Types of Reamers: With Definitions, Diagrams, and Applications

Reamers are precision cutting tools used in the machining and metalworking industry to refine and size holes in various materials. These cylindrical, fluted tools are designed to achieve high levels of accuracy, surface finish, and dimensional integrity in boreholes. There are different types of reamers, each tailored to specific machining applications, workpiece materials, and desired outcomes. Whether it's enlarging an existing hole to precise dimensions, improving the surface finish, or achieving tight tolerances, they play a crucial role in achieving the quality and precision required in many manufacturing processes.

This piece of writing shall explain different types of Reamers. This topic in mechanical engineering is important for your upcoming examinations like SSC JE ME and RRB JE Mechanical Engineering.

What is a Reamer?

Fig 1: Reamer

A reamer enlarges or refines pre-drilled, bored, or cored holes to attain precise dimensions and a polished surface. It operates as a multi-tooth cutter, removing small increments of material. Reamers can be classified based on their intended operation, purpose, and design.

The different types of reamers are explained below:

1. Chucking Reamer with Taper or Parallel Shank (Fluted)

Fig 2: Chucking Reamer with Taper or Parallel Shank (Fluted)

The chucking reamer, often referred to as a machine reamer, features short parallel cutting edges with a bevelled lead and a long recessed body between the shank. It is employed in applications like a drill press or turret lathe, operating at slow speeds, with cutting performed along the flutes. Fluted reamers reduce the tendency to chatter and are known for reaming more accurate work. Their diameter typically ranges from 1-5 to 32 mm for straight shank reamers and from 5 to 32 mm for taper shank reamers.

2. Chucking Reamer (Rose)

Fig 3: Chucking Reamer (Rose)

Distinct from fluted reamers, the chucking rose reamer relies on bevelled edges to carry out all cutting, forming a 45° angle with chamfered cutting edges. The body tapers slightly toward the shank to prevent bending within the hole. This type of reamer can remove a substantial amount of metal and is particularly useful for specific applications.

3. Machine Bridge Reamer

Fig 4: Machine bridge Reamer

Fig 5: Helical Reamer

Machine bridge reamers, illustrated in both straight and helical fluted versions, are designed for portable electric or pneumatic tools in ship-building, structural, and plate work. They feature parallel cutting edges with a long integral lead, and the flutes may be either straight or helical, depending on the specific application. Their diameters range from 6.4 to 37 mm.

4. Machine Jig Reamer

Fig 6: Machine Jig Reamer

Machine jig reamers consist of short, parallel cutting edges with a bevelled lead and a guide between the shank and cutting edges, all integral with a tapered shank for holding and driving. The flutes on these reamers are helical and designed for use with a bushing in the jig to accurately locate the reamer. Their diameters typically vary from 7 to 50 mm.

5. Parallel Hand Reamer with Parallel Shank

Fig 7: Parallel Hand Reamer with Parallel Shank

Parallel hand reamers feature parallel cutting edges with taper and bevel lead, along with a square on the end. They may have either straight or helical flutes and are intended for hand-driven hole sizing, removing minimal amounts of metal (0.05 to 0.125 mm). These reamers slightly taper towards the end for easy starting.

6. Socket Reamer for Morse Taper

Fig 8: Socket Reamer for Morse Taper

Socket reamers come in straight or taper shank types, suitable for both hand and machine-driven operations. They have taper cutting edges to fit Morse taper holes and are available as sets for roughing, pre-finishing, and finishing. Morse taper holes from No. 1 to 6 can be accommodated.

7. Shell Reamer

Fig 9: Shell Reamer

Shell reamers have virtually parallel cutting edges with a sharpened bevel lead and an axial hole for use on an arbour. They are often used for finishing large holes, and different shell sizes can be interchanged with a single arbour to reduce costs. The shell reamer may be of the rose chucking type for truing holes or fluted for finishing, with flutes that can be either straight or helical.

8. Taper Pin Reamer

Fig 10: Taper Pin Reamer

Taper pin reamers can be either hand or machine-driven and feature taper-cutting edges to match pins with a 1 in 50 taper. They come with either a parallel or taper shank for holding and driving, with straight or helical flutes, depending on the application.

9. Expansion Reamer

Fig 11: Expansion Reamer

Expansion reamers are adjustable to compensate for wear or variations in hole size. The expansion is achieved by loosening the clamping nut and pushing the plug inward, causing the 

blades to expand by a small amount.

10. Straight Flute Reamers

Reamers with straight blades feature flutes that run straight along the length of the shaft. These reamers are less suitable for hand use compared to those with twisted flutes, as they have a limited ability to clear chips. Additionally, they are not compatible with reaming split holes containing keyways or longitudinal slots, as the blades may become trapped within the slot, causing an obstruction.

11. Floating Reamers

A floating reamer refers to a typical machine reamer adapted to a floating reamer holder. This specialised device incorporates a collet or chuck on an independent bearing system, enabling it to move independently of the machine drive's axis and align with an existing hole's path. This innovative design eliminates a potential source of machine error during reaming. Even if the drive is eccentric to the hole, this setup can still achieve precise results in terms of maintaining the hole's centerline.

