Reamers: Coating, Types, Applications


Reamers are cutting tools usually used for the reaming process.  They are precise cutting tools used in the machining and metalworking industries for refining and sizing holes in different materials.

They are cylindrical or conical-shaped rotary cutting tools used to enlarge and finish holes that have been drilled, bored, or cored. A reamer cannot be used for making a hole.

A drill is typically used to create a hole in a part. However, drills do not make precisely sized holes because their primary job is to remove large amounts of material as rapidly as possible. Drills are good for holes that do not require precise diameters or smooth surface finishes, such as those for fasteners. In contrast, reamers enlarge an already drilled hole to a specific size with a tight tolerance.

Reamer is the family name for the most precise instruments in common use. They enable basic machinery and even hand effort to create holes with a tolerance of 0.0002 inches. Tolerance is the allowable deviation from a particular dimension. In the context of reaming, it has a direct impact on the precision and functionality of the machined component. Maintaining tight tolerances ensures that completed holes precisely match design specifications, facilitating the correct fit and installation of parts. Whether in aircraft, automotive, or general manufacturing, maintaining accurate tolerances through reaming ensures product uniformity, reduces the possibility of errors, and improves overall performance.

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Cutting materials for reamers

  • Solid carbide
    it is a cutting material suitable for applications up to 63 HRC. It cuts quickly and precisely.
  • CC carrier with cemented carbide
    This material is highly elastic, cuts quickly, and is precise.
  • HSSE (High-Speed Steel)
    This cutting material has strong flexibility and may be used at speeds ranging from tiny to medium.
  • HSS (high-speed steel) 
    it is a cutting material that can withstand up to 1000 N/mm2, has minimal alloy content, and is highly elastic.

Coatings for reamers

  • Titanium nitride is a long-proven standard layer with high hardness, excellent adhesive strength, adequate toughness, and affordability.
  • Titanium carbon nitride has high hardness, strong adhesive strength, high thermal conductivity, and a low friction coefficient against steel.
  • Titanium aluminum nitride is a versatile layer for high-performance machining with fast cutting speeds. It is thermally and chemically stable and has a high hardness, excellent heat resistance, and low thermal conductivity.
  • Titanium aluminium silicon nitrides provide high-performance cutting for machining abrasive or hard materials, including steel up to 63 HRC. They have great hardness and wear resistance.
  • Titanium aluminum carbon nitride is a universal layer for high-performance machining with fast cutting speeds. It has low friction, high hardness, and good oxidation resistance. Thermal conductivity is quite low

Types of reamers

Hand reamers

A hand reamer is a precision-ground cutting instrument that manually expands pre-drilled holes to specific diameters. These often have straight or slightly twisted flute designs, with the tip part at a small angle and tapered lead-in. They are composed of hardened, fragile materials, thus extra precautions must be taken during usage to guarantee exact alignment between the reamer and the hole axis to avoid breakage. Although they function well in light-cutting activities, their precision may not be as good as machine reamers due to manual operation variables. They may not be the ideal solution in situations that require precise tolerance control.

Chucking reamers

These are the most often used reamers, with either a straight or Morse tapered shank. They are also known as machine reamers. The flutes of chucking reamers can be straight or helical. They are frequently installed in a CNC or manual drill press, lathe, mill chuck, or collet, hence the name. The reamer’s tip is normally chamfered at 45 degrees. A chucking reamer is used to enlarge the diameter of an already drilled hole to a more accurate dimension with tighter tolerances.

Adjustable hand reamers

An adjustable hand reamer can accommodate a modest range of sizes. They are often identified by a letter that corresponds to a size range. Disposable blades glide along a tapered groove. Tightening and loosening the restricting nuts at each end changes the size of the cut that can be made.
The flutes’ lack of a spiral limits them to light use (minimum material removal per setting) due to chattering. They are likewise restricted to use in unbroken holes.

