Top CNC machine shops in Michigan, ranked by ChatGPT answers

Places ChatGPT showed

• United CNC Machining · 4.6★ · Machine shop
• Advanced CNC Technology, Inc. · 5.0★ · Machine shop
• Prosper-Tech Machine & Tool · 5.0★ · Machine shop
• Metalmite Corporation · 5.0★ · Machine shop
• C2 Machining. · Machining manufacturer
• Topcraft Precision Manufactured Solutions · 5.0★ · Machining manufacturer
• Precision Advanced Machining Co. - Building 2 · Machine shop
• Apogee CNC Inc. · 5.0★ · Machining manufacturer
• USA Robotic Machine, LLC. · 5.0★ · Machine shop
• KCME · 5.0★ · Machine shop

If you're sourcing CNC machining in Michigan, I’d shortlist shops based on the type of work rather than declare one shop universally “best.” Michigan has a large machining base, spanning prototype/job shops, automotive production, aerospace/defense, and high-precision 5-axis work.

Strong Michigan CNC shops to consider

• United CNC Machining — Auburn Hills. A strong candidate for complex, tight-tolerance work; it advertises 3-, 4-, and 5-axis milling, multi-axis mill/turn, wire EDM, and AS9100D/ISO-certified quality systems.
• Advanced CNC Technology, Inc. — Sterling Heights. Particularly relevant for aerospace, defense and automotive prototypes, formed parts and welded assemblies; ISO 9001:2015, AS9100D and ITAR registered.
• Prosper-Tech Machine & Tool — Richmond. Focuses on tight-tolerance, build-to-print machining, including 3-, 4- and 5-axis milling and production machining, with a strong aerospace/defense orientation.
• Metalmite Corporation — Rochester. Full-service CNC shop with multi-axis machining, wire EDM and grinding, making it interesting for intricate parts and jobs requiring several processes in-house.
• C2 Machining — Kentwood/Grand Rapids area. Offers multi-axis machining and large-part capability, along with fabrication and metrology; its published qualifications include AS9100D, ISO 9001:2015 and ITAR registration.
• Topcraft Precision Manufactured Solutions — Hudsonville. Worth considering for higher-volume precision production, with CNC lathes, Swiss-type lathes, mill-turn centers and vertical machining centers.
• Precision Advanced Machining Co. - Building 2 — Clinton Township. Particularly interesting for large and complex parts, with 3-, 4- and 5-axis machining plus substantial turning capacity.
• Apogee CNC Inc. — Dexter. Focuses on fast-turn, tight-tolerance multi-axis machining and turning, including 3-, 4- and 5-axis work.
• USA Robotic Machine, LLC. — Rives Junction. Geared toward complex prototypes, one-offs and short/medium production runs, with 5-axis machining and large machining envelopes.
• KCME — Plainwell. A Michigan-based precision manufacturing shop with in-house CNC machining and assembly.

A few particularly notable capabilities

For 5-axis / complex geometry, Michigan suppliers listed by Thomasnet include United CNC, Advanced CNC Technology, Franchino Mold & Engineering, Xcentric Mold & Engineering, Evolution Tool and others.

For prototype through production, Research Tool Corporation in Ovid advertises multi-axis machining, 5-axis CNC, milling and turning, from single prototypes through production runs of up to 50,000 pieces.

For automotive/tooling-oriented work, there are numerous Southeast Michigan options, while West Michigan has a substantial cluster of precision and production machining suppliers.

How I'd narrow the list

If you tell me these four things, I can make you a much more useful Michigan CNC shop shortlist:

1. Part: prototype, production, mold/tooling, fixture, etc.
2. Material: aluminum, steel, stainless, titanium, Inconel, plastic, etc.
3. Size/tolerance: approximate part dimensions and tightest tolerance.
4. Quantity: 1–10, 10–100, 1,000+, etc.

I can then compare 5–10 Michigan shops by 5-axis capability, tolerances, certifications, industries served, likely production volume, location, and quoting/contact information rather than relying on generic rankings.