12. Jobbers Reamers

A jobbers reamer is a versatile reamer tool designed with a shank that accommodates usage in both a machine chuck and a tap wrench. It is characterised by having a shank with either a parallel or machine taper and a square end, making it suitable for various machining tasks, hence the term "jobber" or "jobbing" reamer.

13. Diemaker’s Reamers

Typically featuring three flutes with a multi-turn helix, these reamers are well-suited for efficient hole cutting and reaming. They are especially useful for working on holes containing keyways and oil galleries that could potentially cause tools with shallow-angle or straight flutes to become stuck.

14. Structural Reamers

These tools are similar to standard reamers, but they typically feature Morse taper shanks and larger diameters. They are often employed for reaming rivets and pin holes in substantial structural components like ships and bridges. However, structural reamers have become less prevalent as riveting practices have waned.

Reamer Nomenclature

Reamers, precision cutting tools used to enlarge and refine holes in various materials, follow a standardised nomenclature system. This system typically includes parameters such as the reamer type (straight, spiral, or fluted), cutting diameter, shank diameter, number of flutes, and overall length. Each parameter helps users select the right reamer for their specific machining needs, ensuring accurate and consistent hole dimensions. This standardised nomenclature simplifies the identification and usage of reamers across different applications and industries. The nomenclature of Reamers is explained in the diagram below:

Fig 12: Reamer Nomenclature

Fig 13: Entering End of a Parallel Hand Reamer (B)

Comparison of Various Types of Reamers: Features, Applications, and Precision

There are many types of reamers available in industry for mechanical operations. It is important to select the correct type of reamer to work efficiently. For the ease of candidates, a details comparison of various types of reamers is provided in the table provided below. 

Type of Reamer	Design	Application	Precision Level	Suitable For	Adjustability	Typical Material
Hand Reamer	Tapered lead, straight flutes	Manual hole finishing	Moderate	Soft materials, low-volume operations	No	HSS, Carbon Steel
Machine (Chucking) Reamer	Straight or helical flutes, used in machines	High-precision hole sizing in mass production	High	CNC or drilling machines	No	HSS, Carbide
Adjustable Reamer	Expandable blades	Variable diameter hole finishing	Moderate to High	Versatile hole sizes, on-site repairs	Yes	HSS, Tool Steel
Shell Reamer	Cylindrical body without shank	Mounted on arbors for large hole reaming	High	Heavy machining jobs, large bores	No	HSS, Carbide
Tapered Reamer	Tapered body (usually 1:50 or 1:100)	Reaming tapered holes	High	Taper pins, locating holes	No	HSS, Carbide
Expansion Reamer	Slit body with a screw for slight expansion	Reaming slightly worn or undersized holes	Moderate	Reconditioning operations	Slight	Alloy Steel
Combination Reamer	Dual-function (ream + chamfer)	Time-saving dual machining	High	Automated setups, repetitive tasks	No	Carbide, HSS
Carbide Reamer	Made entirely or tipped with carbide	High-speed, precision reaming	Very High	Hard materials, production industries	No	Solid Carbide

Materials Used in Reamer Construction

It is crucial to choose the correct reamer for the operation based on the performance, durability, and cost. The reamer is selected based on the application, workpiece hardness, and desired precision. Below are the commonly used materials in reamer construction:

1. High-Speed Steel (HSS)
2. Cobalt High-Speed Steel (HSCo)
3. Solid Carbide
4. Carbide-Tipped Reamers
5. Tool Steel
6. Powder Metallurgy (PM) Steel

Common Mistakes to Avoid When Using Reamers

• Using the Wrong Type of Reamer: It is necessary to use the correct type of reamer while performing any operation. 
• Improper Hole Pre-sizing: Reamers are not meant to remove large amounts of material.
• Reaming Without Proper Lubrication: Lack of cutting fluid can lead to excessive hat, weak tool and a poor surface finish. 
• Using Dull or Damaged Reamers: A worn-out reamer can produce rough finishes and out-of-spec holes.

Applications of Reamers

The various applications of Reamers are:

• Achieving precise dimensions in engine cylinder bores.
• Fine-tuning holes for bearings and bushings.
• Ensuring accurate alignment of mechanical parts.
• Improving the surface finish of drilled holes.
• Creating smooth and accurately sized holes in firearm barrels.
• Enhancing the quality of holes for dowel pins.
• Machining accurate holes in aerospace components.
• Preparing holes for press or interference fits.
• Precision reaming of gear bores.
• Refining holes for valve seats in engine blocks.

This blog enumerated different types of Reamers and applications. We suggest that you appear in the SSC JE Mechanical mock tests and SSC JE ME Previous Years Papers. Also, get enrolled in the AE/JE Mechanical coaching to get a firm grip on the subject.

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