Centerless Grinding

Centerless Grinding

Superior Thread Rolling provides Centerless Grinding as a stand-alone service, or in combination with our Manufacturing Complete or Thread Rolling services. Explore how our centerless grinding capabilities can provide you with the kind of service you require.

Centerless Grinding Services

Centerless Grinding is used to hold tight tolerances on Outside Diameters with excellent surface finish. Superior Thread Rolling commonly centerless grinds bolt shanks, bushings, studs, pins, and other parts requiring tight tolerance diameter control. It is common for our Centerless Grinding team to hold ±.0001” tolerances.

Centerless Grinding as Preparation for Thread Rolling

To consistently produce the highest quality threads, Superior Thread Rolling performs centerless grinding on the blank prior to rolling. Inconsistently sized, out-of-round, or tapered blanks can result in poor quality threads. Additionally, blanks with surface defects, like lathe turning lines, dings, scratches, pits, etc. can negatively affect the thread on a microscopic level. Centerless grinding before thread rolling allows us to avoid these potential pitfalls of poor blank preparation.

How the Grinding Machine Works

It may be helpful to see how the centerless grinding process works before investing in a company to provide these services. Essentially, the centerless grinding process involves three main parts: The feed wheel (or regulating wheel), the grinding wheel, and the blade.

The Feed Wheel or Regulating Wheel

Consisting of hard rubber, the regulating wheel works by moving the part undergoing the centerless grinding service using a through-feed process.

Centerless Grinding in Action

The Grinding Wheel

The grinding wheel is the abrasive component of the centerless grinding process. This wheel works at a faster fixed RPM than the regulating wheel.

The Blade

The centerless grinding blade is used to maintain contact between the regulating wheel and part being ground. The height of the blade plays an integral role in centerless grinding — if the workpiece is either too high or too low, the resulting part may be deformed.

Centerless Grinding Inspections

Concerning centerless grinding, STR employs a dual inspection process to ensure that parts are manufactured to right tolerances. The two inspection points that each project must involve are calibrated micrometer inspections and oasis thread vision system inspections.

Calibrated Micrometers

When conducting centerless grinding services, our team is rigorous in checking part tolerances as we run them, not waiting until the end to begin inspections. The benefit of inspecting centerless grinding as it is in progress is that it catches any major tolerance issues before an entire run has been completed, ultimately reducing waste that would otherwise occur during faulty runs.

Digital micrometers are used for this initial inspection process, measuring thicknesses, diameters, and depths of centerless grinding effects as they happen. These micrometers are calibrated on a regular basis and handled by trained operators to ensure the inspection is carried out effectively.

Oasis Thread Vision Inspection System

The Oasis Thread Vision inspection system is beneficial because it involves a separate person on a different team who will catch any potential issues that the previous test may miss. By implementing a second phase of centerless grinding inspections, Superior Thread Rolling further verifies the accuracy and precision of our services with a fast, easy to use operator interface.

The major difference between the Oasis inspection process and the calibrated micrometer process is that while the calibrated micrometer inspects concurrently with the grinding process, Oasis Thread Vision inspection begins after the grinding process has finished and the parts have been run through a cleaning line to remove any residual oil left on the surface.

The following list covers the entirety of the Oasis Thread Vision Inspection features:

  • Continuous Image Acquisition for Instant Measurements
  • Retains Data for Future Customer Use
  • Simultaneous Measure of Multiple Dimensions
  • File Linking
  • Non-Contact Operation
  • Accurate to +/- 0.0001 inches
  • Precision Optics
  • Powered by User-Friendly, Full-Featured Software
  • Measured Dimensions Saved in the OASIS Elite
  • Includes Automatic Inspection Reporting
  • 2D Measurement Machine Vision
  • Complete Turn-Key Package — Ready to Run!

Choosing the Right Centerless Grinding Wheel

When choosing a grinding wheel for your project, the major factor to consider is grit. Different grit levels and grinding wheels are required for different part materials, which are typically metals such as silicon carbide or aluminum oxide.

Courser grit levels will result in a faster centerless grinding process and will remove more material, but, as a result, courser grit also produces rougher surface finishes. Finer grit levels, on the other hand, remove less part material, but ultimately leave a smoother surface.