Precision Ground Stainless Steel Bar

Precision Ground Stainless Steel Bar

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Shaanxi Shangyou Stainless Steel Co., Ltd. supplies precision ground stainless steel bar for pump shafts, guide rods, linear-motion parts, rollers, measuring equipment and high-accuracy CNC components. Precision grinding is selected when commercial bright bar cannot provide the required combination of diameter tolerance, roundness, straightness and surface roughness.

First-Screen Procurement Summary

Product Description and Purchasing Logic

Centerless grinding supports long round bars and produces consistent diameters without holding the workpiece between centres. The finished result depends on incoming material condition, grinding allowance, bar length, hardness and straightening sequence. ISO tolerance classes such as h6, h7, h8, h9 or h10 can be discussed, but the tolerance class alone is incomplete: the RFQ must also state straightness, roundness, surface roughness and measurement temperature.

Grade 304 and 316L are commonly used for corrosion-resistant shafts. 17-4PH provides higher strength and is often ground after aging to control the final diameter. Grades 410 and 420 may be hardened and tempered for wear resistance before finish grinding. The selected heat treatment must be completed before final precision grinding unless a controlled dimensional change is included in the process plan.

Processing and Machining Guidance

The normal route includes raw-bar selection, peeling or turning where required, heat treatment, straightening, rough grinding, finish centerless grinding, polishing, dimensional inspection and protected packing. For long shafts, total indicated runout after component machining may differ from raw-bar straightness. The customer drawing should distinguish bar straightness from finished-shaft runout and concentricity.

Material Selection Boundaries

Precision ground bar is not automatically ready for bearing service. Surface hardness, residual stress, wear, lubrication, fatigue, corrosion and mating-material compatibility must be considered. Tight tolerances can be lost through uncontrolled cutting, welding or post-delivery heat treatment. Parts exposed to chloride solutions also require grade selection beyond surface accuracy.

Representative Technical Performance Table

Values are representative engineering references for common conditions. The applicable ASTM/EN standard, section size, ordered condition and MTC control acceptance. Grade 303 is frequently hardness-controlled under ASTM A582, so tensile values should not be assumed without the certified heat data.

Available Processing and Inspection

Typical Applications

• Pump and motor shafts
• Guide rods and linear motion
• Precision pins and rollers
• Valve stems
• Measuring and automation equipment
• Wear-resistant machine parts

RFQ and CTA

Send the drawing with diameter, ISO tolerance class, roundness, straightness, Ra, length, heat-treatment condition and inspection method. Shangyou will confirm process capability before quotation.

FAQ

1. What is centerless-ground bar?

   It is round bar finished by grinding between a regulating wheel, grinding wheel and support blade, allowing long bars to be processed without centre holes.

2. Which tolerance classes are available?

   Common requests include h6 through h10, but capability depends on diameter, grade, hardness, length and straightness. Final values require technical review.

3. Is straightness included in an h9 tolerance?

   No. The h9 designation controls diameter tolerance only. Straightness and roundness must be specified separately.

4. Can hardened 420 bar be precision ground?

   Yes. A typical route is annealed machining, hardening and tempering, straightening, then finish grinding. Heat-treatment distortion must be allowed for.

5. Should 17-4PH be ground before or after aging?

   Final precision grinding is commonly completed after aging because precipitation hardening causes dimensional change. The process sequence should match the drawing and condition.

6. What Ra can be achieved?

   Fine ground and polished Ra levels are possible, but the target must be specified together with diameter, length and inspection method.

7. Can long bars maintain precision straightness?

   Yes within agreed limits, but attainable straightness becomes more demanding as length-to-diameter ratio increases. Special straightening and packing may be required.

8. How is diameter inspected?

   Micrometers, laser measurement or automated gauging can be used. Sampling frequency and measurement temperature should be defined for critical orders.

9. Can ground bars be cut without damaging tolerance?

   Yes, but cutting and end finishing can introduce local burrs or bending. Precision blanks should be inspected after cutting when the final application is sensitive.

10. How are precision bars packed?

    Individual sleeves, separators, protective oil or film and rigid wooden cases are used to avoid scratches, bending and moisture damage.