What is Machining? – Definition, Process, and Tool

Machining is a manufacturing process that refers to a broad range of technologies and techniques. Essentially, machining is defined as removing materials from a workpiece by power machine tools to form the workpiece into a desired design.

The majority of metal parts and components are designed and created using some form of machining during the manufacturing process.

Other materials such as plastics, rubbers, and paper goods are similarly and commonly made through machining processes. Let us explore more closely what machining is, the process of machining, and the tools and technologies used for machining.

What is Machining?

Machining is a method of prototyping and manufacturing that achieves the desired final shape by removing unwanted material from a larger piece of material.

In these processes, a part is constructed by removing material, also known as subtractive manufacturing, as compared to additive manufacturing, which instead involves the controlled addition of material.

What is meant by “controlled,” can vary, but usually means that some form of machine tool is being used.

Machining is a part of the manufacture of many metal products, but it can also be employed to work with other materials, for example, wood, plastic, ceramic, and composite materials. A person who works with machining is called a machinist.

A room, building, or company where machining is conducted is called a machine shop. Much of today’s machining is done by computer numerical control (CNC). With CNC, computers control a mill (or lath, etc.) to move or operate.

This reduces labor costs to a machine shop and improves efficiency because, with CNC, they only need to tend a machine rather than run it. The choice of a CNC services provider or, CNC manufacturer is still a significant choice, as experienced operators setting up and maintaining the machines will still have a big impact on part quality.

What are the different types of machining?

The three primary forms of machining include turning, drilling, and milling. Other operations in the miscellaneous category include shaping, planning, boring, broaching, and sawing. They are:

• Turning: Turning, or lathing, involves rotating a workpiece on the machine while a single-edged cutting tool is held stationary. The cutting tool is moved slowly parallel to the rotational axis of the workpiece, removing material as the workpiece is coupled to the machine.
• Drilling: Drilling is the process of producing a round hole by rotating a cylindrical tool parallel to the workpiece’s axis of rotation. The hole becomes the same diameter as the cylindrical tool.
• Milling: Milling removes material, using rotary cutters, from a workpiece while the feed motion is perpendicular to the rotational axis of the cutting tool. It is one of the most popular forms of machining presently being used.
• Miscellaneous operations are operations that may largely not be machining operations by strict definition in that they may not be swarf removing operations however these kinds of operations are performed at a typical machine tool. An example of a miscellaneous operation would be burnishing for which no swarf (waste material) is produced, but it is still an operation that can be performed at a lathe, mill, or drill press.

How does machining work?

An unmachined workpiece will always have some material removed before it can become a finished product. A finished product means that the workpiece, as per specifications indicated by engineering drawings or blueprints has little or no material removed from it’s outside and/or inside surfaces.

For example, an outside diameter is required on workpiece. A lathe is a machine used to create that part by rotating a steel workpiece fast enough that a cutting tool can then cut steel of the workpiece to produce a smooth, round surface with a specific diameter and surface finish.

A drill can remove steel in the shape and finish of a cylindrical hole. Other tools available for various types of steel removal include milling machines, saws, and grinding machines. The same basic techniques used for metal machining are often similar to the procedures used for cutting wood.

And then there are more modern, and advanced machining procedures such as CNC machining, EDM (electrical discharge machining), ECM (electrochemical machining), laser cutting, or water jet cutting to shape specific pieces of metal.

In today’s product development world, machining typically occurs with a CNC machine (computer numeric control). Simply put, the machine uses computer software to load CAD design models into it and be able to operationally map out tool paths to machine the designs into 3D parts.

CNC machines are capable to machine parts out of a variety of materials of each with finished properties that can be made to the tolerances of .001″ of solid material.

In comparison to rapid prototyping (where every piece is an abs plastic material), it important to note that the machined parts use real materials that match the densities, finishes, and porosity of that of design plans.

Machined parts provide representative testing, models with complete moving parts where friction may be a concern, and for sealed parts that are complementary and requires 0 rings and gasket surfaces.

