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ResourcesMachining DesignReaming: How It Works, Applications, Advantages, and Disadvantages

Reaming: How It Works, Applications, Advantages, and Disadvantages

Xomety X
Written by
Team Xometry
 11 min read
Published May 30, 2024
Reamers. Image Credit: Jiranarak

Reaming is a precision machining operation used to enhance the diameter and finish of a pre-drilled hole. It involves a multi-edged tool known as a reamer, which meticulously carves out material to achieve a highly accurate hole size and smooth surface finish. This process is important in industries in which exact dimensions and finishes are imperative, such as: aerospace, automotive, and medical device manufacturing.

One benefit of reaming is that it can create uniform, high-quality holes with little tool wear and at a comparatively low cost. Nevertheless, it also has drawbacks, like the need for pre-machined holes and the risk of tool damage when not used properly.

This article will discuss reaming, its procedure, the types and designs of reamers, and their vital function in contemporary production. 

What Is Reaming in Manufacturing?

In manufacturing, reaming is a finishing operation that precisely enlarges and smooths the diameter of a pre-drilled hole. It is performed using a multi-edged tool called a reamer, which removes a small amount of material to improve the dimensional accuracy and surface finish of the hole. This process ensures that the holes meet strict specifications for size and finish, which is essential in high-precision engineering applications. Reaming is distinguished from other hole-finishing processes by its ability to achieve tight tolerances and a high-quality surface finish.

What Is the Purpose of Reaming in Manufacturing?

In the production process, reaming helps to precisely finish drilled holes, so they have a smooth surface and exact dimensions. It makes it possible to produce more holes of consistently good quality. When a precise, even surface is required, the technique is essential and calls for an appropriate edge profile and diameter.

What Is the Other Term for Reaming?

While "reaming" is the most commonly used term, it can also be referred to as "reamer machining" when discussing the process in a manufacturing context. This term emphasizes the use of the reamer tool in the machining operation.

How Does Reaming Work?

Reaming works by using a multi-edged rotary cutting tool called a reamer to enlarge and finish the surface of pre-drilled holes. The reamer's edges scrape away a thin layer of material, improving the hole's diameter accuracy and surface finish. It's a critical step for achieving tight tolerances and a high-quality surface in precision-engineering applications.

How Does Reaming Differ From Drilling?

Reaming differs from drilling in that it is a finishing process used to refine the size and improve the surface finish of an existing hole, rather than creating a new hole. Drilling is the initial process of cutting a circular-shaped hole in a workpiece, while reaming uses a reamer to smooth and accurately size the hole created by drilling. Reaming removes significantly less material than drilling and is focused on precision rather than hole creation.

What Are the Applications of Reaming?

Reaming’s ability to create precise holes with excellent surface finishes makes it widely employed in a variety of sectors. Here are some examples of reaming's uses in various industries:

1. Medical

In orthopedic surgery, reaming is a vital process for preparing bones for intramedullary nailing, crucial in repairing long bone fractures. It also plays a significant role in joint-replacement procedures, in which accurate hole dimensions are paramount for the proper fitting and function of joint implants. This precision ensures the longevity and success of surgical outcomes, making reaming indispensable in medical device fabrication.

2. Manufacturing

Reaming is an essential last step in the manufacturing industry that smoothes holes in precision products, such as tools and equipment parts. Achieving the precise tolerances and flawless surface finishes required for high-precision products' functionality and quality is largely dependent on this technique. It ensures that components fit together perfectly, improving the manufactured goods' overall integrity and functionality.

3. Automotive

In the automotive sector, reaming plays a pivotal role in precision tasks such as enlarging and perfecting holes in vital engine components. This process guarantees that parts like brake systems and suspension units meet exact size specifications and possess a refined finish, essential for optimal vehicle performance and safety.

