Skiving and Roller Burnishing: the Process and Why Is It Necessary?

PUBLISHED ON: March 13, 2024
LAST MODIFIED ON: August 9, 2024

POSTED IN: Deep Hole Finishing, Precihole

Precision is the cornerstone of manufacturing cylindrical components such as hydraulic cylinders, pistons, and shafts. Skiving and roller burnishing are critical processes that ensure these parts meet the highest standards of accuracy, surface finish, and consistency required for their diverse applications. Far from being just specialized terms, these techniques are essential for achieving the durability and performance expected in various industries.

So, exactly what is skiving and roller burnishing? At first glance, these might seem like complex, niche processes. But delve a little deeper, and you’ll find that they’re fascinating methods that bring unmatched precision and surface finish to cylindrical workpieces.

Skiving: The Precision Cutter

As mentioned above skiving is a machining process used to produce high-precision smooth surfaces on cylindrical workpieces. It is often employed to improve surface finish, accuracy, and concentricity of cylindrical parts.

This process involves removing a thin layer of material from the surface of the workpiece using a cutting tool called a skiving cutter. The skiving cutter typically has multiple cutting edges arranged in a helical pattern. As the cutter rotates and traverses along the workpiece, it removes material leaving behind a fine finish with precise dimensions.

During the skiving process, it is imperative that the metal bar or tube is securely mounted inside the machine to ensure proper alignment and stability. To ensure precise control of the cutter, an machine operator may adjust the machine’s parameters and tool geometry to achieve tighter tolerances and improved consistent part dimensions.

Coolant or other cutting fluids may be applied during cutting to lubricate the cutting tool, dissipate heat, and flush away chips and debris generated during the machining process. One last light pass with the skiving cutter may be necessary to refine the surface finish further.

Roller Burnishing: The Smooth Operator

Roller burnishing enhances the surface finish and dimensional accuracy of cylindrical workpieces through a unique process that compresses rather than removes material. This technique involves the use of a hardened, highly polished roller tool that is pressed against the rotating workpiece. The pressure exerted smooths and compresses the surface material, yielding a mirror-like finish and significantly reducing roughness without material removal. This method not only achieves tighter dimensional tolerances but also enhances the component’s fatigue resistance.

Securing the workpiece properly within the machine is essential for precise alignment and stability throughout the burnishing process. Selection of the roller tool, based on the workpiece’s material properties, desired surface finish, and dimensions, is crucial for optimal results.

The roller tool’s smooth, cylindrical surface, designed to match the workpiece’s final geometry, contacts the workpiece, applying pressure that plastically deforms the surface layer. This deformation process eliminates surface irregularities and fills in microscopic voids, leading to a denser surface layer with superior mechanical properties.

While coolants or lubricants are commonly used to minimize friction and heat, promoting better surface quality, the roller burnishing process can also be executed dry, depending on the specific requirements and properties of the workpiece.

Common Industries and Applications for Skiving and Roller Burnishing Machines

There are many industries that utilize skiving and roller burnishing machines, especially those that commonly manufacture cylindrical components such as:

Hydraulics and Pneumatics: Skiving and roller burnishing are extensively used in the production of hydraulic and pneumatic components that require high precision and smooth surfaces to ensure efficient operation and the elimination of potential leakage.
Automotive Industry: Skiving and roller burnishing machines are employed in the automotive industry to achieve the required surface finish, dimensional accuracy, and performance characteristics of various parts.
Aerospace Industry: Skiving and roller burnishing are used in the production of critical aerospace components that demand extremely tight tolerances, high strength, and excellent surface finishes.
Oil and Gas Industry: Skiving and roller burnishing machines play a vital role in producing equipment used in the energy industry for oil and gas exploration and production that needs to withstand harsh operating environments.
Machine Tool Industry: These processes are utilized in the manufacturing of machine tool components to help ensure the performance and accuracy of machine tools used in various manufacturing operations.
General Engineering Industries: Skiving and roller burnishing find applications in general engineering industries to help meet the quality and performance requirements for producing a wide range of components.
Medical Device Industry: There is no room for error in the medical device industry. High-precision components require the techniques of skiving and roller burnishing. Cylindrical parts with precise dimensions and smooth surfaces are required to produce precise dimensions and smooth surfaces critical for both internal and external human use.

Skiving Applications

Across the industries mentioned above, the process of skiving is commonly used when manufacturing the following parts:

Hydraulic Cylinder Tubes: Surface finish, smoothness and precise dimensions are required.
Piston Rods: Efficient operation and longevity is a must.
Gun Barrels: Precise bore diameters, smooth rifling, and performance and accuracy for high-quality barrels.
Shafts: Smooth surfaces, tight tolerances and surface finish requirements are necessary for longevity.
Linear Motion Components: Linear shafts and guide rods for smooth finishes and reduced friction are critical for proper linear motion.
Rollers: Rollers used in printing, paper processing, textiles, and other similar industries for fast high-quality throughput.
Transmission Components: Certain gear shafts, input/output shafts, shift rods for precise fine surface finishes, geometrical accuracy, and smooth and efficient power transmission.
Rotary Seals and Bearings: Precise dimensions, smooth surfaces, sealing, and reduced friction for improved longevity.

Roller Burnishing Applications

The roller burnishing process is commonly used when manufacturing the following parts:

Hydraulic Cylinder Tubes: Surface finish and dimensional accuracy along with sealing and smooth operations for hydraulic systems.
Piston Rods: Used for both hydraulic and pneumatic cylinders for mirror finishes, reduced friction, enhance wear resistance, and improving performance and longevity for the applicable market.
Shafts and Spindles: Improve the surface finish and size consistency of shafts and spindles used in various mechanical systems such as automotive transmissions and aerospace components.
Gears: Applied to the gear teeth to improve surface finish and reduce friction that leads to quieter operations, increased efficiencies and improved gear life.
Engine Crankshafts and Camshafts: Achieve fine surface finishes and accuracies for smooth rotation and optimal engine performance.
Gun Barrels: Used to enhance surface finish and bore dimensions for improved accuracy, reducing fouling, and extending the life of the barrel.
Drive Shafts and Transmission Components: Improves surface finish and dimensional accuracy of drive shafts and transmission components for smoother operations and reduces wear in automotive and other industrial applications.
Aerospace Components: Landing gear components, actuators and structural elements require stringent surface finish and dimensional properties are pertinent for compliance in the aerospace industry.
Valve Stems and Seats: Improve surface finish, reduce friction and enhance sealing in valves used across industries such as oil and gas, chemical processing, and power generation in the energy sector.
Medical Implants and Instruments: Critical to achieve smooth surfaces, precise dimensions, and biocompatibility for optimal performance and patient safety.

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