Stock Checking Methods


Stock Checking

Although we all know that Jewellery inventory control is vital to the long-term success of a jewellery wholesaler or retailer business, it is less well known that time plays a big part in the effectiveness of stock checking.

Tight daily inventory control is not just for loss from theft, but also for everyday errors such as misplacement, incorrect labelling, non-returned appro sale or workshop order.

Of course, proof of accurate inventory control will also help insurance claims after a loss for any reason. Evidence that you were doing regular physical stock checking will help to provide the proof that the insurance companies require.

By using The Jewellery Shopkeeper, hereafter referred to as JSK, inventory is fully controlled – but unfortunately things happen that are not recorded on the  JSK database. That’s why physical stock checks are important.

The mention of “stock take” should not cause concern. Nor should physical stock checks require overtime work or disruption of sales. In fact stock checks should be part of the daily routine performed by sales staff during moments when there are no customers waiting for service.

To enable quick stock checks it always helps to limit the area or type of stock being checked at one time. Divide your stock into “bins”. A bin is best to be a localised area such as a display window, cabinet or safe, but it can also refer to a specific type of jewellery such as watches. Places that are separated by a distance: stores, shops, kiosks or travelling salesmen, should be allocated different location codes (aka branch letters) so that those stock checks are independent from each other.

Each bin should have no more than 100 items (or 1000 items if RFID used) so that the stock can be checked in just a few minutes.

Some shopkeepers only do physical stock takes once per year - for jewellery that is not often enough. If, for example, a sale was processed manually during a power outage or other computer failure, it might go uncorrected - and months later that incident will be long forgotten.

Accurate and reliable physical stock checks provide assurance that the computerised records are valid. It is a two-way check.
Stock take methods
1) Manual
2) printed check list
3) keyboard code entry
4) barcode scan entry
5) barcode data collection
6) RFID data collection
7) Bulk checking by weight.

In practice a combination of methods should probably be utilized in your business depending on the places being checked.

Manual inventory control

    • Inventory is not on a computer database. In this case printed or hand-written check lists must be used. Variance is found by visually examining the check sheets.
    • Accuracy is dependant on the operator performing the stock check.
    • Security: none.
    • Speed: poor.

Printed check lists

    • Computer generates a list of items that should be in stock. This is the traditional computerised stock checking method.
    • Ticking off the items on a long list is very time-consuming and for that reason it is only good for checking up to about 50 items.  Labels will need to be read visually and then looked up on the printed list. For stock take of a typical jewellery shop it could take one person a whole day.
    • Accuracy is dependant on the operator performing the stock check.
    • Security: none.
    • Speed: fair to poor.

Keyboard code entry

    • Manually typing the inventory codes that are found into a computer program that can then be instructed to report variances. This will probably not save time compared to the physical check sheets but it does provide better assurance of accuracy.
    • Portable computer terminal is required. Or items can be carried to the fixed computer workstation.
    • Will probably be slower than a printed check list.
    • Security: fair.
    • Speed: poor.

Barcode scan entry

    • Using a barcode scanner instead of typing the inventory codes into a computer program that can then be instructed to report variances. This is faster than manual typing.
    • Wireless scanner is required. Or items can be carried to the fixed computer workstation.
    • Security: fair or good if the report can differentiate scanned from manual entries. JSK does have flags to show manually entered codes.
    • Speed: fair to poor

Barcode data collection

    • This is similar to barcode data entry except that the scanner has a built-in memory to store the scanned codes so the scanner is free to be taken away from the computer network. Thousands of codes can be captured and will be stored in the scanner’s memory until the data is downloaded to the computer workstation.
    • Security: good but some data collection terminals have built-in keyboards that also allow manual entry of codes. These manually entered codes cannot be differentiated by JSK.
    • Speed: fair.

RFID data collection

    • Assuming that the reader is a good one and the RFID tags are suitable for purpose and correctly displayed, RFID data collection is the quickest and most secure method of stock checking.
    • RFID tags are very reliable. Even if physically damaged they can still be read, albeit at a shorter range.
    • Tags do not need to be visible and the read range can be up to 1 metre. Can read through most non-conductive materials.
    • Security: good. (If manual entry is provided it should be disabled on the reader.)
    • Speed: fast.

Bulk checking by weight

    • JSK provides an option to check stock be weight for any mix of items.
    • Practical for total mass (including tare) not exceeding 600 grammes due to limitation of the low cost electronic scales that are commercially available.
    • Accuracy depends on the accuracy of the captured total mass of each item in JSK.
    • Good for up to about 100 items at a time (selected by bin number or supplier voucher number).
    • Security: good.
    • Speed: fast.

