How to quote a CNC part: what to ask before you give a price

The quote that goes wrong is the one priced in ten minutes from the outline of the part. Before you price a CNC part, settle eight things in a fixed order. Start with the drawing's revision and notes, then the material and the quantities. Next come critical features, surface finish, heat treatment and coating, and last the paperwork and delivery. Answer each from the drawing first. Then send the buyer one numbered message asking only what the drawing leaves open, and quote with your assumptions written in.

Why the order matters

Each answer changes the cost of the next. The material decides the cutting speed and the tool life. The quantity decides whether a fixture pays for itself or the part runs on a vice. Heat treatment decides the route: machine, harden, then grind, with stock left for grinding. And a coating of any thickness changes the final size of every thread and bore it touches.

A fixed order also protects you on a busy day. When three drawings land at once, the estimator who works down the same list every time does not skip the line in the corner that says "hardened and ground". That one note changes the route more than any dimension on the sheet.

The eight questions, in order

1. Drawing revision and the notes block. Read the notes before any dimension: the general tolerance standard, edge breaks, hardness, "no tool marks on face A". If the revision letter is missing or the title block says "preliminary", ask which revision to quote against.
2. Material grade, form and supplier. EN8, EN19, SS304 or aluminium 6061 cut very differently. Will you buy bar or plate, or will the buyer send forgings or castings? Is the mill test certificate needed with each lot?
3. Quantity per release and per year. Setup is spread over one release. The yearly figure decides whether a dedicated fixture is worth making.
4. Critical features. Which dimensions does the buyer's inspection check on every piece: bearing seats, sealing faces, hole positions? These decide which machine runs the part and how many pieces you measure.
5. Surface finish. A roughness value on a sealing face may mean grinding or lapping. A cosmetic face that must be free of marks means extra handling and packing.
6. Heat treatment. The hardness, the case depth if any, and whether it comes before or after machining. Who does it, you or the buyer's own vendor?
7. Coating or plating. Type and thickness, and whether drawing dimensions apply before or after plating. Threads and close bores may need masking or a pre-plating size.
8. Paperwork and delivery. The inspection report expected with each lot, packing such as trays or rust preventive, the delivery point, and the date the first lot is needed.

Where the drawing answers a question, write the answer in your costing sheet and move on. Only the gaps go to the buyer.

One message, not eight

Send the gaps together, numbered in the same order, each with the assumption you will use if there is no answer. Plain text works on both email and WhatsApp.

Thank you for drawing 4471, revision C. Before we quote, a few points the drawing leaves open:

(2) Material: we will buy EN19 bar and send the mill certificate with each lot. Please tell us if you will supply forgings instead.

(3) Quantity: we will quote 500 per release and 6,000 a year. Please correct if different.

(6) Heat treatment: the note says bearing seats hardened. We will quote induction hardening through our partner, followed by grinding. Please confirm the hardness range.

(7) Plating: none assumed.

If we do not hear back by [day], we will quote on these assumptions and list them on the quotation.

The numbers are the same as on your list, so the buyer sees that you followed a method. The quantities in the message are only an example.

Who can answer which question

Purchase can answer quantities, delivery and payment. It cannot answer hardness, critical features or finish, and a purchase officer who guesses may guess wrong. Ask for the name of the development or quality engineer who owns the drawing, and send questions 4 to 7 to that person with purchase copied.

An engineer reads a precise technical question as a sign of a capable shop, and often answers it sooner than purchase answers anything.

Imagine a turning shop in Balanagar

Imagine a CNC turning shop in Balanagar, Hyderabad, quoting a pinion shaft in EN19 for a gearbox maker. The details are illustrative. The estimator priced it from the outline: bar stock, turning, a milled keyway. The note in the corner was missed: bearing seats to be induction hardened and ground.

The order came at that price. The shop then had to buy in hardening and grinding, and leave grinding stock it had not costed. A few shafts distorted in hardening and were scrapped. The lot ran at a loss, and the buyer refused a price revision, because the note had been on the drawing all along.

Now the list above sits as a tick column on the costing sheet, with the notes block as line one. Every quote carries an assumptions line, even when the answer is "no heat treatment assumed". On the next shaft enquiry, questions 6 and 7 went to the buyer's development engineer, who answered. The quote priced hardening and grinding separately, came in higher than a rival's, and lost. The estimator's time per quote went up by about half an hour, and the next lot of shafts was not scrapped.

When to skip the questions

Skip the questions message for a repeat part on the same revision: confirm the revision and quantity, and quote. Skip it when the RFQ pack already answers all eight, and list your assumptions instead. No quantity, no date, no revision? Spend no estimator time yet. The note on qualifying a directory enquiry has the questions that sort that out first.

A prototype for ten pieces needs a lighter version of this list. The post on prototype or production orders covers the difference. Once the costing is done, machine hours or part price covers how to show the number to procurement.

The questions weigh differently by process. A grinding job lives on finish, a wire EDM job on the corner radius.

Add the tick column to your costing sheet

Eight rows, the notes block first. Use it on the next three drawings and tick every line before anyone writes a price. Save the questions message on the estimator's phone and computer, so it goes out the same way each time. The CNC machining hub covers each process, and the manufacturing hub the wider factory. If the Balanagar mistake sounds familiar and you want the routine set up across your sales desk, with quotation and proposal follow-up after the quote goes out, tell us what you need.