Now that we understand what machining is, and how it is performed, we understand machining occurs using machining tools, so let’s explore the machining tools and their functions.

What is Machining Tool?

A machine tool is a machine for working or machining metal or other rigid materials, generally when involved with cutting, boring, grinding, shearing, or other methods of deformation. They involve using some sort of tool which does the cutting or shaping.

As a function of every machine tool, workpieces are constrained, with guided motion of the elements of the machine. Where appropriate, the relative motion between the workpiece and the cutting tool (which is termed the toolpath) is controlled or constrained by the machine, not left to be 100 percent “offhand” or “freehand.”

It is a machine that is driven by power rather than muscle, which accomplishes the complexity of required relative motion between the cutting tool and the job which effects the change in size and shape of the job material.

The exact wording of the machine tool definition varies with the user, as discussed in further detail below, but while every machine tool is described as “a machine that helps people to make things”, not every factory machine is accurately described as a machine tool.

Machine tools are generally powered to replace human muscle (e.g., electric, hydraulic, or line shaft), and they are used to make manufactured parts (components) in many ways that include cutting or certain other types of deformation.

The capabilities of machine tools and their inherent precision enabled the economical production of interchangeable parts.

Different Types of Machining Tools and Technologies

Types of Machining Tools

There are numerous types of machining tools, and they can be employed as a single tool or in combination with other tools at various steps in the manufacturing process, to produce the intended part geometry. The principal types of machining tools include:

• Boring tools: These are usually utilized as finishing tools to increase hole size in the workpiece in instances where the bore was inserted previously into the material.
• Cutting tools: Equipment such as saws and shears are normal types of cutting tools. Generally, they are cutting material with known dimensions (for example sheet metal) and then producing a shape.
• Drilling tools: This type of tool consists of a pair of edged rotating tools that cut round holes, perpendicular on the rotary axis.
• Grinding tools: Cutting tools that use a rotating wheel for fine finishes or for light cuts to be performed on a workpiece.
• Milling tools: A milling tool uses a rotating surface that can have many blades to create non-circular holes, or to cut unique shapes out of the material.
• Turning tools: These tools rotate the workpiece about the work axis while a tool shapes it to final form. A lathe is the most common type of turning equipment.

Types of Burning Machining Technologies

Welding and burning machine tools use heat to shape a workpiece. The most common types of welding and burning machining technologies include:

• Laser Cutting: This type of cutting uses a manageable, high-energy beam of light emitted from a laser machine to melt, vaporize, or remove material, subject to the thermodynamics involved in any cutting application. CO2 and Nd: YAG are the dominant laser types in machining applications. Laser cutting is a popular process to generate shapes or etch patterns in steel. Its advantages of course include superb surface finishing and extremely tight tolerance cuts.
• Oxy-Fuel Cutting: Also known as gas cutting the oxy-fuel approach utilizes a combination of fuel gases and oxygen to cut and is arguably the most common machining method used today. Gases such as acetylene, gasoline, hydrogen and propane are preferred as gas media because they are flammable. Oxy-fuel cutting practices have good portability, low dependency on primary power, and can cut thick, hard materials such as hard steel grades.
• Plasma Cutting: The process of plasma cutting utilizes plasma torches to fire an electrical arc to turn inert gas into plasma. Plasma gets extremely high temperatures and is directed at the workpiece at high speeds to melt Base material. It is common to see this cutting process applied to electrically conductive metals that require tight outside cut width and little prep time.

Types of Erosion Machining Technologies

While burning tools make use of heat to melt away excess stock, erosion machining devices use water and electricity to erode the material off the workpiece. The two major types of erosion machining processes are:

• Water Jet Cutting: Water jet cutting uses a high-pressure stream of water to cut through the material. Abrasive powder can be added to the water stream to increase erosion. Water jet cutting is used mostly on materials that would be ruined or distorted from a heat-affected zone.
• Electrical Discharge Machining (EDM): EDM (spark machining), uses electrical arcing discharges to create micro-craters that quickly become complete cuts. EDM is suited for complex shapes in hard materials, with regards to close tolerances. One downside is that the base material must be electrically non-insulating/conductive. Therefore, EDM is limited to ferrous alloys.

