Advantages, Disadvantages and Applications of Reaming Tools

Comprehensive introduction of reamer reaming tools: advantages, disadvantages and application analysis

As a key tool in the field of hole processing, reamer plays an indispensable role in modern mechanical manufacturing. This article will comprehensively introduce the working principle and type characteristics of reamer reaming tools, deeply analyze its significant advantages over other hole processing methods, objectively evaluate its limitations, and explore the selection criteria and typical application scenarios of different reamer types. By comparing with traditional drilling and boring processes, and introducing innovative technologies such as floating reamer handles, readers will gain a comprehensive and in-depth understanding of reamer tools, providing professional reference for tool selection in actual production.

Basic concepts and working principles of reamer reaming tools

A reamer is a multi-edge cutting tool used for precision hole processing, which is specially used for finishing pre-drilled holes to achieve higher dimensional accuracy and surface quality. A reamer usually consists of a working part, a neck and a shank, where the working part contains multiple evenly distributed cutting edges, which work together to remove a small amount of material on the hole wall, thereby correcting the geometry and surface roughness of the hole. The working principle of the reamer is based on its unique structural design: when the reamer rotates and feeds axially, multiple cutting edges participate in cutting at the same time, evenly removing the hole wall material. This multi-edge cutting feature enables the reamer to achieve more stable processing results and higher processing efficiency than single-edge tools6.

Reamers can be divided into many types according to different classification standards. According to the tool structure, they can be divided into integral reamers and adjustable reamers; according to the cutting part material, they can be divided into high-speed steel reamers, carbide reamers and diamond reamers, etc.; according to the chip removal direction, they can be divided into straight groove reamers and spiral groove reamers; according to the use method, they can be divided into hand reamers and machine reamers. Among them, integral carbide reamers are particularly widely used in modern precision machining due to their high hardness, high wear resistance and good bending strength7. The floating reamer handle is an innovative technology developed in recent years. It realizes continuous axial deflection and radial translation through a special internal structure, so that the center of the clamped reamer can easily float 360 degrees around the center of the machine tool spindle in its vertical plane, thereby significantly improving the reaming accuracy.

The cutting process of reamer is a complex metal removal process, involving cutting force, cutting heat, tool wear and other factors. Unlike traditional single-point cutting tools, the multi-edge design of reamer makes its cutting process smoother and the cutting force distribution more even. Under ideal conditions, each cutting edge of the reamer should participate in the same amount of cutting work, so as to ensure that the processed hole has high roundness and cylindricity. However, in actual processing, due to the influence of factors such as the coaxiality error between the machine tool spindle and the reamer, the centrifugal force of rotation, etc., the traditional rigidly connected reamer often only has a few blades protruding on the rotating trajectory circle that are truly involved in cutting, which not only affects the processing quality, but also shortens the tool life12. The existence of this problem has prompted the development and application of new technologies such as floating reamer handles.

Main advantages of reamer reaming tools

Reamer reaming tools have a series of significant advantages in the field of precision hole processing, making them an indispensable processing method in many industrial applications. First of all, in terms of processing accuracy, reamer can achieve extremely high dimensional accuracy and form and position tolerances. The roundness of holes processed by high-performance reamers can be controlled within 1μm, the cylindricity is less than 1.5μm, the roughness can reach Ra0.2μm, and the dimensional accuracy can usually reach H7 and H8 tolerance grades57. Especially when used with floating reamer handles, the roundness and cylindricity of the reamed hole diameter can even reach an ultra-high precision level of 0.002mm, and the surface roughness can also be stabilized at Ra0.2um. This level of precision has approached or reached the processing level of honing and grinding.

Productivity is another major advantage of reamer. Compared with single-point boring, high-performance reamers have 4 to 16 cutting edges, and theoretically their feed speed can be increased by 4 to 16 times, significantly shortening the processing cycle time6. The application of floating reamer handles further improves efficiency. It can automatically align the center of the processed hole and automatically adjust the spindle to ensure that the reamer center line is parallel to the center line of the processed hole, eliminating the tedious tool alignment and calibration process in traditional methods, so that the first processed hole can meet the quality requirements28. In addition, reamer processing can usually avoid the subsequent honing process and directly obtain the required surface quality, which not only reduces the processing steps but also reduces the fixed asset investment3.

In terms of tool life, the reamer also performs well. Especially when using a floating reamer handle, the tool life can be extended by at least 5 times because all the cutting edges of the reamer can be evenly involved in cutting without vibration28. The full carbide integral reamer uses high-quality, highly wear-resistant ultra-fine grain carbide materials, which have good bending strength, high hardness and high wear resistance. Its service life is usually more than 10 times that of high-speed steel reamers and ordinary carbide reamers57. The application of certain special coatings can further improve the wear resistance and service life of the reamer, especially when processing difficult-to-cut materials.

