Technical Drawing Checklist for CNC Machined Parts

A technical drawing for machining is complete when a supplier can quote, make and inspect the part from it without asking a question. That takes a title block with the data fields of ISO 7200, views and dimensions that follow ISO 128 and ISO 129-1, a stated general tolerance, individual tolerances on functional features, material, surface and treatment data, and a named standard for geometrical tolerancing.

What makes a technical drawing complete for machining?

A workshop prices and programs what the drawing says. A requirement that is missing is either guessed by the supplier or discovered at incoming inspection, and both cost more than writing it down. The checklist at the end of this article follows the order in which a machinist reads a drawing: who owns it and which revision it is, how the part is shown, what each dimension may deviate by, what the part is made of, and what the surfaces and edges must look like.

The checklist condenses the entries.

What must the title block contain?

ISO 7200:2004 defines the data fields of a title block: their names, contents and lengths. It lists eight mandatory fields. The revision index is optional in the standard, but in practice a drawing that can change needs one, because the quote and the first article have to refer to a specific version. The standard allows the date of issue alone as the alternative.

Table 1. Title block data fields, ISO 7200:2004

Source: ISO 7200:2004, Tables 1 to 3, read in the identical adoption IS 11665:2009.

ISO 7200 keeps the title block to a minimum. Scale, projection symbol, general tolerance and surface texture requirements stay outside it and appear only when used. The position of the title block on the sheet is set in ISO 5457, the standard for sheet sizes and layout.

Which standards does a machining drawing refer to?

Table 2 lists the ten ISO standards this checklist refers to, with the status of each as of November 2026, read from the catalogue record of a national ISO member.

Table 2. Drawing standards and their status, November 2026

Source: ISO catalogue records as shown by the Institute for Standardization of Serbia (ISS), see Sources.

Two withdrawn standards still appear on drawings. ISO 1302:2002 was withdrawn on 2021-12-20 and replaced by ISO 21920-1:2021 for indicating surface texture. ISO 2768-2:1989 was withdrawn on 2021-02-04, the day ISO 22081:2021 was published, and ISO 22081 does not carry over its tolerance tables; the ISO 2768 article covers what that means for existing drawings. A drawing that cites either one points to a withdrawn standard.

How should views, dimensions and tolerances be shown?

Views, sections and cuts follow ISO 128-3:2022, which is based on the orthographic projection methods of ISO 5456-2. State the projection method with its symbol, and the scale. Read in the wrong method, a drawing puts the views in the wrong places.

ISO 129-1 gives the general rules for presenting dimensions and their tolerances on 2D drawings. In practice:

• Dimension each feature once, so that two values cannot conflict.
• State the general tolerance in or near the title block, for example "ISO 2768-m" (see ISO 2768 general tolerances), so that every untoleranced dimension has an agreed limit.
• Give individual tolerances or an ISO 286 fit on every feature where function sets the limit, such as bearing seats, sealing faces and locating bores. The CNC machining tolerances handbook shows how general tolerances, fits and geometrical tolerances combine on one part.

For form, orientation and location, ISO 1101:2017 defines the symbols and rules, with datum references. ISO 8015:2011 sets the fundamental concepts, principles and rules of the GPS system that ISO 1101 belongs to, and applies to the interpretation of GPS indications on all types of drawings. If a bore must be round and square to a face, write those requirements as geometrical tolerances instead of expecting the size tolerance to cover them.

Name the system. ASME Y14.5-2018 (R2024) is the American standard for geometric dimensioning and tolerancing, maintained by ASME separately from the ISO GPS standards and on stabilized maintenance as of November 2026. A drawing that mixes the two without naming one is ambiguous.

If the tolerances live in a 3D model, say so on the drawing. ISO 1101 allows specifications to be attached to a 3D CAD model under ISO 16792. Without that, send a PDF drawing and a STEP model, and state which one governs when they differ.

What material, surface and treatment data does a supplier need?

Material goes on the drawing as a designation with its standard and delivery condition, not as a trade name: for example EN AW-6082 in temper T6, or steel 1.4404. If the part needs a material certificate, name the type required. EN 10204 defines the types, and the EN 10204 article explains how 2.2, 3.1 and 3.2 differ.

Surface texture is indicated to ISO 21920-1:2021, not ISO 1302. Put a roughness requirement only on surfaces where function needs one, because every requirement on the drawing has to be produced and checked. See Ra and Rz for what the parameters mean.

Edges need a general note. ISO 13715:2017 covers the indication and dimensioning of undefined edges. Without a note, the edge condition is not specified. An edge that needs a defined chamfer is dimensioned like any other feature under ISO 129-1.

Heat treatment and coating each need the process, the required result and the sequence. Name the result as a property with its test method and range, for example a hardness range, and say whether it applies before or after final machining. State which surfaces must stay uncoated or masked.

What should you check before a drawing leaves for quotation?

Each line is a yes or no question the drawing has to answer.

Identification

• Are the eight mandatory ISO 7200 fields filled in?
• Is there a revision index or a date of issue that identifies this version?
• Does the drawing number match the file names of the PDF and the STEP model?
• On multi-sheet drawings, is "sheet n of m" stated?

