Seamless cold drawn precision tube according to EN 10305-1 (DIN 2391), with narrow tolerances, a good surface and special mechanical properties. After the heat treatment +N (NBK) the tubes can be cold formed (bending).

Cold drawn seamless tube and pipe is produced by piercing hot billets and subsequent rolling which reduces their diameter and elongates them. This material is then passed through a die and over a mandrel plug to produce an accurate size and gauge which is the essence of the cold drawing process.

Outside diameter : EN 10305-1 (DIN 2391)
Material : E235 (St. 35) / E355 (St. 52)
Version : +C (BK)
No heat treatment after cold drawing, cold forming very restricted.
: +N (NBK) (annealed)
Suitable for cold forming
Straightness deviation : Outside diameter > 15 mm = 0,25% of the length
Outside diameter 6 – 15 mm (straightened by the eye)
Outside diameter < 6 mm = no guarantee for the straightness
Wall thickness tolerance : +/- 10%

Applications Of Seamless Cold Drawn Precision Tube

Petrol,gas,water pipe,construction,fluid pipe,etc

Great for high-pressure applications such as HPLC

Hydraulic Systems

Derivative of all Honed tubes

resistant to internal pressure

OEM hydraulic cylinder manufacture

hydraulic and pneumatic applications

The Production Method Of Seamless Cold Drawn Precision Tubes According To EN-10305-1 DIN 2391最先出现在Bos-Hyd。

When it comes to high-performance hydraulic cylinders, ​H8 skived and roller burnished tubes​ are a top choice for engineers who demand precision, durability, and smooth operation. But what makes these tubes so reliable?

The Right Steel for the Job​
Not all steel is created equal—especially when it comes to hydraulic applications. The best ​H8 tubes​ are made from:

​High-Quality Carbon Steel (STKM, E355, etc.)​​ – Offers excellent strength-to-weight ratio and machinability.
​Alloy Steel (4140, 4340, etc.)​​ – Ideal for high-pressure systems due to superior fatigue resistance.
​Stainless Steel (304, 316)​​ – Used in corrosive environments (e.g., marine or chemical industries).

Why does material matter?​​

Wear Resistance​ – Harder steels (like alloy grades) last longer under heavy loads.
​Machinability​ – Carbon steel is easier to skive and burnish to ultra-smooth finishes.
​Cost Efficiency​ – STKM/E355 provides a great balance between performance and affordability.

​How Skiving & Roller Burnishing Enhance Performance​

The ​H8 process​ involves two key steps:

1. ​Skiving (Precision Cutting)​​ – A sharp tool removes inner surface imperfections, ensuring a uniform diameter.
2. ​Roller Burnishing (Cold Working)​​ – A hardened roller compresses the tube’s inner wall, creating a mirror-like finish (Ra ≤ 0.2 µm).

​Benefits of This Process:​​
​Lower Friction​ – Smoother surface = better seal performance & less energy loss.
​Higher Pressure Resistance​ – Work-hardened surface resists cracking.
​Longer Lifespan​ – No micro-cracks = reduced wear over time.

Conclusion: The Perfect Match of Material & Process​

Choosing the right steel for ​H8 skived and roller burnished tubes​ ensures maximum durability and efficiency. Whether you need ​carbon steel for cost-effective solutions​ or ​alloy steel for extreme conditions, the key is pairing the material with precision machining.

​Need high-quality H8 tubes?​​ Contact us for custom solutions—your hydraulic systems deserve the best!

How Skiving & Roller Burnishing Enhance Performance最先出现在Bos-Hyd。

E355 Precision steel phosphated tubes are engineered for industries requiring exceptional durability, corrosion resistance, and dimensional accuracy. These tubes undergo ​precision machining​ followed by a ​phosphating treatment, enhancing their performance in high-stress environments.

​Key Benefits of Precision Steel Phosphated Tubes​

​1. Precision Manufacturing for Optimal Performance​

• ​Tight Tolerances (H8/H9):​​ Precision-ground or cold-drawn tubes ensure ​consistent inner diameter (ID) and outer diameter (OD)​, critical for hydraulic cylinders, pneumatic systems, and precision machinery.
• ​Superior Surface Finish (Ra 0.2–0.4 µm):​​ Reduces friction, wear, and energy loss in dynamic applications.
• ​Straightness & Roundness:​​ Minimizes deflection in high-load scenarios, improving component lifespan.

