Technical Selection Guide · Plain Bearings

Wrapped Bronze Bushings (Rolled Bronze Bearings): Material, Design Types & DIN 1494 Metric Sizes

A practical guide to thin-wall bronze bushings wrapped from phosphor-bronze strip — alloy options, oil-pocket / solid-lubricant / oil-hole designs, allowable load and speed limits, and standard metric dimensions per DIN 1494 / ISO 3547.

What Is a Wrapped Bronze Bushing?

A wrapped bronze bushing (also called a rolled bronze bearing or bronze strip bushing) is a thin-wall plain bearing formed by rolling a flat bronze strip into a cylinder with a butt joint, then sizing it to the required diameter. Because the material is produced from rolled strip rather than machined from solid bar, wrapped bushings offer:

• Higher material density and a fine, work-hardened structure from the rolling process.
• Reduced machining cost and a more compact housing envelope than solid cast bushings.
• A lubricant-retention surface — indents, grooves or oil holes can be formed into the bore by rolling or drilling.
• Availability as cylindrical bushes, flanged bushes, thrust washers and special forms.

Standard metric series follow the dimension system of DIN 1494, now aligned with ISO 3547 (Plain bearings — Wrapped bushes), covering nominal bores from 10 mm to 300 mm in the common metric catalogue.

Base Alloys & Chemical Composition

The two standard base alloys are tin–phosphorus bronzes with no lead or zinc in the declared composition:

Both alloys are deoxidised phosphor bronzes: tin provides strength and wear resistance, phosphorus refines the grain and improves fatigue and wear behaviour. The lead-free character simplifies compliance work for RoHS, REACH and food-processing contact applications, although a written material declaration and, where required, migration testing should be confirmed with the supplier for food contact.

Cross-Standard Designation Map (CuSn8)

CuSn8 is specified under several national and international designation systems. Composition windows differ slightly between standards; the governing standard should be agreed with the customer before production.

*Values in the summary table above follow the ASTM B103 (UNS C52100) window. EN CW453K narrows Sn to 7.5–8.5% and widens P to 0.01–0.40%.

Design Types by Lubrication Principle

Within the wrapped-bushing family, three lubrication designs cover most duty classes. Select by load, sliding speed and maintenance access.

Type A — Oil-Pocket (Indented) Bushings

Diamond or spherical indents are rolled into the bore surface. The pockets retain grease or oil in service and distribute it across the running surface, so the bushing runs with a boundary-lubricated film even where re-lubrication is infrequent. This is the general-purpose design for medium loads and moderate speeds.

• Typical base alloys: CuSn8 / CuSn6
• Hardness: HB 90–120
• Working temperature: −195 °C to +280 °C
• Allowable load: 150 N/mm²
• Allowable sliding speed: 2.5 m/s

Type B — Solid-Lubricant Bushings

Diamond or round pockets are filled with a specially selected polymer solid lubricant during production. The lubricant area covers about 25% of the bearing surface, giving low friction and consistent wear behaviour where external lubrication is impractical or undesirable. This design suits dry-running and maintenance-free applications.

• Friction coefficient: 0.06–0.25
• Working temperature: −100 °C to +250 °C
• Allowable load: 150 N/mm²
• Allowable sliding speed: 1.5 m/s
• Allowable PV (dry): 2.6 N/mm²·m/s  ·  Allowable PV (oil): 15 N/mm²·m/s

Type C — Perforated (Oil-Hole) Bushings

Uniformly spaced holes are drilled through the wall of the wrapped bronze strip. At assembly the holes are filled with oil or grease and the bushing is sealed at both ends, acting as a self-contained oil reservoir. This design stores a large lubricant volume and suits middle-load, low-speed positions where re-lubrication access is limited.

• Typical base alloys: CuSn8 / CuSn6
• Hardness: HB 90–120
• Working temperature: −195 °C to +280 °C
• Allowable load: 150 N/mm²
• Allowable sliding speed: 2.5 m/s

Performance Summary

Values shown are catalogue limits for selection purposes. For a given application, verify against the operating envelope with the bearing manufacturer — load, speed and temperature act together, and the allowable combination is defined by the PV limit.

Application Areas

Standard Metric Sizes (DIN 1494 / ISO 3547)

Cylindrical bushings are offered from 10 mm to 150 mm nominal bore in the standard series; flanged bushings from 25 mm to 300 mm. The tables below show representative rows — bores, outside diameters and available lengths. The symbol • indicates a standard available combination.

Cylindrical bushings (excerpt)

Flanged bushings (excerpt)

Sizes outside the catalogue range can be produced to customer drawings, including custom lengths, thrust washers, ball-cup forms and special lubrication patterns.

Installation & Tolerance Notes

• Inside diameters are quoted after press-fit: the free-state bore closes when the bushing is pressed into the housing, so check I.D. against the shaft in the installed condition.
• Standard O.D. tolerances follow the ISO 3547 series — e.g. +0.065/+0.030 for 10–18 mm O.D., +0.100/+0.055 for 50–80 mm, up to +0.260/+0.170 for 250–315 mm.
• Chamfer dimensions f1 / f2 are given for the leading and trailing edges to ease assembly and prevent edge loading.
• For Type C (oil-hole) bushings, fill the holes with the selected oil or grease at assembly, then seal both ends as specified in the drawing.

Compliance Notes

• The declared alloys contain no lead or zinc additions, which supports RoHS and REACH conformity assessments.
• For food-processing contact, confirm the specific alloy and, for Type B, the solid-lubricant filler against the relevant food-contact framework (e.g. FDA 21 CFR, EU 1935/2004, NSF/ANSI 51) and request a material declaration from the supplier.
• Custom lubrication patterns, flange forms and material mixes should be agreed in writing before production.

FAQ

What is the difference between a wrapped bushing and a solid cast bushing?

A wrapped bushing is rolled from bronze strip into a thin-wall cylinder, giving higher density, closer tolerances and lower machining cost. A solid cast bushing is machined from a casting and is used where greater wall thickness or a heavier section is required.

Which wrapped bushing type suits dry running?

Type B (solid-lubricant embedded) is intended for dry or maintenance-free operation, with an allowable PV of 2.6 N/mm²·m/s in dry conditions and a friction coefficient of 0.06–0.25.

Are DIN 1494 and ISO 3547 the same?

DIN 1494 is the long-standing German metric series for wrapped bushes; the international dimension and tolerance system is ISO 3547, which the DIN series now aligns with. Both are used in catalogues for metric cylindrical and flanged bushings.

Technical selection guide · Wrapped / rolled bronze bushings · DIN 1494 / ISO 3547 metric series · Alloys CuSn8 (EN CW453K / UNS C52100) & CuSn6 (EN CW452K / UNS C5191)