CNC Machining and Assembly Cell FOD Guide

By FODBag.com · Updated November 10, 2026

Reviewed by Trent Powell, Founder, FODBag · Reviewed: November 10, 2026

CNC Machining and Assembly Cell FOD Playbook: Clear Chips, Count Tooling and Hand Off Clean

Quick answer: In machining, FOD is chips, swarf, burrs, broken inserts and coolant residue that hide in bores, threads and blind holes. Clear chips at each setup and before parts leave the machine, account for small tooling, recover every piece of a broken tool, inspect critical features per the routing, and confirm condition at a defined hand-off to assembly.

This playbook is for machinists, cell leads, quality inspectors and assembly supervisors. It uses the public IAQG guidance on process debris and tool accountability and NASA MSFC-STD-3598 Rev. D (a flight-hardware standard used as a reference model) and works a hand-off inspection example with checked arithmetic. The routing, cleanliness criteria and part drawings define what clean means for your parts; the counts below are invented and the routine is a FODBag suggestion.

What the opened sources support

IAQG guidance names machining chips as a manufacturing process debris with risk of affecting product (IAQG SCMH 3.4.2 Rev. D, slide 26), and its examples show chips as a foreign object during machining that must be thoroughly cleaned from parts, and as FOd when embedded in a cavity and not removed (IAQG SCMH 3.4.2 Rev. D, slide 7). It expects tool accountability that knows where tools are at all times and reports lost tools or broken pieces (IAQG SCMH 3.4.2 Rev. D, slide 31), and shows a tool tip left in an engine becoming damage (IAQG SCMH 3.4.2 Rev. D, slide 33). NASA requires that when a tool breaks in use, all pieces are recovered and inspected by a FOD Monitor or quality representative, and a lost-tool procedure starts if any piece is missing (NASA MSFC-STD-3598 Rev. D, 5.8.2.2 and 5.8.2.3).

Where chips hide

• Blind holes and threads, where chips pack at the bottom.
• Cross-drilled holes and intersecting passages.
• Pockets, ribs and corners of the part.
• Fixtures, vises and the table, where chips fall into the next setup.
• Coolant lines and tool holders that carry chips between jobs.

Cell routine

1. At each setup: clear chips from the table, fixture and tool holders before loading the part.
2. At tool change: count inserts and small tooling in and out; recover every piece of a broken tool.
3. Before parts leave the machine: clear chips with approved methods, inspect critical features per the routing and cap openings.
4. At hand-off: bag small parts, tag the condition and sign.

Hand-off to assembly

Define who confirms the part is clean, what they check and what record they sign. Chips found at assembly are a sign that the cell step failed, so feed the finds back to the cell. What counts as clean (visual, flush, particle count) comes from your drawing or process specification, not from this page.

Worked example: a hand-off inspection of 12 parts

This example is illustrative, not a customer case. Each of 12 parts has 6 features to check at hand-off, which is 12 × 6 = 72 checks. 66 passed first time and 6 found chips, which were removed and rechecked. The 6 chip finds by feature type:

Check: 12 × 6 = 72; 66 + 6 = 72; first-pass rate 66 ÷ 72 = 91.7% and chip-find rate 6 ÷ 72 = 8.3%; 3 + 2 + 1 = 6. Half of the finds were blind holes, so the cell adds a dedicated blind-hole clearing step and a flush before the part leaves the machine, and next week’s hand-off rate shows whether it worked.

What good looks like

• Chips are cleared at every setup and before parts leave the machine.
• Tooling is counted in and out and every piece of a broken tool is recovered.
• Critical features are inspected per the routing and openings are capped.
• The hand-off to assembly has a named checker, criteria and a signed record.
• Chip finds at hand-off are fed back to the cell.

Matching FODBag products and resources

Machining cell FOD products: FOD cans; FOD buckets; Clear FOD bags; FOD tool bags; FOD signs.

About FODBag. FODBag.com, a Powell Pack Products company in Mesa, Arizona, has made FOD bags, FOD tape, FOD stickers, FOD signs, FOD posters, FOD cans and FOD containers since 2016. FOD tape is 2 in × 108 ft and FOD signs start at $29.99. Questions? Call 602-874-1313, Monday–Friday, 9:00 a.m.–5:00 p.m. Arizona time.

Sources opened for this page

1. IAQG SCMH 3.4.2 Rev. D, FOD Prevention Program: Guidance in Support of IAQG Standard 9146 (June 19, 2023) — Slides 7, 26, 31 and 33 on process debris, chips as FO and FOd, and tool accountability. Opened and read for this page on November 10, 2026.
2. NASA MSFC-STD-3598 Rev. D, Standard for Foreign Object Damage/Foreign Object Debris (FOD) Prevention (effective July 26, 2021) — Sections 5.8.2.2 and 5.8.2.3 on broken tools. Opened and read for this page on November 10, 2026.

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