Machining is a manufacturing term encompassing a broad range of technologies and techniques. It can be roughly defined as the process of removing material from a workpiece using power-driven machine tools to shape it into an intended design.
Most metal components and parts require some form of machining during the manufacturing process. Other materials, such as plastics, rubbers, and paper goods, are also commonly fabricated through machining processes. Let’s learn in detail what is machining, its process, and the tool and Technologies use for it.
What is Machining?
Machining is a prototyping and manufacturing process that creates the desired final shape by removing unwanted material from a larger piece of material. In these processes, a part is built by removing material, this process is also known as subtractive manufacturing, in contrast to additive manufacturing, in which a controlled addition of material is used.
Exactly what the “controlled” part of the definition implies can vary, but it usually implies the use of machine tools.
Machining is a part of the manufacture of many metal products, but it can also be used on other materials such as wood, plastic, ceramic, and composite material. A person who specializes in machining is called a machinist.
A room, building, or company where machining is done is called a machine shop. Much of modern-day machining is carried out by computer numerical control (CNC), in which computers are used to control the movement and operation of mills, lathes, and other cutting machines. This increases efficiency, as the CNC machine runs unmanned therefore reducing labor costs for machine shops.
What are the different types of machining?
The three principal machining processes are classified as turning, drilling and milling. Other operations falling into miscellaneous categories include shaping, planning, boring, broaching, and sawing. They are:
- Turning- Turning or Lathing involves rotating the workpiece on a machine, while a single-edged cutting tool remains stationary. The cutting tool is slowly moved parallel to the workpiece’s rotational axis, removing material as it goes.
- Drilling – Drilling results in creating a round hole by rotating a cylindrical tool parallel to the workpiece’s axis of rotation. The hole created is equal in diameter of the tool that was used.
- Milling – Milling is the process of removing material, using rotary cutters, from a workpiece in a feed motion perpendicular to the rotational axis of the cutting tool. This is one of the most common forms of machining used today.
- Miscellaneous operations are operations that strictly speaking may not be machining operations in that they may not be swarf-producing operations but these operations are performed at a typical machine tool. Burnishing is an example of a miscellaneous operation. Burnishing produces no swarf but can be performed at a lathe, mill, or drill press.
How does machining work?
An unfinished workpiece requiring machining will need to have some material cut away to create a finished product. A finished product would be a workpiece that meets the specifications set out for that workpiece by engineering drawings or blueprints.
For example, a workpiece may be required to have a specific outside diameter. A lathe is a machine tool that can be used to create that diameter by rotating a metal workpiece so that a cutting tool can cut metal away, creating a smooth, round surface matching the required diameter and surface finish.
A drill can be used to remove the metal in the shape of a cylindrical hole. Other tools that may be used for various types of metal removal are milling machines, saws, and grinding machines. Many of these same techniques are used in woodworking.
More recent, advanced machining techniques include precision CNC machining, electrical discharge machining (EDM), electrochemical machining (ECM), laser cutting, or water jet cutting to shape metal workpieces.
In modern product development, machining is most often done using a CNC machine, which stands for Computer Numeric Control. In essence, the machine uses computer software to take CAD design models and map out tool paths, turning the designs into 3D machined parts. The CNC can create parts from a wide variety of materials, in varying types of finishes, with tolerances created to the nearest .001” from solid material.
Unlike rapid prototyping, parts are machined using real materials reflecting the density, finish, and porosity of the finished design. Machined parts can be used for representative testing, models including sliding components where friction is a factor, and for sealed components requiring 0 rings and gasket surfaces.
Now we know what is machining and how it’s done, we know machining is done by machining tool so let’s learn about different machining tools and their uses.
What is Machining Tool?
A machine tool is a machine for handling or machining metal or other rigid materials, usually by cutting, boring, grinding, shearing, or other forms of deformations. Machine tools employ some sort of tool that does the cutting or shaping.
All machine tools have some means of constraining the workpiece and provide a guided movement of the parts of the machine. Thus, the relative movement between the workpiece and the cutting tool (which is called the toolpath) is controlled or constrained by the machine to at least some extent, rather than being entirely “offhand” or “freehand”.
It is a power-driven metal cutting machine which assists in managing the needed relative motion between the cutting tool and the job that changes the size and shape of the job material.
The precise definition of the term machine tool varies among users, as discussed below. While all machine tools are “machines that help people to make things”, not all factory machines are machine tools.
Today machine tools are typically powered other than by the human muscle (e.g., electrically, hydraulically, or via line shaft), used to make manufactured parts (components) in various ways that include cutting or certain other kinds of deformation. With their inherent precision, machine tools enabled the economical production of interchangeable parts.
Different Types of Machining Tool and Technologies
Types of Machining Tools
There are many types of machining tools, and they may be used alone or in conjunction with other tools at various steps of the manufacturing process to achieve the intended part geometry. The major categories of machining tools are:
- Boring tools: These are typically used as finishing equipment to enlarge holes previously cut into the material.
- Cutting tools: Devices such as saws and shears are typical examples of cutting implements. They are often used to cut material with predetermined dimensions, such as sheet metal, into a desired shape.
- Drilling tools: This category consists of two-edged rotating devices that create round holes parallel to the axis of rotation.
- Grinding tools: These instruments apply a rotating wheel to achieve a fine finish or to make light cuts on a workpiece.
