Reamers are widely used to finish already drilled holes and to achieve the desired dimensional accuracy.
But each application has a specific surface finish, toughness, and accuracy requirements, making it important to have different types of reamers for different applications.
Reamers are available in different types and are classified based on their material, geometry, and application. Some of the popular reamers include chucking, tapered, shell, car, expansion, straight, helical flute reamers, etc. Chucking reamers with straight shanks are the most popular type of reamers and are used for general-purpose reaming.
|Type of Reamer||Features|
|Chucking Reamer||Specially used in lathes|
|Morse taper reamer||morse taper sleeves or holes|
|Tapered reamer||Used for precision fitting of tapered pins.|
|Die-maker Reamer||Used for reaming die punches and other tools|
|Welding Equipment Reamer||Used for reaming welding guns and other welding equipment|
|Car Reamer||Used for reaming of structural steel plates|
|Jobbers Reamer||Compatible with machine and hand-reaming tools|
|Straight Flute Reamers||No twist flute|
|Helical or Spiral Flute Reamer||Provides better chip clearance|
|Expansion Reamers||Slight varying diameter|
|Shell reamer||multi-fluted, end-cutting tool|
This article discusses different types of reamers in detail and sheds some light on the application of reamers. In the end, the article also differentiates between reaming, drilling, and boring operations.
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Types of Reamers
Reamers are generally used when high-precision holes with a dimensional accuracy of around 0.001" are required.
Reaming can be performed on lathes, drilling machines, machining centers, milling machines, or by hand.
Regardless of the capabilities of your machine, the effectiveness of your machining processes depends on the selection of the appropriate tool.
There are different types of reamers that can be used for different applications, making it important to understand their significance.
Types of Reamers Based on Their Application
Chucking reamers usually have a straight shank or a morse taper shank that is easily clamped in a collet or a jaw chuck, such as a 3-jaw or 4-jaw chuck of a lathe.
These are the most popular type of reamers and are compatible with lathes, screw machines, and drill presses.
Chucking reamers are used to smoothen and finish holes made in cast iron or other heat-treated metals like annealed steel.
These reamers are generally available in straight flute and helical flute (inclined at more than 30°) configurations.
Morse Taper Reamers
Morse Taper Reamers are specially designed to accurately finish the morse taper sleeves or holes. It may be operated by hand or by machine.
The reamers contain taper cutting edges that are compatible with Morse taper and a tapered or parallel shank.
Morse taper is particularly found in lathe spindles for better clamping of the workpiece, minimizing the risk of accidents.
These reamers are available in straight flute and helical flute configurations.
Tapered reamers have tapered cutting faces and are designed to generate tapered holes for tapered pins.
These reamers are generally used with hand tools to produce tapered holes in thin material.
Die Maker Reamers
Die Maker Reamers can be used to manufacture die punches, and steel rule dies.
These are utilized for cutting and reaming holes with keyways and oil passages, which could otherwise be difficult to machine with a shallow angle or straight flute reamer.
Welding Equipment Reamers
Welding Equipment Reamers are utilized for the precise finishing of cap-type electrodes, welding guns, and other kinds of welding equipment.
Cars Reamers are used for reaming the structural steel plates of rail cars, truck frames, pressure vessels, and bridges.
These reamers are one of the thickest reamers and have high rigidity, making them suitable for heavy-duty reaming operations.
Jobber's reamers are the type of reamers that can be used with the machine as well as tap wrench.
These reamers have a morse tapered or parallel shank to be clamped on a machine, with a square tip to be used by hand on a tap wrench.
Types of Reamers Based on Their Material
High-Speed Steel (HSS) Reamer
HSS is the most commonly used material for reamers as it is inexpensive and suitable for almost all materials.
These reamers are best suited for small-scale and DIY applications where moderate tool life with a good surface finish is desirable.
Carbide (Tungsten-carbide, Tantalum-carbide, and Titanium-carbide)
Carbide reamers are more expensive than high-speed steel, but these reamers have high abrasion resistance, resulting in a longer tool life and a superior finish.
These reamers are generally suitable for finishing holes in cermets, metals, and ceramic materials.
Their high strength and hardness allow them to be used to even drill holes in some softer materials.
However, they are comparatively more brittle, hence, must be mounted and handled with extreme care to avoid cracking and chipping.
Types of Reamers Based on Their Design
Straight Flute Reamers
The flutes of these reamers do not twist over the shaft's length.
These are employed for reaming of bushing holes to precise specifications during assembly work.
