Guide
How Do You Write a Metal Price Adjustment Clause for Machined Parts Without Overpaying?
A metal price adjustment clause is a supply-agreement term that lets the unit price of a machined part move with the market price of the metal it is cut from, using a named index, a fixed base month and a written rule, instead of leaving the supplier to ask for a surcharge whenever bar or plate gets dearer. The short answer: adjust only the material share of the price, tie it to the metal the supplier really buys, trigger it on a review date and a threshold rather than every price tick, and make it work in both directions.
By Saola Manufacturing engineering team · Published · Updated
General information, not legal advice. Contract wording and governing law vary; have counsel review any clause before you sign.
This guide is for a purchasing manager who has a twelve-month agreement on stainless, brass or aluminum parts and has just been asked for a material surcharge. It covers the mechanics of an adjustment clause: what to index, how much of the price to index, and what dates and limits keep the clause fair. It does not quote prices or suggest percentages, because the right thresholds depend on your part, your metal and your volume.
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When is a metal price adjustment clause worth putting in a supply agreement?
When the agreement runs long enough, or the metal is a large enough share of the part price, that a supplier cannot hold a fixed price without padding it for risk. For a short order of parts where machining time dominates the price, a fixed price is simpler and usually the better deal.
Parts cut from bar stock or plate carry a material cost that follows the metal market, while setup, machining time, finishing and inspection do not. On a repeat program at annual volumes in the five-figure range, a supplier quoting a fixed price for twelve months is taking a view on where the metal will go. A careful supplier prices that view into the quote as a cushion; a less careful one sends a surcharge letter mid-year.
An adjustment clause replaces the cushion and the surprise with a rule. You pay for metal at what it costs, and not more, and the supplier is not forced to guess. The trade-off is administration: someone on each side has to run a review on schedule. If your material share is small, or the agreement is short, that effort is not worth it.
A surcharge request that arrives on an agreement with no adjustment clause is a request to change the written price. Whether you have to accept it depends on the contract and the governing law, which is a question for counsel. What you can do without a lawyer is use the request as the moment to agree a clause that applies from then on.
Which index should the clause use?
Name the index of the metal the supplier actually buys, by its full title and series code, from a source both sides can check. An index whose product mix differs from the bar or plate on your drawing will move for reasons that have nothing to do with your cost.
The U.S. Bureau of Labor Statistics publishes a guide for exactly this task. It says there is no single index titled "the Producer Price Index," so a clause must cite each series by its full title and code, and it recommends not-seasonally-adjusted data, because seasonally adjusted indexes are not appropriate for price adjustment (BLS PPI price adjustment guide). The guide also says to pick an index that represents the costs of providing the item, rather than the price of the item itself, to avoid a circular loop in which sellers wait for the index to rise and the index waits for sellers to raise prices.
That warning matters for machined parts. The FRED series PCU33273327 is the BLS producer price index for machine shops and for turned product, screw, nut and bolt manufacturing, set to December 2003 equals 100 and published monthly. It is a good example of how a series is identified, but it measures what machine shops charge, so it is the wrong index for a metal clause: it already contains the machining labor and margin you are trying to keep fixed. Use a series for the mill product itself, such as the steel, aluminum or copper-alloy form the supplier buys, or a published price both sides can read, and confirm that the form (bar, plate, tube) and alloy family match your part.
The federal government shows a second model. The Defense acquisition clause DFARS 252.216-7000 does not use an outside index at all. It moves the contract price by the same percentage as the contractor's own established catalog price for the mill product. That works for standard mill products sold from a public price list, but a commercial buyer usually cannot audit a supplier's list price, so ask for the supplier's mill invoices as the check, or agree an outside series instead.
Which clause design fits which situation?
Use an index-linked clause on the material share for long agreements on bar or plate parts, a fixed price for short ones, and invoice pass-through only where no usable index exists. Leaving the price open is the weakest choice.
The table sets out the common designs with the situation each one fits and the risk to check. It describes structures, not recommended values.
| Design | How it works | Fits when | Main risk |
|---|---|---|---|
| Fixed price for the period | No adjustment; the supplier carries metal risk | Short agreement, or material is a small share of the price | Supplier pads the price, or asks for a surcharge mid-term |
| Index-linked, material share only | Material line multiplied by the index change between base month and review month | Long agreement on bar, plate or tube parts | Wrong index, or a clause that only lets price rise |
| Supplier catalog-price model (DFARS style) | Whole price moves with the seller's own established price for the mill product | Standard mill product sold from a public list | Hard to audit; moves the whole price, not just the metal |
| Invoice pass-through | Material line follows the mill invoice | Special alloys with no usable index | Audit burden; weaker incentive for the supplier to buy well |
| Open price | Price left to be settled later | Rarely a good choice | Under UCC 2-305 the price becomes a reasonable price at delivery, which invites a dispute |
What thresholds, review dates and limits keep the clause fair?
Fix a base month, a review schedule, a threshold below which nothing changes and a cap on how far the price can move, and make each of them apply in both directions.
