2. Slower processing speed: Reaming's processing speed is generally slower than drilling because the reamer's cutting speed is lower.

During reaming, appropriate cutting fluids must be used for cooling, lubrication, and cleaning to prevent built-up edge formation and promptly remove chips. Compared to honing and boring, reaming offers higher productivity and can easily ensure hole precision. However, reaming cannot correct positional errors of the hole axis; positional accuracy must be ensured by the previous process. Reaming is not suitable for machining stepped holes and blind holes.

Reaming operationexample

Yes, coolant is typically needed during reaming. Coolant helps reduce friction and heat buildup, extend the reamer's lifespan, and improve the surface finish and dimensional accuracy of the hole.

Reaming typically achieves a dimensional accuracy of IT9 to IT7 grades and a surface roughness Ra of 3.2 to 0.8 μm. For medium-sized holes requiring high precision (such as IT7 grade holes), the drill-expand-ream process is a commonly used typical machining method in production.

Reaming is an indispensable process in the metalworking industry, offering precision, consistency, and excellent surface finishes. By understanding the reaming process, selecting the right tools, and adhering to best practices, manufacturers can achieve high-quality results and meet the demanding requirements of modern engineering applications.

The diameter of the reamer is usually 0.1 to 0.5 mm larger than the pre-drilled hole, depending on the required precision and hole size. Choose the appropriate reamer diameter based on the tolerance requirements of the hole to ensure the machined hole meets the dimensional specifications.

Reaming operationPDF

Machine Reamers: Designed for use with machine tools, these reamers offer higher precision and are suitable for high-volume production.

To ensure the accuracy of reaming, the workpiece must first be firmly fixed on the fixture to keep it stationary to avoid sliding or shaking during processing.

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Reaming operationsteps

2. Smooth Surface Finish: The multi-edge design of reamers results in a superior surface finish, reducing the need for additional finishing processes.

To avoid built-up edge formation, reaming typically employs lower cutting speeds (for high-speed steel reamers processing steel and cast iron, the speed should be less than 8 m/min). The feed rate depends on the diameter of the hole being processed; larger diameters require higher feed rates. The feed rate commonly ranges from 0.3 to 1 mm/r for high-speed steel reamers processing steel and cast iron.

Carbide Reamers: Made from carbide materials, these reamers are used for high-speed applications and for reaming harder materials like stainless steel and titanium. They offer superior wear resistance and longer tool life.

Reaming involves the use of a multi-cutting edge tool called a reamer. The reamer is rotated and fed into the hole, removing a small amount of material from the interior surface. This action results in a hole with precise dimensions and a fine finish.

Shell Reamers: Used for larger holes, these reamers have replaceable cutting edges, reducing tool replacement costs. They are typically used with arbors and are suitable for operations requiring larger diameters and higher cutting forces.

3. Higher requirements for equipment accuracy: Reaming requires higher accuracy of equipment, otherwise the size accuracy and roundness of the hole will not be able to meet the requirements.

Reaming is a machining process used to enlarge and finish holes that have already been drilled or bored. The primary purpose of reaming is to improve the accuracy of the hole diameter and enhance the surface finish. This process is particularly important when tight tolerances and smooth surfaces are required.

Drilling: The initial process of creating a hole in a workpiece using a drill bit. Drilling is typically faster but less precise than reaming and boring, often leaving rough surfaces and less accurate diameters.

Boringoperation

During the reaming operation, avoid stopping the reamer midway or pecking the hole wall with the reamer. Keep pushing the reamer from the top of the hole to the bottom of the hole until the reamer is completely out of the hole.

ReamingTool

4. Limited processing materials: Not all materials are suitable for reaming. For example, very hard or very brittle materials may not be suitable for reaming.

The reamer is fed into the hole at a controlled speed and feed rate. Typically, reaming speeds range from 15 to 60 meters per minute (m/min), and feed rates can be between 0.05 to 0.20 mm per revolution (mm/rev). Lubrication is often used to reduce friction and heat generation, with common coolants being soluble oils or cutting oils.

Generally, holes may have slight burrs after reaming. To ensure the smoothness and functionality of the hole, deburring is typically necessary. Deburring can be done using hand tools, deburring machines, or chemical methods to ensure the edges of the hole are smooth and burr-free.

Reamingprocess in drilling

The selection of reamer material should be based on the material being machined and the processing requirements. Common reamer materials include High-Speed Steel (HSS) and carbide. HSS reamers are suitable for general purposes and soft materials, while carbide reamers are ideal for high-hardness materials and high-precision machining.

Adjustable Reamers: These reamers have an adjustable cutting diameter, making them versatile for different hole sizes. They are ideal for low-volume production or custom work, requiring different hole sizes without needing multiple reamers.

Reaming operationon lathe machine

Taper Reamers: Used for creating tapered holes, commonly found in applications requiring a precise fit for tapered pins or plugs.

Understanding the distinctions between reaming, drilling, and boring is essential for selecting the right process for specific applications

1. Higher cost: Compared to drilling, reaming requires specialized reamers and more complex machining equipment, making it more expensive.

Before reaming, a hole is first created using a drill bit or boring tool. The initial hole is typically slightly smaller than the final desired diameter. For instance, if the final hole diameter needs to be 10.00 mm, the pre-drilled hole might be 9.80 mm.

The reaming allowance significantly impacts the quality of the reamed hole. If the allowance is too large, the load on the reamer increases, the cutting edges dull quickly, and it becomes difficult to achieve a smooth surface finish and maintain dimensional tolerances. Conversely, if the allowance is too small, it cannot remove the tool marks left by the previous process, resulting in no improvement in hole quality. Generally, the rough reaming allowance is set between 0.35 to 0.15 mm, while the finish reaming allowance ranges from 0.15 to 0.05 mm.

Hand Reamers: Used for manual operations, hand reamers have a long, tapered lead for easy entry into the hole. They are typically adjustable and used for small-scale projects or repairs.

Tappingoperation

4. Extended Tool Life: Reamers offer longer tool life and lower maintenance costs, especially those with replaceable cutting edges.

Boring: A machining process that enlarges and refines an existing hole using a single-point cutting tool. Boring improves the accuracy of the hole diameter and can correct alignment issues but may not achieve the fine surface finish that reaming provides.

Reaming: The final finishing process that ensures the hole has precise dimensions and a smooth surface. Reaming is used after drilling and/or boring to achieve the highest level of accuracy and surface quality.

After reaming, the hole is inspected for dimensional accuracy and surface quality. Tolerances for reamed holes can be as tight as ±0.005 mm, depending on the application.

The reamer is mounted on the machine, ensuring proper alignment and stability. The setup often involves checking the runout, which should be within 0.02 mm to avoid inaccuracies.

Reaming is an important machining process to enlarge and finish previously drilled holes. It can achieve precise hole diameters, improve surface finish, and ensure concentricity. It is precious in applications requiring tight tolerances and high-quality surface finishes, such as automotive and aerospace. If you are interested in reaming, let's continue reading.

Choosing the appropriate reamer is crucial. Factors to consider include the material of the workpiece, the hole size, and the desired surface finish. For example, high-speed steel (HSS) reamers are common for general purposes, while carbide reamers are used for harder materials.