The relatively low requirements of the reamer for machine tools are also worth noting. Traditional high-precision hole processing often requires high-precision boring machines or grinders, but with the use of floating reamer handles, even ordinary lathes, drilling machines and other equipment can process high-precision hole products28. This feature enables small and medium-sized enterprises to achieve precision hole processing without huge equipment investment, greatly reducing production costs and technical barriers. At the same time, the reamer processing process is stable and reliable, easy to operate, and does not require expensive tool setting instruments for repeated debugging, avoiding the generation of scrap during the debugging process5.

From an economic perspective, although the initial tool cost of reamer processing may be high, considering factors such as processing efficiency, tool life and scrap rate, its single-hole processing cost is often several times lower than that of using imported high-end boring tools or honing processes5. Especially in mass production, the reamer does not need to be frequently replaced and adjusted, and the auxiliary working hours are greatly reduced, further improving the overall economic benefits6. For processing scenarios using expensive materials (such as Inconel alloys and titanium alloys commonly used in the aerospace field), the cost savings brought by the high stability and low scrap rate of the reamer are particularly significant6.

Limitations of reamer reaming tools

Although reamer has many advantages in the field of hole processing, it also has some inherent limitations. Understanding these limitations is crucial for the correct selection of processing technology. Limitations in geometric accuracy are one of the most obvious disadvantages of reamer. Although reamer can provide extremely high dimensional accuracy and surface finish, it is often not as ideal as boring in terms of geometric tolerances such as hole roundness, straightness and verticality.7 In particular, when the floating sleeve is used to clamp the reamer, it can only correct the hole diameter and roughness of the processed bottom hole, but cannot correct the position deviation of the hole. Even if the reamer sleeve is used for guidance, the hole position deviation can only be partially corrected, and the cylindricity of the hole is still difficult to guarantee.7 This feature determines that the reamer is not suitable for processing scenarios with extremely high requirements for hole position accuracy.

Reamers also have certain limitations in process adaptability. Traditional reamers usually require pre-processed holes to have good initial conditions, because the reaming allowance is generally small (about 0.1-0.3mm), and excessive allowance will cause tool overload and rapid wear.6 This means that before using the reamer, it must go through pre-processing processes such as drilling and reaming, which increases the complexity of the process. In addition, the adjustment range of cutting parameters for reamer is relatively limited. Once a reamer of a specific diameter is selected, the processed hole diameter is basically fixed, unlike boring tools, which can be easily adjusted to change the hole diameter size6. Although some specially designed drilling and reaming composite tools attempt to combine drilling and reaming, they often have problems such as difficult chip removal and difficulty in taking into account the requirements of different processes in actual applications, especially when processing blind holes.4.

Chip removal and cooling problems are also common challenges in reaming. If the chips generated during the reaming process are not removed smoothly, it is easy to scratch the machined surface or cause the tool to get stuck. Although the internal cooling reamer design (such as the KKJ series high-speed internal cooling reamer) effectively improves this problem through the central axial coolant channel, this design requires the machine tool to have corresponding internal cooling function support5. When the equipment lacks internal cooling function, it can only rely on external pouring of cutting fluid, which will cause the cutting speed to decrease and require the external cutting fluid to maintain sufficient pressure to achieve the ideal effect5. For deep hole reaming, cooling and chip removal issues are more prominent. Even if an internal cooling design is adopted, the cooling effect will gradually weaken as the hole depth increases.

From the perspective of tool cost and maintenance, the initial purchase cost of high-precision reamers, especially solid carbide reamers and special reamers, is relatively high. Although it may be more cost-effective from the perspective of long-term use, this high initial investment may not be economical for small-batch production or R&D trial production scenarios. In addition, the sharpening and reconditioning of reamers require professional equipment and technology, which is difficult for ordinary users to complete by themselves. It usually needs to be sent back to professional manufacturers for processing, which increases maintenance costs and downtime67. In contrast, boring tools with indexable inserts are more flexible and convenient in insert replacement and adjustment.

In terms of material adaptability, although modern reamers can process a variety of materials from ordinary carbon steel to high-temperature alloys, for some special materials (such as high-toughness, high-hardness or high-wear-resistant materials), it is still necessary to develop special reamers, and general reamers often perform poorly. For example, when processing superhard materials such as hardened steel and ceramics, conventional reamers are prone to rapid wear and even chipping. Special materials (such as PCD or polycrystalline diamond) or reamers with special geometric designs are required to achieve satisfactory results6.

Characteristics and selection criteria of different types of reamers

There are many types of reamers. According to different processing requirements and conditions, it is necessary to select the appropriate type of reamer. Solid carbide reamers represent the development direction of high-precision reamers. Their blades and cutter bodies are made of solid ultra-fine grain carbide materials, which have good bending strength, high hardness and high wear resistance7. This type of reamer avoids the disadvantages of welded blades. By optimizing the cutting edge geometry parameters, it adapts to high-speed cutting requirements, and adopts internal cooling design to ensure the cooling effect during deep hole processing. Solid carbide reamers are particularly suitable for high-precision, mass production scenarios, and can meet H7 and H8 tolerance requirements. The surface roughness can reach Ra3.2 or above7. However, its cost is relatively high and it is generally not adjustable. It is suitable for precision processing with fixed aperture.