CNC Machining

Computer numerical control machining (CNC machining) is considered a computer-aided machining process that can be utilized with many other types of tools.

To utilize CNC machining, software is necessary and programming (typically in G-code) is produced to control a machining tool so that it can create a workpiece to specification.

CNC machining is an automated process, as opposed to one guided by hand. Some advantages include:

• High productions cycles: Once the CNC machine has been coded correctly, it generally requires little maintenance or downtime, which means less overall lead time as production speed increases.
• Low manufacturing costs: Because it has a fast turnover and requires little manual labor, CNC machining can be an economical process to manufacture parts, especially for long production runs.
• Consistent production: CNC machining is typically reliable and produces high accuracy; there will usually be more design consistency across a lot of products.

Precision Machining

Any machining process with exceedingly small cutting tolerances (typically between 0.013 and 0.0005 mm) or surface finishes finer than 32T will be considered precision machining. Like CNC machining, precision machining can be used in a wide array of fabrication processes and tools.

There are numerous factors that can affect the precision of a precision tool cut including stiffness, damping, and geometric accuracy. Motion control and the speed of the machine at rapid feed rates may also (and can) play a factor in precision machining applications.

What Are the Benefits of Machining?

There are several advantages of machining:

1. Reliability

The machining process operates continuously without interruption at any day or time of the week. The chips are machined from the raw materials and transformed into finished products and supplied to the OEM international market as quality tools.

Downtime only occurs if service is required and/or repair comes into play. Machines operate dependably; it doesn’t matter whether it’s a weekday, weekend or holiday.

2. Requires Less Human Labor

With the advancement of technology in the productions of manufactured products, machining is automated.

The machining processes are controlled either fully or partially automated though computers or robots, which can reduce production costs when they are involved; as a result of the lack of human efforts.

If the material is added and controlled to the process, it requires limited supervision or monitoring but does require maintenance of oversight.

3. High Production

The possesses enormous productivity potential because they can typically do that amount of work as drilling, more surface finishes, milling, and spinning in a short time.

4. Identical Products

The finished product – the cutting metals – are homogeneous and have few, if any, production errors despite the rapid production rate. Consequently, the products are marketable because they quality has improved.

5. Increase Profit and Reduce Efforts

One more reason that you need to machine your metal devices is to also increase profits and greatly reduce efforts. Some people might think, and I understand, how can you determine that machining is related to increased profits? The fact of the matter is machining is going to be a little costly, but it is very beneficial.

With a machined metal, you will not only reduce the cost to produce but also save a lot of time and effort. As helpful as these advantages might be, if you want to get one, it is always wiser to check whether the has the right machine in place, and ensures no errors while doing the machining work.

6. Improved Efficiency

Machining is one of the optimal methods of increasing efficiency in metals. When metals are machined, they are almost always fitted with internal quality assurance detectors. This contributes to a great deal of efficiency in enhancing speed of production in the metals and effective use of raw materials.

Machining has also always been seen as a great way to maintain high-level standards in metalworking and part fabrication. In addition to increasing efficiency, machining has also been regarded as one of the methods of cutting costs.

This is due to a reduction in consumption cost, so it saves money. In general, it lowers costs which adds on to the benefits from pursuing machining operations.

7. Increased Accuracy

Most of the metals that are machined are used in the manufacturing industries – this includes locations where manual turning and milling is performed. They can also be machined in the healthcare setting, but as a point you must remember, they all involve a lot of accuracy.

On this note, they become metals that are machined due to their level of accuracy. This is clear proof of how machining is important in ensuring you have an accurate level of metal, and means accurate level of completion with your tasks.

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