic, so wherever that bin ends up it still says what is inside it. Both are legitimate choices. Doing both everywhere, without a written rule about which applies where, is how stores end up with two labels disagreeing about the same part.

Location labelling is the right default for static pick faces. A wall of Panda Shelf Bins sits in a fixed grid on shelving, and the grid is what the picker navigates. A PSB 301 measures 315 x 100 x 60 mm outside, so the face turned towards the aisle is only about 100 mm across, and it is far easier to carry the address on the shelf edge than on that small panel. The same reasoning applies to Koala pick bins on their shelving units, and to Supra or Rhino bins hung on louvre panels. When the bin is a consumable and the position is permanent, put the truth on the position.

Bin labelling wins when the container itself is the moving unit. A Tote AK-421 at 400 x 255 x 100 mm outside is a kitting box: it is filled in the store, wheeled to a line, emptied and returned. A Mammoth bin at 820 x 315 x 300 mm holds castings and moves on a crash cart between a machining bay and an assembly bay. In both cases the location tells you nothing useful, because the tote's address at any given moment is somewhere between the store and station four. Here the card has to be on the bin, and it has to survive the round trip without being torn off by a sleeve or a stack.

Most Indian plants end up with a deliberate hybrid, and the discipline lies in writing down which is which. A workable rule reads like this: every storage position gets a permanent location label carrying the address and the part slotted to it, and only containers that leave their position get a bin label, which carries the part and a barcode but never a location code. That last clause matters more than it looks. If a travelling tote carries a location code, somebody will eventually return it to the wrong place because the tote told them to, and you will spend a week working out why the count went wrong.

What goes on the card, and what must never go on it

The card is not a specification sheet, and the commonest failure in Indian stores is putting far too much on it. On a face 100 mm wide, every extra line steals height from the part number, which is the only element a picker reads at speed. Five items earn their place: the part number, set large and in a font where zero and letter O are clearly different; a short plain-language description; the location code; the unit of measure; and one barcode. A sixth, minimum and maximum quantity, is worth adding only if a named person actually reviews it. Everything beyond that belongs in the system, not on the plastic.

What must never appear is a longer list than what should. No price, because the card is visible to visitors, contractors and customers walking the floor, and prices change anyway. No supplier name, for the same commercial reason and because sourcing moves. No employee name, because the person leaves and the card outlives them by years. No drawing revision, because revisions change faster than labels and a stale revision printed on a bin is worse than no revision at all. And no handwritten date, which within six months is always either wrong or the start of an argument nobody can settle.

Set the type for the worst case, not for the showroom. A picker reads at arm's length, standing, often in poor light at the bottom shelf of a rack. On a 60 mm tall front face like a Supra SB 1 or a Panda 301, you realistically have room for one line of part number at eight to ten millimetres of character height, a smaller description line and the code. Use a plain sans-serif, capitals for the part number only, sentence case for the description because full capitals slow reading down. Avoid any font where the digit one, capital I and lower-case l collapse into the same vertical stroke.

Part number: the largest element, in a face where 0/O and 1/I are unmistakable
Description: three or four words your pickers actually say, not the ERP long text
Location code: same grammar and same position on every card in the store
Unit of measure: written out as NOS, KG, MTR or SET so nobody has to assume
Barcode: one only, fixed position, with its quiet zone kept clear
Min and max: optional, and only where somebody reviews the numbers

Designing a location code people can read aloud

A location code has one job that is easy to forget: it has to be spoken. Somebody will read it out across a noisy shop floor, or over the phone from a Bengaluru plant to a Chennai one, and the listener has to write it down correctly the first time. That rules out long strings, mixed-case codes and clever abbreviations. A four-part code with fixed field widths, such as zone, bay, level and position written as A-12-3-04, is readable, sortable and speakable. Fixed widths matter because a code that is sometimes A-1-3-4 and sometimes A-12-3-04 will not sort correctly in any report you ever run against it.

Be deliberate about the characters you allow. Excluding I, O and Q from the alphabet costs you almost nothing and removes the commonest transcription errors against 1 and 0. If codes will be read from a distance or copied by hand, consider dropping S and Z as well, since both get misread as 5 and 2 under poor light. Keep letters to the zone position and let everything else be numeric. Write the permitted character set into the standard document, because the second person who has to create a location will otherwise invent their own convention, and the third will invent a different one.

Two further rules save years of trouble. First, sort order should follow walk order, so the code that sorts first is the one nearest the door on the picking route and a picklist printed in code order is also a route. That is the cheapest possible link between labelling and picking speed, and it costs nothing if you get it right before printing. Second, never encode anything into a code that can change: not department, not owner, not ABC class, not supplier. Codes are addresses, not attributes. The day a rack moves from assembly to spares, a code that reads ASM becomes a lie and relabelling the aisle is the only cure.

