Arbor milling is a cutting process which removes material via a multi-toothed cutter. An arbor mill is a type of milling machine characterized by its ability to rapidly remove material from a variety of materials. This milling process is not only rapid but also versatile.
This process progressively makes a surface to the user's specifications as the material is moved against the milling tool or the workpiece stays stationary while the arbor milling cutter moves across it to provide the desired shape. There are two types of milling that involve the directional movement of the workpiece, conventional and climb. If the workpiece is moving the opposite direction of the tool rotation this is called conventional milling. If the workpiece is moving the same direction as the tool rotation, this is called climb milling. [1]
Arbor milling is commonly performed on a horizontal milling machine. The tool is mounted on an arbor/mandrel (like an axle) that is suspended between the spindle and arbor support. This type of machine allows the tool to be placed in numerous positions in relation to the workpiece.
The workpiece involved in arbor milling can be a flat material or a shaped material: either one can be worked with desirable results. The hardness of the materials milled should be no harder than Rockwell C25 (Rockwell scale), but workpieces harder than this can be successfully milled. Materials with good or excellent machinability include aluminum, brass, mild steel, cast iron, and thermoset plastics. Though initially ductile, stainless steel tends to work harden and thus has only a fair compatibility with this milling process (though it is in the feasible range).
Although high speed tool steel has been used in the past it is quickly being replaced by carbide, ceramic, or diamond tooling. Because carbide inserts are long lasting and easily replaced, they lend themselves to high production. Ceramic tools are brittle but can withstand high temperatures. This makes high speed machining possible. Diamond tools are used to achieve a superior surface finish (though they can only be used on non-ferrous materials).
In most applications, tolerances can be held within ±0.005 in. For precision application, tolerances can be held within ±0.001 in. It is possible to have a surface finish range of 32 to 500 microinches, but typically the range is 63 to 200 microinches. Finish cuts will generate surfaces near 32 to 63 microinches, roughing cuts near 200 microinches.
The most common tool styles used in arbor milling are double angle, form relived, plane, and staggered tooth, among many other tool styles. The double angle milling cutter can make a wide variety of V-shaped cuts with straight surfaces in the material. A form relieved milling cutter can produce U-shaped cuts with curved surfaces, unlike the double angle cutter, into the material. A plane milling cutter can produce surfaces similar to a planer but can make varying contours across the material. A staggered tooth milling cutter can produce a rectangular groove in the material at varying depths and widths. The cutters can be stacked to mill combined profiles. The typical width of cuts made by arbor milling range from 0.25 in to 6 in, and the typical depths range from 0.02 in to 0.05 in.
Mechanical properties of the workpiece may be affected with a built-up edge or dull tool. Arbor Milling can create an untempered martensitic layer on the surface of heat-treated alloy steels, about 0.001 in thick. Other materials are affected very little by arbor milling.
Shown are the suggested ranges for cutting speeds and feed rates using high speed tool steel under dry cutting conditions at a 0.015 in depth of cut. Generally cutting speeds are lower for hard materials, higher for soft materials. Both cutting speeds and feed rates can be substantially increased when coolants are used and carbide tooling is substituted for steel tooling. Typical Speeds and Feeds
Workpiece Material | Hardness (Hardness Brinell scale) | Cutting Speed (sfpm) | Feed Rate (ipt) |
---|---|---|---|
Aluminum | 70 to 125 | 300 to 500 | 0.006 to 0.010 |
Brass | 60 to 100 | 110 to 275 | 0.007 to 0.009 |
Cast Iron | 250 to 320 | 30 to 55 | 0.005 to 0.006 |
Mild Steel | 275 to 325 | 60 to 80 | 0.006 |
Stainless Steel | 275 to 325 | 40 to 55 | 0.006 |
Plastics | ... | 150 to 350 | 0.006 |
Due to high cutting speeds a cutting fluid is required to lubricate and cool the tool and workpiece. The fluids can increase tool life, cutting speeds, and the quality of the finished surface. There are three common cutting fluids: mineral, synthetic, and water-soluble oils. These fluids can be applied by spraying, misting, or flooding the workpiece.
Workpeice | Cutting Fluid | Application method |
---|---|---|
Aluminum | None, mineral oil, fatty oil | Spray, flood |
Brass | Mineral oil, specialty fluid | Spray, flood |
Cast Iron | Soluble oil, chemical and synthetic oil, none | Spray, flood |
Mild Steel | Chemical and synthetic oil, soluble oil | Spray, flood |
Stainless Steel | Sulferized mineral oil, fally soluble oil, chemical and synthetic oil | Spray, flood |
Plastics | Mineral oil, soluble oil, cold air, none | Spray, flood, air jet |
The router is a power tool with a flat base and a rotating blade extending past the base. The spindle may be driven by an electric motor or by a pneumatic motor. It routs an area in hard material, such as wood or plastic. Routers are used most often in woodworking, especially cabinetry. They may be handheld or affixed to router tables. Some woodworkers consider the router one of the most versatile power tools.
