| Sigma Machine Inc. Milling, EDM | Kalamazoo, MI | MillingEDM | - |
| Skamar Machine Milling, Turning · ISO 9001 | Cleveland, OH | MillingTurning | ISO 9001 |
| Slim Haney Machining Inc Milling, Turning, Welding | Tulsa, OK | MillingTurningWelding | - |
| SMT Machine & Tool Milling, Turning, Welding, Casting | Green Bay, WI | MillingTurningWeldingCasting | - |
| Snyder Industries Inc Milling, Turning, Welding · ISO 9001 | Tonawanda, NY | MillingTurningWelding | ISO 9001 |
| South Bend Form Tool Co Milling, Turning, EDM | South Bend, IN | MillingTurningEDM | - |
| South Eastern Machining Inc Milling, Turning, Bending, Welding · ISO 9001 | Pelzer, SC | MillingTurningBendingWelding | ISO 9001 |
| Southeastern Machining Milling, Turning, Welding · ISO 9001 | Worthington, OH | MillingTurningWelding | ISO 9001 |
| Specialty Precision Machining Milling, Turning, Laser · ISO 9001 | Stockton, CA | MillingTurningLaser | ISO 9001 |
| SRS Fabrication Inc. Milling, Turning, Bending, Welding, Waterjet | North Las Vegas, NV | MillingTurningBendingWeldingWaterjet | - |
| Steel Plate Fabricators Milling, Turning, Bending, Laser, Welding, Waterjet, Metal AM | Knoxville, TN | MillingTurningBendingLaserWeldingWaterjetMetal AM | - |
| Steel Valley Fabricators, LLC Milling, Bending, Welding | Braddock, PA | MillingBendingWelding | - |
| Summit City Precision Machining LLC Milling, Turning, EDM · ISO 9001 | Fort Wayne, IN | MillingTurningEDM | ISO 9001 |
| Summit Machine Solutions Milling, Welding | Akron, OH | MillingWelding | - |
| Summit Machine Tool LLC Milling, Turning | Oklahoma City, OK | MillingTurning | - |
| Superior Machine & Tool Milling, Turning, Welding · ISO 9001 | Fort Wayne, IN | MillingTurningWelding | ISO 9001 |
| Superior Process Solutions Milling, Turning, Bending, Laser, Welding, Metal AM | Springfield, MO | MillingTurningBendingLaserWeldingMetal AM | - |
| Susquehanna Metal Work, LLC Milling, Bending, Welding, Stamping | Columbia, PA | MillingBendingWeldingStamping | - |
| Swihart Industries Milling, Turning · ISO 9001 | Dayton, OH | MillingTurning | ISO 9001 |
| Swiss Technologies Inc. Milling, Turning, Welding, Stamping · ISO 9001 | Knoxville, TN | MillingTurningWeldingStamping | ISO 9001 |
| Synergy Core Manufacturing Milling | Denver, CO | Milling | - |
| Tampa Bay Machining Milling, Turning, Welding, EDM · ISO 9001, AS9100, ITAR | Tampa, FL | MillingTurningWeldingEDM | ISO 9001, AS9100, ITAR |
| TCMS Inc Milling, Turning, Welding | Oklahoma City, OK | MillingTurningWelding | - |
| Tecma Milling, Turning, Welding, Waterjet, EDM, Stamping, Casting · ISO 9001, AS9100, ITAR, NADCAP | Sacramento, CA | MillingTurningWeldingWaterjetEDMStampingCasting | ISO 9001, AS9100, ITAR, NADCAP |
| TEKE Machine Corporation Milling, Turning · ISO 9001, AS9100 | Rochester, NY | MillingTurning | ISO 9001, AS9100 |
| Temco Precision Machining Milling, EDM · ISO 9001, AS9100 | Manchester, NH | MillingEDM | ISO 9001, AS9100 |
| Teton Machine Co Milling, Turning · ISO 9001, AS9100, ITAR | Payette, ID | MillingTurning | ISO 9001, AS9100, ITAR |
| The Gent Machine Company Milling, Turning · ISO 9001, IATF 16949 | Cleveland, OH | MillingTurning | ISO 9001, IATF 16949 |
| Theonics Milling, Turning, Bending, Welding, EDM · AS9100, ITAR, ISO 13485 | Huntsville, AL | MillingTurningBendingWeldingEDM | AS9100, ITAR, ISO 13485 |
| Thomason Machine Works Inc Milling, Turning, EDM · ISO 9001 | Rockford, IL | MillingTurningEDM | ISO 9001 |
| Tinker Manufacturing Milling · ISO 9001, ITAR | Bedford, NH | Milling | ISO 9001, ITAR |
| Titletown Manufacturing LLC Milling, Welding | Green Bay, WI | MillingWelding | - |
| Tobar Industries Milling, Turning, Bending, Welding | San Jose, CA | MillingTurningBendingWelding | - |
| Toledo Metal Spinning Company Milling, Bending, Laser, Welding, Stamping · ISO 9001 | Toledo, OH | MillingBendingLaserWeldingStamping | ISO 9001 |
| Tolerance Tool & Engineering Milling, Turning, Welding · ISO 9001, ITAR | Detroit, MI | MillingTurningWelding | ISO 9001, ITAR |
| Toolcraft LLC Milling | Fort Wayne, IN | Milling | - |
| Toron Manufacturing Milling, Welding | Elkhart, IN | MillingWelding | - |
| Total Concept Enterprises, Inc. Milling, Turning, Bending, Welding | Fresno, CA | MillingTurningBendingWelding | - |
| Toth Industries Inc Milling, Turning, Bending, Casting · ISO 9001 | Toledo, OH | MillingTurningBendingCasting | ISO 9001 |
| Trans Machine Technologies SC Milling, Turning, Bending, Laser, Welding, EDM, Casting · ISO 9001 | Greenville, SC | MillingTurningBendingLaserWeldingEDMCasting | ISO 9001 |
| Tri-Gon Precision, Inc. Milling, Turning, Welding, EDM | Colorado Springs, CO | MillingTurningWeldingEDM | - |
| Tri-Tec Industries Milling, Turning, Welding | Charlotte, NC | MillingTurningWelding | - |
| Tri-V Tool & Manufacturing Co Milling, Turning, Bending, Welding, Waterjet, EDM · ISO 9001 | Omaha, NE | MillingTurningBendingWeldingWaterjetEDM | ISO 9001 |
| TRK Fabrication Milling, Turning, Bending, Welding, Waterjet | Akron, OH | MillingTurningBendingWeldingWaterjet | - |
| Tucson CNC Machining, Inc. Milling, Turning, Bending, Casting | Tucson, AZ | MillingTurningBendingCasting | - |
| Turner Machine Co Inc Milling, Turning, Welding | Tulsa, OK | MillingTurningWelding | - |
| Ultimate Precision Tech Milling, Turning, EDM | Houston, TX | MillingTurningEDM | - |
| Unique Machine & Tool Co Milling | Phoenix, AZ | Milling | - |
| United Grinding & Machine Co Milling, Turning, Bending, Laser, Welding, Waterjet, EDM, Casting · ISO 9001 | Canton, OH | MillingTurningBendingLaserWeldingWaterjetEDMCasting | ISO 9001 |
| United Machine & Tool Milling, Turning, Laser, Welding · ISO 9001 | Goodlettsville, TN | MillingTurningLaserWelding | ISO 9001 |