Adjustable reamers offer users greater flexibility. They can change diameter within a certain range through mechanical adjustment to compensate for tool wear or adapt to different aperture requirements6. Adjustable reamers are divided into two main types: expandable reamers and radially adjustable reamers. Expandable reamers target the average aperture and can expand multiple times until the surface roughness no longer meets the requirements; radially adjustable reamers achieve fine diameter adjustment through a precision thread mechanism6. Adjustable reamers are particularly suitable for machining scenarios with relatively large tolerances but not extremely high surface finish requirements, as well as working conditions where tool wear is rapid and frequent replacement is uneconomical. However, the structure of adjustable reamers is relatively complex, and their rigidity and precision are usually slightly lower than those of integral reamers.

The floating reamer shank is an important innovation in reaming technology in recent years. It is not the reamer itself, but the key interface component connecting the machine tool spindle and the reamer. The special structure inside the floating reamer shank allows continuous axial deflection and radial translation, allowing the reamer center to float 360 degrees around the center of the machine tool spindle in its vertical plane. This design effectively compensates for the deviation between the reamer center and the center of the processed hole, eliminating the influence of the radial runout of the machine tool spindle. When using a floating reamer handle, the reamer can automatically align the hole center to ensure that the reamer center line is parallel to the center line of the processed hole, so that all blades are evenly involved in cutting, significantly improving the processing quality and extending the tool life. The radial floating range of the floating reamer handle can usually reach 1.5mm, and the swing angle range can reach 1°. The floating amount can be accurately controlled by adjusting the nut and the centering sleeve.

High-speed internal cooling reamers (such as the KKJ series) are specially optimized to address the problem of insufficient cooling of traditional reamers. The center is provided with a coolant channel that goes straight through the blade along the axial direction. High-pressure cutting fluid is injected from the tail of the handle and rushed out from the blade hole to effectively cool the cutting area and remove chips. This design is particularly suitable for deep hole processing and difficult-to-cut materials processing, and can significantly improve processing quality and tool life. The gun-type reamers and multi-joint reamers in the KKJ series are designed for high-speed cutting of CNC machine tools. They are easy to operate and do not require debugging. The cutting volume is much larger than that of single-edge boring tools. When the equipment lacks internal cooling function, cutting fluid can also be poured externally, but the processing efficiency will be reduced.

There are many factors to consider when selecting a reamer: the processing material determines the material and coating selection of the reamer. For example, high-performance reamer with specific coating may be required for processing stainless steel; the size and depth of the aperture affect the aspect ratio and cooling method selection of the reamer; the precision requirements determine whether a floating shank or a solid carbide reamer is required; the production batch affects whether it is more economical to choose a standard reamer or an adjustable reamer; the equipment conditions determine whether an internal cooling reamer can be used or whether a floating compensation function is required. 67. Generally speaking, large-scale high-precision production is suitable for solid carbide reamers with floating shanks; small batches of multiple varieties are suitable for adjustable reamers; deep hole processing gives priority to internal cooling design; ordinary equipment processing of high-precision holes requires a floating reamer shank to compensate for machine tool errors. 

Application scenarios and development trends of reamer

Reamer reaming tools have been widely used in many industrial fields due to their high precision and high efficiency. Automobile manufacturing is one of the industries with the most concentrated use of reamers, especially the precision hole processing of key components such as engine cylinder blocks, cylinder heads, connecting rods, crankshafts, etc., which has a large demand for reamers and extremely high requirements18. Floating reamer handles are particularly widely used in automobile engine production lines. They can stably ensure the dimensional accuracy and form and position tolerances of key matching holes, while greatly improving production efficiency. For example, the pin holes and bolt holes of engine cylinders usually require roundness and cylindricity within 0.005mm and surface roughness below Ra0.4. These requirements can only be stably achieved by high-performance reamers with floating handles.

The requirements for reamers in the aerospace field are more stringent. The industry uses a large number of difficult-to-process materials such as titanium alloys and nickel-based high-temperature alloys, and the precision of part hole processing is extremely high6. The reaming of aerospace parts requires not only precise dimensions, but also special requirements for the fatigue performance of the holes. Therefore, reamers with special geometric shapes and coatings are often used. In these applications, the high stability and low scrap rate of the reamer are particularly important, because aerospace materials are usually very expensive, and reducing scrap can directly bring significant cost savings6. High-performance reamers play an irreplaceable role in the precision hole processing of key parts such as aircraft landing gear and engine blade tenons.

Energy equipment manufacturing is another important application field of reamers, including precision hole processing of large equipment such as wind power equipment, hydropower turbines, and nuclear power components13. These equipment are usually large in size, high in value, and have a harsh working environment, and have extremely high requirements for the accuracy and surface integrity of key matching holes. Hydraulic components such as cylinders, pump bodies, and valve blocks are also typical application scenarios for reamers. The quality of the inner holes of these components directly affects the performance and reliability of the hydraulic system13. Although the demand for reamers in medical equipment manufacturing is not large, the precision requirements are extremely high, especially the precision hole processing of medical devices such as artificial joints and orthopedic implants, which requires specially designed micro reamers to complete.