U.S. Machine Shops (NAICS 33271) Investment Primer [1]

This is a rollup page. In the North American Industry Classification System (NAICS), the five-digit industry 33271 contains exactly one six-digit industry, 332710, so the two are effectively the same thing. This page gives the level's own official figures and then points you to the detailed leaf primer for the full investment case.

1. Overview

Machine shops turn customer designs into precision metal, plastic, or composite parts, generally in low volumes on a job or order basis. They are essential suppliers to aerospace, defense, industrial machinery, vehicles, medical devices, semiconductors, energy, and maintenance markets.

Because NAICS 33271 has only one child industry, everything true of the five-digit level is true of the six-digit level 332710. Investors have two routes — a small group of listed custom-manufacturing operators and marketplaces (none a clean pure play) and a large field of private independent shops and acquisition platforms. The industry combines attractive niches with commodity-like capacity: specialized, qualified shops can earn strong returns, while undifferentiated shops compete mainly on price and delivery. See the 332710 primer for the full treatment.

2. What's inside — and why this level equals its one child

NAICS is a nested system: each five-digit industry breaks into one or more six-digit industries. NAICS 33271 breaks into a single one:

When a five-digit industry has just one child, the parent and child cover the same establishments, the same output, and the same companies. So this page does not repeat the child's analysis — it confirms the size at this level and hands off to 332710.

Two scope boundaries matter when reading any figure below. Adjacent activities sit in other codes — precision turned products under NAICS 332721, fasteners under NAICS 332722, non-automotive stamping under NAICS 332119, plate work under NAICS 332313, metal finishing and heat treating under NAICS 33281, automotive stamping under NAICS 336370, and industrial-machinery repair under NAICS 811310.[1] And captive machining performed in-house at an original equipment manufacturer (OEM), government facility, or other business is classified with that parent activity. Sales at this level are therefore not the value of every machined part made in the United States, and should not be described as the total addressable market for CNC machining.

3. Size (rollup figures)

These are the federal measures for NAICS 33271. They match the child level because the two are the same population; the child primer's revised research verified each figure directly against the underlying federal release.

Which revenue number to use. Four federal programs size this industry and they do not agree exactly: $44.73 billion of 2022 Economic Census receipts,[5] $45.30 billion of 2022 Annual Business Survey revenue,[7] $45.68 billion of 2022 BLS sectoral output,[4] and $46.54 billion of 2023 AIES sales.[2] The spread reflects different survey frameworks, definitions, and vintages, not four measurements of the same thing. Use one consistently, cite which; do not average or add them. The same caution applies to the firm counts — 16,876 in the 2022 Economic Census[5] against 16,719 employer firms in the 2022 Annual Business Survey[7] — where the roughly 1% gap is a program difference rather than industry change. The Annual Business Survey also reports 225,683 employees for 2022, close to the 223,313 County Business Patterns count for 2023.[6][7]

Concentration. This is an unusually fragmented industry, and the newer establishment-size data reinforce it. The largest four firms accounted for about 2% of revenue, the largest eight about 3.6%, the largest twenty about 7%, and the largest fifty about 12%.[5] The Herfindahl-Hirschman Index (HHI) — a standard measure of concentration where the U.S. Department of Justice treats anything below 1,500 as unconcentrated — was roughly 3.5, essentially atomistic.[5] Size distribution tells the same story from the other end: 83.3% of employer establishments have fewer than 20 employees and 94.9% have fewer than 50.[6] No single operator moves the market.

Undercount caveat. These are employer statistics: they exclude owner-only (nonemployer) businesses, and the available machine-shop nonemployer field is suppressed, so no owner-only count should be inferred.[7] They also omit captive machining done in-house at an OEM, government facility, or other business, which is classified with the parent activity. Note too that an establishment is a single physical location while a firm may own several — which is why establishment counts exceed firm counts here.[6][7] Because small and individual ownership dominates this industry, the true establishment count is higher than the employer figure shown.