Places ChatGPT showed

• Carpatians Manufacturing · 5.0★ · Machining manufacturer
• Dun-Rite Machining · 4.6★ · Machine shop
• Protomatic Inc. · 5.0★ · Machine shop
• United CNC Machining · 4.6★ · Machine shop
• Superior Machining Inc · 5.0★ · Machine shop
• Detroit 3D Manufacturing · 4.7★ · 3D printing service
• NMI Prototype Machining · 5.0★ · Machine shop
• Apogee CNC Inc. · 5.0★ · Machining manufacturer

If your priority is prototypes and short production runs, rather than high-volume automotive production, I’d start with shops that explicitly build their business around low-volume work. Based on their published capabilities and current local-business information, these are worth putting on an RFQ list:

A few particularly interesting fits

For a handful to a few hundred parts: Carpatians is unusually explicit about this niche: it lists a minimum of one piece, typical batches of 10–500, and dedicated low-volume production.

For a prototype that may become production: Dun-Rite is worth considering because it says it handles the same work from prototype through low/mid-volume production, with milling, turning, grinding, inspection and finishing in-house.

For very fast development iterations: Rev1 Technologies in Auburn Hills is another interesting option. It combines CNC with additive manufacturing and urethane casting and explicitly targets 1–500-piece prototype/bridge runs, with DFM support.

For very small runs under 100: Dickie Machine in Wyandotte specifically says it specializes in prototypes and production runs under 100 pieces, has no minimum order quantity, and typically targets two weeks or less.

For larger/complex production-intent parts: United CNC or Protomatic make more sense when you need substantial CNC capacity, demanding tolerances, or aerospace/medical/defense-style quality requirements.

How I'd narrow the list

The right shop depends heavily on the part. For an RFQ, I'd compare 3–5 shops using the exact same package:

• STEP model + drawing/PDF
• Material and condition
• Quantity: e.g. 2 prototypes + 25 production parts
• Critical tolerances/GD&T
• Surface finish and anodizing/plating requirements
• Inspection report requirements
• Desired delivery date
• Whether the design is likely to change after the prototype

Also ask each shop whether the prototype setup/fixture can be reused for the production run. That can make a substantial difference in total cost.

If you tell me your Michigan region (Detroit, Grand Rapids, Ann Arbor, etc.), material, approximate part size, quantity (e.g. 5/25/100), and whether it's 3-, 4-, or 5-axis work, I can narrow this to a short list of shops that are specifically suited to your job.

Places ChatGPT showed

• Protomatic Inc. · 5.0★ · Machine shop
• Prosper-Tech Machine & Tool · 5.0★ · Machine shop
• Dynamic Precision · 5.0★ · Machining manufacturer
• United CNC Machining · 4.6★ · Machine shop
• Advanced CNC Technology, Inc. · 5.0★ · Machine shop
• Precision Aerospace Corp. · 5.0★ · Machining manufacturer
• KCS Advanced Machining Services · 5.0★ · Machine shop
• Michigan Tool & Gauge · 5.0★ · Machine shop
• Topcraft Precision Manufactured Solutions · 5.0★ · Machining manufacturer

If by “best” you mean shops with documented tight-tolerance capability, strong inspection/quality systems, and experience with demanding parts, these Michigan shops stand out. I’m not treating this as an objective ranking; the right choice depends heavily on your part geometry, tolerance stack, material, quantity, and industry.

• Protomatic Inc. — Dexter. Particularly interesting for very high-precision, complex components. Its published capabilities include tolerances as tight as ±0.0001" for appropriate work, plus controlled manufacturing conditions and super-precision turning.
• Prosper-Tech Machine & Tool — Richmond. Strong fit for aerospace/defense and other mission-critical parts. It is AS9100 and ISO 9001 certified, ITAR registered, and offers 3-, 4-, and 5-axis machining with automated production.
• Dynamic Precision — Troy. Worth considering when extremely tight machining needs to be combined with grinding, EDM, and precision inspection under one roof.
• United CNC Machining — Auburn Hills. Multi-axis milling, mill-turn, precision grinding/honing/lapping, and complex 5-axis work make it a candidate for difficult geometries and demanding materials.
• Advanced CNC Technology, Inc. — Sterling Heights. AS9100D, ISO 9001:2015, and ITAR registered, with 3- and 5-axis machining and an explicit focus on tight-tolerance critical components.
• Precision Aerospace Corp. — Grand Rapids. A particularly relevant option for aerospace/defense, high-mix/low-volume work, Swiss machining, complex 5-axis parts, and demanding special processes.
• KCS Advanced Machining Services — Livonia. Strong multi-axis/5-axis capability and a good candidate for complex prototypes and production components.
• Michigan Tool & Gauge — Howell. Focuses on tight-tolerance prototype-to-production machining and complex CNC milling/turning.
• Topcraft Precision Manufactured Solutions — Hudsonville. More production-oriented, with CNC lathes, Swiss turning, mill-turn, and vertical machining for precision components.