4. Pumps

One procedure that is essential to the manufacturing of pumps is reaming. It's important to ensure that parts like impellers and casings have the precise size of holes needed for optimum performance. This precision ensures smooth functioning and simple assembly of pumps, which are often at the core of industrial systems, rather than just obtaining a snug fit. Pump reliability and effectiveness could be seriously jeopardized without reaming.

5. Aerospace

Reaming is indispensable in aerospace manufacturing, in which precision is non-negotiable. It's employed to form exact fastener holes in critical components like wings and landing gear. This ensures a secure assembly and robust performance of aircraft parts, which are essential for the structural integrity and safety of the aircraft during flight.

6. Bearings

Reaming is used to produce precise holes in bearings. These are essential components of many machines and pieces of equipment, and reaming is the process used to create exact holes in them. It ensures that bearings fit snugly and operate smoothly, which is essential for the longevity and reliability of machinery.

What Are the Advantages of Reaming?

Reaming offers several advantages in manufacturing:

  1. High Precision: It produces holes with tight tolerances and excellent surface finishes.
  2. Efficiency: Reaming can be performed quickly, enhancing productivity.
  3. Versatility: It can be used on a variety of materials and is suitable for both hand and machine operations.
  4. Cost-Effective: The tools required for reaming are generally low-cost, and the process can be economical for finishing holes.
  5. Surface Finish: Decreasing the feed rate during reaming can improve the surface finish of the hole.

What Are the Disadvantages of Reaming?

Despite its benefits, reaming also has some disadvantages:

  1. Pre-Machined Holes Required: Reaming cannot create a hole; it can only enlarge and finish pre-drilled or pre-machined holes.
  2. Tool Wear: If not used correctly, there is a risk of tool breakage and wear.
  3. Dimensional Control: There is less control over the dimensions of holes compared to other processes like boring.

What Are the Common Problems in Reaming?

Some common problems encountered during reaming include:

  1. Poor Fit Quality: Reaming tools only follow the existing hole. This can result in poor fit quality if the initial hole is not accurately drilled or if there are deviations in the hole's dimensions. This can lead to scrap parts and rework.
  2. Damage to Inserts: Cutting inserts in reaming tools may get damaged, especially if the workpiece material has problems or if the cutting circumstances are not ideal. There could be additional expenses and downtime associated with reconditioning or replacing the inserts due to this damage.
  3. Lost Production Time: When reaming tools become damaged and require reconditioning or replacement, it can lead to lost production time. Reconditioning processes can be lengthy, causing delays in production schedules and impacting overall efficiency.

What Are the Different Types of Reaming Tools?

There are various types of reaming tools, each designed for specific applications:

  1. Hand Reamers: Used primarily for manual operations to improve the fitting of parts.
  2. Stub Screw-Machine Reamers: These reamers can be identified by a transverse pinhole in the shaft, which allows them to be used in a floating reamer holder. This feature is common in many reamer styles and is particularly useful for applications with shallow holes.
  3. Shell Reamers: Designed for reaming large holes and often used in a machine setup.
  4. Chucking Straight-Fluted Reamers: Chucking straight-fluted reamers are designed for machine use, featuring straight flutes and a smooth shank for collet or chuck mounting. They're ideal for precise hole finishing, but not suited for hand-reaming due to their straight flute design.
  5. Taper Pin Reamers: These have tapered flutes for precision fitting of tapered pins and can have various flute designs. They are categorized by tip diameter, root diameter, and length.
  6. Carbide Reamers: Made from hard materials like tungsten-carbide, titanium-carbide, and tantalum-carbide, these reamers are very brittle and must be handled carefully to avoid damage.
  7. Diemaker’s Reamers: Diemaker's reamers are characterized by their three flutes cut on a multi-turn helix, making them suitable for rapid cutting. They are especially useful for reaming holes with keyways and oil galleries, in which other tools with shallow-angle or straight flutes might jam.

How To Choose a Reamer?