4. Investable universe

Value at this level is entirely within child 332710, so the same names apply. There is no listed pure play, and the child's revised research quantifies why. Proto Labs (New York Stock Exchange: PRLB) is the closest large direct proxy, with CNC-machining revenue of $243.3 million, or 45.6% of 2025 revenue, alongside injection molding, additive manufacturing, sheet metal, and outsourced network capacity; consolidated gross margin was 44.5% and operating margin 4.7%.[8] Xometry (Nasdaq: XMTR) is a marketplace rather than an operator, with $629.6 million of 2025 marketplace revenue at a 34.7% marketplace gross margin — a spread between customer orders and supplier fulfillment cost, not shop-floor manufacturing margin, and CNC revenue is not broken out.[9] NN, Inc. (Nasdaq: NNBR) reported $422.2 million of 2025 revenue across a broader engineered-products platform that also stamps, welds, and assembles.[10] Air Industries Group (NYSE American: AIRI) is the most direct but the smallest, at $47.9 million of 2025 revenue with attendant customer-concentration and balance-sheet risk.[11]

The more direct route is private: independent shops plus sponsor-backed platforms, and the field is now broader than this page previously showed. It includes CORE Industrial Partners (Cadrex, Fathom Digital Manufacturing, PrecisionX),[12] Centerbridge Partners (Precinmac),[13] L Squared Capital Partners (BTX Precision),[14] the D. E. Shaw-supported Threadlock Precision in aerospace and defense machining,[15] and Re:Build Manufacturing, which has bought specialist machining operations serving demanding applications.[16] Full company detail, revenue exposure, and platform lists are in the 332710 primer.

5. How the money works

A shop quotes material, programming and setup, machine time, tooling, inspection, outside finishing, and delivery; repeat programs generally beat prototypes because setup and first-article cost spreads over more parts. Economics turn on machine and spindle utilization, setup versus cutting time, skilled-labor availability, material pass-through, scrap and rework, and customer mix. Labor is the largest broadly observable cost: 2023 County Business Patterns payroll of $14.23 billion against 2023 AIES revenue of $46.54 billion implies roughly 30.6%, though that is a directional cross-survey comparison only — payroll excludes benefits, contract labor, and owner compensation, and the two programs report on different frameworks.[6][2]

Factory overhead creates operating leverage, so a modest volume decline can cause a much larger earnings decline; on the way up, overtime, expedited material, outside processing, and tool wear cap incremental margins, and Proto Labs notes that a quick-turn model requires capacity investment ahead of demand.[8] Normalize earnings before interest, taxes, depreciation, and amortization (EBITDA) across a cycle against maintenance capital spending and free cash flow.

Federal data at this level still do not provide a reliable margin benchmark, and one tempting shortcut should be resisted: 2023 AIES revenue less operating expenses leaves $7.60 billion, or 16.3% of revenue,[2][3] but that is an AIES expense spread, not an industry EBITDA, EBIT, or net margin — Census expense definitions differ from company GAAP reporting, and the subtraction says nothing about cash earnings available to owners. See 332710 for the full walkthrough.

6. Demand drivers

Demand follows customers' production schedules, maintenance needs, product launches, capital spending, and inventory cycles. Aerospace and defense can provide long backlogs; general industrial, vehicle, and semiconductor-equipment work is more cyclical.

The structural supports the child now documents are real but forward-looking, not guaranteed. The Reshoring Initiative recorded 244,000 announced U.S. manufacturing jobs from reshoring and foreign direct investment in 2024.[17] Automation is both an enabler and a competitive requirement — multi-axis machines, pallet pools, robots, and in-process inspection raise unattended hours but also raise capital intensity — and U.S. orders for metalworking machinery reached $5.74 billion in 2025, 22.5% above 2024 after three years of decline; that is a machine-tool capital-spending indicator rather than machine-shop revenue, but it signals a renewed investment cycle.[18] Digital quoting and marketplaces lower transaction friction and expose local shops to national demand while increasing price transparency and shifting quotation risk, a hazard Xometry flags directly.[9] Additive manufacturing is not purely a substitute threat: the current NAICS definition includes additive work done by machine shops, and printed metal parts usually still need machining of mating surfaces, threads, and critical tolerances.[1]

7. Regulation

Machine shops are lightly regulated relative to utilities or finance but face real operating rules. The Occupational Safety and Health Administration (OSHA) governs machine guarding, hazardous-energy control, electrical safety, and noise,[19] and metalworking-fluid mist and skin contact require fluid management, ventilation, and exposure controls.[20] The Environmental Protection Agency (EPA) and state agencies regulate spent solvents, oils, coolants, and metal-bearing waste under the Resource Conservation and Recovery Act (RCRA), with requirements scaled to how much hazardous waste a shop generates;[21] shops discharging oily wastewater or running finishing processes may also fall under the EPA's Metal Products and Machinery effluent guidelines, implemented through discharge permits.[22] Defense work can trigger the International Traffic in Arms Regulations (ITAR) and export controls[23] plus Department of Defense cybersecurity obligations, including the Defense Federal Acquisition Regulation Supplement (DFARS) and Cybersecurity Maturity Model Certification (CMMC).[24] Regulated customers separately impose quality-system certifications and approved-supplier status — commercial barriers rather than statutes, but ones where a single quality escape can cost rework, chargebacks, or program disqualification far exceeding the original part revenue. Detail is in 332710.

