What is Machining and Machine Tools?

Machining is a controlled material-removal technique using machine tools to cut a material (typically metal) to a specified final form and size. Subtractive manufacturing refers to procedures with 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 using machine tools. Machining makes metal products and wood, plastic, ceramics, and composites. A machinist is someone who specializes in machining.

In this reading, we will delve into the definition of machining and machine tools, as well as their various applications, types, advantages, and disadvantages. We’ll also explore the steps involved in machining.

Let’s begin!

What Is Machining or Machine Tools?

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 shop is a room, building, or company that specializes in machining. Many modern machining processes use computer numerical control (CNC), which uses computers to control the movement and operation of mills, lathes, and other cutting equipment.

This improves efficiency by allowing the CNC machine to run unattended, lowering labor expenses for machine shops.

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, shaving machines, planer machines, and so on. These are examples of machine tools.

Finally, we use a cutting tool to remove the material from the workpiece’s surface. To carry out the operation, it must be harder than the workpiece. We divide cutting tools into two categories: single point and multipoint.

Applications

Most technical components, such as gears, bearings, clutches, tools, screws, and nuts, require dimensions and form correctness as well as a satisfactory surface polish to function properly.

Performing techniques such as casting and forging, for example, are unable to achieve the required accuracy and polish. Machines and grinders accomplish the semi-finishing and finishing of such prepared parts, known as blanks.

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; and extend its service life.

Types of Machining and Machine Tools

We categorize different types of machining processes into conventional and non-conventional machining. The conventional machining machines are lathe machines, grinding tools, shapers, planers, milling machines, drilling machines, and presses.

The non-conventional machining include electron-beam machining, electrical-discarge machining, electrochemical machining, ion beam machining, laser machining, plasma arc machining, etc.

Conventional Machining

A conventional machining process involves performing the machining in a traditional manner, without the use of 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:

Lathe (Turning) Machine

The horizontal metal-turning machine, often known as an engine lathe, is the most significant of all machine tools. The design of other machine tools incorporates many of its core mechanical principles, making it the father of all machine tools.

A simple machine tool, the engine lathe performs a variety of tasks such as 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.

Internal cylindrical operations include the majority of common hole-machining operations, such as drilling, boring, reaming, counterboring, countersinking, and threading with a single-point tool or tap.

Grinding Machines

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 is grinding.

Modern grinding machines ground hard or soft items to tolerances of plus or minus 0.0001 inch (0.0025 millimeters).

Shapers and Planers

During shaping and planning operations, single-point tools handle flat surfaces, grooves, shoulders, T-slots, and angular surfaces. 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.

Milling Machine

In these types of machining processes, a milling machine feeds the workpiece against a rotating cutting tool known as a milling cutter, which cuts metal.

We offer cutters of various shapes and sizes for a wide range of milling operations. Milling machines are capable of cutting flat surfaces, grooves, shoulders, inclined surfaces, dovetails, and T-slots.

We use various form-tooth cutters for cutting concave forms and convex grooves, rounding corners, and cutting gear teeth.

Drilling Machine

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.

Presses

Shearing, blanking, shaping, drawing, bending, forging, coining, upsetting, flanging, squeezing, and hammering are some of the operations used to make metal parts. Presses with a movable ram, which can press against an anvil or a base, are necessary for all these operations.

You can power the moving ram with gravity, mechanical connections, hydraulic, or pneumatic systems.

Non-Conventional Machining And Machine Tools

Traditional machining processes are based on the idea that the tool is tougher than the workpiece. However, traditional processes cannot machine some materials due to their hardness or brittleness.

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:

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). EBM serves as an alternative to light optics production methods in the semiconductor sector.

Electrical-Discharge Machining (EDM)

A feed mechanism maintains a spark gap of 0.0005 to 0.020 inches (0.013 to 0.5 millimeters) between the electrode and the workpiece, immersing them in a dielectric liquid.

Spark discharges flush away the particles by melting or evaporating the small particles of the workpiece, while the electrode advances. The procedure allows for the machining of dies, molds, holes, slots, and cavities in nearly any shape. It is accurate but slow.

Electrochemical Machining (ECM)

ECM replicates electroplating in reverse. This process dissolves metal from a workpiece at a controlled rate using direct current in an electrolytic cell. One electrode travels closer to the other, machining the anode workpiece into a complementary shape 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. The aircraft engine and automobile industries use ECM for deburring, drilling small holes, and machining exceptionally hard turbine blades, among other applications.

Ion Beam Machining (IBM)

The semiconductor industry and aspheric lens production use IBM because it enables precise machining of nearly any material.

Examples of employing the technology include texturing surfaces to improve adhesion, producing atomically clean surfaces on devices like laser mirrors, and altering the thickness of thin coatings.

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)

This method can successfully cut most metals, including those that an oxyacetylene torch cannot. We have used heavy-duty torches to cut aluminum alloys up to six inches (15 centimeters) thick and stainless steel up to four inches (10 centimeters) thick using the PAM technique.