When selecting a reamer, consider the material to be reamed, the diameter of the hole, the amount of stock to be removed, and the desired accuracy and finish.

What Is the Importance of Choosing a Reamer?

Choosing the right reamer is important for precision in traditional and CNC machining. It ensures the hole is accurately sized and has a smooth finish, which is essential for the high levels of precision required in industries like aerospace and automotive manufacturing.

How Does the Choice of Reamer Impact the Reaming Result?

The choice of reamer significantly affects the reaming result. Using the correct reamer type and size can lead to a high-quality surface finish, superb hole quality, and close dimensional tolerance. So, yes, reamer choice has a major effect.

How To Use a Reamer?

Using a reamer correctly is essential for achieving the desired precision in machined holes. Here's a step-by-step guide on how to use a reamer:

  1. Secure the Workpiece: Ensure that the workpiece is held securely and will not slide or rock during the reaming process.
  2. Pre-Drill the Hole: Drill the hole to slightly less than the final diameter. The size of the drill should be chosen based on the reamer size; for reamers up to 1/2", subtract 2% to 4% from the reamer diameter.
  3. Apply Lubricant: If necessary, apply a light-cutting oil or coolant to the material to facilitate smoother cutting and prolong the life of the reamer.
  4. Insert the Reamer: Place the reamer into the hole. If using a hand reamer, ensure it is properly aligned with the hole's axis.
  5. Ream the Hole: Turn the reamer with steady pressure. For machine reaming, use the machine's feed mechanism. For hand reaming, use a tap wrench or similar tool to turn the reamer. Avoid applying excessive force, which can lead to oversizing the hole or damaging the reamer.
  6. Check the Size: Regularly check the hole size during the reaming process to ensure that the desired diameter is achieved.

When To Use a Reamer?

Reamers are useful for: achieving exact hole diameters, clean surfaces, and the removal of burrs and defects from prior machining operations.

What Are the Materials That Are Suited for Reaming?

Reaming is suited for a variety of materials, including: plastics, metals, and composites. The reamer construction can be from high-speed steel (HSS), cobalt alloys, or carbide materials.

What Are Tips for Using a Reamer?

When using a reamer, it's important to follow best practices to ensure the best results. Here are some tips:

  1. Use the Right Cutting Fluid or Lubricant: Proper lubrication can reduce friction and heat, leading to a better finish and longer tool life.
  2. Maintain Proper Speed and Feed Rate: Adhere to recommended speeds and feeds to prevent tool wear and achieve the desired surface finish.
  3. Apply Consistent Pressure: Even and steady pressure ensures uniform cutting and prevents irregularities in the hole's finish.
  4. Check Hole Sizing Regularly: Frequent checks can prevent over-reaming and ensure that the hole dimensions remain within the desired tolerances.
  5. Deburring and Cleaning: After reaming, remove any burrs and clean the hole to ensure a smooth finish.
  6. Practice and Gain Experience: Like any skill, proficiency with reaming comes with practice, so take the time to learn and improve.

Is Reaming Hard?

No, reaming is not considered a heavy-cutting operation and is generally more stable and faster than boring and grinding.

Will a Reamer Straighten a Hole?

Yes, a reamer can straighten a bored hole to very fine tolerances and shape conical holes.

What Is the Difference Between Reaming and Boring?

Reaming is used to refine the interior walls of an existing hole for a smoother finish and precise size. Compared to reaming, boring can create larger hole sizes and is used to enlarge holes.


This article presented reaming, explained it, and discussed its various applications and how it works. To learn more about reaming, contact a Xometry representative.

Xometry provides a wide range of manufacturing capabilities, including machining and other value-added services for all of your prototyping and production needs. Visit our website to learn more or to request a free, no-obligation quote.


The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.

Xomety X
Team Xometry
This article was written by various Xometry contributors. Xometry is a leading resource on manufacturing with CNC machining, sheet metal fabrication, 3D printing, injection molding, urethane casting, and more.

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