Floating reamers

They can fix incorrect alignment between the previously drilled hole and the axis of the reaming tool. Floating reamers have two replaceable and customizable cutting edges that are kept together in one slot and allowed to drift radially. They are designed exclusively for rotational workpieces on turret lathes.

Shell reamers

They are designed for larger holes. They are distinct fluted tips that fit onto preexisting shanks. This feature lowers their cost because they utilize less material and have fewer stages to make.

They are utilized in screw machines, drill presses, automatic screw machines, lathes, and other applications. They are an economical choice for large-hole reaming processes.

Expandable reamers

The outer diameter of its fluting can be modified, allowing the operator to ream a hole that is not a standard size. They can also be useful for machinists who need to sharpen dull reaming blades. After sharpening, the expandable reamer can be resized to fit the necessary dimensions.

Tapered reamers
Tapered reamers are conical in shape and have a specified angle. They are employed to add a little taper to pre-drilled cylindrical holes. Tapered holes are typically necessary to accommodate tapered pins for locating purposes or tapered shafts with Morse tapers, a standard taper used in tooling.
Drill reamers
Time can be saved by drilling and reaming simultaneously with the use of a drill reamer, sometimes referred to as a reaming drill. A reaming drill is ideal for drilling through holes. It should be noted that if exceptionally fine holes are required, drilling with a separate reaming operation is preferred.

Jobber reamers.
They are reamer tools with a shank that can be used in both a machine chuck and a tap wrench. A reamer is often referred to as a jobber or jobbing reamer if it has a parallel OR machine taper shank and a square end to the shank.

Carbide reamers

Carbide reamers are cutting tools constructed of carbide, which is recognized for its great hardness and wear endurance, making them ideal for machining high-hardness, high-strength materials such as stainless steel and titanium alloys
Carbide reamers are suited for machining areas with exceptional abrasion resistance, allowing the reamer to last longer while producing an outstanding hole finish. Solid carbide reamers create a faultless hole around their axis rather than spending time on the already drilled hole.
However, they are exceedingly brittle and must be handled and applied with the greatest care to avoid fracture and breakage.

Alignment reamers

Alignment reamers are strong reaming tools used in manufacturing to increase hole precision. It operates by expanding and aligning holes, making them straight and parallel, which is required for many mechanical components to function properly. Because of its accuracy, the alignment reamer is widely employed in machinery and equipment manufacturing.

Straight Flute reamers

They have flutes that run parallel to the shaft. These reamers are less appropriate for manual usage than those with twisted flutes since they have a restricted ability to clean chips. Furthermore, they are not suitable for reaming split holes with keyways or longitudinal slots, as the blades may become trapped within the slot, generating a blockage.

Diemaker’s reamers

These reamers, which typically have three flutes and a multi-turn helix, are ideal for cutting and reaming holes efficiently. They are particularly beneficial for working on holes with keyways and oil galleries, which could lead tools with shallow-angle or straight flutes to get lodged.

Structural reamers

These tools are comparable to ordinary reamers, except they usually have Morse taper shanks and bigger diameters. They are frequently used for reaming rivets and pin holes in large structural components such as ships and bridges.


  • They are frequently used to create accurate holes with a high level of accuracy and surface quality.
  • To provide smooth and straight walls, they are also used to improve the surface finish of a pre-drilled hole.
  • They can be used to remove burrs or sharp edges that remain after drilling or cutting operations.

Precautions to follow when utilizing reamers

  • Wear adequate personal protection equipment, including safety glasses, gloves, and a dust mask.
  • Choose a suitable reamer for your purpose.
  • Use cutting fluids to reduce heat and friction while increasing tool life.
  • When reaming, apply calm and steady pressure and prevent rapid changes in speed or direction.



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Kabita Sharma

Kabita Sharma, a Central Department of Chemistry graduate, is a young enthusiast interested in exploring nature's intricate chemistry. Her focus areas include organic chemistry, drug design, chemical biology, computational chemistry, and natural products. Her goal is to improve the comprehension of chemistry among a diverse audience through writing.

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