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Most stainless steel orders we see begin with a grade number on a drawing. The questions that decide whether the job runs well come next. How will the bar behave on your machine? How tight does the diameter need to be? What will the finished part face in service? At Precision Ground Bars, we’ve supplied stainless steel bar stock since 1970, to customers ranging from screw machine shops to pump manufacturers. Here’s how we approach the material and bar condition questions that matter before a bar reaches your machine.
Matching Stainless Steel Bar Stock to Your Part, Your Machine, and Your Tolerance
A grade number is where most stainless orders start, but it rarely tells the whole story. Your part’s application, how it will machine, the tolerance it needs, and the condition the bar ships in all affect what you should order.
Start with the part, then pick the grade
Stainless steel is chosen for its mechanical properties, including ductility and resistance to creep, corrosion, and oxidation. Machinability also varies by grade and material condition. Because stainless steel grades offer different combinations of these properties, the useful question is which characteristics your part depends on most.
A fastener, a pump shaft, and a surgical instrument can all call for stainless, but each pushes the selection in a different direction. Stainless fasteners rely on corrosion resistance and high strength. Pump shafts need tight diameter control and straightness. Medical parts bring their own grade preferences. Defining the job first keeps you from overbuying or underspecifying.
The grades we carry, and where most buyers land
At Precision Ground Bars, our stainless steel lineup includes 303, 304/304L, 316/316L, 410, 416, 420, 430, 440, 455, 13-8 PH, 15-5 PH, 17-4 PH, A286, Duplex, and Nitronic 60. Of those, 304, 316, and 430 are the most frequently used grades.
Some grade direction comes from specific applications. In medical work, 304 is used for surgical instruments and equipment, while 316, with its higher nickel content, is used in devices that contact bodily fluids. We’ve covered several head to head grade comparisons in other posts, including 303 vs 304 vs 316 and 410 vs 416, so here we’ll focus on how the bar will machine, the tolerance it needs, and the condition it ships in.
When machinability and galling resistance drive the choice
For rotating, sliding, and oscillating parts such as shafts, wheels, and pivots, our bearing shaft quality stainless bar is non galling, non seizing, and non magnetic in the annealed condition. Selenium, or sulfur and phosphorus, additions improve its machinability and resistance to seizing, which makes it a practical fit for screw machine products, valves, aircraft parts, shafts, gears, bolts, and screws. Our earlier post on bearing shaft quality steel covers these properties in more detail.
When diameter tolerance and straightness decide the order
For shafts, bar condition matters alongside the grade. Our pump shaft quality stainless bar comes in 316, 410, 420, and 17-4 PH, in sizes from 1/2 inch to 5 inch, and is centerless ground for tight diameter tolerance and straightness. Our post on pump shaft quality tolerance covers the full specifications.
If your shafts run at high speed, turned, ground, and polished bar is another option. TGP is made predominantly from stainless steel grades and responds well to heat treating.
Shapes and forms beyond round bar
Not every part starts from round stock. Our stainless steel bars come in hexagon, square, and round shapes. If your part starts from tube, our stainless steel round tube is available seamless or welded, in austenitic grades from 304 to 316L and sizes from 1/16 inch to 12 inch. We can cut tube to custom sizes for your application.
Preparing the bar for your machine
Choosing the right grade is only half the job. The bar also has to load and run cleanly. Our centerless grinding service delivers tight dimensional tolerances, precise roundness, and a clean surface finish. On the Swiss screw machine parts we supply material for, such as drive shafts, pins, bushings, and pump shafts, centerless grinding supports precise manufacturing.
We also cut bar stock to your exact length specifications and chamfer bar ends for smoother indexing. Precision straightening returns a bar to its intended shape after distortion from heating, welding, or cooling. Our centerless ground bar stock is available in various levels of hardness, with flat ends and other custom options.
What to send us with your quote request
A clear quote request tells us the grade, dimensions, and processing your order needs. Include the grade, the shape, the diameter, the length, and the quantity. Add the bar condition you need, such as centerless ground, pump shaft quality, bearing shaft quality, or TGP, along with any cutting, chamfering, or straightening. Put those specifications in the quote information field of our Submit a Quote form.
Bring us the drawing
If you’re deciding between a bearing shaft quality bar and a pump shaft quality bar, or you’re unsure whether hex or round stock fits your setup better, call us with the print in hand. We’ll talk through the part and the machine it’s going on. We’re in Palos Hills, Illinois, and our team is available Monday through Friday, 8 AM to 5 PM.
Submit your requirements through our Submit a Quote form, or call (800) 818-0822 toll free or (708) 880-7277 locally.
FAQs
Which stainless steel grades do you carry?
303, 304/304L, 316/316L, 410, 416, 420, 430, 440, 455, 13-8 PH, 15-5 PH, 17-4 PH, A286, Duplex, and Nitronic 60.
What diameter tolerance do you hold on pump shaft quality stainless bar?
For pump shaft quality bars under 1 inch OD, the specified diameter tolerance is +0/−0.002 inch.
Do you offer stainless bar in shapes other than round?
Yes. Our stainless steel bars come in hexagon, square, and round shapes. Stainless steel round tube is also available, seamless or welded.
Can you prepare bars before they ship?
Yes. We offer centerless grinding, bar stock cutting to your specifications, bar chamfering, precision straightening, and custom packaging.
