How a Design Change Moves a Quotation: A Change Log for Tooling, Material and Timing

A design change reaches a quotation through one of three lines: tooling, material or timing. It touches tooling when the revision needs new or modified tooling, a different setup, or a fixture that did not exist in the previous build. It touches material when the revision changes the specified material, grade, finish, tolerance, packaging or the yield a supplier assumed when they first priced the part. It touches timing when the revision adds a step, re-sequences production, or asks for a schedule shorter than the one the first quote was built on. So the question to send with a revision is not "how much more is it?" but "which line of your previous quote does this change move, and which line does it leave alone?"

Ask for the lines that did not move, too

When a supplier answers a revision with a single new total, you lose the ability to compare. Ask for the same line structure you received the first time, with an explicit note on each line saying whether it is affected, unaffected, or not yet known. "Not yet known" is an honest and useful answer; it tells you the revision is still open and gives you something to chase. What you want to avoid is a sentence like "minor adjustment, no impact" that names no line at all, because you cannot compare it against the other supplier's "minor adjustment" and you cannot revisit it later when the change turns out to be larger than expected.

It also helps to ask whether an effect is one-time or recurring: tooling and setup are usually one-time, while material, finish and added process steps usually follow every unit. You are not asking for a number at this stage, only for the shape of the change. Suppliers answering in this shape is what makes two quotes comparable, and it is the single most useful thing you can request before you ask anyone to reprice.

The three lines, in buyer language

Tooling. Ask whether the change can be produced with the tooling already quoted, whether existing tooling needs modification, or whether new tooling is required. Ask who owns the tooling and where it will be held — that is a commercial question you should settle in writing, not a detail to inherit from a previous project. If the answer is "we will see when we get to it," record it as open rather than as settled.

Material. Ask whether the revision changes the material specification itself, or only what is done to it. A change of grade, coating, finish or packaging is a material question; a change of tolerance is often both a material and a tooling question, because tighter tolerance can mean more scrap, more inspection, or a different process. Ask the supplier to state which of those they assumed. Two suppliers can answer the same drawing differently simply because one assumed existing material stock and the other assumed a fresh buy.

Timing. Ask when the schedule clock starts: at drawing approval, at deposit, at material availability, or at tooling completion. Ask whether the revision moves that start, adds a step before it, or compresses what follows. Timing questions are the ones most often answered verbally and least often written down, and they are usually the reason two quotes that look identical on paper behave differently once you commit.

A change log to send with every revision

Copy the block below into your own document and fill in what you can answer yourself. Leave the rest blank rather than guessing — a blank field is a question you can ask, while a guessed field becomes an assumption the supplier may quietly adopt.

Change ID:
Date raised:
Drawing or part reference affected:
Previous quote reference:
What changed — before:
What changed — after:
Who requested the change (buyer / supplier / other):

Line 1 — TOOLING
  Does existing tooling still work? (yes / no / unknown)
  Is modification or new tooling required? (none / modify / new)
  One-time or per-unit effect? (one-time / per-unit / unknown)
  Tooling ownership and storage:
  OPEN QUESTION TO SUPPLIER:

Line 2 — MATERIAL
  Material specification changed? (yes / no / unknown)
  Finish, coating, tolerance or packaging changed? (yes / no / unknown)
  Assumption about existing stock or fresh buy:
  One-time or per-unit effect? (one-time / per-unit / unknown)
  OPEN QUESTION TO SUPPLIER:

Line 3 — TIMING
  When does the schedule clock start?
  Does the revision move that start? (yes / no / unknown)
  Does it add a step or compress what follows?
  What must happen before production can start?
  OPEN QUESTION TO SUPPLIER:

Requested from supplier: restate the quote in the same line structure,
marking each line as affected / unaffected / not yet known.

Using the log when two quotes disagree

When two suppliers return different answers to the same revision, check the log before you check the totals. In most cases the disagreement is not about price at all: one supplier assumed the tooling exists, the other assumed it has to be made; one priced the material you specified, the other priced a substitute they assumed would be acceptable; one started the clock at approval, the other started it at deposit. Ask each supplier to restate those assumptions in writing against your log. Once the assumptions match, the remaining difference is a genuine commercial difference you can negotiate; before they match, any comparison is between two different products.

Do not average the two answers and do not treat the lower one as the more accurate one. An unexplained low answer on a revision is often a sign that a line was left out, not that a supplier is more efficient.

What a quotation does not tell you

A few cautions worth keeping next to the log. Incoterms describe where delivery responsibility and risk shift between the parties; they do not by themselves prove quality outcomes or payment terms, so a term appearing on a quote should not be read as evidence of either. A screening result, a directory listing or a mention of a standard is not a certification — treat any certificate claim as something to be verified separately, with the issuing body and scope confirmed, before you rely on it.

For general background on quality management systems, ISO publishes an overview of ISO 9001. That is context for how a supplier may structure quality management; it does not tell you which line of a quotation a design change moved, and it is not a substitute for asking the tooling, material and timing questions above. Nothing here is legal, customs or regulatory advice, and the questions are editorial suggestions for your own process rather than requirements you must follow.

What a review can and cannot do

Keep the change log with the affected quotation and mark tooling, material and timing questions that are still open. The Sourcing Desk worksheet can help prepare a local draft brief; it does not send it or confirm a supplier response. Re-quote and approval decisions need the actual revised specification and supplier answers.

Your next action on this topic

Take the revision you are holding right now, copy the change log, and fill in only the fields you can answer yourself. Mark any line you cannot answer as "unknown" and write one question under each of the three lines. Then send the log with your brief and ask each supplier to return their quote in the same line structure, marking each line as affected, unaffected or not yet known — that single request is what turns a changed drawing into a quotation you can actually compare.