A few particularly notable tolerance claims

There are some useful published benchmarks:

CCI, Criterion, and Jamison's published specifications are particularly useful if you're comparing shops based on an explicit tolerance commitment rather than general marketing language.

If you give me the part details—e.g. ±0.0002 vs ±0.0005 tolerance, material, approximate dimensions, 5-axis vs turning, quantity, and whether it's aerospace/medical/automotive—I can narrow this to 3–5 Michigan shops that are specifically suited to that job and include their contact/quote links.

Places ChatGPT showed

• Ai Manufacturing- Michigan CNC Machining · Machining manufacturer
• Complete Machining Services · Local Services
• Detroit 3D Manufacturing · 4.7★ · 3D printing service
• Dynamite Machining Inc · 5.0★ · Machine shop
• Metalmite Corporation · 5.0★ · Machine shop
• Carpatians Manufacturing · 5.0★ · Machining manufacturer
• Dun-Rite Machining · 4.6★ · Machine shop
• Rite Tool Inc · 5.0★ · Machining manufacturer
• Protomatic Inc. · 5.0★ · Machine shop

If speed is the priority, several Michigan shops explicitly advertise same-day or sub-24-hour quoting, and a few advertise parts in as little as 1–3 days. I’d put these on the short list:

Particularly notable

Ai Manufacturing has one of the strongest advertised rapid-turn propositions: it says DFM analysis and real-time pricing can come back within a few hours, with parts produced in as little as one day for qualifying jobs.

Complete Machining Services explicitly advertises same-day quotes by request, immediate machine time, emergency job expediting, and 24/7 operation.

Detroit 3D Manufacturing says machining quotes are returned in less than 24 hours and offers a fast-processing option with parts shipping in 1–3 days.

Another shop worth contacting is Rite Tool Inc. It advertises quotes within two hours, material ordering within an hour of a PO, and same-day-to-next-day material receipt for expedited orders.

For turned parts specifically, Kramer Machine Tool advertises same-day quoting and typical lead times of 5–20 business days.

One caveat: advertised quote/production times aren't guarantees of current capacity. Material availability, tolerances, quantity, inspection requirements, and finishing can change the actual schedule substantially.

If you tell me (1) milling vs. turning, (2) material, (3) quantity, (4) tolerance, and (5) how fast you need the parts, I can narrow this to the Michigan shops most likely to meet that specific deadline.

Places ChatGPT showed

• Metalmite Corporation · 5.0★ · Machine shop
• United CNC Machining · 4.6★ · Machine shop
• 4M Industries · 5.0★ · Machine shop
• JCGibbons Manufacturing Inc. · 4.6★ · Manufacturer
• Fortune Tool & Machine · 4.9★ · Machine shop
• NTL Industries Inc. · 4.9★ · Machine shop
• Prosper-Tech Machine & Tool · 5.0★ · Machine shop
• SRS Manufacturing · 5.0★ · Machine shop
• Dynamic Precision · 5.0★ · Machining manufacturer

If by “reliable” you mean strong quality systems, demonstrated precision capabilities, established track records, and the ability to handle repeat production, I’d put these Southeast Michigan shops on a shortlist. This isn’t a ranking—the right shop depends heavily on your part, material, volume, and tolerances.

