Resin pass-through adjustments, worked part by part from each customer's clause.

When a period closes, someone on your team pulls the index values each agreement names, finds every part molded in that resin, works out the change and writes to each customer: a revised price list for one, a letter with the math for another, an entry in a supplier portal for a third. Then the new prices go into your own system before the next invoice.

For the test, AI goes back over copies of adjustments you already made. For each one it drafts the calculation sheet and the customer notice, showing the index row, the months averaged, the weight used and the result. Anything the clause doesn't settle is listed as a question for your reviewer instead of answered.

The index has to be the one the clause names. Agreements point to different publishers: Plastics News, CDI (Chemical Data, part of ICIS since 2020), ICIS's own assessments, or Chemical Market Analytics by OPIS, built from the former IHS Markit base chemicals business. Each carries several rows per resin, such as HDPE for injection or blow molding and PP homopolymer or copolymer, often as a low and a high, with contract kept apart from spot. Plastics News itself discourages using its chart alone as a contract index, processor-to-customer contracts included, and limits republishing its data, which matters when a customer asks for the page behind a letter. The draft names the publisher, row and column, and the low, high or midpoint the clause calls for.

Timing rules are the easiest to get wrong. A clause may compare averages, not month-end values, and it may lag. One packaging maker's published terms adjust each quarter on CDI's net movement over the second, third and fourth months before the adjustment date, once those months are final, and disregard any non-market adjustment CDI makes. Other clauses fix a base month at the quote, or move only when the index leaves a set band. US polypropylene contracts are generally set by formula from polymer-grade propylene (PGP) plus an adder, so a PP move usually traces back to the monthly monomer settlement.

The weight has to be the clause's weight. Quotes usually give part weight in grams while North American indexes move in cents per pound, so the draft converts at 453.6 grams to the pound unless the clause sets its own factor, as those published terms do. The clause decides whether the weight is the net part or includes a share of a cold runner or a scrap allowance, and whether regrind earns a credit. Prices may be per piece or per thousand. A recycled-content part can follow one index for its virgin share and another for its recycled share, and colorant, glass fill and additives usually sit outside a base-resin index unless the agreement brings them in.

Engineering resins often have no index. For polycarbonate, nylon or acetal, an agreement may instead allow an increase backed by the resin maker's or distributor's price letter, after written notice. The draft checks that the letter covers the exact grade on the drawing and that the notice period is met.

A new price counts only once the customer's PO carries it. Until the buyer revises the price on their PO or scheduling agreement, their payables team pays the old one, and the gap comes back as a short payment. Decreases matter as much as increases, because customers watch the same index. Your reviewer, the person who ran these adjustments, checks each part's index row, months, weight, arithmetic and notice against what your team sent.

With a yes, the next index posting runs through the same steps. Depending on your clauses, that is a monthly cycle or the run-up to a quarterly one, inside about 30 days.

Every calculation sheet and notice waits for your reviewer or account lead to approve, change or hold it, and nothing reaches a customer or your price file until a person releases it. The scoring table stays in use through the live month.