At O’Hare Precision Metals, we’ve been grinding round bar stock since 1970. Engineers and buyers ask us regularly which grinding process suits their part. The answer depends on geometry, length, and what happens to the bar after it leaves our facility.
Both processes hold tight tolerances and produce smooth surfaces. Knowing which one fits your application saves you time, reduces secondary work, and gets your bar to your floor ready to run.
How Each Grinding Process Works and When to Choose One
Centerless grinding supports the workpiece between two wheels without any centering device. We control wheel speed, feed rate, and workpiece positioning to hold tolerances up to .0001 inches and surface finishes of 8 micro inches or better. It handles long bar stock efficiently, up to 9 inches in diameter and 50 feet in length.
OD grinding mounts the part between centers and shapes its external surface against the wheel. We run CNC and manual OD grinding, with CNC rotary dressers for intricate radii, profiles, and spherical radii. In-process gauging checks dimensions during the grind, not after.
Centerless Grinding: Best for Straight Bar Stock at Consistent Diameter
If your part is a straight cylindrical bar that needs a precise diameter and a clean surface finish, centerless grinding is the right process. The bar is supported continuously along its length, which is what makes it so effective for long stock.
Our specialized grinding division handles parts up to 7 inches in diameter and 24 feet in length. That consistent diameter across the full bar length means your CNC machines spend less time on cleanup and more time cutting features.
OD Grinding: Best for Profiles, Contours, and Existing Parts
OD grinding is the right call when your part has a taper, a spherical radius, or a specific external profile. It also works well on existing forgings and castings where an outside surface needs to reach a final dimension.
CNC rotary dressers on our OD equipment handle intricate radii and complex profiles accurately. In-process gauging keeps dimensions on target throughout the entire cycle, so there are no surprises when the part comes off the machine.
Choosing Between the Two: A Practical Guide for Buyers
Part geometry is the clearest guide. Straight cylindrical bar stock at a precise diameter goes to centerless grinding. Parts with contours, profiles, or complex external geometry go to OD grinding. Volume and length factor in, too, since centerless handles longer bars more efficiently.
Material is rarely the deciding factor. We run both processes on stainless steel, alloy steel, carbon steel, aluminum, titanium, nickel alloys, brass, copper, bronze, and tool steel. Tell us the geometry and tolerance, and we’ll confirm the right process quickly.
In-House Services That Work Alongside Grinding
After grinding, many customers add saw cutting, burnishing, chamfering, turning, or polishing before the bar ships. Our CNC automated cold saws cut up to 7 inches in diameter with clean ends and tight length tolerances. Burnishing follows grinding on shaft fillets and sealing surfaces to close porosity and create compressive residual stress.
Polishing is available for stainless steel, aluminum, brass, copper, bronze, and titanium to specific RA finishes. Having all of these services in-house means your order moves through multiple operations without leaving our Arlington Heights facility.
Quality Control and ISO Certification
Every order runs through quality control inspections at each phase of operation, whether we’re doing centerless or OD grinding. We’ve maintained that standard since 1970. We’re ISO 9001:2015 certified, and our certification page has the full details if your quality system requires verified suppliers.
That consistent inspection process is one reason manufacturers across automotive, aerospace, medical, military, and industrial sectors keep coming back to us. Quality isn’t checked once at the end. It’s confirmed at every step.
Get a Quote From O’Hare Precision Metals Today
Superior in Steel Production and Machining Operations, that’s been our standard since 1970, and it’s what you get with every order. Share your part geometry, material, tolerance requirement, and downstream use. We’ll confirm the right grinding process and any supporting services before you order. Rated 5.0 stars on Google, we’ve earned that trust one precision-ground bar at a time.
Submit your details through our quote form at ohareprecision.com/request-a-quote, call us at (847) 640-6050, or email sales@ohareprecision.com. Visit our contact page for current availability. Include your material grade, diameter, length, and tolerance requirement so we can respond with exactly what you need.
FAQs
What tolerance does centerless grinding hold?
O’Hare Precision Metals holds tolerances up to .0001 inches with surface finishes of 8 micro inches or better on centerless ground round bar stock.
What sizes does your grinding equipment handle?
Centerless grinding goes up to 9 inches in diameter and 50 feet in length. Our specialized division handles up to 7 inches in diameter and 24 feet in length.
When should I choose OD grinding over centerless?
Choose OD grinding when your part has a taper, external profile, or spherical radius. Centerless grinding works best for a straight cylindrical bar at a consistent diameter.
Do you offer services after grinding?
Yes. Saw cutting, burnishing, polishing, chamfering, turning, and custom machining are all available in-house at our Arlington Heights facility. No outside vendors required.