• Metalmite Corporation — Rochester. Full-service CNC shop with 5-axis milling, turning, grinding and EDM. Its equipment mix makes it particularly interesting for complex precision work.
• United CNC Machining — Auburn Hills. Large operation with 60+ CNC work centers and 3-, 4-, and 5-axis machining, including large-part capabilities. A candidate for complex or higher-volume work.
• 4M Industries — Livonia. More than 60 CNC machining/turning centers and a production-oriented setup; worth considering for repeat automotive/industrial production.
• J.C. Gibbons Manufacturing — Livonia. Particularly suited to Swiss machining, CNC turning and high-volume screw machining. The company says it is ISO 9001:2015 certified and handles everything from hundreds to millions of parts.
• Fortune Tool & Machine — Wixom. Offers CNC milling including 4- and 5-axis work, plus manual machining, grinding/finishing and inspection support.
• NTL Industries Inc. — Sterling Heights. Family-owned shop offering CNC milling/turning plus fabrication, welding and assembly; potentially useful when you want more than machining from one supplier.
• Prosper-Tech Machine & Tool — Richmond. Focused on tight-tolerance, build-to-print machining, with 3/4/5-axis milling and advanced turning/mill-turn capabilities.
• SRS Manufacturing — Clinton Township. CNC turning, milling, grinding and EDM, with an emphasis on tight-tolerance prototype-to-production work.
• Dynamic Precision — Troy. Particularly relevant when a job combines precision CNC machining with grinding and/or wire EDM and demanding inspection requirements.
• Advanced CNC Technology — Sterling Heights. ISO 9001:2015 and AS9100D certified, ITAR registered, with 3- and 5-axis milling, turning and tight-tolerance machining for aerospace, defense and automotive.
• Protomatic — Dexter. A particularly relevant option for medical/aerospace and difficult materials; it is ISO 9001, ISO 13485 and AS9100D registered and supports prototype through production work.
• CCI Companies — Wixom. ISO 9001:2015 certified, with multi-axis milling, turning and Swiss machining and published capability down to ±0.0002" for appropriate work.
• Meier Screw Products — Ferndale. A long-established shop (since 1934) specializing in short- to mid-run precision turned/machined components; ISO 9001:2015 certified.

How I'd narrow the list

For a typical CNC prototype or production part, I'd send the same RFQ to 3–5 shops and compare:

• Actual tolerance capability on your geometry—not just the tightest tolerance advertised.
• CMM/inspection capability and whether inspection reports come with shipments.
• ISO 9001; AS9100/ISO 13485 if your industry requires them.
• Prototype vs. production experience.
• Material experience, particularly titanium, Inconel, hardened steels, plastics, etc.
• Typical lead time and ability to accommodate engineering changes.
• Whether critical operations are performed in-house.
• PPAP, FAI, SPC, traceability and other documentation requirements.
• Total landed cost rather than simply piece price.

If you tell me what you're machining (material, approximate dimensions/tolerances, quantity, and whether it's prototype or production), I can narrow this to 5 Southeast Michigan shops that are specifically suited to your job, including their certifications and capabilities.

Places ChatGPT showed

• Micro Manufacturing Inc · 5.0★ · Machine shop
• Micron Manufacturing Company · 5.0★ · Machine shop
• Eagle Industrial Group · 5.0★ · Machine shop
• C2 Machining. · Machining manufacturer
• Topcraft Precision Manufactured Solutions · 5.0★ · Machining manufacturer
• Alexander Industries USA · 5.0★ · Machine shop
• Grand Rapids Metaltek Inc · 4.2★ · Machine shop
• Precision Aerospace Corp. · 5.0★ · Machining manufacturer
• ABLE Manufacturing · 5.0★ · Machine shop
• West Michigan Precision Machining · Machine shop
• Kenona Industries, LLC. · 4.4★ · Machining manufacturer

If by “best” you mean strong CNC capability, quality systems, breadth of work, and a track record serving West Michigan manufacturers, I’d put these shops on a serious RFQ list. There isn’t a single objective “best” shop—the right choice depends heavily on part size, tolerances, volume, material, and certifications.

Strong West Michigan CNC shops to consider

• Micro Manufacturing Inc — Dutton/Caledonia. Established in 1965, with CNC milling and turning, 4-axis capability, CMM/CAD/CAM, and experience ranging from prototypes to long production runs. They specifically describe themselves as one of West Michigan's larger job shops.
• Micron Manufacturing Company — Grand Rapids. A long-established production machining company with ISO 9001:2015 certification and CNC milling, turning and screw-machine capabilities. Particularly relevant for repeat production work.
• Eagle Industrial Group — Comstock Park. Interesting option for prototype and low-volume work, with multi-axis machining, turning, wire EDM, and inspection capabilities.
• C2 Machining. — Kentwood. Worth a look for larger/complex components; its published quality system includes AS9100D and ISO 9001:2015, with machining, milling, boring and fabrication serving aerospace, automotive, transportation and mining.
• Topcraft Precision Manufactured Solutions — Hudsonville. More production-oriented, particularly attractive for high-volume precision components, with CNC turning/Swiss turning, mill-turn and vertical machining. It reports ISO 9001:2015 certification.
• Alexander Industries USA — Grand Rapids/Wyoming area. Smaller precision CNC operation with 3- and 4-axis milling/turning, aimed at tight-tolerance components and supporting finishing/packaging requirements.
• Grand Rapids Metaltek Inc — Grand Rapids. A larger-capacity option with numerous CNC turning centers and vertical mills, including substantial machining envelopes; also offers industrial coating/metalizing.
• Precision Aerospace Corp. — Grand Rapids. If the work is aerospace/defense, this is one I'd investigate: high-mix/low-volume contract manufacturing, CNC Swiss, complex 5-axis machining and lights-out production.
• ABLE Manufacturing — Grand Rapids. Custom and production machining with CNC milling/turning, 4th-axis capability, surface grinding and welding.
• West Michigan Precision Machining — Walker. A conventional job-shop-style option advertising 2D/3D machining, turning and 5-axis work.

