Reamers are an important tool for any engineer or machinist. They are used to enlarge holes and improve the accuracy of drilled holes. They leave smooth walls and improve the precision of the hole processing surface within a certain tolerance range.
What is a Reamer?
A reamer is a rotating cutting tool used to enlarge holes and improve the accuracy of pre-drilled holes. When drilling holes in materials, it is common to leave defects on the surface of the material, such as irregular surfaces and misalignments.
Reamers are designed with a series of cutting edges, usually spiral (but sometimes straight fluted) to eliminate these hole processing defects. The result is a smooth, accurate and dimensionally correct hole, usually with a tolerance of H7.
Reamer tools are particularly critical in applications where precision is critical. The most common are in industries such as aerospace, automotive, medical industries and fasteners and fixtures that require a series of precise positioning points.
Reamers are commonly used in a variety of applications. But the most common are to enlarge drilled holes to specific sizes, deburr holes, and prepare holes for thread cutting.
Different Types of Reamers
There are many different types of reamers, each with their own specific uses. The most common types of reamers include:
Machine Reamers
Machine reamers, also called chuck reamers, are general-purpose cutting tools that come in a variety of materials. These include high-speed steel (HSS), carbide, and HSSE (high-speed steel with cobalt). The type of material depends on the specific application.
Typically, reamers are wide and have either a straight or Morse taper shank. Straight shank reamers are clamped into a collet chuck, drill chuck, or hydraulic chuck. Whereas Morse taper shank reamers are clamped into a Morse taper chuck or clamped to the tailstock of a lathe. Machine reamers usually have standard shank sizes, while reamers usually have shank sizes that are parallel to the diameter.
Hand Reamers
Hand reamer tools are a type of reamer that is operated by hand. They are usually used for light machining operations such as enlarging and smoothing the inside of a previously machined hole. Or machining holes that are worn or damaged. Hand reamers are also used for machining small holes that are too small for a machine reamer to reach. Since carbide reamers are not suitable for manual operation, manual reamers are usually only available in HSS (high speed steel).
These types of reamers are usually inexpensive and easy to use. However, they are slow compared to machine reamers. This is because all operations must be done by hand. If used improperly, such as user errors, the hole may be damaged. Manual reamers have a square design on the top of the shank so that they can be used with a tap wrench.
Taper Reamer
Taper reamer is a taper reamer that is used for reaming holes of the same taper. The reamer is used to ream holes on the workpiece that have been drilled (or reamed). The main purpose is to improve the machining accuracy of the hole and reduce its surface roughness. It is a tool used for finishing and semi-finishing holes, and the machining allowance is generally small. They have a tapered shank that matches the taper. The taper of the reamer ensures that the taper fits accurately into the hole, and the cutting edge ensures that the hole is smooth and burr-free.
Taper pin reamers are usually made of high speed steel (HSS) or carbide. High-speed steel reamers are a good choice for general purpose reaming, while carbide reamers are better suited for reaming harder materials.
Adjustable Reamers
An adjustable reamer is a reamer that can be adjusted to different sizes. Because of this, they are very versatile and can be used for a variety of reaming operations. Adjustable reamers are usually made of high-speed steel (HSS) or carbide.
An adjustable reamer has a shank that can be adjusted by loosening one nut and tightening another. This allows the reamer to be expanded to the desired size. Adjustable reamers are often used for light-duty reaming, such as enlarging and finishing the inside of a drilled or punched hole. As the cutting edge wears, you can adjust them to slightly enlarge it to return it to its original size. Once a regular reamer wears out, it is no longer useful.
Modular Reamers
Modular reamers are reamers with separate cutting heads that can ream holes of different sizes. This makes them more precise than adjustable reamers, but they can also be more expensive. They are usually made of high-speed steel (HSS) or carbide. High-speed steel reamers are a good choice for general-purpose reaming, while carbide reamers are better suited for machining harder materials.
Modular reamers typically have a threaded shank with a precise taper for precise positioning onto modular adapters. The reamer can be easily changed depending on the required size or material that needs to be reamed. Modular reamers were introduced in response to rising tool cost pressures. They offer a high degree of flexibility and reduce the frequency of tool changes that fluctuate over time.
Base Materials of Reamers
Reamers are typically made from either high-speed steel or carbide.
Both carbide and high-speed steel are strong and durable materials. But they have different properties that make them better suited for different applications.
Carbide Reamers
Carbide is a very hard material made from tungsten carbide and cobalt. It is often used in the manufacture of cutting tools because it can withstand high temperatures and wear. Carbide reamers are a good choice for reaming harder materials. Such as steel, stainless steel, high-temperature alloys, and cast iron. They also run at faster feed rates and have longer tool life if the right cutting conditions are provided.
High Speed Steel Reamers
High speed steel is a less expensive material than carbide, but it is still strong and durable. It is made from tungsten, chromium, and vanadium. High speed steel reamers are a good choice for general purpose reaming and machining softer materials, such as mild steel, aluminum, and brass.
High Speed Steel vs. Carbide Reamers
The best reamer substrate for you will depend on your specific needs and requirements. If you need a reamer that can withstand high temperatures and high wear, carbide is a good choice. If you are on a budget, high speed steel is a good choice.
Reamer Geometry
The geometry of the reamer depends on the specific application.
Left-Hand Reamers
Left-hand reamers are designed for through holes. The spiral helps push the chips out of the hole to prevent interference between the flutes and the material. Left-hand reamers work well with interrupted cuts such as cross holes or keyways.
Right-Hand Reamers
Right-hand reamers are used for machining blind holes. Because the flutes pull the chips out of the pre-drilled hole, this prevents the chips from clogging up at the bottom of the blind hole and preventing the reamer from being damaged. The right-hand spiral is also effective when encountering cross holes or keyways.
Straight Groove Reamers
Straight groove reamers are the most common type of reamers. They are a good choice for general purpose hole enlargement and perform well in both blind holes and through holes.
Spiral groove reamers vs. straight groove reamers
The straight groove design can effectively push the chips upward to prevent chips from accumulating at the bottom of the processed hole. It is very suitable for processing through holes or blind holes with a small ratio of hole depth to reamer diameter. The main technical parameters of blind hole straight groove reamers include cutting diameter, reamer length, number of grooves and material type. This type of reamer is suitable for processing most metals and alloy materials, especially aluminum alloys and other non-ferrous metals.
Characteristics and application of spiral reamers Spiral reamers, whose blades are designed in a spiral shape, are suitable for processing blind holes with larger hole depths. The spiral blade allows chips to be discharged smoothly along the spiral groove. Compared with straight groove reamers, spiral reamers can effectively prevent chip accumulation and chip evacuation problems when processing deep holes.Spiral reamers are often used to process non-ferrous metals, stainless steel and softer materials such as cast iron.
The most suitable reamer geometry design will depend on your specific needs and requirements.
If you are machining a blind hole, a right-hand spiral reamer is a good choice.
If you are machining a through hole, a left-hand spiral corner reamer is a good choice. If you are machining a softer material, a straight groove corner reamer is a good choice.