​2. Phosphating Treatment for Enhanced Durability​

• ​Corrosion Resistance:​​ The phosphate coating acts as a barrier against ​rust, oxidation, and chemical exposure, extending service life in harsh environments.
• ​Improved Lubricity:​​ The microcrystalline phosphate layer enhances ​oil retention, reducing friction and wear in moving parts.
• ​Paint & Coating Adhesion:​​ Phosphating provides an ideal surface for ​additional coatings (e.g., paint, powder coating, or chrome plating)​.
• ​Wear Resistance:​​ The treated surface resists ​scoring and galling, making it ideal for high-contact applications.

Materials Used in E355 Precision Phosphated Tubes​

Superior Performance Of E355 Precision Steel Phosphated Tubes最先出现在Bos-Hyd。

Hydraulic cylinders are the backbone of heavy machinery, construction equipment, and industrial systems. Among the many factors influencing their performance and durability,hard  ​chrome plating quality​ stands out as a decisive element. As producers dedicated to engineering reliability, we emphasize that the chromium plating process is not merely a surface treatment—it is a precision engineering step that directly impacts cylinder lifespan, efficiency, and operational cost. Below, we analyze how plating quality affects hydraulic cylinder longevity and why superior chroming practices matter for your operations.

1. Why Hard Chrome Plating Matters in Hydraulic Cylinders​

Chromium plating (often termed “chromed cylinders”) is applied to cylinder rods and barrels to:

• ​Reduce Friction: A smooth, hard chromium layer minimizes metal-to-metal contact between the piston rod and seals, lowering wear and energy loss.
• ​Prevent Corrosion: The inert chromium oxide (Cr₂O₃) layer resists moisture, chemicals, and contaminants, critical for outdoor or high-humidity environments.
• ​Enhance Surface Hardness: Chrome’s hardness (typically 600–700 HV) protects against abrasion from particulates in hydraulic fluid.

However, ​subpar plating quality​ compromises these benefits, leading to premature failure.

2. Key Factors in Chromium Plating Quality​

As manufacturers, we scrutinize three core aspects of plating to ensure optimal performance:

​A. Adhesion Strength​

Poor adhesion causes peeling or flaking, exposing the base metal to corrosion and abrasion.

• ​Our Approach:
• Surface Preparation: Rigorous degreasing, pickling, and polishing to ensure micro-smoothness and chemical bonding​Electroplating Parameters: Controlled current density, temperature, and plating time to achieve uniform, defect-free layers​Adhesion Testing: Cross-hatch tests and tensile adhesion tests (ASTM B571) validate coating integrity.

​B. Coating Thickness Uniformity​

Inconsistent thickness creates weak points. Thin areas wear faster, while excessive thickness may cause dimensional inaccuracies.​Our Approach:​Automated Thickness Monitoring: In-line coating gauges ensure ±0.0005 mm tolerance across the rod surface. ​Post-Plating Inspection: Laser micrometers and magnetic induction tools verify uniformity.

​C. Surface Finish​

A rough or porous chrome surface accelerates wear and traps contaminants.

Our Approach:Polishing: Final buffing achieves a mirror-like finish (Ra < 0.1 μm), reducing friction and fluid retention. Electropolishing: Optional step to enhance surface smoothness and corrosion resistance.

3. The Cost of Poor-Quality Chromium Plating​
Cheap or inconsistent plating may save upfront costs but leads to:

​Reduced Cylinder Lifespan: Premature wear necessitates frequent overhauls or replacements.
​Increased Downtime: Failures in critical applications (e.g., construction cranes, excavators) disrupt operations.
​Environmental Risks: Corrosion-induced leaks contaminate machinery and surroundings.
For instance, a cylinder with substandard plating in a mining application may fail within 6 months, whereas a premium chromed cylinder lasts 5+ years under similar conditions.

4. How We Ensure Premium Chromium Plating​
As a hydraulic cylinder manufacturer, we integrate quality control at every stage:

​Material Selection: Use high-purity steel rods like 4140 cylinder rod to prevent hydrogen embrittlement during plating.
​Process Optimization: Advanced electroplating baths with strict chemical ratios (e.g., chromium trioxide concentration).
​Environmental Controls: Temperature and pH stability during plating to avoid micro-cracks.
​Third-Party Testing: Independent labs validate compliance with ISO 6108 (Chrome Coatings) and SAE AMS 2434 standards.

The Critical Role of Hard Chrome Plating Quality in Hydraulic Cylinder Longevity​最先出现在Bos-Hyd。

AISI 4130 steel (UNS G41300), also known as 4130 Chromoly steel, is a chrome-molybdenum series low alloy steel with high strength, toughness and hardenability, usually used in quenched and tempered condition.

