A skived and roller burnished tube, often called an SRB tube, is a precision steel tube manufactured through two specialized processes: skiving and roller burnishing.
SRB tubes are widely used as cylinder barrels in hydraulic and pneumatic cylinders because they offer excellent dimensional accuracy, low surface roughness, good roundness, and a high-quality inner surface.
Compared with conventional honed tubes, skived and roller burnished tubes can provide high production efficiency while maintaining the precision required for demanding hydraulic applications.
In this guide, we will explain what an SRB tube is, how it is manufactured, its advantages, typical applications, and how to choose the right tube for your hydraulic cylinder.
1. What Is a Skived and Roller Burnished Tube?
A skived and roller burnished tube is a precision steel tube whose internal surface is finished by skiving followed by roller burnishing.
During the skiving process, a cutting tool removes a controlled amount of material from the inside diameter of the tube. This operation improves the dimensional accuracy and removes surface imperfections.
The tube then passes through a roller burnishing process. Hardened rollers press against the internal surface under controlled pressure, smoothing and strengthening the surface.
The result is a tube with:
- Accurate internal diameter
- Low surface roughness
- Improved roundness
- Good straightness
- A smooth and consistent internal surface
- Improved surface properties
- Excellent suitability for hydraulic cylinder applications
Because of this combination of machining processes, SRB tubes are sometimes referred to as skived and roller burnished tubes, SRB tubes, or skived tubes.
2. How Does the Skiving and Roller Burnishing Process Work?
The manufacturing process generally consists of several stages.
Step 1: Preparation of the Steel Tube
The starting material is normally a suitable precision steel tube or cold drawn steel tube.
Depending on the required specification, commonly used materials include grades such as E355, ST52, C45, and other carbon or alloy steels.
The tube must have sufficient dimensional accuracy and material quality for subsequent internal machining.
Step 2: Skiving
Skiving is a high-precision internal cutting process.
A skiving head equipped with cutting edges is passed through the inside of the tube. The cutting tool removes a controlled layer of material from the internal surface.
Skiving can effectively remove:
- Surface defects
- Oxide layers
- Minor dimensional irregularities
- Uneven internal material
At the same time, it brings the internal diameter closer to the required final dimension.
The amount of material removed depends on the original tube condition and the required finished dimensions.
Step 3: Roller Burnishing
After skiving, the tube enters the roller burnishing stage.
In this process, hardened rollers are pressed against the internal surface with controlled force.
Unlike skiving, roller burnishing is primarily a surface finishing and plastic deformation process rather than a conventional cutting operation.
The rollers smooth the surface peaks and compress the surface layer.
This produces a smoother internal surface and can improve the surface characteristics of the tube.
Step 4: Final Inspection
After processing, the tube is inspected according to the customer's technical requirements.
Typical inspection parameters include:
- Inside diameter
- Wall thickness
- Roundness
- Straightness
- Surface roughness
- Length
- Mechanical properties
- Surface condition
Additional non-destructive testing or material certification may also be required depending on the application.
3. What Is the Difference Between Skiving and Roller Burnishing?
Although the two processes are normally performed together for SRB tubes, they have different functions.
| Process | Main Function | Typical Result |
|---|---|---|
| Skiving | Removes material from the ID | Accurate internal dimension |
| Roller Burnishing | Smooths and compresses the surface | Low roughness and improved surface properties |
In simple terms:
Skiving controls the geometry.
Roller burnishing improves the surface.
The combination of both processes allows manufacturers to produce high-quality cylinder tubes efficiently.
4. Why Are SRB Tubes Used for Hydraulic Cylinders?
The internal surface of a hydraulic cylinder barrel has a direct influence on seal performance, friction, leakage, and service life.
An SRB tube provides a precision internal surface suitable for piston and seal movement.
For hydraulic cylinder manufacturers, important advantages may include:
High Dimensional Accuracy
The internal diameter can be controlled to tight tolerances, helping manufacturers achieve the required piston-to-cylinder fit.
Low Surface Roughness
A smooth internal surface helps reduce friction between the cylinder tube, seals, and moving components.
Good Roundness
Good roundness is important for maintaining consistent sealing conditions around the piston.
Improved Surface Quality
Roller burnishing can produce a uniform and smooth internal surface while also improving the characteristics of the near-surface material.
High Production Efficiency
Compared with some conventional internal finishing methods, SRB processing can be highly efficient, particularly for high-volume cylinder tube production.
5. Skived and Roller Burnished Tube vs. Honed Tube
One of the most common questions from hydraulic cylinder manufacturers is:
What is the difference between an SRB tube and a honed tube?
Both can be used for hydraulic cylinders, but their manufacturing processes are different.
| Feature | Skived & Roller Burnished Tube | Honed Tube |
|---|---|---|
| Main process | Skiving + roller burnishing | Honing |
| Material removal | Cutting + surface deformation | Abrasive machining |
| Production efficiency | Generally high | Depends on honing process |
| Internal surface | Smooth, precision finished | Honed surface with cross-hatch pattern |
| Typical application | Hydraulic cylinders | Hydraulic and pneumatic cylinders |
| Suitable for mass production | Yes | Yes |
| Final selection | Depends on cylinder design and requirements | Depends on cylinder design and requirements |
There is no universal answer that one process is always better.
The appropriate choice depends on:
- Cylinder design
- Required tolerance
- Surface roughness
- Seal system
- Production volume
- Tube dimensions
- Material
- Cost requirements
- Customer specifications
For this reason, hydraulic cylinder manufacturers should select the tube according to the complete technical specification rather than choosing solely based on the finishing process.
6. What Materials Are Used for SRB Tubes?
SRB tubes can be manufactured from different grades of carbon steel and alloy steel.
