Steel Bar and Sheet Scale

Why do steel bar and sheet need a scale of their own?

In the steel trade, the load being weighed differs from a warehouse pallet in three ways. The first is length: reinforcing bar and sections usually arrive longer than the platform. The second is density: steel carries a great deal of weight in a very small volume and puts that weight on a narrow strip of the platform. The third is the way it is loaded: bundles are usually set down by crane, hook or forklift, and the moment of landing involves impact.

The steel bar and sheet scale is built with a double-chassis platform to meet these three conditions. The materials used in the platform are dimensioned to withstand a load at least 200 per cent above the scale’s capacity. That margin is there not for the weight being measured but for the impact as a bundle lands and for the load concentrating at a single point. The surface is protected with electrostatic oven-baked paint; given the abrasive effect of mill scale and dust in a rolling mill, damaged paint should be repaired promptly.

Choosing capacity and platform length together

On this scale, capacity and platform length are not chosen separately; the technical table gives suitable sizes for each capacity. A practical way to read it:

• 1,500 kg: 120 × 120 and 120 × 150 cm. For weighing cut pieces, cut sheet and small sections in retail sales.
• 3,000 kg: from 120 × 150 cm to 120 × 240 cm. For bundle weighing at hardware stores and smaller steel dealers.
• 6,000 kg: from 120 × 180 cm to 150 × 300 cm. For medium-sized bundles in wholesale trade and at workshop goods-in.
• 10,000 and 15,000 kg: from 120 × 240 cm to 150 × 600 cm. At mill exits, in large stockyards and for sheet packs.

As the platform gets longer, the number of load cells rises too. On short platforms four cells, one at each corner, carry the load evenly; on a platform stretching to 4 or 6 metres, cells added at intermediate points let a bundle placed in the middle be carried without the deck bending. Domestically produced OIML R60 load cells are used. Where the listed options fall short, dimensions and capacity can be specified to order.

Long bar, sagging sheet: setting the platform length

A load longer than the platform does not always mean a wrong reading. Both ends of a tightly strapped bundle that does not bend may stick out beyond the platform; provided those ends are in free air and the bundle’s balance point lies within the deck, the scale still sees the full weight. The trouble starts when the load flexes under its own weight and rests on the floor or a nearby trestle; at that moment part of the weight escapes off the scale.

For this reason, platform length is set not by the top-selling product but by the product that sags most easily. Small-diameter rebar, thin sheet packs and long slender sections are the most critical loads in this respect. If a business sells both short cut pieces and full-length bundles, a long platform such as 150 × 400 cm or 150 × 600 cm covers both needs. Centring the load on the platform every time and checking by eye that its ends hang free is the most important habit to teach the operator.

Use in sales: piece counting, records and tickets

In steel and sheet sales the weighing result goes straight onto the invoice. The indicator’s RS 232 output lets each weighing be printed as a ticket or label and the record passed to a computer, so no copying errors creep in between the weighbridge ticket and the delivery note. Since every sale priced by weight falls under weights and measures legislation, periodic inspection of the scale should be planned from the start.

The indicator’s piece counting function can be used to check quantities of bars of the same diameter and length. First a set number of bars is weighed to teach the indicator the unit weight, then the whole bundle is weighed and the indicator works out the count. For example, if a bundle of bars weighing about 19 kg each reads 1,140 kg, the bundle holds about 60 bars. Because rolling tolerances make individual bar weights differ slightly, this result should be treated as a quick check, not an exact count.