If you belong to the manufacturing industry, you should be aware of the modern technologies being used in manufacturing processes and metal machining. It is performed to develop different industrial parts at a broad range with extreme precision and accuracy.
With modern technology development, the latest micromachining with laser technology has replaced the traditional manual-operated metal cutting. The word “Machining” is a manufacturing process that covers a wide range of techniques and technologies.
The machining process belongs to the category of subtractive manufacturing, in which the material is removed from the workpiece to produce the desired product. The metal can get shaped into any desired design by using several power-machine tools. Forging and Casting are also a part of the machining process.
In this article, we will mainly discuss metal machining and its different techniques to choose the suitable machining process according to the requirements to fulfill the customers’ needs. So, let’s get started.
What Is Metal Machining?
Metal machining is a subtractive manufacturing process used to develop metal parts, machine components, and different industrial tools. Various methods are involved in metal machining to attain the desired product design regarding shape, diameter, size, finishing, and surface quality.
Different Machining Process Types
Machining processes are categorized into two major types: non-conventional and conventional methods. The material is removed with the help of thermal or chemical energy in the non-conventional machining process. On the other hand, machining’s conventional process mainly consists of single-point cutting, multi-point cutting, and abrasive cutting, and it is widely used for metal machining.
Some of the different metal material removal processes are discussed below:
1. Mechanical Machining Processes
In this process, a single sharp-edged cutting tool is used to remove material from the workpiece. The single-point cutting process is mainly used during turning operations. The spindle rotates the workpiece, and the cutting tool moves along the axis of the workpiece to remove material.
Turning operations feature boring, grooving, cut-off, facing, and threading. Also, it includes complex contours, tapers, slots, and threads.
Planning and shaping processes are also included in the single-point cutting processes.
In this process, multiple sharp-edged cutting tools are fed against the workpiece for material removal. The most critical functions of multi-point cutting are milling and drilling. In a cylindrical cutting tool, the sharp tooth rotates at high speed to remove the workpiece material. While performing the milling operation, the rotating tool is used to develop various features on the workpiece.
Some of the joint milling operations performed on milling machines are chamfering and face and end milling. Milling processes can create different kinds of pockets, slots, and complex contours. A milling machine is also used for drilling and boring purposes. Two more types of milling are broaching and sawing, which will be discussed later in this article.
2. Abrasive Machining
Abrasive machining is a process in which an abrasive tool is used to remove the workpiece material. This process is also used for shaping and forming various features on the workpiece. Surface finishing can also be done by abrasive machining.
The cutting tool’s abrasive grains are bounded into the rotating wheel used for the grinding process. Grinding can also be performed by the surface grinder or on the cylindrical grinding machine. The abrasive material is used for abrasive jet machining, and it is also used with water for abrasive water jet machining. Horning, ultrasonic machining, and lapping are also types of abrasive machining.
3. Chemical Machining
The most commonly used type of chemical machining is electrochemical machining, in which the chemical is used to remove the material from the workpiece. It is used for mass production. It is only feasible for conductive materials that are hard to machine using conventional methods. This process is also carried out for surface finishing and deburring.
4. Thermal Machining
The thermal machining method is used to remove the material from the highly rigid material – hard to machine. Torch cutting, EDM, and electron beam machining are some of the main types of thermal machining. Electric discharge machining (EDM) is used to produce complex geometries with extreme precision. However, this process consumes time and is not feasible for mass production.
Metal Machining Through CNC Machine
CNC machine is the most critical and fundamental machine of every machine shop. Computer numeric control (CNC) machines are used to manufacture the workpiece in which the product design is converted into the physical shape. CNC comes with pre-programmed software, which reads the design parameters and executes the specific operations like grinding, milling, turning, facing, and boring.
Firstly, the design is developed on the CAD software and then transferred to the CNC machine for execution. Using CNC machining for manufacturing products eliminates the possibility of human error and produces high-quality products.
Working Principle of CNC Machine
CNC machines are equipped with direct open and closed-loop control to regulate the machine’s speed and position. In an open-loop system, the signals are transmitted in only one direction between the drive controller and the motor, and an open-loop control executes the operations which require less force and speed. In a closed-loop system, the controller takes feedback from the machine to diagnose the machines’ errors and faults, and closed-loop control is used where the products are needed to get machined at high speed and accuracy.
Most of the machine shops are equipped with 2-axis CNC machines, and some of them also hold 3-axis (or more) CNC machines. A stepper or servo motor is used for positioning tools according to the specifically programmed code.