Matching label size to the bins you actually own

Before buying label stock, measure the flat area on the bins in your store, not on a catalogue photograph. Front faces are always smaller than people assume once corner radii and moulded features are taken out. Outside dimensions give you the ceiling to work from: a Supra SB 1 at 125 x 100 x 60 mm and a Panda Shelf Bin 301 at 315 x 100 x 60 mm both present roughly 100 x 60 mm to the aisle. A Hippo 612/T at 100 x 110 x 53 mm gives about 110 x 53, a Bull Bin 5 at 168 x 102 x 74 mm gives about 102 x 74, and a Rhino ARTB-05 at 109 x 104 x 49 mm gives a shallow 104 x 49.

Larger containers change the problem rather than solving it. A Tote AK-421 at 400 x 255 x 100 mm offers a 400 mm long side and a 255 mm end, and the temptation is to fill both. Resist it. Label the end that faces the aisle when the tote sits on its shelf, and if totes are stacked, label the same end every single time so the pattern is learnable. A Mammoth bin at 820 x 315 x 300 mm has room for a large card, which genuinely helps when a code must be read from a passing forklift, but a big label also invites people to add information that will go stale.

Standardise on two or three card sizes for the whole store, chosen to fit the smallest faces you actually use. Two usually do the job: a small card for anything with a face under roughly 110 mm, and a larger one for tote ends, Mammoth faces and pallet positions. The benefit here is not aesthetic. Fewer sizes means fewer stock items to run out of, fewer print templates to keep in step, less chance of somebody loading the wrong roll at seven in the morning, and a realistic chance that blank stock in the right size still exists in the cupboard three years from now.

Two families defeat any normal card and need their own answer. A Roo Tilt Bin RTB 1 is a small tilting unit, with the cabinet measuring 50 (L) x 73 (W) x 92 (H) mm and the bin itself 69/42 (L) x 62 (W) x 80/69 (H) mm, and an ACO 18 component organiser cabinet at 457 (H) x 424 (W) x 164 (D) mm holds a grid of small drawers. Neither offers a usable face for a full card. The workable answer is to number the position permanently and mount a printed index on the cabinet frame mapping position numbers to part numbers, replaced as a single sheet when anything changes.

Printing and materials that survive coolant, sunlight and hands

Direct thermal and thermal transfer labels look identical on day one and behave nothing alike by month three. Direct thermal uses no ribbon: the stock darkens under the print head, and it will also darken under sunlight, under a hot surface and under friction from a sleeve. That makes it a perfectly good choice for a thirty-day kanban card meant to be thrown away, and a poor choice for a shelf label you expect to read five years from now. Thermal transfer with a resin ribbon on a synthetic facestock is the workhorse for anything permanent, and it is what coolant-splashed and oily areas actually need.

Match the facestock to the aisle rather than to the plant. A dry, air-conditioned electronics sub-store in Bengaluru or a clean assembly bay in Chennai can run paper cards in pockets for years without complaint. A machining bay in Coimbatore or Rajkot, where coolant mist settles on every surface and hands are permanently oily, needs polyester or polypropylene stock, ideally over-laminated. Sunlight is the underrated killer. A mezzanine store in Ahmedabad or a shed with north-light glazing will fade dye-based inkjet output within a couple of months and pull the reds out of anything printed on a colour office printer inside a year.

Office laser and inkjet printing has a place, but a narrow one. Toner sits on the surface and rubs off plastic label sheets under a thumb; it survives well inside a closed pocket and badly on an exposed adhesive label. Whichever route you choose, run a two-week trial before committing to a thousand labels. Print five samples, mount them on the worst bins in the worst aisle, and at the end wipe them with the coolant or cleaner your operators really use, rub each one with a thumb twenty times and try to scan them. Anything that fails that test will fail everywhere else in the store too.

Permanent shelf and bin labels: thermal transfer, resin ribbon, synthetic facestock
Short-life kanban and dated cards: direct thermal, treated openly as consumable
Oily and coolant areas: over-laminate the card, or move it into a closed pocket
Sunlit mezzanines and skylight bays: no dye inkjet and no plain uncoated paper
Wash-down areas: card holders rather than adhesive, card removed before washing
Always trial five labels for two full weeks before you print in bulk

Mounting: adhesive, pocket, slot and the removal problem

All of these bins are moulded polypropylene copolymer, and that matters for adhesion. Polypropylene is a low surface energy plastic, so ordinary paper labels with general-purpose adhesive lift at the corners within months, faster on a curved or radiused front face and faster still in the humidity of Mumbai, Navi Mumbai or Kolkata. Wipe the face with isopropyl alcohol before applying anything, press the whole label rather than just the middle, and accept that adhesive on plastic is always a compromise. Wherever you can mount a card instead of sticking one, do that: a label pocket, a card slot, a shelf-edge rail or a louvre-panel rail.