Datasheet & Specification

Below is material AISI 4130 Chromoly steel datasheet including chemical composition, density, thermal expansion coefficient, thermal conductivity, yield strength, hardness, etc.

AISI SAE 4130 Chemical Composition

The table below lists AISI 4130 chemical composition.

AISI 4130 Material Properties

Material AISI 4130 steel mechanical properties are given in the table below.

SAE 4130 Steel Heat Treatment

The following table shows alloy 4130 chromoly steel heat treatment and rockwell hardness.

Material Properties & Chemical Composition Of SAE4130 Chrome Steel最先出现在Bos-Hyd。

Chrome polished rods are high-grade steel rods with a ​mirror-like chrome finish, offering ​exceptional hardness, corrosion resistance, and smooth surface quality. These rods are widely used in ​hydraulic cylinders, linear motion systems, industrial machinery, and automotive applications​ where precision and durability are critical. BOS HYDRAULIC specialize in manufacturing ​top-tier chrome polished rods​ with ​strict quality control, advanced processing techniques, and decades of industry expertise. Our products meet ​ISO, ASTM, and DIN standards, ensuring reliability in the most demanding environments.

How Are Chrome Polished Rods Manufactured?

​Step 1: High-Quality Steel Selection​

We start with ​precision-drawn, cold-rolled steel bars​ (grades like ​1045, 4140, or stainless steel) to ensure ​high tensile strength and dimensional accuracy.

​Step 2: Precision Turning & Grinding​

​Centerless grinding​ ensures ​tight tolerances (±0.005mm)​​ and a perfectly cylindrical shape.
​Hard chrome plating​ (thickness ​20-50 microns) is applied for ​wear and corrosion resistance.

​Step 3: Superfinishing & Polishing​

Our advanced polishing process includes:
​Multi-stage abrasive polishing​ for a ​Ra ≤ 0.1µm surface roughness​ (ultra-smooth finish).
​Electrolytic polishing​ (for stainless steel rods) to enhance ​corrosion resistance and aesthetics.

​Step 4: Quality Inspection​

Every rod undergoes ​strict testing, including:
​Hardness testing (HRC 60-65)​​
​Surface roughness analysis​
​Dimensional accuracy checks​
​Salt spray testing (500+ hours for corrosion resistance)​

What Are Chrome Polished Rods?​最先出现在Bos-Hyd。

Chrome plated tubings are widely used across industries due to their ​durability, corrosion resistance, and sleek aesthetic appeal. The electroplating process coats steel pipes with a thin layer of chromium, enhancing their strength and longevity while providing a polished, mirror-like finish. At BOS HYDRAULIC, we specialize in high-quality chrome plated steel pipes, ensuring ​premium materials, precise engineering, and competitive pricing. Whether for industrial, commercial, or decorative applications, our products meet the highest industry standards.

When buying chrome plated tubing,Clients more care about?​​

​1. Corrosion & Wear Resistance​

A high-quality chrome plating should ​prevent rust and oxidation, especially in humid or corrosive environments. Customers prioritize ​thick, even plating layers​ for maximum protection.

​2. Surface Finish & Aesthetic Quality​

A ​smooth, mirror-like finish​ with no scratches or imperfections is crucial for decorative and automotive applications. Buyers inspect for ​uniform gloss and defect-free surfaces.

​3. Strength & Durability​

Industrial buyers focus on ​load-bearing capacity, impact resistance, and fatigue strength​ to ensure long-term performance in demanding conditions.

​4. Customization Options​

Many clients need ​specific dimensions, thicknesses, or bending shapes​ for unique projects. A reliable supplier should offer ​custom cutting, threading, and fabrication services.

​5. Compliance with Industry Standards​

Reputable manufacturers adhere to ​ISO, ASTM, or DIN standards, ensuring safety and reliability. Customers verify ​material certifications and testing reports​ before purchasing.

What Do Customers Look for When Buying Chrome Plated Tubing?​最先出现在Bos-Hyd。

STKM13C Cylinder Tube is the standard carbon steel tubes for hydraulic cylinder purpose,After seamless cold drawing, the inner diameter is processed by high-precision boring, the inner tolerance can reach H7 H8, and the surface roughness is 0.2-0.4um.

JIS STKM 13C cylinder tube and SAE 1020 aim at mechanical structural uses with similar but less working pressure than that of ST52 cylinder tube. However, such material is suitable for lathing and other further processing. ST52 and ST52.3 cylinder honed tubes are with good weld-ability, high yield strength to bear high pressure, and good impact resistance in low temperature.  If the working pressure is not high, STKM 13C honed tube is also a good choice, because the cost is relatively low than ST52.