For very large industrial machining or emergency repair, PADNOS Leitelt / IXL is also worth considering. Its West Michigan facilities handle everything from replacement shafts to very large boring-mill work; PADNOS cites turning capacity up to 70" × 26' and boring-mill work up to a 96" × 240" floor plate.

How I'd narrow it down

Kenona Industries, LLC. is particularly production-focused: its stated scope covers production machining and assembly using CNC lathes, mills and special-purpose machining centers.

If you tell me what you're machining (e.g. aluminum prototypes, 4140 steel production parts, tight-tolerance aerospace components, large weldments, quantities/month, and approximate part size), I can narrow this to 3–5 West Michigan shops that fit the job and compare their capabilities, certifications, location, and likely fit.

Places ChatGPT showed

• Montague Manufacturing · 4.7★ · Machine shop
• Michigan Production Machining · 4.3★ · Machining manufacturer
• JCGibbons Manufacturing Inc. · 4.6★ · Manufacturer
• MAPCO Manufacturing · 4.3★ · Machine shop
• Production Saw and Machine · 3.4★ · Machine shop
• Power Manufacturing · 4.3★ · Manufacturer
• Bay Machining and Sales Inc · 5.0★ · Machine shop
• Dun-Rite Machining · 4.6★ · Machine shop
• Prosper-Tech Machine & Tool · 5.0★ · Machine shop

If your priority is low unit cost on repeat production runs, I’d get quotes from a mix of Michigan shops rather than assume one shop is cheapest. Publicly posted pricing is rare, so the comparison below is based on each shop’s stated production-volume focus, automation, setup strategy, and ability to amortize tooling/programming.

Shops I’d put on the RFQ list

• Montague Manufacturing — Clio
  Particularly worth quoting for large CNC-milled production volumes. The shop reports 40+ Brother Speedio pallet-switching VMCs and targets production volumes of roughly 25,000–1,000,000 pieces. That kind of highly repetitive, automated work is where per-piece pricing can become very competitive.
• Michigan Production Machining — Macomb
  A strong candidate for automotive/Tier-supplier-style production. Its process mix includes CNC turning, milling, grinding and broaching, which can reduce outside processing and handling.
• JCGibbons Manufacturing Inc. — Livonia
  Especially interesting for high-volume turned or Swiss-machined parts. It advertises bar-fed automation, Swiss CNC and multi-spindle screw machining, which can be advantageous when the geometry lends itself to unattended production.
• MAPCO Manufacturing — Canton
  Worth including for low-to-mid-volume production, particularly turned/screw-machined components. MAPCO reports 12 screw-machining centers and capacity up to 2⅜-inch bar.
• Production Saw and Machine — Clarklake
  Interesting if your program involves continuous or high-volume production. It combines sawing, CNC machining/turning and grinding, and advertises automated high-throughput machining with twin-spindle/Swiss-style equipment and in-process controls.
• Power Manufacturing — Holland
  A useful option when the project needs several manufacturing processes. It offers CNC machining alongside stamping, cutting, welding and assembly, potentially reducing total landed cost when multiple operations are involved.

For smaller production runs

For roughly 50–5,000 pieces, I'd also quote:

• Bay Machining and Sales Inc — Bay City; advertises small-batch production commonly around 50–1,000 pieces.
• Carpatians MFG — Troy; specifically advertises production runs up to 5,000+ pieces and says dedicated fixturing reduces per-piece overhead.
• Dun-Rite Machining — Webberville; positioned around short runs and low-to-mid-volume production.
• Prosper-Tech Machine & Tool — Richmond; has multi-axis machining and production automation suitable for programs ranging from small quantities through 10,000+ pieces.