Base month. State the month and year of the base price, not an index value, as the BLS guide advises. Say which version of the data governs: BLS notes that monthly values can be revised for up to 4 months after first publication and are final after that (BLS guide), so the clause should name first-published or final values and give the approximate calculation date. Monthly data are not tied to a calendar day, so avoid "as of the 30th."
Threshold and cadence. A threshold, sometimes called a dead band, means small index movements do not trigger a change, which saves both sides a monthly recalculation. Pair it with a review cadence tied to how often the supplier really buys metal. The BLS guide gives annual adjustment as its example; a volatile metal may justify a shorter cycle, at the price of more administration. Choose the numbers from the supplier's quote breakdown, not from a template.
Timing of the change. The federal clause applies an increase only to deliveries after its effective date and not to quantities already scheduled before it. Copy that principle: a change takes effect on a stated date and does not reach back to released orders.
Symmetry and limits. The DFARS clause requires the contractor to report decreases promptly and cuts the price by the same percentage, and it caps aggregate increases while setting no cap on decreases. The BLS guide notes that parties may agree on floors or ceilings. Write both sides of that: decreases flow back as automatically as increases, and a ceiling on increases is matched by a floor. Add a successor-series clause for the day the index is discontinued, as the BLS guide recommends.
Exit. The federal clause lets the buyer cancel the undelivered part of an order after an increase request without liability. Ask counsel whether a comparable right fits your agreement, because it is what keeps a cap from becoming a negotiating bluff.
What does the law say about an open price?
The Uniform Commercial Code lets a sale contract exist even if the price is not settled, but it fills the gap with a reasonable price at delivery, which is a court's judgment and not a formula. That is why an open price is a poor substitute for a written index.
Under UCC section 2-305, parties who intend to be bound can conclude a contract even though the price is not settled. If nothing is said about price, or the parties were to agree and did not, or the price was to follow a market standard that nobody sets or records, the price becomes a reasonable price at the time of delivery. A price left to one party to fix must be fixed in good faith, and if the parties intend not to be bound until a price is agreed and it never is, there is no contract (UCC 2-305, Cornell Legal Information Institute).
Two points follow for buyers. First, a clause that says price "will follow the market" without naming a series is exactly the kind of standard the section describes as possibly unset, and it invites a dispute about what was meant. Second, this is a domestic sales-law rule. If the parts cross a border, the UN sales convention may govern instead; ask counsel whether the CISG applies to your purchase and what it changes.
What should you ask for in the RFQ so the clause is easy to write?
Ask every bidder to price material as a separate line, state the alloy and stock form, and say which index or invoice basis they would accept. Quotes built that way can be compared and indexed without a second round.
Ask for the material line in the quote itself: alloy and temper, stock form, stock weight charged per part, and the base-month metal price per unit weight used. Ask bidders to name the series or price source they would use for adjustment and how often they would review it. A supplier who cannot say what metal they buy, or in what form, cannot support an indexed clause. The broader quote package is covered in the RFQ package guide, and the other cost lines you will want broken out are in the machining cost drivers guide.
Saola quotes CNC turned and milled parts from its lead plant in Vietnam. If you want the material line broken out and an adjustment basis proposed, say so in the RFQ note when you send the drawing.
Frequently asked
Should an adjustment clause work in both directions?
Yes. A clause that lets the price rise but never fall is a surcharge, not an adjustment mechanism. The federal clause, DFARS 252.216-7000, requires decreases to be passed on as well as increases, and the BLS guide notes that floors and ceilings can both be agreed.
Can the clause use a published metal price instead of a government index?
It can, provided both sides can read the same source, the series or product is named exactly, the base month is fixed and the clause says what happens if the source changes or disappears. The BLS guide cautions that unofficial estimates and conversions are easier to challenge.
How often should the price be reviewed?
The BLS guide uses annual adjustment as its example and asks that the frequency and base period be stated. A shorter cycle fits a volatile metal but adds work on both sides, so match it to how often the supplier really buys metal.
What if the index I chose is discontinued or renamed?
The BLS guide treats a renamed or recoded series as the same series, and suggests a default provision that falls back to the next higher-level series. Write that fallback into the clause, with a rule for a missing month.
Does this guide recommend a threshold or a cap?
No. Thresholds and caps depend on the material share of the part, how volatile the metal is and how long the agreement runs. Set them from the supplier's material breakdown and have counsel review the final wording.
Sources
- Producer Price Index (PPI) Guide for Price Adjustment, U.S. Bureau of Labor Statistics, 2021
- DFARS 252.216-7000, Economic Price Adjustment, Basic Steel, Aluminum, Brass, Bronze, or Copper Mill Products, Acquisition.gov, JAN 2023
- UCC 2-305, Open Price Term, Legal Information Institute, Cornell Law School, accessed 2026
- Producer Price Index by Industry: Machine Shops, Turn Products, Screw, Nut, Bolt Manufacturing, Federal Reserve Bank of St. Louis (FRED), data from U.S. Bureau of Labor Statistics, accessed 2026