The bins carry a service range of minus ten to plus seventy degrees Celsius, which is wider than most label adhesives are comfortable with. If your bins pass through a hot wash, a cold room, or sit under a summer shed roof in Gujarat, the adhesive fails long before the plastic does. Choose the adhesive for the process, not for the container. If the process includes washing, stop sticking altogether: a bin that gets washed should carry a removable card in a holder, taken out before the wash and replaced after it, or it should carry no identity of its own and take it from the location instead.

Every label you stick, you will one day have to remove. That sounds trivial until you have a hundred bins with grey adhesive residue collecting coolant and dust, and a stores team that has quietly concluded relabelling is not worth the effort. Residue is the exact point at which most schemes stop being maintained. Holders, rails and card slots cost more at purchase and much less over five years, because swapping a card in a slot is a five-second job that anybody will do, while scraping and re-sticking is a ten-minute job that nobody will do at four in the afternoon.

One rule gets broken constantly: do not cover the moulded markings. These bins carry a resin identification code 05 for polypropylene along with food-safe and recyclable marks, and most ranges carry a moulded size or type identifier as well. That moulded identifier is how your purchase team reorders exactly the right bin two years later without measuring anything. Cover it with a large label and you have turned a self-describing part into an anonymous grey box, and somebody will end up sending a photograph and a tape-measure reading to the stockist to work out what to buy. Position cards to leave those marks visible.

Barcodes: placement, geometry and the tilt-bin trap

Barcode placement is a geometry problem far more than a printing one. Fix one position and never vary it, bottom-left of the card on every card in every aisle, because a picker's scanner arm learns a position and stops searching for it. Keep the quiet zone clear on both sides of a linear code; a border, a ruled line or the edge of a pocket cutting into that white space is the single commonest cause of failed reads. Never place a code on the underside of a bin, across a moulded rib or seam, or on a radius, because the curve distorts the bars at exactly the angle a scanner uses.

On small faces the code type matters a great deal. A linear barcode needs bar height to tolerate scan angle, and on a Rhino ARTB-05 face of roughly 104 x 49 mm, or a Koala AKP-01 front of about 105 x 60 mm, a legible linear code eats most of the space your part number needs. A two-dimensional code, Data Matrix or QR, carries the same data in a much smaller square and reads at any rotation, which suits small bins and tilted faces. Before committing to 2D, confirm that your existing scanners are imagers rather than laser units, because laser scanners cannot read 2D codes at all.

Tilt bins hide a trap that only shows up in use. A Roo Tilt Bin swings forward on its pivot, so a code printed on the bin's own front face rotates downward and away from the operator at precisely the moment the bin is open and the part is being taken. If you intend to scan at the point of issue, put the scannable code on the cabinet frame or the shelf edge beside the bin, where it stays still and vertical. Keep the human-readable part number on the bin front if you wish, but the machine-readable code belongs on the part of the assembly that does not move.

Colour coding: one meaning, few colours, one written key

Colour coding fails for one reason far more often than any other: the store allows colour to mean more than one thing. Somebody colours the fastener aisle by thread type, somebody else colours the assembly aisle by shift ownership, a third person starts using red for rejects, and within a year red means three different things depending on where you happen to be standing. Pick exactly one dimension for the whole store and write it down. Common dimensions that work are material state, ownership, movement class or physical hazard. Choose one of them. Not two, and definitely not one scheme per zone or per supervisor.

Limit the palette to five colours plus a neutral, and do it for practical reasons rather than aesthetic ones. Bin colour is a manufacturing choice, so before designing a scheme you must confirm with your stockist which colours are actually available across the ranges and sizes you use, and what the lead times look like. A scheme built around a colour you cannot reorder in Navi Mumbai next quarter has an expiry date built into it. Red-green colour vision deficiency is common enough among men that any two meanings separated only by red and green will eventually be confused, and older high-bay lighting shifts colours badly.

