Skip to content 
When a machined part fails, most shops blame the CNC setup. The real problem often starts with the bar stock. If your bar holds an inconsistent diameter, that variation carries straight into every cut your machine makes.
We’ve been grinding bar stock at our Franklin Park, IL facility since 1994. Buyers come to us after dealing with out-of-tolerance material that pushed their scrap rates up. Better bar means better parts, every time.
How Grinding Tolerance Directly Shapes Your Machined Part Quality
A ground bar gives your CNC equipment a consistent, reliable starting point. Without that, your machine compensates for diameter variation before it cuts a single feature. That compensation shows up later as scrap, rework, or failed assemblies.
Our centerless grinding operation holds tolerances as tight as plus or minus .0001 inch with a microfinish down to 8RA. Those numbers give your machining process a stable foundation to work from, whether you’re turning shafts, milling pockets, or producing close-tolerance bores.
Diameter Consistency Across the Full Bar Length
Tolerance means the diameter holds to the nominal dimension across the entire bar, not just at one end. A bar that drifts even slightly across its length passes that variation into every turned feature. For shafts running in close-fitting bores, that drift is the difference between a part that fits and one that doesn’t.
Forte Precision Metals‘ grinding operation covers bars up to 7 inches in diameter and up to 24 feet in length in a single pass. That full-length consistency matters for aerospace shafts, hydraulic components, and heavy industrial parts, where a re-setup midway through creates a tolerance break in the bar.
Surface Finish and What 8RA Does for Your Process
A bar ground to 8RA reduces tool wear on your subsequent machining passes and gives coatings a better surface to adhere to. In some cases, it removes an operation entirely because the bar arrives ready for assembly without an additional finishing step needed from your team.
Rough bar surfaces create friction variation in sliding contact applications and accelerate wear on cutting tools. Starting from a ground surface keeps those variables out of your process from the beginning, so your machine runs cleaner, and your tooling lasts longer across more production cycles.
Materials We Grind and How Grade Affects the Outcome
Alloy grades like 4140, known for hardness penetration and wear resistance, and 4340, a nickel-chromium-molybdenum grade with high fatigue strength, grind predictably and hold tight tolerance well. Both are common in highly stressed aerospace and automotive components where dimensional accuracy is non-negotiable.
Stainless grades like 303, with added sulfur for good machinability, and 316, carrying molybdenum for best corrosion resistance, behave differently under the wheel. Tool steels like D2 and H13 are also part of our regular material offering. We stock and grind across all nine material families to cover the full range of what our customers need.
Companion Services That Support Ground Bar
When a bar leaves our grinding operation, it often needs one or two more steps before it reaches your shop floor. Our bar chamfer service removes burrs and sharp edges from bar ends so stock loads cleanly into your equipment. Bar straightening using rotary machines covers ferrous and non-ferrous bars and includes pipe straightening.
Custom machining handles parts at tolerances of plus or minus .005 inch. Metal turning and milling both hold plus or minus .001 inch. Polishing runs up to a number 8 mirror finish with electroplating available. Every order ships in cardboard tubing, wooden boxes, wood crates, or custom wood boxes, depending on what the job requires.
The Quality System That Backs Every Ground Bar
We are ISO 9001:2015 certified and have operated under that standard since 1994. Our quality process runs Advanced Quality Planning, Statistical Process Control, Gauge R&R, and Machine Capability Studies. Those tools keep our grinding operation in control and our measurements accurate on every order.
When your application requires documentation, we have the system ready. Aerospace, medical, and oil and gas buyers rely on that traceability to meet their own customer requirements. We ship nationally and worldwide from Franklin Park, IL.
Get a Ground Bar That Your Machining Process Can Actually Work With
Sourcing bar stock that already holds the tolerance your part needs removes one major variable from your process. Our team is here to match the grind specification to what your design actually calls for, not just the tightest number available.
Call us at +1 (847) 451-8888, Monday through Saturday, 7 AM to 5 PM. You can also visit fortemetals.com/request-a-quote and submit your specs directly. We’ll follow up with availability and options for your material and diameter requirements.
FAQs
What is the tightest tolerance your grinding operation holds?
Forte Precision Metals holds tolerances as tight as plus or minus .0001 inch with a microfinish down to 8RA on ground bar stock.
What is the largest bar you can grind in one pass?
Our centerless grinding operation handles bars up to 7 inches in diameter and up to 24 feet in length.
Which materials does Forte Precision Metals stock and grind?
We stock and grind nine material families, including stainless steel, alloy steel, carbon steel, aluminum, titanium, tool steel, and nickel alloys.
Do you offer services beyond grinding?
Yes. Bar chamfering, straightening, custom machining, turning, milling, polishing, saw cutting, and packaging, all on site in Franklin Park, IL.
