Scales and measuring tools: no reliable count without a checked scale

Not every stock can be counted piece by piece. Screws, gaskets, cable or rolled goods are often weighed or measured, and the result is only as good as the instrument. If a scale shows one per cent too much, the error sits in every position counted and comes to light only when the book stock does not fit. A checked scale is therefore the basis of a reliable count. This article shows how to check, label and document scales and measuring tools before the count.

Where instruments determine the figure

• Counting scales that calculate a number of pieces from the weight.
• Pallet scales and floor scales for bulk goods and large packages.
• Length measurement for cable, rolled goods and profiles.
• Level measurement in containers and tanks.

Checks before the count

1. Is there evidence for each instrument of the last inspection or calibration, with date and the body that carried it out?
2. Is an inspection mark fixed to the device, and is it still valid?
3. Does the scale stand level and stable, and does it read zero without a load?
4. Does the measuring range fit? The load must not exceed the maximum capacity and must not be so far below it that the display becomes imprecise.
5. Does the display agree with a known test weight?
6. Are display, unit and power supply in order?

Whether and in what form an official inspection is required for your scales you settle with the responsible body and your quality officer. Here we are concerned with counting practice.

Pieces from weight (illustrative example)

When counting by weight a reference value is determined first: 100 pieces are counted out and weighed. They weigh 2.40 kg, so one piece weighs 24 g. The crate with the material weighs 61.80 kg gross, the empty container (tare) 1.80 kg. Net that is 60.00 kg or 60,000 g. Divided by 24 g this gives 2,500 pieces.

Now the effect of an error: if the scale shows one per cent too much, 60.60 kg net appears on the display, and the result is 2,525 pieces. That is 25 pieces too many, caused by the instrument alone. For an item with a high unit value this is no small matter. The reference itself can also vary: choose the reference quantity large enough and, if in doubt, weigh several samples.

Independence in measuring too

The second team determines the piece weight itself and does not take over the value of the first team. If possible, do not use the same scale, otherwise a device error flows into both counts. If the results differ, the device is checked first and the position is then counted again.

Documenting, labelling, storing

A list of measuring instruments belongs in the count instructions, with number, type, location, measuring range, last evidence and test value on count day. The count sheet states which instrument was used for counting. If a scale is replaced, this is noted with the time. If there is no evidence at all for a device, record that explicitly and count with another device or piece by piece, where that is possible.

Measuring instruments get a number of their own and a visible tag with the date of the last evidence and the next date. Test weights are stored clean and dry so that their value is preserved, and they are not used for other purposes. After a knock or transport every scale is checked again against the test weight.

In short

Without a checked instrument every weighed figure remains an estimate. AuditMaster includes the instruments used in the count instructions and in the inventory record. Checking and labelling the scales themselves is the task of the operator and the responsible bodies.