Automatic Screw Machine Process Description

Function: What does it do?

An automatic screw machine is a specific type of lathe usually used to machine small to medium parts fromScrew Machine various sizes of bar stock. 1 Most automatic screw machines have several slides and spindles that all hold various types of tools (drills, form tools, milling cutters, taps, dies, etc.). This gives the machine the ability to machine very high volumes of turned components with minimal supervision and high precision.

There are two main types of automatic screw machine: the Brown & Sharpe or Turret-type and the Swiss-type. Each may have anywhere from 1 to 8 spindles.

The Brown & Sharpe/Turret-type screw machine is no longer actively made, but is still run in hundreds of job shops due to its reliability and long life. It is cam-operated.

The Swiss-type screw machine is incredibly precise, able to hold tolerances to within a few micrometers. Most Swiss machines have a secondary spindle with live tooling and a guide bushing next to the cutting tools for added rigidity.

Application & Benefit: What can I use it for? Why will it help me?

A single operator can supervise several different automatic screw machines at the same time, interfering only for setup and changeover. 2 Multi-spindle screw machines are much faster since each spindle does its work simultaneously and independently. The machines can achieve greater precision than other types of lathes due to their use of a guide bushing and collet, which reduce the space between the workholding and the tool and thus increase rigidity and accuracy.

Common Industries

The automatic screw machine is versatile and is used in virtually all industries, especially for very small or thin pieces. The Swiss-type screw machine is widely used by the medical and orthotic industries for precision parts.

Common Processes
  • Shafts
  • Pins
  • Knobs
  • Screws
  • Bolts
  • Orthotics
  • Medical device components

Process: How does it work?

The screw machine was originally designed for the production of screws, where the bar stock is held firmly in a moving headstock and turned against a fixed cutting instrument. Whether CNC or cam-operated, a screw machine will have the following components: base, headstock, hollow work spindle, front tool slide, rear tool slide, and turret. 3 Many will also have an end-finishing tool.

Major Screw Machine Manufacturers

Acme Gridley, Browne & Sharpe, Citizen, Conomatic, Davenport, Glidemeister, Hardinge, Index, Miyano, New Britain, Star, Tornos, Traub

Notes:

  1. James Bralla, Handbook of Manufacturing Processes, 90-91. http://www.thomasnet.com/articles/custom-manufacturing-fabricating/cnc-turning-swiss-machines.
  2. George Schneider, Jr., Cutting Tool Applications (Farmington Hills, MI: ASM International, 2002), 69.
  3. Ibid., 68.