If you need precision grinding services for parts such as standard or deep hole carbide drill blanks, you need a shop with centerless grinding capabilities

Parts that are long in length and/or large in diameter are extremely challenging to grind using traditional methods like OD grinding. To ensure consistent quality, you need a centerless grinding shop that has the right capabilities and expertise to handle these parts. 

United Centerless Grinding & Thread Rolling offers centerless precision grinding services for these long and large diameter parts using bar grinding and thru feed grinding processes.  

How Do Bar Grinding and Thru Feed Grinding Work?

Bar Grinding

Bar grinding and thru feed grinding are go-to methods for simple parts that maintain consistent roundness through the length of the piece. While bar grinding is best used for single-diameter parts longer than 15”, thru feed grinding is a great centerless grinding option for slightly shorter parts. 

During thru feed grinding and bar grinding, cylindrical workpieces are inserted through one side of the machine, passing between two wheels that grind all surface points. The part then exits the machine on the opposite side, rounder and straighter, meeting all tolerance specifications. 

Sounds easy enough—but couldn’t a lathe yield this same outcome? 

Technically, yes, but lathes place length constraints on parts. Because lathes are on centers, they aren’t equipped to hold parts in place once they reach a certain length. If you were to grind an exceptionally long part on a lathe, you would need support on each end of the bar, and the operator would have to continuously run back and forth turning the part. Also, turning long parts typically results in an unacceptable amount of deflection because the part is only being supported on the ends.

Since bar grinding and thru feed grinding machines don’t have the same size constraints as a lathe, they’re better equipped for manufacturing long workpieces.  

Common Use Cases for Bar Grinding and Thru Feed Grinding 

If your part checks some or all of these boxes, it could be an excellent candidate for bar grinding or thru feed grinding:  

Thru feed grinding

  • Large diameter. Bar stock requiring grinding to achieve close tolerances, good roundness and straightness characteristics for your bar feeders can be performed at a number of shops but United CGTR has the capability of grinding bar stock up to 5.75” in diameter. Now, factor in longer bar lengths that no longer fit the parameters for being able to be turned on a lathe and you’ve found the specialty niche that United CGTR excels at. Thanks to our larger than standard equipment and our outboard support mechanisms we are able to support and grind large diameters while maintaining your required tolerances. At United CGTR we can grind parts with these large diameters as well as smaller diameters down to .030”.
  • Length greater than six feet. Do you struggle to find turning houses that are able remove stock while maintaining round and straight parts for your bar feeder equipment? Due to the dimensional constraints imposed by a lathe, bar grinding is the most viable solution for long parts. We have the capabilities to grind parts measuring up to 30 feet in length. 
  • Thin walls. Grinding thin wall metal tubing is a complex process. When not done properly, it can create issues like shape distortion, surface roughness, or residual stresses. We’re capable of grinding thin walls with varying minimum wall thicknesses dependent on the diameter of the part. For instance, we can grind a part with a 0.5” diameter down to .015” or .02” wall thickness and a part with a 5” diameter down to .09” wall thickness. 
  • Exotic materials. Materials like Inconel and cobalt are notoriously challenging to work with. Traditional machining tools aren’t always strong enough to compete with their hardness, strength, and low thermal conductivity. With bar grinding and thru feed grinding, we don’t run into that issue. We can even grind carbide with our ultra-strong diamond wheel. And if you need a titanium part, we’re fully qualified to precision grind titanium with our PWA106 certification.
  • Straightness requirements. Bar grinding and thru feed grinding can straighten parts through machining if enough stock is being removed but here at United CGTR we can mechanically straighten parts with diameters up to 3.5”, which is ideal for when we receive bars that have minimal stock and are bent and out of round upon receipt.
  • Tight tolerances. Our bar grinding machines consistently hold tolerances to .0005” and depending on the same and length all the way down to .0002”

Need bar grinding or thru feed grinding services for your part? Trust United Centerless Grinding & Thread Rolling to get the job done right. Contact us today for a free estimate!