Multi-spindle Turning

Multi-spindle turning produces high volumes of small to mid-size rotational parts by machining multiple parts simultaneously on a multi-spindle lathe.

Overview

Multi-spindle turning (multi-spindle lathe or screw machine turning) runs multiple spindles in parallel to machine several parts at once. The process excels at repeating turning operations—OD/ID turning, facing, grooving, drilling, and basic cross features—on bar-fed parts with short cycle times and strong part-to-part consistency.

Choose it for high-volume production where tooling amortization and setup time get spread over many parts. It’s common for small, axisymmetric components with multiple simple operations and tight cost targets.

Tradeoffs: flexibility is limited versus CNC; changeovers and dialing-in can be time-consuming, so it’s a poor fit for prototypes or frequent revisions. Feature complexity is constrained by station count and tool access, and secondary ops may be needed for complex milled geometry. Best ROI comes from stable demand, stable prints, and bar-stock-friendly designs.

Common Materials

  • 12L14 Steel
  • 1018 Steel
  • 303 Stainless Steel
  • 360 Brass
  • Aluminum 6061
  • Acetal (Delrin)

Tolerances

±0.001"

Applications

  • Hydraulic fitting bodies
  • Brass plumbing fittings
  • Threaded bushings and spacers
  • Electrical connector pins
  • Valve stems and seats
  • Screws, studs, and specialty fasteners

When to Choose Multi-spindle Turning

Run multi-spindle turning for stable, high-volume parts where cycle time drives piece price and the design is unlikely to change. It fits bar-fed, mostly rotational parts with multiple simple turning/drilling steps and consistent material supply. Expect the best economics when you can commit to longer runs or blanket orders.

vs 2-Axis CNC Turning

Choose multi-spindle turning when annual volume is high enough that the lower cycle time outweighs longer setup and higher tooling cost. It’s a strong fit for repeat jobs where the routing is stable and you want the lowest cost per piece. For frequent revisions or short runs, 2-axis CNC usually wins on flexibility.

vs Manual Lathe

Choose multi-spindle turning when you need production throughput and repeatability that a manual lathe can’t sustain. Multi-spindle machines hold process consistency across long runs and reduce labor content per part. Manual lathes make sense for one-offs and rework, not sustained production.

vs Mill-turn (Live Tooling)

Choose multi-spindle turning when the part is primarily turned and the cost target is driven by high volume, not feature consolidation. Multi-spindle machines run faster for simpler geometries and can beat mill-turn on piece price once amortized. If the part needs significant milled features in one setup, mill-turn is usually the cleaner path.

vs Swiss Turning

Choose multi-spindle turning when the part is not extremely long/slender and you’re prioritizing multi-part parallel output over ultra-precise support near the cut. Multi-spindle often wins on throughput for stubby parts and fittings. Swiss is better for small diameters with high L/D ratios and tight control of deflection.

Design Considerations

  • Keep the part bar-stock friendly: constant or slowly varying OD and reasonable stock size availability
  • Minimize non-axial features; if cross-holes or flats are required, standardize their size and location to reduce station/tooling complexity
  • Use standard thread forms and avoid multiple thread types on the same part unless necessary
  • Hold tight tolerances only where they functionally matter; excessive all-over tolerancing increases setup time and scrap risk
  • Provide clear callouts for critical-to-function diameters, runout/concentricity, and surface finish so the shop can assign the right stations and gaging
  • Avoid frequent design revisions mid-program; small geometry changes can force re-timing, re-tooling, and re-qualification