8. Consolidation

Fragmentation — visible in the low concentration ratios and in the 94.9% of establishments under 50 employees[5][6] — creates room for roll-ups, and the growing sponsor list in section 4 shows capital is pursuing it. Platforms can centralize purchasing, sales, quality systems, automation, and spare capacity. But this is not a simple roll-up: skilled employees, customer approvals, local relationships, and shop-level scheduling are hard to integrate. Entry barriers are modest for basic machining and much higher for tight-tolerance, hard-material, multi-axis, or customer-qualified work, which is where durable advantage sits. Value must come from operating improvement and customer diversification, not merely higher acquisition multiples or added leverage.

9. Risks

Key risks are industrial cyclicality and order deferrals; customer or end-market concentration; low utilization and fixed-cost deleverage; mis-quotes and fixed-price material exposure; machine downtime; quality escapes; slow customer qualification; and, in acquisitions, integration and leverage. Public exposure often includes non-machining businesses; private exposure carries liquidity and reporting risk.

Two risks the child now quantifies deserve emphasis at this level. On labor and succession: machine shops employed an estimated 64,080 machinists at a median $23.62 per hour in the May 2023 occupational survey, 24.2% of industry employment,[25] and BLS projects machinist employment roughly flat from 2024 through 2034 with tool-and-die-maker employment down 11%, while still expecting about 34,200 annual openings for the combined occupations — almost entirely replacement demand.[26] On trade and input costs: 80.3% of respondents to the National Association of Manufacturers' fourth-quarter 2025 survey said they had paid tariffs on imported manufacturing inputs during 2025, and 72.1% of those looking to hire cited skilled production workers including machinists.[27] Full list in 332710.

10. How to invest & outlook

For investment approach and current outlook, use the 332710 primer — the analysis is identical at this level. In short: public investors should separate direct machining revenue from marketplace, tooling, or unrelated manufacturing exposure and watch organic machining growth, gross margin, backlog, customer concentration, capital expenditure, free cash flow, and return on invested capital; private investors should prioritize recurring qualified programs, diversified customers, modern equipment, clean quality records, credible maintenance-capital budgets, and capable second-line management. Machine tools without customers, operators, or approvals have limited earning power, so asset value alone is not a floor.

Current indicators are mixed, and the child now puts numbers on both sides. The broader fabricated-metal-products sector ran at 76.9% capacity utilization in June 2026, below its 78.5% long-run average,[28] and the machine-shop Producer Price Index rose only about 0.6% year over year through June 2026, indicating little industry-wide pricing momentum.[29] Against that, Proto Labs' CNC-machining revenue grew 17.6% in 2025, evidence that differentiated channels can take share in a flat market.[8] The outlook is neutral-to-selective: aerospace, defense, localization, and automation offer support, but modest capacity utilization and weak broad pricing leave undifferentiated commodity shops exposed. The best investments are specialized, qualified, operationally disciplined businesses bought at valuations that recognize both capital intensity and cyclicality.

Sources

[1] U.S. Census Bureau, "2022 NAICS Definition: 332710 Machine Shops," 2022, https://www.census.gov/naics/?details=332710&input=332710&year=2022

[2] U.S. Census Bureau, "Annual Integrated Economic Survey: Machine Shops Sales," 2023, https://data.census.gov/table/AIESINVTIMESERIES.AIES00INV?q=332710

[3] U.S. Census Bureau, "Annual Integrated Economic Survey: Machine Shops Operating Expenses," 2023, https://data.census.gov/table/AIESEXP02TIMESERIES.AIES00EXP02?q=332710%3A+Machine+shops

[4] U.S. Bureau of Labor Statistics, "Current-Dollar Sectoral Output for Manufacturing: Machine Shops," updated 2026, https://fred.stlouisfed.org/series/IPUEN332710T300000000

[5] U.S. Census Bureau, "2022 Economic Census: Concentration Ratios and Receipts, NAICS 33271," 2022, https://www.census.gov/programs-surveys/economic-census.html

[6] U.S. Census Bureau, "2023 County Business Patterns," 2025, https://www.census.gov/data/datasets/2023/econ/cbp/2023-cbp.html

