Copper price and busbar quotations: how to index the metal

Why a fixed copper price does not hold

A busbar quotation usually carries a validity window of a few weeks. Copper does not. If a supplier quotes a fixed metal price for a year, one of two things happens. The supplier adds a risk margin to cover the possibility of a price rise, or the price quietly changes at the first order after a movement. Neither is a working commercial arrangement.

The same problem appears from the buyer's side. A price that is fixed for twelve months looks secure until the supplier asks for a review. The review then becomes a negotiation about the whole price, including conversion and margin, when only one input has moved.

A metal index separates the two. The conversion, plating, packing and margin stay as quoted. The metal line follows a published reference on an agreed cycle. Both sides know what will move and by how much before the first purchase order is placed.

Define the metal content in kilograms

The index needs a quantity to act on. That quantity is the metal content per part, expressed in kilograms, not the finished weight of the bar alone. Use the input mass, because that is what the supplier buys and what the price of copper applies to.

For a simple bar, the finished mass is length times width times thickness times density. Add the yield allowance for the blank and the scrap that is not recovered. If the part is punched from a coil, the input mass may be 20 to 30 per cent above the finished mass. If it is cut from bar with little waste, the difference is smaller.

Write the number into the agreement with its basis. State the bar size, the density used, the yield allowance and whether the scrap credit is included in the metal line. A single figure of kilograms per part without that basis will be argued about at the first reset.

Where a family of parts shares a price list, use a metal content per part for each item. A single average across a family will overcharge the small parts and undercharge the large ones, and the error compounds over a year.

Choose one reference price and define it precisely

A reference has to be published, independent and available to both parties after the event. The London Metal Exchange is the common choice for copper traded internationally. Local exchanges and producer list prices are used where the supply chain is domestic or where the mill prices against a local basis.

The precise definition matters as much as the source. LME cash settlement, the three-month price and the official monthly average are different numbers. So are the morning and afternoon sessions. Pick one, write its name and its publication time, and keep using it.

Currency is the second half of the reference. Copper is usually quoted in US dollars, while the busbar may be priced in pounds or euros. The clause needs an exchange rate source and a fixing date, or the currency movement will swamp the metal movement. A monthly average from a named central bank is usually easier to administer than a daily rate.

Test the definition against a real invoice before signing. Take the reference value for a past month, apply the formula and compare the result with what the price would have been. If two people in the same meeting get different answers, the definition is not tight enough.

Set the lag and the reset period

There is always a gap between the price a fabricator pays for metal and the price the buyer sees on an index. The mill may price a coil at the time of order, the fabricator may hold stock for weeks and the finished part may ship later again. The clause should reflect that reality rather than pretend it does not exist.

A common structure is a monthly reset using the average of the index over a defined window, applied to orders in a later month. For example, the average of the previous month might set the price for the current month. Another structure uses a quarterly reset with the average of the preceding quarter. The right choice depends on the stocking pattern and the length of the programme.

An illustrative reset

Assume a busbar quoted at £22.00 with a metal content of 2.00 kg per part and a base copper reference of £8.50 per kg. The metal line in the quote is £17.00 and the remaining £5.00 covers conversion, plating, packing and margin.

In the reset month the reference averages £9.10 per kg. The movement is £0.60 per kg. Multiply by the 2.00 kg content to get £1.20 per part. The new price is £23.20, and the non-metal lines stay at £5.00. If copper had fallen to £7.90, the price would fall by the same method to £20.80.

The arithmetic is deliberately simple. Complexity belongs in the definitions, not in the sum. If the formula needs a spreadsheet with eight tabs, it will be applied inconsistently and disputed every quarter.

Include the scrap treatment in the same example. If the agreement gives the supplier a scrap credit at a percentage of the index, the credit should move with the index as well. Otherwise a rising copper price increases the metal charge but leaves the credit fixed, and the supplier is compensated twice for the same movement.

The clauses that prevent arguments

A workable index clause has six parts: the reference, the content, the currency, the averaging window, the effective date and the direction. Add a dispute route for the case where the published value is corrected or unavailable, and the clause is complete.

The direction is the part buyers most often forget. A clause that only allows an increase is not an index, it is a floor. State that the price moves up and down by the same formula, and that the buyer receives the benefit of a fall from the next effective date. Suppliers rarely object to this when it is presented as the other half of the same mechanism.

Some agreements add a dead band, where movements smaller than a stated percentage are ignored until the cumulative movement passes the threshold. That reduces administration on small movements, but the band must be symmetric and the cumulative position must be tracked. A one-sided band is a slow price increase.

• Reference: publication, price type and session
• Content: kilograms per part and the basis of the figure
• Currency: source and fixing date for the exchange rate
• Window: the averaging period and the days included
• Effective date: when the new price applies to orders
• Direction: increases and decreases on the same formula
• Dispute: what happens if the reference is corrected or missing

Keep the model and the clause in step

The quotation model and the index clause should describe the same part. If the model says the metal content is 2.00 kg but the clause uses 2.30 kg, the difference is a hidden margin that will be paid every month. Review both documents together at each price review.

Revisit the content when the drawing changes. A wider bar, an extra hole or a different bend changes the mass and the yield, and the clause should be updated before the next order. The same applies when the process route changes from bar to coil, or when a new nesting improves the yield.