| Shrettech Tool & Machine LLC Milling, Turning, Welding, Grinding | Racine, WI | MillingTurningWeldingGrinding | - |
| Silicon Valley Precision Inc Milling, Turning, Welding, Casting, Grinding, Finishing · ITAR | Livermore, CA | MillingTurningWeldingCastingGrindingFinishing | ITAR |
| Sirois Tool Company, Inc Milling, Turning, EDM, Grinding, Assembly | Berlin, CT | MillingTurningEDMGrindingAssembly | - |
| SJC Precision Inc Milling, Laser, Punching, Welding, Stamping, Grinding · ISO 9001, ITAR | Milpitas, CA | MillingLaserPunchingWeldingStampingGrinding | ISO 9001, ITAR |
| SJD Machining, Inc Milling, Turning, EDM, Grinding, Finishing | Meadville, PA | MillingTurningEDMGrindingFinishing | - |
| Skytop Machine and Tool, Inc Milling, Turning, Waterjet, Welding, Grinding | Port Matilda, PA | MillingTurningWaterjetWeldingGrinding | - |
| Smith Metal, LLC Milling, Turning, Swiss, Laser, Waterjet, Bending, Welding, EDM, Grinding, Finishing · ISO 9001 | Augusta, MI | MillingTurningSwissLaserWaterjetBendingWeldingEDMGrindingFinishing | ISO 9001 |
| Soflo Machining Milling, Turning, Laser, Waterjet, Welding, Grinding, Finishing · ISO 9001, AS9100 | Coral Springs, FL | MillingTurningLaserWaterjetWeldingGrindingFinishing | ISO 9001, AS9100 |
| Sonic Aerospace Inc Milling, Turning, Grinding, Finishing, Assembly · ISO 9001, AS9100 | Chandler, AZ | MillingTurningGrindingFinishingAssembly | ISO 9001, AS9100 |
| Sonic Manufacturing Corporation Milling, Welding, EDM, Grinding, Finishing, Assembly · AS9100, NADCAP | Elk Grove Village, IL | MillingWeldingEDMGrindingFinishingAssembly | AS9100, NADCAP |
| Soteria LLC Milling, Turning, Welding, Grinding, Finishing | Anniston, AL | MillingTurningWeldingGrindingFinishing | - |
| South Central Manufacturing Corp Milling, Turning, Welding, Grinding | Summersville, MO | MillingTurningWeldingGrinding | - |
| Southern Ohio Manufacturing Milling, Turning, Laser, Bending, Welding, Grinding, Finishing | Amelia, OH | MillingTurningLaserBendingWeldingGrindingFinishing | - |
| Southern Precision Machining Milling, Turning, Grinding, Finishing · ISO 9001, AS9100, ITAR | Shelbyville, TN | MillingTurningGrindingFinishing | ISO 9001, AS9100, ITAR |
| Specialty Machine Milling, Turning, Swiss, Laser, Bending, Welding, EDM, Grinding, Assembly · ISO 9001, AS9100, ITAR | Lago Vista, TX | MillingTurningSwissLaserBendingWeldingEDMGrindingAssembly | ISO 9001, AS9100, ITAR |
| Specialty Roller and Machine Inc Milling, Turning, Grinding | Berwick, PA | MillingTurningGrinding | - |
| Specialty Tool & Die Company Inc Milling, Turning, Bending, Welding, Stamping, Grinding, Assembly | Kokomo, IN | MillingTurningBendingWeldingStampingGrindingAssembly | - |
| Spectrum Custom Molds & Manufacturing, Inc Milling, Turning, Laser, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001 | Palmetto, FL | MillingTurningLaserWeldingEDMGrindingFinishingAssembly | ISO 9001 |
| SPG Surface Technologies, LLC Turning, Grinding | New Orleans, LA | TurningGrinding | - |
| SPM Milling, Turning, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001 | Portland, OR | MillingTurningWeldingEDMGrindingFinishingAssembly | ISO 9001 |
| Spring Creek Machining, Inc Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding, Finishing | Lowell, AR | MillingTurningWaterjetBendingWeldingEDMGrindingFinishing | - |
| Springfield Tool and Die Milling, Turning, Grinding, Assembly | Duncan, SC | MillingTurningGrindingAssembly | - |
| Spyco Industries Inc Milling, Turning, Waterjet, Grinding · ISO 9001 | Burr Ridge, IL | MillingTurningWaterjetGrinding | ISO 9001 |
| Square Deal Machining Inc Milling, Turning, Laser, Bending, Welding, Grinding, Finishing, Assembly | Marathon, NY | MillingTurningLaserBendingWeldingGrindingFinishingAssembly | - |
| Standard Machine, LLC Milling, Turning, Welding, Casting, Grinding, Finishing | Cleveland, OH | MillingTurningWeldingCastingGrindingFinishing | - |