- Milling tools: A milling tool employs a rotating cutting surface with several blades to create non-circular holes or cut unique designs out of the material.
- Turning tools: These tools rotate a workpiece on its axis while a cutting tool shape it to form. Lathes are 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: A laser machine emits a narrow, high-energy beam of light that effectively melts, vaporizes, or burns material. CO2 and Nd:YAG lasers are the most common types used in machining. The laser cutting process is well-suited for shaping steel or etching patterns into a piece of material. Its benefits include high-quality surface finishes and extreme cutting precision.
- Oxy-fuel cutting: Also known as gas cutting, this machining method employs a mixture of fuel gases and oxygen to melt and cut away material. Acetylene, gasoline, hydrogen, and propane frequently serve as gas media due to their high flammability. This method’s benefits include high portability, a low dependence on primary power sources, and the ability to cut thick or hard materials, such as sturdy steel grades.
- Plasma cutting: Plasma torches fire an electrical arc to transform inert gas into plasma. This plasma reaches extremely elevated temperatures and is applied to the workpiece at high speed to melt away unwanted material. The process is often used on electrically conductive metals that require a precise cut width and minimal prep time.
Types of Erosion Machining Technologies
While burning tools apply heat to melt excess stock, erosion machining devices use water or electricity to erode material off the workpiece. The two main types of erosion machining technologies are:
- Water jet cutting: This process uses a high-pressurized stream of water to cut through the material. The abrasive powder may be added to the water stream to facilitate erosion. Water jet cutting is typically used on materials that can suffer damage or deformation from a heat-affected zone.
- Electric discharge machining (EDM): Also known as spark machining, this process uses electric arcing discharges to create micro-craters that rapidly result in complete cuts. EDM is used in applications requiring complex geometrical shapes in hard materials and at close tolerances. EDM requires the base material to be electrically conductive, which limits its use to ferrous alloys.
Computer numerical control machining (CNC machining) is a computer-aided technique that can be used in conjunction with a broad range of equipment. It requires software and programming, usually in the G-code language, to guide a machining tool in shaping the workpiece according to preset parameters.
As opposed to manually guided methods, CNC machining is an automated process. Some of its benefits include:
- High production cycles: Once the CNC machine has been properly coded, it usually needs minimal maintenance or downtime, allowing for a faster production rate.
- Low manufacturing costs: Due to its turnover speed and low manual labor requirements, CNC machining can be a cost-efficient process, particularly for high-volume production runs.
- Uniform production: CNC machining is typically precise and yields a high level of design consistency among its products.
Any machining process that requires unusually small cutting tolerances (between 0.013 mm and 0.0005 mm, as a rule of thumb) or surface finishes finer than 32T may be considered a form of precision machining. Like CNC machining, precision machining can be applied to a wide number of fabrication methods and tools.
Factors such as stiffness, damping, and geometric accuracy can influence the exactness of a precision tool’s cut. Motion control and the machine’s ability to respond at rapid feed rates are also important in precision machining applications.
What Are the Benefits of Machining?
There are several advantages of machining:
The machining process takes place continuously without any breakdown despite the time or day of the week. The chips and the raw materials are converted into finished products and released into the market as high-quality tools. Breakdowns are very minimal as they may occur when maintenance is required or during a repair. Machines work reliably; it doesn’t matter whether it’s a weekday, weekend, or holiday.
2. Requires Less Human Labor
Due to the development of technology, machining in manufacturing industries is automated. The process is mainly controlled by computers or robots that usually cut down production costs by eliminating human labor. During the controlled material addition, the process requires minimal supervision and oversight for maintenance purposes.
3. High Production
The process brings about high productivity because they generally do a massive amount of work such as drilling, better surface finish, milling, and spinning in a relatively short period.
4. Identical Products
The finished products, such as the cutting metals, are homogenous and have very little or no errors despite the high rate of production. As a result, the products become marketable due to their improved quality.
5. Increase Profit and Reduce Efforts
Another great reason you need to machine your metal devices is to help increase profits and reduce efforts. Some people may wonder, how does machining relate to increased profits? The fact is that machining makes devices a little expensive, but it is, on the other hand, very beneficial.
With a metal that has undergone machining, you will not only reduce the production cost, but it will also save much of your time and effort. Despite this advantage, it is always advisable if you want to purchase one, to be sure to check if the machine is right and whether it is error-free while working.
6. Improved Efficiency
Machining is one of the best ways that can help increase the efficiency of your metals. When machining the metals, they are always fitted with internal quality assurance detectors. This brings along a lot of efficiency in terms of increasing the speed of production of the metals and ensuring good usage of raw materials.
More to this, machining is always considered a remarkable way of ensuring high-level standards of metalworking and part fabrication. More to increase efficiency, machining is considered one of the ways to cut down expenditure costs.
This is due to its ability to drop the consumption cost; therefore, reducing money wastage. In short, it reduces expenditure; thus, adding to the benefits of carrying out the machining process.
7. Increased Accuracy
Most of the metals that undergo machining are used in the manufacturing industries. This includes places that require manual turning and milling processes. They can also be used in the healthcare sector, but the point you need to note here, all these sectors involve a lot of accuracy.
On this, they turn into metals that have undergone machining due to their accuracy level. This is clear evidence of how machining is essential in ensuring increased accuracy on your metals, which translates to accuracy in completing your tasks.