The Difference Between Round Bar, Drill Rod and Shafting

The Difference Between Round Bar, Drill Rod and Shafting

Metal can be produced in a wide variety of sizes and shapes. These shapes can often look similar – such as pipe and tube – but have very different attributes and applications.

This is also true for three round shapes: round bar, drill rod, and shafting.

Round Bar

Round bar is exactly as it sounds; a long, cylindrical metal bar. Round bar is available in a variety of metals including hot rolled or cold rolled steel, stainless steel, aluminum, alloy steel, brass and more; and in many different diameters ranging from 1/4″ up to 24”.

Steel Round Bars

Steel round bars are available in hot rolled or cold rolled. Hot rolled round bar is typically used for applications like construction where finish and precise dimensions aren’t a priority. Conversely, cold rolled round bar is used for applications where a superior surface finish and exact dimensions are essential. Some common applications of steel round bar include frameworks, supports, braces, shafts, and axles.

Stainless Steel Round Bars

Stainless steel round bars are highly corrosion resistant. The stainless steel will tolerate high levels of acidity and can be used in chlorine bearing environments or alkaline solutions.

Aluminum Round Bars

Aluminum round bars possess light weight and strong corrosion resistance, while being easy to machine and cut. Common applications of aluminum round bar include supports, trim, shaft, braces, pins, and dowels.

Brass Round Bars

Brass round bars are used when strength, electrical conductivity, corrosion resistance, and spark resistance are important. Brass is easy to machine and has an attractive sheen when polished. Some examples of brass bar applications are marine hardware, instruments, fasteners and fittings.

Drill Rod

Drill rods are manufactured from tool steel that has been ground to a tight tolerance diameter. While typically round, drill rods may also be fabricated in square shapes. They are also often tempered prior to machining. This process involves heating the steel to relieve the hardness and to make the steel more workable. The steel is then air cooled before machining begins. Common applications of drill rods include drill bits, taps, dowel pins, shafts, and reamers. They are also used to manufacture hammers, files, and punches.

There are two basic types of drill rod: water and oil hardened:

Water Hardened Drill Rods

Water hardened drill rods are not heavily alloyed, allowing the material to be more easily machined than the oil hardened variety. During the water hardening process, the rod is heated until glowing red then plunged into a vat of water to cool. The result is a hard, durable metal which is easily machined. However, it is not suitable for welding. Water hardened drill rods are used in the manufacturing of hammers and files.

Oil Hardened Drill Rods

Oil hardened drill rods are easily welded and machined and are very tough and durable. During the oil hardening process, the rod is heated until glowing red then plunged into a vat of warm oil. This causes the surface to become extremely hard. Oil hardened drill rods are used for general tool making.

Shafting

Shafting, also known as ‘Turned Ground and Polished’ shafting, refers to round bars made with fine precision and high-quality steel. They are polished to ensure flawless and perfectly straight surfaces. The manufacturing process is designed for extremely close tolerances for surface finish, roundness, hardness, and straightness which ensures a long service life with reduced maintenance.

Shafting bars are commonly used often used in applications that require high accuracy, such as weather measuring devices, laboratory tools, high-speed motor shafts, drive shafts, pump shafts, and ball bushings. In these scenarios, the bar is often required to rotate at high speeds. Thus extreme straightness is critical to prevent unwanted vibration and wear on bearings.

Shafting is manufactured through induction hardening.

Induction hardening

Induction hardening is a non-contact heating process which uses electromagnetic induction to produce the required heat. The steel is placed into a strong alternating magnetic field which causes an electric current to flow through the metal, generating heat. During this process the core of the steel remains unaffected and retains its physical properties. The steel is then quenched in water, oil, or a special polymer which causes the surface layer to form a martensitic structure which is extremely hard.

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