Common Screw Machine Methods For Machined Parts

Common Screw Machine Methods

1. Turning

• Reducing the diameter of the workpiece.

• External cylindrical shaping.

• Includes straight turning, taper turning, and profiling.

2. Facing

• Creating a flat surface at the end of the part.

• Usually the first operation after bar stock is fed in.

3. Drilling

• Creating axial holes.

• Often followed by other internal machining steps like boring or tapping.

4. Boring

• Enlarging and finishing drilled holes to precise diameters.

5. Reaming

• Further finishing of a drilled hole for very tight tolerances.

6. Tapping

• Cutting internal threads.

• Can be done by rigid tapping or floating tap holders.

7. Thread Rolling / Thread Cutting

• Thread Rolling: Cold-forming threads using dies (stronger threads, no material removal).

• Thread Cutting: Using a threading tool or die to cut threads.

8. Knurling

• Rolling a pattern onto the part surface for grip (e.g., tool handles).

9. Grooving

• Cutting narrow channels into the outside or inside diameter.

10. Parting (Cut-off)

• Cutting off the finished part from the bar stock.

• Final step before ejection.

11. Cross Drilling

• Drilling holes perpendicular to the main axis (radial holes).

• Often used in fittings or connectors.

12. Milling (on CNC screw machines)

• Creating flats, slots, or other non-rotational features using live tooling.

13. Slotting

• Creating keyways or other internal features.

14. Broaching (sometimes secondary op)

• Pushing/pulling a toothed tool through the part to form keyways or internal shapes.

15. Burnishing

• Surface finishing technique using pressure to improve finish and hardness.

Top Screw Machine Brands

Cam-Operated (Automatic) Screw Machines

1. Brown & Sharpe

   • Classic American brand, used widely for decades.

   • Excellent for bar-fed cam-driven operations.

2. Davenport

   • Known for multi-spindle cam screw machines.

   • High-speed, high-volume production.

3. Acme-Gridley

   • Famous for multi-spindle automatic lathes.

   • Heavily used in the automotive and fastener industries.

4. New Britain

   • Robust multi-spindle machines.

   • Often found in older, heavy-duty production shops.

CNC Swiss-Type (Sliding Headstock) Screw Machines

1. Citizen (Miyano/Cincom)

   • Highly respected Japanese brand.

   • Excellent for medical, aerospace, and high-precision work.

2. Star Micronics

   • Another major Swiss-type machine brand.

   • Known for innovation and high-speed operation.

3. Tsugami

   • Offers both Swiss-type and fixed-headstock CNC lathes.

   • Popular in precision manufacturing.

4. Tornos

   • Swiss company, one of the oldest in the world.

   • Legendary in the watchmaking and micro-precision industries.

5. Hanwha

   • Korean manufacturer.

   • Solid and cost-effective Swiss-type CNC machines.

6. Nakamura-Tome

   • High-performance multi-axis turning centers.

   • Excellent for complex part machining.

7. Index / Traub

   • German-built, high-end CNC turning centers.

   • Offers precision and flexibility.

8. Eurotech

   • Italian CNC screw machines.

   • Known for multi-axis, high-automation lathes.