Machining is a controlled material-removal technique that cuts a material (typically metal) to a specified final form and size. Subtractive manufacturing refers to the procedures that have this common pattern, as opposed to additive manufacturing, which involves the controlled addition of material. The precise meaning of the “controlled” element of the phrase varies, although it frequently entails the use of machine tools.
Machining is used to make numerous metal items, but it can also be used to make other materials like wood, plastic, ceramics, and composites. A machinist is a person who specializes in machining. A machine shop is a room, building, or company where machining is done. Computer numerical control (CNC), which uses computers to control the movement and operation of mills, lathes, and other cutting equipment, is utilized for a lot of modern machining. This improves efficiency by allowing the CNC machine to run unattended, lowering labor expenses for machine shops.
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In this article, you’ll get to know the definition, applications, purpose and functions, diagram, types, operations, working, advantages, and disadvantages of the machining process. You’ll also be introduced to the term machine tool.
What is a machining process?
Machining is the process of shaping and sizing materials to a specific form and size. Typically, machining relates to metalworking, although it can also refer to the manufacture of wood, plastic, ceramic, stone, and other materials. If you have raw materials that you wish to mold into a certain shape for a specific purpose, you’ll employ machining procedures to do it. Nuts and bolts, vehicle parts, flanges, drill bits, plaques, and a range of other equipment and things used in a variety of industries are examples of machined products.
Machining can also be seen as a crucial finishing technique in which tasks are created to the appropriate dimensions and surface polish by gradually eliminating surplus material from the prepared blank in the form of chips using a cutting tool(s) that are pushed through the work surface (s). A machine tool is power-driven equipment that removes extra material in the form of chips to size, shape, and process a product to the desired accuracy. Lathe Machines, Drilling Machines, Shaping Machines, Planer Machines, and so on. These are examples of machine tools. Finally, to remove the material of the workpiece’s surface, a cutting tool is employed. To carry out the operation, it must be harder than the workpiece. Cutting tools are divided into two categories; single-point and multi-point.
Most technical components, such as gears, bearings, clutches, tools, screws, and nuts, require dimensions and form correctness as well as a good surface polish to function properly. Performing techniques such as casting and forging, for example, are unable to achieve the required accuracy and polish. Such prepared parts, known as blanks, require semi-finishing and finishing, which is accomplished through machining and grinding. Grinding is essentially the same as machining. Machining to a high degree of accuracy and polish allows a product to • meet its functional requirements • increase its performance • extend its service life.
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Diagrams of machine tools are below.
Types of machining processes
Machining processes are categorized into two; conventional and non-conventional machining processes.
A conventional machining process is one in which the machining is done using the traditional way, that is, without the use of any sophisticated methods. As a result, this machining method is also known as traditional machining. Sharp point cutting tools, such as the taper tool in the lathe machine for tapering, are employed in this technique for machining. The following are the types of conventional machining processes and their operations:
The horizontal metal-turning machine, often known as an engine lathe, is the most significant of all machine tools. Many of its core mechanical principles are included in the design of other machine tools, making it the father of all other machine tools. The engine lathe is a simple machine tool that can be used for a range of operations including turning, facing, and drilling. It turns and bores with a single-point cutting tool. Turning procedures include turning straight or tapered cylindrical shapes, grooves, shoulders, and screw threads, as well as facing flat surfaces on the ends of cylindrical pieces, and entail cutting extra metal from the exterior diameter of a workpiece in the form of chips. Most common hole-machining operations, such as drilling, boring, reaming, counterboring, countersinking, and threading with a single-point tool or tap, are included in internal cylindrical operations.
Grinding machines use a spinning abrasive wheel, also known as a grinding wheel or an abrasive belt, to remove microscopic chips from metal parts. The most precise of all the basic machining techniques are grinding. Hard or soft items are ground to tolerances of plus or minus 0.0001 inch using modern grinding machines (0.0025 millimeters).
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Shapers and planers
Single-point tools are used to machine flat surfaces, grooves, shoulders, T-slots, and angular surfaces during shaping and planning operations. The largest shapers can process components up to 36 inches long and have a 36-inch cutting stroke. The shaper’s cutting tool oscillates, cutting on the forward stroke and automatically feeding the workpiece toward the tool on the return stroke.
In these types of machining processes, the workpiece is fed against a rotating cutting tool called a milling cutter in a milling machine, which cuts metal. For a wide range of milling operations, cutters of various shapes and sizes are offered. Flat surfaces, grooves, shoulders, inclined surfaces, dovetails, and T-slots are all cut with milling machines. For cutting concave forms and convex grooves, rounding corners, and cutting gear teeth, various form-tooth cutters are utilized.
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Drilling machines, also known as drill presses, use a twist drill to make holes in metal. They also employ a range of other cutting tools to accomplish basic hole-machining operations like reaming, boring, counterboring, countersinking, and tapping internal threads with a tapping attachment.