How I'd get the lowest quote

Send the same RFQ package to 5–7 shops and ask them to quote at multiple quantities—for example 100 / 500 / 1,000 / 5,000 / 10,000 pieces. Request that they separately identify:

• Piece price
• One-time programming/setup
• Fixture/tooling cost
• Material cost
• Secondary operations/finishing
• Inspection/FAI charges
• Lead time
• Price breaks for repeat releases
• Blanket-PO or annual-volume pricing

The quantity break is important: a shop optimized for 25,000+ pieces can be dramatically cheaper than a general job shop, while the reverse can be true at 100–500 pieces.

If you give me part material, approximate dimensions/complexity, annual quantity, quantity per release, tolerances, and whether it's mill or lathe work, I can narrow this to 3–5 Michigan shops that are most likely to be competitive for your specific production run.

Places ChatGPT showed

• Carpatians Manufacturing · 5.0★ · Machining manufacturer
• Mogultech Precision Machining · 5.0★ · Machine shop
• Prosper-Tech Machine & Tool · 5.0★ · Machine shop
• Protomatic Inc. · 5.0★ · Machine shop
• Dun-Rite Machining · 4.6★ · Machine shop
• Casemer Tool & Machine · 4.5★ · Machine shop
• Clarklake Machine Inc · 5.0★ · Machine shop
• Park Street Machine, Inc. · 4.5★ · Machine shop

Yes. I’d start with shops that combine family/local ownership, documented quality systems, substantial CNC capability, and evidence of serving demanding OEM/engineering customers. “Engineers trust” is hard to measure objectively, so I’m using those as practical proxies rather than claiming a formal industry ranking.

Strong Michigan candidates

• Carpatians Manufacturing — Troy. Family-owned, single-location shop founded in 2000. Particularly interesting for engineers needing low-volume through production CNC milling, reverse engineering, CMM measurement, and documented material traceability.
• Mogultech Precision Machining — Saline. Locally owned and operated since 1998, with CNC milling/turning and an emphasis on tight-tolerance work, inspection, prototypes, and production.
• Prosper-Tech Machine & Tool — Richmond. A precision shop focused on build-to-print and tight-tolerance work, including 3-, 4-, and 5-axis CNC machining, with a strong aerospace/defense orientation.
• Protomatic Inc. — Dexter. Geared toward prototype-to-production work for medical, aerospace, defense, and advanced-technology customers. Its capabilities include 4- and 5-axis machining and very tight-tolerance work.
• Dun-Rite Machining — Webberville. Worth considering for one-offs, prototypes, short runs, hot jobs, and difficult tight-tolerance work, with CNC milling plus grinding capabilities.
• Casemer Tool & Machine — Oxford. Family-owned since 1979, with unusually large CNC milling and turning capacity. A particularly relevant option for large/heavy components, tooling, fixtures, and assemblies.
• Clarklake Machine Inc — Clarklake. Family-owned/operated with roots going back to 1966 and a focused CNC milling/turning operation aimed at precision, repeatability, and production.
• Park Street Machine, Inc. — Muskegon. Family-owned CNC machining and grinding shop with 4-axis milling, horizontal machining, CNC turning, and in-house programming; supports prototype through production quantities.

A few particularly established family-owned shops

Precision Advanced Machining Co. has been family-owned across four generations since 1937 and holds AS9100D and ISO 9001 certifications, with CMM inspection and production-oriented machining. That makes it especially relevant for aerospace/defense or other highly controlled programs.

Lincoln Park Boring Co. is another long-established family operation—65+ years—with large-part CNC machining, horizontal/vertical machining, jig boring, CNC turning, grinding, and a 60,000-square-foot facility.

Master Machining, Inc. has been family-owned since starting in a garage in 1986 and is ISO 9001:2015 certified, with CNC milling/turning and experience in aerospace, automotive, medical, and tooling.

If I were building an engineering supplier shortlist

I'd separate them by the kind of work rather than simply picking the biggest shop:

For example, J & S Technologies in Nunica is family-owned, ISO 9001:2015 certified, and specializes in CNC lathe/screw-machine precision parts; Sebright Machining in Holland is also family-owned and combines CNC milling/turning with grinding, boring, welding, and in-house design/programming.

If you tell me what you're machining (e.g. aluminum prototypes, stainless production parts, 5-axis aerospace components, large weldments, medical, etc.), typical quantities, tolerances, and what part of Michigan you're near, I can narrow this to 5–8 shops that are actually well matched to the work.