Radio Frequency Identification (RFID) for Jewellery Inventory Checking

Background

Although RFID was invented in the mid 1900’s it is only in the past decade that the UHF (ultra high frequency) passive electronics has been developed and standardised into a practical system that can “simultaneously” read hundreds of tags in close proximity to each other.
Many types of active and passive RFID systems are in common use today, from HF (high frequency) NFC (near field communications) tags as used in entry control and cellphones, to low frequency passive tags used in dogs and cats, active tags (with built-in power cells) used for sports timing and large UHF passive tags used on road vehicles for toll gates. In this article I am only going to refer to UHF passive tags.
The special RFID reader sends out a powerful (about the same power as a cellphone) radio pulse at about 900 MHz. This is captured by an antenna built into the RFID tag which in turn transforms it into a voltage that powers a tiny electronic chip. The chip then uses this power to transmit a unique code which has been pre-recorded in the chip back using the same built-in antenna. This radio signal is captured by the RFID reader that had just a moment earlier sent the activation pulse. The data contains hundreds of bits of information. About a hundred bits of that information makes up the 24-character code that JSK needs to identify the item.
The tag that had just been read then “goes to sleep” for a fraction of a second and in that way gives other tags in its vicinity the chance to be read. The reader’s transceiver cycle repeats hundreds of times per second so that is appears to us that the reads are simultaneous.
The reader reads each tag over and over again while hoping to find new tags, so, if you have a tray of 100 items and you scan it with the reader for two seconds it will possibly have read each tag about 4 times. The reader aggregates all duplicates and only saves one of each code.

RFID Readers and Tags

Jewellers all want RFID tags that are tiny and can be hidden from view. At the same time they want to be able to read the tags from more than a metre away. It is just impossible to do both those things.
A tiny 10x15mm tag will only read at a distance of a couple of centimetres. While a tag 50mm long can be read from a metre or more away. And both depend on a good, long-range reader.
Problems with readers

An unexpected problem with any long-range reader is that it reads too well. A long range reader is not suitable for use at point-of-sale nor back-office use where a single tag must be read. Fortunately all readers have the option to reduce the power.
Portable readers also do not usually have the ability to directly enter the code into a computer workstation. A special short range desktop reader is available for point-of-sale and back-office use.

Problems with tags

There are numerous potential problems where UHF RFID tags are used.
Bear in mind that the size of the built-in antenna is important and a bigger antenna can collect and transmit more radio waves than a smaller antenna. But that is only part of the story.
What matters most is the radio frequency tuning of the antenna. A large antenna that is out of tune is worse than a small antenna that is properly tuned.
All manufacturers factory tune their antennas correctly – but us users spoil them. Here are the most common ways to spoil an antenna’s tuning.
Mounting it against a material other than air. If encapsulated in plastic it is important to leave an air gap between the tag and the plastic unless the tag is pre-tuned for plastic encapsulation. Even mounting the tag against glass reduces its range – although having a sheet of grass between the tag an the reader makes little effect on range.
Folding the tag – this folds the antenna.
Mounting the tag in close proximity to a heavy object – this seems to “suck the RF energy away”.
A easy-reading or large tag “swamps out” nearby small or weak tags. When having a mix of tags in one place they should ideally all be the same type otherwise you might find that you need to spend more than usual time or closeness of the reader in order to read all the tags in the group.

Types of tags

Tags can either be single use, like with the traditional jeweller labels, or re-usable.
The RFID tags are typically ten times more costly that barcode labels and so the cost of labels is a factor to consider when deciding to use RFID. Also, tags that read easily are typically five times the size (in area) of barcode labels. For these two reasons Shopkeeper Solutions have developed a range of re-usable tags and jewellery mounts.
Reusing re-usable tags and stands
The re-usable tags are secured to the jewellery with a disposable nylon tie. The tie is cut and removed using a small tool. The human-readable label is pealed off and the tag is ready to be linked to a new item.

Human-readable identification

The single-use  RFID tags can be printed on using any barcode label printer. It works but it is the main reason why the label is “single-use”.
On the re-usable tags one has the option to use the traditional barcode label – in which case the barcode label is attached as usual to the jewellery or the barcode/text label can be stuck against the RFID tag.
Another option is to use a low-cost label printer to print small rectangular labels to stick against the RFID tag or ring stand.

Linking RFID tag to JSK codes

The Jewellery Shopkeeper and The Business Shopkeeper has a special utility to quickly re-allocate an RFID tag to a new stock code. A special desktop RFID reader makes this easy.