Treat colour as a hint that shortens the search, never as the data itself. The test is simple: if every bin in your store were swapped for grey ones tomorrow, could the operation still run purely on the labels? If the answer is no, colour is carrying information it should not be carrying, and a single delivery in the wrong colour will cause a real error. Colour should shorten the walk, so that a supervisor can say the rework bins are the yellow ones at the aisle head, while the card still carries the part number, the location and the barcode that make the transaction correct.

The key must exist as a physical document. One sheet, laminated, dated and version numbered, posted at every store entrance and filed with the stores SOP, listing each colour with the supplier's colour name, a plain description, its single meaning and one line on what to do when you see it. Crucially, list the unassigned colours as well and state plainly that they carry no meaning, so a stray blue bin arriving from another plant does not acquire a meaning by rumour. If a colour is not on the sheet, it means nothing, and that sentence should appear on the sheet itself.

Material state: incoming, quality hold, released, rework, scrap
Ownership: own stock against customer-supplied or free-issue material
Movement class: fast, medium and slow movers, for slotting and cycle counting
Cell allocation: where one store feeds several assembly cells or lines
Handling caution: where a genuine physical or handling risk exists
Whichever one you pick, the other four are then banned across the whole store

Worked example: a fastener and sub-assembly store near Pune

Take a machining and sub-assembly unit on the outskirts of Pune with three distinct storage populations. Fasteners, dowels and small turned parts sit in Bull Bin 5 units, 168 x 102 x 74 mm outside with 145 x 86 x 66 mm inside, hung on louvre panels beside the assembly benches. Electrical items, terminals and small bought-out parts live in Panda Shelf Bin 301s at 315 x 100 x 60 mm on shelving units. Kits go out to the line in Tote AK-421s at 400 x 255 x 100 mm, and rough castings wait in Mammoth bins at 820 x 315 x 300 mm along the far wall.

The decisions follow directly from the rules above. Every position gets a permanent location label on the louvre rail or the shelf edge, and only the totes carry bin labels, holding the part number and a Data Matrix code but no location code. Two card sizes cover the entire store, a small card for the louvre rails and shelf edges and a larger one for tote ends and Mammoth faces. The machining side uses thermal transfer on polyester because of coolant carry-over, while the assembly side uses paper cards in pockets, which are cheaper and quicker to change when a model changes over.

What this buys is not a number you can put in a report; it is a set of specific arguments that stop happening. A kit that comes back half full carries a bin label, so it returns to the right place instead of the nearest empty gap. A rework bin is yellow and visible from the aisle head, so it does not get quietly worked into the next kit. A new helper is walked down the aisle once, shown the key sheet at the entrance and left to pick from the cards. And when a Bull Bin cracks, it is replaced without touching a single label, because the label was never on the bin.

Worked example: labelling inside an ESD protected area

Storage inside an ESD protected area, which most electronics assembly units in Bengaluru, Chennai and the Delhi NCR belt now operate, breaks one assumption behind the colour scheme. Conductive and dissipative mouldings are pigmented by their compound, so their colour is decided for you and is simply not available as a signal. Trying to run a five-colour material-state scheme inside an EPA using those bins is impossible from the start. The clean answer is to move the colour signal off the bin and onto the shelf-edge card or the rail, so the same scheme reads continuously across the boundary while the bins stay whatever the ESD requirement dictates.

Label materials deserve a second thought inside an EPA. Ordinary plastic label pockets and large plastic-faced labels are insulative and can hold charge; whether that matters in your case depends on the item, the distance and your own EPA control plan, which is the document that should decide the question rather than a labelling article. The practical habits are to keep label area small, prefer paper cards to large plastic pockets inside the protected area, keep labels away from the open face where boards are handled, and to get your ESD coordinator to approve the label material as part of the standard rather than after an audit finding.

Do not use colour to mean ESD safe. The property belongs to the moulding, not to the pigment, and the moment your store teaches people that a particular colour means protected, somebody will bring in an ordinary bin of the same colour from another aisle and it will be trusted without question. Protection is verified by the product family and by your own controls; the card may state it in words if that helps a new operator, but it must never be the primary indicator. The same logic applies to any safety-critical property in any industry: colour supports a decision, it does not make the decision.

Rolling it out on a live store without stopping picking

Do not relabel a working store in a single weekend shutdown. Pick one aisle, preferably a busy one with a sceptical picker, and run the new standard there for two weeks while everything else stays exactly as it is. The point of a pilot is to be told what is wrong by people who will never read a document: that the card is unreadable from the bottom shelf, that the code is awkward to say aloud, that the pocket catches a sleeve, that the yellow sits too close to the orange under those lights. Fix all of it before printing for the whole store, because after that the cost of changing your mind multiplies.