[7] U.S. Census Bureau, "Nonemployer Statistics by Demographics: Employer and Nonemployer Statistics," 2022 data, https://data.census.gov/table/ABSNESD2022.AB00MYNESD01B?codeset=naics~33271&g=010XX00US

[8] Proto Labs, "2025 Form 10-K," 2026, https://www.sec.gov/Archives/edgar/data/1443669/000144366926000010/prlb-20251231.htm

[9] Xometry, "2025 Form 10-K," 2026, https://www.sec.gov/Archives/edgar/data/1657573/000119312526066959/xmtr-20251231.htm

[10] NN, Inc., "2025 Form 10-K," 2026, https://www.sec.gov/Archives/edgar/data/918541/000091854126000023/nnincform10-k2025.htm

[11] Air Industries Group, "2025 Form 10-K," 2026, https://www.sec.gov/Archives/edgar/data/1009891/000121390026035731/ea0282298-10k_airindustries.htm

[12] CORE Industrial Partners, "Portfolio Overview," 2026, https://coreipfund.com/wp-content/uploads/2026/02/CORE-Two-Pager_February-2026.pdf

[13] Centerbridge Partners, "Private Equity Portfolio: Precinmac," 2026, https://www.centerbridge.com/private-equity

[14] L Squared Capital Partners, "Executing the Consolidation Playbook at BTX Precision," 2025, https://www.lsquaredcap.com/l-squared-off-to-a-quick-start-executing-consolidation-playbook-at-btx-precision-with-nine-acquisitions-completed/

[15] Threadlock Precision, "Acquisition of J&F Machine," 2025, https://www.prnewswire.com/news-releases/threadlock-precision-supported-by-the-d-e-shaw-group-acquires-jf-machine-to-expand-us-aerospace-and-defense-precision-manufacturing-network-302585139.html

[16] Re:Build Manufacturing, "Acquisition of Wonder Machine," 2025, https://rebuildmanufacturing.com/?p=2732

[17] Reshoring Initiative, "2024 Reshoring Report," 2025, https://reshorenow.org/june-9-2025/

[18] Association for Manufacturing Technology, "Manufacturing Technology Orders Set Record in December 2025," 2026, https://www.amtonline.org/article/manufacturing-technology-orders-set-record-in-december-2025

[19] Occupational Safety and Health Administration, "Machine Guarding: General Requirements," current, https://www.osha.gov/etools/machine-guarding/introduction/general-requirements

[20] Occupational Safety and Health Administration, "Metalworking Fluids," current, https://www.osha.gov/metalworking-fluids

[21] U.S. Environmental Protection Agency, "Hazardous Waste Generator Regulatory Summary," current, https://www.epa.gov/hwgenerators/hazardous-waste-generator-regulatory-summary

[22] U.S. Environmental Protection Agency, "Metal Products and Machinery Effluent Guidelines," current, https://www.epa.gov/eg/metal-products-and-machinery-effluent-guidelines

[23] U.S. Department of State, "Defense Trade Controls Compliance Program Guidelines," current, https://www.pmddtc.state.gov/sys_attachment.do?sys_id=1216c09a1b671d14d1f1ea02f54bcb25

[24] U.S. Department of Defense, "DFARS Subpart 204.75—Cybersecurity Maturity Model Certification," 2025, https://www.acq.osd.mil/dpap/dars/dfars/html/current/204_75.htm

[25] U.S. Bureau of Labor Statistics, "Occupational Employment and Wage Statistics: NAICS 332710," May 2023, https://www.bls.gov/oes/2023/may/naics5_332710.htm

[26] U.S. Bureau of Labor Statistics, "Occupational Outlook Handbook: Machinists and Tool and Die Makers," current, https://www.bls.gov/ooh/production/machinists-and-tool-and-die-makers.htm

[27] National Association of Manufacturers, "Fourth Quarter 2025 Manufacturers' Outlook Survey," 2025, https://nam.org/2025-fourth-quarter-manufacturers-outlook-survey/

[28] Federal Reserve, "Industrial Production and Capacity Utilization: Table 7," July 2026, https://www.federalreserve.gov/releases/g17/current/table7.htm

[29] U.S. Bureau of Labor Statistics, "Producer Price Index: Machine Shop Job Work and Job Order Repairs," updated 2026, https://fred.stlouisfed.org/data/PCU3327103327100

For the full investment case — detailed public-company exposure tables, private platform lists, cycle indicators, and the complete sourcing — see the 332710 primer.