Advantages of Our STKM13C Cylinder Tube

1.High precision tolerances;

Our STKM13C  honed tube can meet ID tolerance H7, H8, H9, … etc according to the customer’ requirements, and its I.D dimension.

2.Seamless tube with high pressure resistance;We only use seamless cold drawn tubes to produce honed pipes, which means our honed tubing can work under higher pressure, thus our honed pipes are more reliable for hydraulic cylinder applications.

3.High Smooth inside surface;

The roughness of our honed pipe is Max Ra 0.4 microns ID finish (16Max Ra ID Finish).

Flexible order quantity: we accept small quantity orders, even if there is only one piece of hydraulic cylinder tubing we can produce and supply.

4.Good weld ability: The weld ability of our honed barrel tubing is very good, this is quite helpful for manufacturing the cylinders.

The Benefit Of JIS G3445 STKM13C Cylinder Tube最先出现在Bos-Hyd。

AISI 4140 steel is a low alloy steel containing chromium, molybdenum, and manganese. It is widely used across numerous industries and is an excellent material choice due to its toughness, high fatigue strength, and abrasion and impact resistance.

Surface Of SCM440 Alloy Steel Rod:  Black,Grounded,Peeled/Turned,Polished

CHEMICAL COMPOSITION

HEAT TREATMENT OPTION

• +A: Annealed (full/soft/spheroidizing)
•  +N: Normalized
• +NT: Normalized and tempered
• +QT: Quenched and tempered (water/oil)

FABRICATION AND HEAT TREATMENT

Machinability
AISI 4140 alloy steel has good machinability in the annealed condition.
Forming
AISI 4140 alloy steel has high ductility. It can be formed using conventional techniques in the annealed condition. It requires more pressure or force for forming because it is tougher than plain carbon steels.
Welding
AISI 4140 alloy steel can be welded using all conventional techniques. However, the mechanical properties of this steel will be affected if it is welded in the heat-treated condition, and post-weld heat treatment should be performed.
Heat Treatment
AISI 4140 alloy steel is heated at 845°C (1550°F) followed by quenching in oil. Before hardening, it can be normalized by heating it at 913°C (1675°F) for a long period of time, followed by air cooling.
Forging
AISI 4140 alloy steel is forged at 926 to 1205°C (1700 to 2200°F)
Hot Working
AISI 4140 alloy steel can be hot worked at 816 to 1038°C (1500 to 1900°F)
Cold Working
AISI 4140 alloy steel can be cold worked using conventional methods in the annealed condition.
Annealing
AISI 4140 alloy steel is annealed at 872°C (1600°F) followed by slowly cooling in the furnace.
Tempering
AISI 4140 alloy steel can be tempered at 205 to 649°C (400 to 1200°F) depending upon the desired hardness level. The hardness of the steel can be increased if it has a lower tempering temperature. For example, a tensile strength of 225 ksi can be achieved by tempering at 316°C (600°F), and tensile strength of 130 ksi can be achieved by tempering at 538°C (1000°F).
Hardening
AISI 4140 alloy steel can be hardened by cold working, or heating and quenching.

SCM440 Alloy Steel Rod Forged 42crmo4 Round Bar最先出现在Bos-Hyd。

DIN 2391 St 52 Roller Burnished Steel Tubes

Roller burnishing is performed on the return stroke. The plastic deformation taking place provides a surface finish of Ra= 0.05 – 0.20 µm – better than broaching, grinding or even honing. Roller burnishing also means an improvement in surface hardness.Roller burnishing steel tubes made mainly for the hydraulic cylinder industry and other applications where fine-finishing of the internal diameter of a tube is required, Primarily for hydraulics in the contracting, mining and construction industries.

Standard :DIN 2391(EN 10305-1)

Steel grades : St 52 (E355)

I.D. tolerance：H8

Inside diameter :between 20-1500 mm

Outside diameter : between30-1600mm

Tolerance of Wall Thickness ±7%

Surface finishing: roughness Ra < 0.40 µ (average 0.15÷0.35 µ)

Chemical composition and property of DIN2391 ST52 Cold drawn seamless Roller burnished steel tubes

BOS HYDRAULIC stock cold drawn steel tubes, seamless DIN 2391 grade St 52, or welded DIN 2393  grade St52.3, in stress relieved conditions (BK+S).The tubes are hot rolled according to DIN 2448/1629,grade St52 On request St52.3 N ( normalised tubes).

honed tube,chrome plated bar,hydraulic cylinder barrel supplier and manufacturer

The Chemical Composition Of DIN 2391 St 52 Roller Burnished Steel Tubes最先出现在Bos-Hyd。