Cut over aisle by aisle, never part number by part number, because a half-converted aisle is exactly where errors live. During each aisle's cutover, leave the old label in place with a dated OLD marking for a defined window of one or two weeks, so anybody working from memory or from an older picklist still lands in the right place, then strip the old labels on a single scheduled pass. Picking never stops for any of this. Put the aisle sequence on a board at the store entrance so production planning knows which aisle is being touched on which day and can plan issues around it.

The step everybody skips is verification before application. The correct sequence is to freeze the location master for that aisle, print the labels, then walk the aisle with the printed set and a scanner and check every card against what is physically in the position, before any adhesive or card goes anywhere. A meaningful share of cards will be wrong on the first pass, and it is far cheaper to discover that with a stack of paper in your hand than after mounting. Only then mount them, do a quantity spot check on ten locations, and have the aisle signed off by name and date.

Label printer, one spare ribbon, and the settings note taped to the printer body
Blank stock in each of your two or three card sizes, plus one aisle's worth extra
Holders, pockets or rail sections with fixings, counted out per aisle beforehand
Isopropyl alcohol and a lint-free rag for cleaning bin faces before application
A printed, dated copy of the colour key sheet for the aisle team to work from
An exception log book: every location that could not be labelled, and why

Keeping the standard alive: ownership, change control and the printer

A standard without an owner reverts to masking tape. Name one person who owns the labelling standard and one named backup, and put both names on the key sheet itself so there is no ambiguity about who to ask. The print template file lives on a shared drive at a known path, not on somebody's laptop, and beside it sits a one-page note recording the exact print settings: printer model, darkness, speed, label stock part, ribbon part and template version. That note is what lets a different person, eighteen months later, reprint a single card that matches the two hundred around it.

Write down two change rules and then enforce them. Creating a new location code or altering the code grammar needs the owner's approval, because codes leak into picklists, into reports and into people's memories, and a quiet change breaks all three at once. Assigning a new meaning to a colour requires the key sheet to be updated, re-dated and re-posted the same day; if the sheet is not updated, the colour has no meaning and nobody is obliged to respect it. Handwritten labels are allowed only as a logged exception with a forty-eight hour life, recorded in a small book kept beside the printer.

Treat label stock and ribbons as stocked items with their own minimum and maximum, held in a bin with a proper card like anything else, because running out of ribbon is the commonest single reason a store stops labelling. Keep enough of each card size on hand to relabel a full aisle at short notice. If the store runs a single shift on one printer, consider holding a second unit, because replacement printers and consumables do not arrive the same day in Nashik, Coimbatore or Rajkot, and two weeks without a printer is long enough for the marker-pen habit to return permanently.

Auditing the labels, and specifying the next bin order

Audit labels the way you audit stock: on a sample, on a schedule, by walking. Once a quarter, take thirty locations per zone at random and check five things. Is the card readable from a metre away, at the shelf height it actually occupies? Does the barcode read first time? Is the card firmly held? Does the code match the system? And does any colour present match the key sheet? Record only the fail count and the specific locations, and fix them within the week. If one zone keeps failing on adhesion, that zone has the wrong mounting method, not careless staff.

Learn the ageing signs so replacement becomes planned rather than reactive. Curled corners with a grey line of dust along the label edge mean the adhesive has let go and the card will be gone inside a month. A general grey wash across a direct thermal label means heat or sunlight, and that whole aisle is now on borrowed time. Reds and magentas fading while blues stay strong is normal sunlight behaviour, and it is a genuine warning if red carries meaning in your scheme. Cracked, brittle pockets usually indicate ultraviolet exposure, and they will keep cracking until the pocket material itself changes.

Bring the labelling standard into the purchase specification for the next bin order, because colour is a procurement decision as much as a design one. Specify colour alongside range, size and quantity. Order a modest buffer of each colour so a broken bin gets replaced in the correct one rather than whatever happens to be on the shelf that day. Confirm with your supplier that the colours you have designed around are available in every size you use, and what the lead time is for each. A colour that is easy in one size and a six-week wait in another will quietly break the scheme.

This is where working through an established stockist earns its keep. Shreeram Metafusion Engineers Pvt. Ltd., at Shop-1, Gagangiri CHS, Sector 17, Vashi, Navi Mumbai, has been an authorised stockist of ALKON Plastics for over thirty years, and the catalogue runs to more than 476 products across nine ranges. That includes the louvre panels, rails, universal rail, stands, trolleys and crash carts that a good labelling scheme actually mounts on. The mounting hardware matters as much as the printer, because if there is nowhere to hold a card, the card ends up stuck to plastic. Specify the rail and the holder in the same order as the bins.