| Stanfordville Machine & Manufacturing Co Inc Milling, Turning, Swiss, Welding, EDM, Grinding · ISO 9001, AS9100 | Poughkeepsie, NY | MillingTurningSwissWeldingEDMGrinding | ISO 9001, AS9100 |
| Stanton Precision Products L.L.C Milling, Turning, Swiss, Grinding · CMMC | Butler, NJ | MillingTurningSwissGrinding | CMMC |
| Stark Industrial, LLC Milling, Turning, Swiss, Welding, EDM, Grinding · ISO 9001 | North Canton, OH | MillingTurningSwissWeldingEDMGrinding | ISO 9001 |
| Starlite Diversified Inc Milling, Turning, Welding, EDM, Grinding | Meadville, PA | MillingTurningWeldingEDMGrinding | - |
| Starn Tool & Manufacturing Company Milling, Turning, EDM, Grinding, Finishing · ISO 9001, ITAR | Meadville, PA | MillingTurningEDMGrindingFinishing | ISO 9001, ITAR |
| Steel River Manufacturing, LLC Milling, Grinding · ISO 9001 | Spring, TX | MillingGrinding | ISO 9001 |
| Steelcrest Precision, Inc Milling, Turning, Swiss, Welding, EDM, Grinding, Assembly · ISO 9001, AS9100 | Wauseon, OH | MillingTurningSwissWeldingEDMGrindingAssembly | ISO 9001, AS9100 |
| Steer Machine Tool and Die Corporation Milling, Turning, Welding, Grinding | Honesdale, PA | MillingTurningWeldingGrinding | - |
| Stellar Precision Components. Ltd Milling, Turning, EDM, Grinding · ISO 9001, AS9100 | Jeannette, PA | MillingTurningEDMGrinding | ISO 9001, AS9100 |
| Stephen J Hartman Milling, Turning, Welding, Grinding | Sykesville, MD | MillingTurningWeldingGrinding | - |
| Stephens Precision, Inc Milling, Turning, Welding, EDM, Grinding, Assembly · ISO 9001, AS9100, ITAR | Bradford, VT | MillingTurningWeldingEDMGrindingAssembly | ISO 9001, AS9100, ITAR |
| Stever Locke, Inc Turning, Stamping, Grinding, Finishing, Assembly · ISO 9001, AS9100, ITAR | Honeoye Falls, NY | TurningStampingGrindingFinishingAssembly | ISO 9001, AS9100, ITAR |
| Stigtec Manufacturing Milling, Welding, EDM, Grinding, Finishing, Assembly | San Marcos, CA | MillingWeldingEDMGrindingFinishingAssembly | - |
| Stone Machine Co. Inc Milling, Turning, Grinding, Finishing | Chester, NH | MillingTurningGrindingFinishing | - |
| Stork Precision Machining LLC Milling, Turning, Welding, EDM, Grinding · ISO 9001, CMMC | Washington, MO | MillingTurningWeldingEDMGrinding | ISO 9001, CMMC |
| Straton Industries Inc Milling, Turning, Stamping, EDM, Grinding, Finishing, Assembly · AS9100, ITAR, CMMC | Stratford, CT | MillingTurningStampingEDMGrindingFinishingAssembly | AS9100, ITAR, CMMC |
| Streamline Machine Source Inc Milling, Laser, Waterjet, Grinding · ISO 9001 | Greenville, MI | MillingLaserWaterjetGrinding | ISO 9001 |
| Strickland Machine Co LLC Milling, Turning, Welding, Stamping, Grinding, Finishing, Assembly | North Chesterfield, VA | MillingTurningWeldingStampingGrindingFinishingAssembly | - |
| Strohwig Industries, Inc Milling, Turning, Casting, EDM, Grinding, Finishing, Assembly · ISO 9001, ITAR, CMMC | Richfield, WI | MillingTurningCastingEDMGrindingFinishingAssembly | ISO 9001, ITAR, CMMC |
| Sturdy Grinding & Machining Inc Grinding, Finishing · ISO 9001 | New Haven, MI | GrindingFinishing | ISO 9001 |
| Sugar River Machine Inc Milling, Turning, Welding, Grinding, Finishing, Assembly | South Beloit, IL | MillingTurningWeldingGrindingFinishingAssembly | - |
| Sulzer Machine & Manufacturing Inc Milling, Welding, Grinding · ISO 9001 | Mosinee, WI | MillingWeldingGrinding | ISO 9001 |
| Summit Machine Solutions LLC Milling, Welding, Grinding | Akron, OH | MillingWeldingGrinding | - |
| Sunnycor Inc Milling, Turning, Grinding, Assembly · AS9100, ITAR | Torrington, CT | MillingTurningGrindingAssembly | AS9100, ITAR |
| Sunset Industries Inc Milling, Turning, Swiss, Casting, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100, ITAR, CMMC | Mentor, OH | MillingTurningSwissCastingEDMGrindingFinishingAssembly | ISO 9001, AS9100, ITAR, CMMC |