Reaming is a cutting procedure that enlarges existing hole diameters more precisely while improving the surface finish of the hole walls. Reaming is a finishing technique for high-precision holes that uses a multi-edged tool. High penetration rates and shallow cuts result in high-quality surface finishes, better hole quality, and precise dimensional tolerances. The tools used for the reaming operation are termed a “Reamer.”
Sharpening a workpiece’s dimensions, surface finish, and tolerance level are the main goals of reaming holes in it. Manufacturers employ reamer machining because it is the most efficient and cost-effective choice.
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Reamers
A reamer is a cylindrical or conical-shaped rotary cutting tool used to enlarge and finish holes that have been drilled, bored, or cored. A reamer cannot be used for making a hole. Reamer is the family name for the most precise instruments in common use. T
hey enable basic machinery and even hand effort to create holes with a tolerance of 0.0002 inches. Tolerance is the allowable deviation from a particular dimension. In the context of reaming, it has a direct impact on the precision and functionality of the machined component. Maintaining tight tolerances ensures that completed holes precisely match design specifications, facilitating the correct fit and installation of parts. Whether in aircraft, automotive, or general manufacturing, maintaining accurate tolerances through reaming ensures product uniformity, reduces the possibility of errors, and improves overall performance.
Cutting materials for reamers
- Solid carbide
it is a cutting material suitable for applications up to 63 HRC. It cuts quickly and precisely. - CC carrier with cemented carbide
This material is highly elastic, cuts quickly, and is precise. - HSSE (High-Speed Steel)
This cutting material has strong flexibility and may be used at speeds ranging from tiny to medium. - HSS (high-speed steel)
it is a cutting material that can withstand up to 1000 N/mm2, has minimal alloy content, and is highly elastic.
Similarities between reaming and drilling
- Hole fabrication includes both drilling and reaming.
- Both procedures are classified as conventional machining or metal-cutting operations.
- Both procedures fall under the subtractive manufacturing methodology (or top-down approach), in which layers of unnecessary material are gradually removed from the solid blank. This is in contrast to the additive manufacturing process, in which material is added one layer after another to create a 3-D component.
- Chips are necessary for both procedures because the material is removed in the form of chips.
- Heat generation, burr development, and residual stress are all inherent in both processes; however, the degrees vary. Cutting fluid can be used in both stages if necessary.
Differences between reaming and drilling
- Drilling is done to create a hole in a solid surface while reaming is used to complete the internal surface of an existing hole.
- Drilling is the initial step in hole-making. After drilling, either boring or reaming might be done, depending on the situation. Reaming can only be done if a hole exists. So reaming is done only after drilling (or boring).
- Metal cutting drills usually have two cutting blades. As a result, drills are classified as double-point cutting tools.
Reamer has a considerable number of cutting edges (at least 4). So, a reamer is a tool with several cutting points. - Drilling operations can readily expand the axial length of the hole. Reaming does not change the axial length of the hole. Only the size of the hole can be slightly increased.
- The Material Removal Rate (MRR) in drilling is substantially higher than in the reaming process.
Comparison between reaming and boring
Reaming and boring are two different hole-making procedures that manufacturers use to produce or refine existing holes in a workpiece. Despite certain similarities, they serve diverse functions and have distinct properties.
- Reaming is a procedure that focuses on improving the inside walls of an existing hole, such as one made by a drill bit. Boring is a metal-cutting process. It uses a single-point cutting tool or boring head to increase the diameter of an existing hole.
- Reaming and boring both require material removal, but they serve distinct functions in the hole-making process. Reaming is the process of refining the inside walls of an existing hole, which is often made with a drill bit, to produce a smoother finish and a more exact hole size. In contrast, boring is utilized for larger holes and can yield greater hole sizes than reaming.
- Boring enlarges the existing hole, whereas reaming focuses on improving the hole’s surface finish and dimensional accuracy.
- Reaming uses a multi-point cutting tool called a reamer, whereas boring uses a single-point cutting tool known as a boring head.
- Reaming provides a better surface quality and accuracy than boring. This is because the multi-point cutting tool used in reaming eliminates material from the hole’s interior walls in an even manner, resulting in a high-quality surface finish. Boring, on the other hand, provides excellent positional accuracy but yields a coarser surface polish than reaming.
Problem during the reaming process
- Poor finish owing to unequal chamfers, incorrect margins, excessive spindle runout, and chatter. To address this issue, we can utilize a regrind reamer with small margins to ream lower tensile materials, reduce speed and increase feed rate, and employ power feed unless the material is hard.
- Misalignment and insufficient cutting effort result in an oversized hole. To resolve this issue, we can utilize a bushing and a floating reamer holder for varying hole sizes.
- Crooked holes because they were not drilled straight. Correct prior drilling operations can remove this problem.
Applications of reaming
- Reaming is often used to improve interior surfaces in metallic components like nuts, cylinders, and shafts.
- It is a crucial procedure in the automobile sector, where it is used to refine the inner surface of engine cylinders, resulting in a smoother and more accurate surface finish and improved engine efficiency.
- In addition to its employment in the automotive and aerospace industries, reaming is used in a variety of other applications that demand high dimensional precision and a smooth surface finish.
Advantages of the reaming process
- Low cost of tools and equipment.
- The finishing expenses were modest, and cleaning and deburring were also required.
Reducing the feed rate enhances the surface finish. - Reaming is performed under optimal conditions at one-third the speed and two-thirds the feed rate of drilling.
- The most exact holes are center drilled, bored, and reamed to finish size.
- Reaming tools and equipment are noted for their durability and long lifespan, which can lead to cost savings over time.
References
- https://gammons.com/reaming
- https://waykenrm.com/blogs/what-is-reaming/
- https://www.canadianmetalworking.com/canadianmetalworking/article/cuttingtools/take-advantage-of-reaming
- https://www.difference.minaprem.com/machining/difference-between-drilling-and-reaming/
- https://www.britannica.com/technology/planer
- https://www.slideshare.net/slideshow/naman-jain-reaming-ppt/51407161
- https://www.mechanicalfunda.com/2016/02/what-is-reaming.html
