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Uncover Three Benefits of Porous Media™ Bearings for a Precision Rotary Table

Uncover Three Benefits of Porous Media™ Bearings for a Precision Rotary Table

X-ray inspection systems are in high demand. Known for their ability to identify anomalies, they have become crucial to ensure quality and proper operation across a wide range of industries, which include:

  • Medical
  • Manufacturing
  • Food Packaging
  • Electronics
  • Defense
  • Plastics

While high tech software may be used to analyze images, the collection of an accurate image relies on the precision rotary tables found within the housing system. Precision rotary tables are also used for the milling and machining of precision tools. At their most basic, the precision rotary table consists of a motor or drive assembly and a spindle. For accurate data collection, the determining factor is the spindle.

There are innumerable contact spindles on the market today, and while orifice bearing options are available as well, New Way® wants to empower our customers with the knowledge to understand the differences between products, and see why porous media based air spindles are the right choice for you.

It’s All in the Design

Transitioning from oil-based bearings to air bearings is the first step in the right direction. The use of pressurized air provides the necessary lift and separation, removing friction and creating a cascade of benefits, which include:

  • New Way T-Series Air SpindleImproved precision
  • Higher speeds
  • No wear
  • Less heat generation
  • Decreased maintenance downtime

Within the category of air bearings we find two main groups:

  1. Orifice compensation, utilizing a series of hole(s) or grooves to supply air to the bearing surface.
  2. Porous media, utilizing the natural permeability of porous carbon. Millions of holes inherent to the material enable the even distribution of air across the bearing surface.

The key differentiator between orifice and porous media is how the air is distributed. Our Technical Report 1 covers this topic in detail, but the most important point, concerns the pressure gradient created by the bearing. With orifice bearings you have spikes and dips in pressure, while porous media produces a smooth, consistent air film, allowing for even distribution and ease of operations.

This fundamental design difference directly affects the operations of a precision rotary table, including its end product—which could be an X-ray inspection of the pacemaker designed for you or a loved one. Let’s look at three ways this design difference benefits precision rotary table operations.

Three Benefits of Porous Media in a Precision Rotary Table

Crash Resistance

One of the biggest concerns you might have when considering an orifice based bearing design is their response to a loss of air supply. Should your air supply be lost, an orifice bearing will crash, oftentimes meaning a hard, metal to metal contact and damaging both your bearing surface and your stator surface. Even under non-power loss conditions, orifice based bearings can fail due to the “pneumatic hammer effect,” whereby a loss of pressure on one side causes the bearing to rise, resulting in a pressure increase, starting the cycle again until resonance damages the system.

These scenarios become particularly problematic as precision rotary tables have become more widely adopted. Any failure in the rotary table means downtime for repair, costing you both time and money for new parts.

Conversely, porous media naturally acts as a restrictor for the air supply, creating a consistently thin air cushion with a never before seen combination of damping and stiffness. Even in a worse case scenario where a crash is unavoidable, the soft carbon face (at a compression strength of 91 MPa) means the carbon will absorb the blow, protecting your guide surface and other components which might be difficult or costly to replace.

Higher Precision

In addition to crash safety, air bearings also offer a massive improvement when it comes to precision. When you couple the manufacturing imperfection of ball bearings with the wear induced on multiple rotating surfaces, asynchronous and synchronous errors manifest, impacting precision and creating hysteresis error. By removing all dynamic components and suspending the rotor on a 5 micron thick layer of air, synchronous error is standardized and asynchronous error is almost entirely eliminated.

Additionally, because an air bearing based system doesn’t need to contend with unequal pressure loadings or the internal momentum and inertia inherent to a ball bearing based system, porous media based rotary tables boast nano scale accuracy.

Improved reliability

New Way Air Bearing products have shown massive increased reliability over their contact and orifice bearing brethren. Because rotary tables and spindles built on porous media have no dynamic parts in contact with one another, friction is eliminated, and so is the wear and tear which would inevitably lead to a spalled bearing.

A New Way for Precision Rotary Tables

Servo Drive Rotary Stages are New Way’s all encompassing solution for your highly toleranced precision rotary needs. By combining one of our air spindles with a slotless, brushless motor and a precision rotary encoder capable of 1.1 arcsecond precision, we’ve developed a fully matured solution for rotary needs. The Servo Driven Rotary Stage offers up to 1,184,000 counts/rev and has already shown it’s acumen in the field, positioning the Keck Observatory’s azimuthal encoder.

T-Series Air Spindles provide our highest levels of precision ideal for precision rotary table operations. Available in several standard sizes in both round and square stator configurations, our T-series spindles provide off-the-shelf frictionless rotary motion with the tightest air gap, narrowing radial, and axial error motion up to 0.1 µM.

Thrust bushings can be utilized as a precision rotary table by floating the table on top of the thrust face. Thrust bushings are available in a range of standard sizes.

For precision rotary tables requiring the least amount of precision, we offer a unique combination of our Flat Round Bearings and Air Bushings. By placing the flat bearings in a ring configuration with the air bushing as the center ‘spindle,” a precision rotary table can be created.

Why Are You Waiting?

Whether it’s for an X-ray system inspecting a life-saving medical device, or for machining critical electronic parts, New Way has the components available to create a precision rotary table to meet your requirements. Start taking advantage of porous media’s increased precision and reliability in your operations. Contact us today for your complimentary consultation to determine the right components for your precision rotary table!

Learn More About the Porous Media Difference