Bar Stock and Bar Feeders


Straight Talk About Bar Stock and Bar Feeders

Turning bar stock that’s not completely straight can have a negative impact on manufacturing efficiency. For one thing, uneven rotating material oscillates, which creates vibrations that are transmitted to the cutting zone, so you can’t safely operate at optimum spindle speeds. Otherwise, the vibrations can impact part quality and accelerate tool wear.

Although bar stock suppliers strive to deliver bars that are uniform and straight, variations from batch-to-batch are common. Even bars held to industry standards typically have 1/8” straightness variation in any 5 feet of hot finished stainless-steel bars, and 1/16” straightness variation in any 5 feet of cold finished stainless.

This may not seem like much of a deviation, but at faster rotation speeds even these variations can cause serious problems, especially for high-precision parts. The problem becomes even more pronounced with hex, square and other profiled stocks, which create greater friction than round stock when rotating. Often these bar shapes are extruded and, sometimes, asymmetrical which can also create uneven weight distribution.

Another concern is that bar stock straightness can deviate from one batch or supplier to another. Therefore, if the spindle speed of the turning machine is set to accommodate a given batch of bar stock, and then stock from another batch is mixed in, you could end up with a number of bad parts at the end of a production run.  

The solution to these potential problems is a bar feeder that provides reliable bar stock support to eliminate vibrations that impact the speed and accuracy of your turning process.

Your specific applications will determine the kind of bar feeder that provides the support you need. Some of the attributes you may need are: 

  • Hydrodynamic support that uses evenly distributed oil between the guide tube ID and the bar stock OD. With increasing speed, the hydrodynamic force centers the bar stock to reduce vibrations. 
  • A V-guide outboard bar stock stabilizer that further reduces vibrations. 
  • Intelligent synchronization that continuously monitors sliding headstock and bar feeder movement for precise, vibration-free bar loading. 
  • For high-speed sliding headstock machines running small diameter bars, a 3-S synchronization option eliminates transmission delays for worry-free operation. 
  • A Swiss safety connection eliminates the unsupported area between the bar feeder and turning machine, again, reducing vibration. 
  • An available assortment of precision guide channels for proper support of bar stock diameters within the bar feeder’s range, that can be quickly and easily changed to keep production moving.


To learn more about how the right bar feeder eliminates concerns over bar stock straightness, contact your local LNS representative, or call 513-528-5674.