Helical or Spiral Flute Reamers
Helical or spiral flute reamers are ideal for reaming keyways, slots, oil passages, etc., into brass or bronze.
The spiral flute arrangement facilitates easy chip clearance, making them suitable for machine and hand-reaming applications where chip clearance is of utmost importance.
Left-hand spiral reamers are excellent for through holes because the flute typically pushes the chips out in front of the reamer.
In contrast, right-hand spiral reamers pull the chips out of the hole, making them ideal for reaming blind holes.
Expansion reamers are special reamers that can be expanded along their lengths to ream holes of variable depths.
These reamers are similar to shell reamers with a threaded bolt along its axis which helps to expand and retract the reamer head.
As a result, these reamers lack the rigidity of solid reamers and can only be used to remove small amounts of material to smoothen the surface.
Shell reamers have an axial hole which is useful for mounting on arbors.
These reamers are used to finish large holes for bearings and other similar high-precision items.
Applications of Reamers
Reamers are one of the most widely used tools in manufacturing applications for producing holes with tight tolerances for a perfect fit.
The construction and fabrication industry requires reaming to produce holes for riveting and other fastening applications.
A perfectly machined hole that fits the rivet with tight tolerance allows for minimal vibrations, thereby enhancing the rigidity of the structure.
Similarly, in the manufacturing industry, reaming is used to produce smooth holes with tight tolerance for keyways, shafts, slots, etc.
Generally, straight flute reamers are preferable for machining metals like free machining steel, which produce small chips that are easily cleared away.
Helical or spiral flute reamers are best suitable for reaming keyways, slots, oil passages, etc., where there is minimal space available for chip clearance.
Reaming vs Drilling vs Boring
Drilling, boring, and reaming are metal-cutting processes that differ in terms of material removal rate, the resulting hole surface, and operation sequence.
|Operation sequence||Performed to finish the hole surface and improve the size||Performed to produce a new hole||Performed to enlarge a previously drilled hole|
|Material Removal Rate (MRR)||Minimal MRR||Higher MRR||MRR is relatively higher than reaming|
|Surface finish||A highly finished surface finish is attained||Poor surface finish||Comparatively rough surface finish than reaming|
|Cutting Tool||Reamer (multi-point cutting tool)||Drill bit (a multi-point cutting tool)||Boring bar (a single-point cutting tool)|
|Speed||High RPM||Very high RPM||Comparatively slower RPM|
|Machines||Usually, lathe and drill presses can perform reaming||Drill Press, pillar drill, mill, etc||Lathe and milling machines can perform boring|
Drilling is the process of making a hole in the workpiece, whereas boring is performed to enlarge that hole to achieve the required diameter.
On the other hand, reaming is used for finishing the hole while slightly enlarging its diameter.
As a result, drilling involves the highest material removal rate (MRR), followed by boring and reaming.
Generally, drilling and reaming utilize multi-point cutting tools, while boring involves a single-point cutting tool that provides the ability to perfectly size the hole.
The amount of stock provided for reaming is determined by the quality and size of the hole.
A general rule of thumb is that around 0.010" to 0.015" of dimensional tolerance is recommended during drilling and boring operations for efficient reaming.
For small diameter holes, such as 1⁄32", the clearance provided for reaming is around 0.003" to 0.006".
A pillar drill or a drill press can be used for performing all three operations, but a lathe is preferable for boring operations.
Reamers are used to remove very small amounts of materials to generate a precise hole.
There are various types of reamers depending on the design, material, and shape, with each type having a specific application.
A left-handed spiral-fluted reamer with negative shear action is recommended for reaming cast iron, brass, and plastics as it prevents chips from reentering the spiral flutes and damaging the hole.
Reamers are designed for minimal material removal to attain a good surface finish. As a result, it must be ensured that the hole to be reamed is equal to or slightly smaller than the reaming tool.
It is a finishing process, so it is important to run the reamers at the right speeds and feeds to attain accurate size, straightness, and finish.
Frequently Asked Questions (FAQ)
Can reaming be used to make threaded holes?
No, you can't make a threaded hole by reaming. It can only be used to make a hole larger and smooth it out after it has been drilled or bored.
What safety measures should be taken while reaming?
The safety precautions to be taken while performing reaming operation includes wearing an eye/face shield, hearing protection, safety shoes, gloves, and a protective coat. Never remove chips or burrs with your hands.
Which type of cutting fluid is ideal for reaming?
The ideal cutting fluid for reaming is soluble oil, as it provides excellent lubrication to facilitate smooth movement of the reamer inside the hole, resulting in a smooth surface finish.
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