Rack and bin location labels: a scheme people and scanners can read

A count that records only the item and the quantity can say that something is wrong, but not where to look. When a line shows 12 pieces short, someone has to search every shelf to find out why. A location code on every shelf, bin and floor space fixes this: each reading carries a place as well as an item, and a variance can be followed back to a shelf. This article describes a numbering scheme that people can read at a glance and a scanner can read from a distance.

A scheme in four parts

Use a code that follows the way a person walks: zone, rack, level, bin. For illustration, A-03-2-04 means zone A, rack 03, level 2, bin 04.

• Zone: one letter for a room, a hall or an area of the yard.
• Rack: two digits, numbered along the aisle in the same direction every time, starting from the entrance.
• Level: one digit, counted from the floor up, so level 1 is the lowest.
• Bin: two digits, counted from left to right as you face the rack.

Keep the code the same length everywhere, with leading zeros, so that a list sorts correctly in Excel. Do not use the letters O and I as zone letters, because they are mistaken for 0 and 1. If the numbers follow the way a person walks, the scanning order becomes the walking route, and a skipped bin is noticed quickly. Never put the item name into a location code. A location says where, and the item standing there can change.

Where the label goes

A label that cannot be reached or seen does not get scanned.

• Fix it to the front edge of the beam under each bin. If every rack uses the same position, for example the left end of the bin, nobody has to hunt for the label.
• Print the code in large characters next to the barcode. People read the text, scanners read the bars. The text should be readable from two metres.
• For high levels, make the label larger so that it can be scanned from the floor, and tilt it if necessary.
• Where there is no beam, as with floor stacks and pallet places, use a floor label protected against forklift wear, or a label on the nearest post.
• Where dust collects or cleaning is frequent, choose a material that withstands rubbing and washing, and wipe the labels regularly.
• After fixing, scan each label from the place where the worker will actually stand, at normal distance. Try the top level and the dark corners as well.

When a bin holds more than one item

Real bins often contain more than one item. There are three ways to deal with it:

1. Where possible, divide the bin and give each part its own code (04A, 04B).
2. If it cannot be divided, mark the bin "mixed". The counter scans each item separately within the same location and enters the quantities.
3. The same item in several locations is normal. So the key of the record must be location plus item, not the item alone. Marking a bin as mixed is a temporary measure, so plan after the count to divide the bin or move the items.

Rolling out and keeping it accurate

For illustration, a hall with 12 racks, 5 levels per rack and 8 bins per level has 12 × 5 × 8 = 480 locations. Do not label them all at once. Go zone by zone: fix the labels, test-scan them and update the location list, which holds each code with a short description. When racks are moved or rebuilt, correct the labels and the list the same day. An outdated label is worse than none, because it gives a wrong answer with confidence. Each month, pick 20 labels and check them against the list.

Summary

A location code is only a few characters, but it is the cheapest way to know where to look when a difference appears. Smart Inventory prints new labels for shelves and bins that have none or have damaged ones, and reads location labels and item labels with handheld scanners so that every quantity carries its location.