Flat plate profile cutting, stainless steel groove cutting, and massive, hardened steel turning on lathes are all applications for this procedure.

Ultrasonic machining (USM)

By vibrating abrasive particles in a water slurry that circulates through a tight space between a vibrating tool and the workpiece at a high frequency, USM removes material from a workpiece.

The tool, which is shaped like the cavity to be created, oscillates at 19,000 to 40,000 hertz with an amplitude of around 0.0005 to 0.0025 inches (0.013 to 0.062 millimeters) (cycles per second).

The tool removes material by vibrating the abrasive grains against the workpiece’s surface. Hard, brittle materials, whether electrical conductors or insulators, typically undergo ultrasonic machining.

Cutting semiconductor materials (such as germanium), engraving, drilling fine holes in glass, and machining ceramics and precious stones are all frequent USM applications.

A modified version of the procedure, known as ultrasonic twist drilling, involves turning an ultrasonic tool against a workpiece without the need for an abrasive slurry. This type of USM has drilled holes as small as 80 micrometers.

Chemical Machining (CHM)

By using a controlled chemical action, this nonelectrical technique eliminates metal from specific or general locations. You might use masking tape to protect areas that don’t require removal.

The process bears similarities to the creation of metal printing and engraving plates. Chemical machining techniques include chemical blanking, which cuts blanks of thin metal components, and chemical milling, which removes metal from selected or entire sections of metal parts.

Photochemical machining (PCM)

PCM is a branch of CHM that employs a combination of photographic and chemical etching techniques to create components and devices in a variety of metals, particularly stainless steel.

Water-Jet Machining

The water-jet machining process blasts water through small nozzles at extremely high pressures to cut through materials such as polymers, masonry, and paper.

Water-jet machining has several advantages over other methods: it produces no heat, the workpiece does not distort during machining, the process can begin anywhere on the workpiece, no pre-machining preparation is required, and the procedure produces minimal burrs.

Especially in finishing operations, the offshore business occasionally adds an abrasive to the water to speed up material removal. When using this approach, the offshore business uses saltwater as the working fluid.

Steps Involved in Machining and Machine Tools

There are six steps involved in machining, which include revewing and approval of the work’s technical drawing. Additionally, the process involves designing appropriate machining methods and ensuring quality control.

Step 1: Review and Approval of the Workpiece’s Technical Drawings

The quality of the blueprints or technical drawings that the machinists will use as a basis for their work is critical before they begin machining a product.

As a result, the machine shop assigned to the task must confirm the various data contained in the technical drawings submitted to them with the client.

They must ensure that the dimensions, forms, materials, and degrees of precision selected for each part of the machined workpiece are clearly defined and legitimate.

In a field like precision machining, even the tiniest misunderstanding or error can have a significant impact on the end product’s quality. Furthermore, these various criteria will guide the selection of the tools and machining method used to create the part.

Step 2: Designing or Prototyping the Final Product

Computer modeling or prototypes of machined parts with complex geometry can be beneficial when manufacturing these parts. This stage offers you a better concept of how the machined part will look in the end.

For instance, when creating bespoke gears, one can obtain a 3D image of the part and its numerous sides by entering various data into sophisticated software.

Step 3: Choosing the Appropriate Machining Techniques

Depending on the chosen material for the item and its degree of complexity, some machining processes may be more effective than others in producing the intended outcome.

Machinists can employ a variety of industrial machining methods, including milling, boring, mortising, drilling, and rectification, among others.

Step 4: Selecting the Appropriate Machine Tool

The level of complexity and precision required for a new part dictate the selection of manual or CNC machine tools. Computerized equipment, such as CNC boring machines, may be necessary, for example.

This type of machine can prove to be quite useful when making multiple copies of a part.

You might also require a machine tool that can operate on five different axes instead of just three, or one that can produce parts with non-standard dimensions.

Step 5: The Machinist Will Machine The Item

If you successfully followed all the preceding stages, you should be able to machine the workpiece without any issues. The machinist will be able to build the item from a block of the specified material and complete it with manual and digital cutting equipment.

Step 6: Quality Control

Quality control is crucial to ensure that the manufactured part satisfies all the original requirements of the machine it is a mechanical component for. We accomplish this by subjecting the parts to a variety of tests and using tools such as a micrometer.

Advantages And Disadvantages of Conventional Machining

Advantages:

It is almost impossible to get a high level of surface finish.
A variety of materials, including wood, plastic, composites, and ceramics, are machinable.
Screw threads, very straight edges, accurate round holes, and other geometric aspects are all achievable.
Dimensional accuracy is excellent.

Disadvantages:

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 cube curvature components is tough.
The current layout cannot accommodate the component’s frequent design modifications.

Advantages And Disadvantages of Non-Conventional Machining