A circular saw or a buzz saw, is a power-saw using a toothed or abrasive disc or blade to cut different materials using a rotary motion spinning around an arbor. A hole saw and ring saw also use a rotary motion but are different from a circular saw. Circular saws may also be loosely used for the blade itself. Circular saws were invented in the late 18th century and were in common use in sawmills in the United States by the middle of the 19th century.
Metalworking is the process of shaping and reshaping metals in order to create useful objects, parts, assemblies, and large scale structures. As a term, it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale: from huge ships, buildings, and bridges, down to precise engine parts and delicate jewelry.
Machining is a manufacturing process where a desired shape or part is created using the controlled removal of material, most often metal, from a larger piece of raw material by cutting. Machining is a form of subtractive manufacturing, which utilizes machine tools, in contrast to additive manufacturing, which uses controlled addition of material.
A drill bit is a cutting tool used in a drill to remove material to create holes, almost always of circular cross-section. Drill bits come in many sizes and shapes and can create different kinds of holes in many different materials. In order to create holes drill bits are usually attached to a drill, which powers them to cut through the workpiece, typically by rotation. The drill will grasp the upper end of a bit called the shank in the chuck.
Broaching is a machining process that uses a toothed tool, called a broach, to remove material. There are two main types of broaching: linear and rotary. In linear broaching, which is the more common process, the broach is run linearly against a surface of the workpiece to produce the cut. Linear broaches are used in a broaching machine, which is also sometimes shortened to broach. In rotary broaching, the broach is rotated and pressed into the workpiece to cut an axisymmetric shape. A rotary broach is used in a lathe or screw machine. In both processes the cut is performed in one pass of the broach, which makes it very efficient.
Drilling is a cutting process where a drill bit is spun to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multi-point. The bit is pressed against the work-piece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the work-piece, cutting off chips (swarf) from the hole as it is drilled.
The phrase speeds and feeds or feeds and speeds refers to two separate parameters in machine tool practice, cutting speed and feed rate. They are often considered as a pair because of their combined effect on the cutting process. Each, however, can also be considered and analyzed in its own right.
In machining, a tool bit is a non-rotary cutting tool used in metal lathes, shapers, and planers. Such cutters are also often referred to by the set-phrase name of single-point cutting tool, as distinguished from other cutting tools such as a saw or water jet cutter. The cutting edge is ground to suit a particular machining operation and may be resharpened or reshaped as needed. The ground tool bit is held rigidly by a tool holder while it is cutting.
Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates.
Milling cutters are cutting tools typically used in milling machines or machining centres to perform milling operations. They remove material by their movement within the machine or directly from the cutter's shape.
A lathe center, often shortened to center, is a tool that has been ground to a point to accurately position a workpiece on an axis. They usually have an included angle of 60°, but in heavy machining situations an angle of 75° is used.
An end mill is a type of milling cutter, a cutting tool used in industrial milling applications. They can have several end configurations: round (ball), tapered, or straight are a few popular types. They are most commonly used in "milling machines" that move a piece of material against the end mill to remove chips of the material to create a desired size or shape. It is distinguished from the drill bit in its application, geometry, and manufacture. While a drill bit can only cut in the axial direction, most milling bits can cut in the radial direction. Not all mills can cut axially; those designed to cut axially are known as end mills.
In machining, boring is the process of enlarging a hole that has already been drilled by means of a single-point cutting tool, such as in boring a gun barrel or an engine cylinder. Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole. Boring can be viewed as the internal-diameter counterpart to turning, which cuts external diameters.
In the context of machining, a cutting tool or cutter is typically a hardened metal tool that is used to cut, shape, and remove material from a workpiece by means of machining tools as well as abrasive tools by way of shear deformation. The majority of these tools are designed exclusively for metals.
Grinding is a type of abrasive machining process which uses a grinding wheel as cutting tool.
Planing is a manufacturing process of material removal in which the workpiece reciprocates against a stationary cutting tool producing a plane or sculpted surface. Planing is analogous to shaping. The main difference between these two processes is that in shaping the tool reciprocates across the stationary workpiece. Planing motion is the opposite of shaping. Both planing and shaping are rapidly being replaced by milling.
Surface grinding is done on flat surfaces to produce a smooth finish.
Metal spinning, also known as spin forming or spinning or metal turning most commonly, is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part. Spinning can be performed by hand or by a CNC lathe.
Milling is the process of machining using rotary cutters to remove material by advancing a cutter into a workpiece. This may be done by varying directions on one or several axes, cutter head speed, and pressure. Milling covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes for machining custom parts to precise tolerances.