The appropriate grade depends on the cylinder's operating conditions and the customer's specification.
Commonly considered materials include:
E355
E355 is widely used for precision applications and is a common choice for hydraulic cylinder tubes.
It offers a useful combination of strength, machinability, and availability.
ST52
ST52 is a commonly used designation in hydraulic and mechanical applications. When customers specify ST52, it is important to confirm the applicable standard and exact material requirements rather than assuming that all ST52 products are identical.
C45
C45 is a medium-carbon steel commonly used for mechanical components and can be selected for certain cylinder applications depending on the design.
Alloy Steels
For demanding applications, alloy steels may be considered when higher strength or other enhanced mechanical properties are required.
The material should always be selected based on the actual operating requirements and applicable standard.
7. What Specifications Should You Consider When Buying an SRB Tube?
When requesting a quotation for a skived and roller burnished tube, providing only the tube diameter is usually not enough.
A complete RFQ should ideally include:
1. Internal Diameter
For example:
ID: 80 mm
The required ID tolerance should also be specified.
2. Outside Diameter
For example:
OD: 100 mm
This determines the nominal wall thickness together with the ID.
3. Wall Thickness
Wall thickness is closely related to cylinder pressure and structural requirements.
4. Length
Specify whether you require:
Random length
Fixed length
Cut-to-length pieces
5. Material Grade
For example:
E355
The applicable material standard and delivery condition should also be confirmed.
6. ID Tolerance
The required tolerance can have a significant effect on the machining and final application.
7. Surface Roughness
Specify the required internal surface roughness according to the cylinder design and seal requirements.
8. Straightness
Straightness is particularly important for long cylinder tubes.
9. Roundness
Good roundness helps maintain consistent sealing and piston movement.
10. Inspection and Certification
Customers may require:
- Material Test Certificate
- EN 10204 3.1 certificate
- Ultrasonic testing
- Eddy current testing
- Dimensional inspection
- Surface inspection
The exact inspection requirements should be agreed before production.
8. What Are the Typical Applications of SRB Tubes?
The primary application of SRB tubes is hydraulic cylinder manufacturing.
Typical applications include:
Construction Machinery
SRB tubes can be used for cylinders in:
Excavators
Loaders
Cranes
Bulldozers
Concrete equipment
Agricultural Machinery
Applications may include:
Tractors
Harvesting machinery
Agricultural implements
Hydraulic lifting systems
Material Handling Equipment
SRB tubes are also suitable for cylinders used in:
Forklifts
Lifting platforms
Handling equipment
Industrial Hydraulic Systems
They may be used in:
Hydraulic presses
Injection molding equipment
Industrial machinery
Automation systems
Mining and Heavy-Duty Equipment
For demanding environments, the tube material, dimensions, mechanical properties, and inspection requirements must be selected according to the specific operating conditions.
9. What Are the Advantages of SRB Tubes?
The main advantages of skived and roller burnished tubes include:
1. Precision internal dimensions
Suitable for applications requiring controlled ID tolerances.
2. Smooth internal surface
Helps support reliable piston and seal movement.
3. Good surface consistency
Provides a controlled internal surface for hydraulic cylinder applications.
4. High production efficiency
The SRB process can be efficient for producing large quantities of precision cylinder tubes.
5. Suitable for large-diameter tubes
The process can be applied to a wide range of tube dimensions depending on the manufacturer's equipment and process capability.
6. Reduced secondary machining
A properly processed SRB tube can reduce the amount of additional internal finishing required by the cylinder manufacturer.
10. How to Choose Between SRB and Honed Tubes?
There is no single answer for every hydraulic cylinder.
When choosing between SRB and honed tubes, consider the following:
Choose Based on the Cylinder Design
The seal system and piston design should be considered first.
Choose Based on Required Surface Finish
Different cylinder designs may have different surface roughness requirements.
Consider Production Volume
For large-volume production, process efficiency can be an important factor.
Consider Tube Dimensions
The required ID, OD, wall thickness, and length can influence the most suitable manufacturing process.
Consider Cost
The total cost should include not only the tube price but also subsequent machining, processing, inspection, and production costs.
Follow the Customer's Drawing
If the customer provides a technical drawing or specification, the tube should be manufactured according to the specified requirements rather than selecting a process based only on general industry practice.
11. How to Specify a Skived and Roller Burnished Tube
A clear specification helps avoid misunderstandings between the buyer and supplier.
A typical specification might look like:
SRB Tube
Material: E355
ID: 100 mm
ID tolerance: Customer specified
OD: 120 mm
Length: 3000 mm
Internal surface roughness: Customer specified
Straightness: Customer specified
Surface condition: Skived & roller burnished
Inspection: According to agreed specification
Material certificate: EN 10204 3.1, if required
The exact values should always be determined according to the hydraulic cylinder design.
12. Conclusion
A skived and roller burnished tube is a precision steel tube produced by combining two processes: internal skiving and roller burnishing.
Skiving removes a controlled amount of material to achieve the required internal dimensions, while roller burnishing improves the internal surface and compresses the surface layer.
This combination makes SRB tubes an important solution for hydraulic cylinder manufacturers, especially where dimensional accuracy, surface quality, production efficiency, and consistent performance are important.
However, choosing the right tube requires more than comparing prices or choosing between "honed" and "SRB."
The correct selection should consider the complete specification, including:
Material + ID + OD + wall thickness + tolerance + surface roughness + straightness + roundness + length + inspection requirements.
If you are sourcing skived and roller burnished tubes for hydraulic cylinders, providing a complete technical specification or drawing is the best way to obtain an accurate quotation and ensure the tube meets your application requirements.
