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Precision Ground Stainless Steel Bar
| MOQ: | 5ton |
| Price: | Based on grade, size, surface, processing, quantity and current raw material market price. |
| Standard Packaging: | Standard seaworthy export packing with bundles, waterproof wrapping, pallets or wooden cases. |
| Delivery Period: | 7-15 |
| Payment Method: | L/C,D/A,D/P,T/T,Western Union |
| Supply Capacity: | Stock supply, regular production and custom manufacturing available. |
Precision Ground Stainless Steel Bar
SEO Opening Paragraph
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
| Purchase Item | Supply Information |
|---|---|
| Grades | 304/304L, 316/316L, 410, 420, 17-4PH, selected duplex grades |
| Diameter | 3–80 mm common precision range; larger ground diameters by project review |
| Tolerance | Typical ISO h6–h10 options depending on grade, diameter and length |
| Straightness | Specified per metre or total length; precision levels by agreement |
| Roundness | Controlled with diameter tolerance and process capability |
| Surface Roughness | Project-specific Ra, commonly from fine ground to polished |
| Length | Random, 3 m, 6 m or cut-to-length with end finishing |
| Testing | Diameter mapping, roundness, straightness, Ra, hardness and PMI |
| Processing | Centerless grinding, polishing, facing, chamfering and straightening |
| Documents | MTC 3.1 plus dimensional inspection report |
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
| Grade / Designation | Key Chemistry (wt.%) | Density g/cm³ | Tensile MPa | Yield MPa | Elong. % | Hardness | Heat Treatment / Condition |
|---|---|---|---|---|---|---|---|
| 304 / S30400 / 1.4301 | C≤0.08; Cr 18–20; Ni 8–10.5 | 7.93 | ≥515 | ≥205 | ≥40 | ≤201 HB | Solution annealed; not hardenable by heat treatment |
| 316L / S31603 / 1.4404 | C≤0.03; Cr 16–18; Ni 10–14; Mo 2–3 | 8.00 | ≥485 | ≥170 | ≥40 | ≤217 HB | Solution annealed; rapid cooling after hot work |
| 17-4PH H900 / S17400 / 1.4542 | C≤0.07; Cr 15–17.5; Ni 3–5; Cu 3–5; Nb+Ta 0.15–0.45 | 7.75 | ≥1310 | ≥1170 | ≥10 | Approx. 40 HRC or higher | Solution treated, then aged at 482°C for H900 |
| 420 / S42000 / 1.4021 | C 0.15–0.40; Cr 12–14 | 7.74 | ≥515 | ≥275 | ≥18 | ≤241 HB annealed | Annealed for machining; harden and temper after processing |
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
| Process / Inspection | Purpose | Ordering Note |
|---|---|---|
| Saw cutting / cold sawing | Fixed lengths and production blanks | State length tolerance, squareness and burr requirement |
| Peeling / turning | Remove hot-worked surface and improve diameter | State final raw size and machining allowance |
| Centerless grinding | Control diameter, roundness and surface | State ISO tolerance, straightness and Ra separately |
| Chamfering / facing | Improve loading, assembly and length control | Provide angle, width, radius or finished length |
| PMI / chemistry verification | Confirm alloy family and heat identity | XRF does not independently confirm L-grade carbon |
| Hardness / mechanical tests | Verify condition and grade requirements | Test method, sampling and condition must match the standard |
| UT / third-party inspection | Evaluate internal quality and witness compliance | Define method, acceptance class, coverage and report |
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
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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.
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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.
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Is straightness included in an h9 tolerance?
No. The h9 designation controls diameter tolerance only. Straightness and roundness must be specified separately.
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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.
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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.
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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.
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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.
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How is diameter inspected?
Micrometers, laser measurement or automated gauging can be used. Sampling frequency and measurement temperature should be defined for critical orders.
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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.
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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.