Shearing, blanking, shaping, drawing, bending, forging, coining, upsetting, flanging, squeezing, and hammering are some of the operations used to make metal parts. All of these operations necessitate presses that have a moveable ram that can be pressed against an anvil or a base. Gravity, mechanical connections, hydraulic or pneumatic systems may all be used to power the moving ram.
Traditional machining processes are based on the idea that the tool is tougher than the workpiece. However, some materials are too hard or brittle to be machined using traditional processes. The usage of extremely hard nickel-based and titanium alloys in aviation engines, for example, has sparked interest in nontraditional machining techniques, particularly “electrical methods.” Below are the various types of non-conventional machining techniques:
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Electron-beam machining (EBM)
EBM can cut holes as small as 0.001 inches (0.025 mm) in diameter or slots as narrow as 0.001 inches in materials with a thickness of up to 0.250 inches (6.25 millimeters). In the semiconductor sector, EBM is also employed as an alternative to light optics production methods.
Electrical-discharge machining (EDM)
The electrode and workpiece are immersed in a dielectric liquid, and a feed mechanism maintains a spark gap between the electrode and the workpiece of 0.0005 to 0.020 inches (0.013 to 0.5 millimeter). The particles are flushed away as spark discharges melt or evaporate small particles of the workpiece, and the electrode advances. The procedure is used to machine dies, molds, holes, slots, and cavities of practically any shape. It is accurate but slow.
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Electrochemical machining (ECM)
ECM replicates electroplating in reverse. In this process, metal is dissolved from a workpiece with direct current at a controlled rate in an electrolytic cell. The anode workpiece is machined into a complementary shape as one electrode travels closer to the other to maintain consistent spacing. The lack of tool wear and the ability to process a harder workpiece with a softer cathode tool are two advantages of ECM. ECM is used in the aircraft engine and automobile industries for deburring, drilling small holes, and machining exceptionally hard turbine blades, among other things.
Ion beam machining (IBM)
IBM is utilized in the semiconductor industry and the production of aspheric lenses because it allows for precise machining of nearly any material. Texturing surfaces to improve adhesion, producing atomically clean surfaces on devices like laser mirrors, and altering the thickness of thin coatings are all examples of how the technology is employed.
Laser machining (LM)
LM is a technique for cutting metal or refractory materials that involves melting and vaporizing the material with an intense laser beam. Drilling with a laser is used to cut microscopic holes (0.005 to 0.05 inch [0.13 to 1.3 millimeters]) in materials that are too tough to process using standard methods, although it is energy-intensive because the substance must be melted and vaporized to be removed.
Plasma arc machining (PAM)
Most metals, including those that cannot be cut successfully with an oxyacetylene torch, can be cut with this method. The PAM technique has been used to cut aluminum alloys up to six inches (15 centimeters) thick and stainless steel up to four inches (10 centimeters) thick using heavy-duty torches. Flat plate profile cutting, stainless steel groove cutting, and massive, hardened steel turning on lathes are all applications for this procedure.
Other methods of non-conventional machining process include:
- Ultrasonic machining (USM)
- Chemical machining (CHM)
- Photochemical machining (PCM)
- Water-jet machining
Watch the video below to learn how machining processes work:
Advantages and disadvantages of conventional and non-conventional machining processes
Advantages of conventional machining
The following are some of the benefits of the machining process.
- It is almost impossible to get a high level of surface finish.
- Machining is done on a variety of materials, including wood, plastic, composites, and ceramics.
- Screw threads, very straight edges, accurate round holes, and other geometric aspects are all achievable.
- Dimensional accuracy is excellent.
Disadvantages of conventional machining
The following are the limitations of the machining process.
- The operator’s efficiency determines the correctness of the components produced.
- Manufacturing is lacking consistency. As a result, a complete inspection of the component is required.
- The operator’s requirements are lowering output rates.
- The labor problem will be severe due to the massive volume of manpower engaged.
- Manufacturing complicated shapes such as parabolic Curvature components and Cubicle Curvature components is tough.
- The component’s frequent design modifications can’t be accommodated in the current layout.
Advantages of non-conventional machining processes
The following are the benefits of conventional machining methods:
- It has a high level of precision and surface finish.
- Because no physical tool is utilized, there is no tool wear.
- They don’t make chips, let alone minuscule chips.
- In operation, these are quieter.
- It’s simple to automate.
- It is capable of machining any complex shape.
Disadvantages of non-conventional machining processes
Below are the limitations of non-conventional machining:
- Initial or setup costs are high.
- Labor with a high level of ability is necessary.
- The metal removal rate is lower.
- Machining necessitates more power.
- It is not cost-effective for large-scale manufacturers.
Machining processes or machine tools are categorized into conventional and non-conventional processes. The non-conventional is just the new ways of machining while the convention is the old method of machining which we listed to turning, drilling, grinding, shaping, planning, etc. That is all for this article where the definition, applications, purpose, diagram, types, operations, advantages, and disadvantages of the machining process are being discussed.
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