Views and dimensions

• Are the projection symbol and scale shown?
• Is every feature visible in a view or section (ISO 128-3), and dimensioned once?

Tolerances

• Is a general tolerance class written in or near the title block, and does it cite ISO 2768-1:1989 rather than an undated part 2?
• Does every functional feature have an individual tolerance or an ISO 286 fit?
• Do geometrical tolerances name ISO 1101 or ASME Y14.5, and do they have datums?

Material and treatment

• Is the material given as a standard designation with delivery condition?
• Is the required EN 10204 certificate type stated?
• Do heat treatment and coating state process, result, sequence and masked surfaces?

Surface and edges

• Is surface texture indicated to ISO 21920-1, and only where needed?
• Is there a general edge note, or ISO 13715 indications on the edges that matter?

Files and request

• Are PDF drawing and STEP model both included, with a statement of which one governs?
• Do the request and drawing together give the quantities, the packaging and the documents required?

What does an incomplete drawing cost?

The cost of a missing entry rarely shows on the drawing itself. It appears as a question before the quote, which delays the quote. It appears as an assumption inside the quote, which the price then depends on. Or it appears at incoming inspection, when the supplier measured to one reading of the drawing and the buyer expects another. The last one also puts the parts at risk.

Our network works to ISO 2768-m as standard and tighter where the drawing specifies it. If the drawing is missing or incomplete, see design engineering.

Frequently asked questions

What must a technical drawing for CNC machining contain?

A title block with the ISO 7200 data fields, views with a stated projection method, dimensions to ISO 129-1, a general tolerance class, individual tolerances on functional features, the material designation and delivery condition, surface texture and edge requirements, and any heat treatment or coating with its sequence.

Which title block fields does ISO 7200 make mandatory?

Eight: legal owner, identification number, title, document type, date of issue, sheet number, creator and approval person. The revision index, number of sheets and language code are optional in the standard.

Is ISO 1302 still valid for surface texture symbols?

No. ISO 1302:2002 was withdrawn on 2021-12-20 and replaced by ISO 21920-1:2021. A drawing for a new part should cite ISO 21920-1.

Should a drawing follow ISO 1101 or ASME Y14.5?

Either can work, but the drawing has to name one. ISO 1101:2017 belongs to the ISO GPS system with ISO 8015:2011, ASME Y14.5-2018 (R2024) is the American system, and a drawing that mixes the two without naming a standard is ambiguous.

Is a 3D model enough without a drawing?

Only if the tolerances and notes are attached to the model and the contract says so. ISO 1101 allows geometrical specifications to be attached to a 3D CAD model under ISO 16792. Otherwise send a PDF drawing for the requirements and a STEP model for the geometry, and state which one governs if they differ.

Sources

1. ISO 7200:2004, Data fields in title blocks and document headers (ISS, national ISO member: stage 90.93, confirmed 2025-01-08)
2. IS 11665:2009, identical adoption of ISO 7200:2004, Tables 1 to 3 and clause 4 (Bureau of Indian Standards, public copy)
3. ISO 128-1:2020, General principles of representation, Part 1 (ISS: confirmed 2026-05-20)
4. ISO 128-3:2022, Views, sections and cuts (ISS)
5. ISO 129-1:2018, Presentation of dimensions and tolerances, general principles (ISS: stage 90.92, 2026-06-17)
6. ISO 5457:1999, Sizes and layout of drawing sheets (ISS: confirmed 2026-09-07)
7. ISO 5456-2:1996, Projection methods, orthographic representations (ISS: confirmed 2025-01-08)
8. ISO 1101:2017, Geometrical tolerancing (ISS: confirmed 2022-10-03)
9. ISO 8015:2011, GPS fundamentals, concepts, principles and rules (ISS: confirmed 2021-12-10)
10. ISO 21920-1:2021, Surface texture, indication (ISS: published 2021-12-20, replaces ISO 1302:2002, stage 90.92 since 2025-10-07)
11. ISO 1302:2002, withdrawn 2021-12-20, replaced by ISO 21920-1:2021 (ISS)
12. ISO 13715:2017, Edges of undefined shape, indication and dimensioning (ISS: confirmed 2024-10-29)
13. ISO 2768-1:1989, General tolerances, Part 1 (ISS: published, revision project listed)
14. ISO 22081:2021, General geometrical and size specifications, published 2021-02-04, listed as replacing ISO 2768-2:1989 (ISS)
15. ISO 2768-2:1989, withdrawn 2021-02-04 (ISS: stage 95.99)
16. E DIN EN ISO 22081:2021-12, note that ISO 22081 cannot technically replace ISO 2768-2 (DIN Media)
17. ISO 286-1:2010, ISO code system for tolerances on linear sizes (ISS: confirmed 2026-06-19)
18. ASME Y14.5-2018 (R2024), Dimensioning and Tolerancing, stabilized maintenance (ASME)

Questions on a drawing? sales@ertas.engineering

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