Types of CNC Machines and Applications
In today’s modern world, almost all of the machine parts are produced on CNC machines. Some of the most commonly performed operations on CNC are bending, drilling, boring, grinding, laser cutting, plasma cutting, routing, and ultrasonic welding. Many machines, including lathes, mills, water jet machines, and EDM, are operated by CNC.
Some of the commonly used CNC machines are:
CNC Lathes: In the CNC lathe, the material is clamped into the machine’s chuck, and machines remove the material by rotating the workpiece at high speed in a circular direction. It is possible to develop complex geometries on CNC lathes. These machines can only operate at two axes (X and Z).
CNC Mills: CNC mills are generally capable of operating at 3-axis (X, Y, and Z), whereas some of them are also equipped with an additional axis. The designer develops a program, which is then installed into the machine that executes the program-specific functions to build the required product. Its operations are almost similar to the CNC lathes.
Plasma Arc Cutters: Plasma Arc cutters are used to cut the metal or any other material at a very high temperature. This process needs to be done at high temperatures and speed. The plasma is produced using an electrical arc and compressed air gas to cut the material.
Water Jet Cutters: CNC-operated water jet cutters are used to cut hard materials using high water pressure. Some abrasive material is also used in conjunction with the water for deburring and surface finishing. It can manufacture mechanical parts of complex geometry. Water jet applications include the mining industry, aerospace industry, and automobile industry.
Processes Involved in Metal CNC Machining
The manufacturing has to go through a lot of machining processes to develop a finished product. Some of these processes are discussed below:
Milling is one of the essential processes in manufacturing a workpiece. It is also used to fabricate metal tools. Milling is performed to produce symmetric metal parts, slots, holes, pockets, and complex contours. Custom-designed brackets and fasteners are the most common example of the milling process.
The cutting tools used for the milling process are made up of carbide, high-speed steel (HSS), high-speed cobalt steel, and carbon steel. The tool selection depends upon the nature of the material of the workpiece. Sometimes coolant is also supplied while milling the rigid or hard material.
While performing a turning operation, the workpiece is mounted into the machine’s chuck and rotated rapidly. Then the tool moves along the axis of the workpiece to remove material. This process is performed to reduce the diameter or length of the workpiece. The tools selection in turning operation depends upon the product requirements.
Turning is also performed to add some features to the products, and it may use a single or multi-point cutting tool. Shafts and fasteners are also fabricated through this procedure.
The manufacturers use different raw materials such as nickel, brass, zinc, steel, titanium, and magnesium for turning operations. Material selection depends on some of its mechanical properties, including cost, strength, machinability, and resistance to wear. Turning leads towards more extended tool life and excellent surface finishing.
Some of the features you can create by turning process are: holes, tapers, contoured surfaces, diameter variation, and slots
In reaming, a tool with multiple cutters is used to increase the size of a pre-drilled hole. It can be performed on the milling machines by switching the tool with the reamer, usually made up of HSS or carbide, and it comes in various sizes.
Boring is the process in which we increase the depth or enlarge the existing drilled or cast holes. There are three different types of boring;
Line boring (boring bar supporting one of both ends)
Back boring (machining a hole at the back part of the workpiece)
Lathe boring (Using single-point cutting tool to tapering holes)
Grinding can be performed by using a grindstone, grinding wheel, or grinder. It is performed for the abrasive machining process, which is carried for surface finishing and to enhance the surface quality of the product. This process can also be carried out with the help of CNC machining.
It is a widely used technique by manufacturers to achieve a specific metal surface. This process is also known as deburring, in which the unnecessary material is removed from the workpiece. It is also performed to engrave a specific texture on the workpiece, obtain the desired surface quality, or achieve the metal workpiece’s required diameter.
The process of broaching can produce various odd shapes. It also helps in removing the unwanted material from the workpiece. It is performed with the help of a toothed tool, also known as broach. The broach can be used linearly for linear broaching, and it can get used with the lathe machine for rotary broaching.
Metal shaping is carried out to obtain a product’s specific shape to fulfill the customers’ requirements. This process includes forging in which the hot metal is hammered or pressed to get the required profile. For shaping, the metal component is heated up to 75 percent beyond its melting temperature.
9. Laser engraving
You may have observed that many company products are engraved by a company’s name, and it is done with the help of laser engraving. It is widely used at the industrial level for high-precision labeling and marking. Laser engraving is used for permanent marking, and this process is flexible, requires less lead time, and is cost-effective.
Stamping or marking your product via laser engraving leaves an impressive impact on your client. In today’s world, almost every industry is equipped with the technology of laser engraving.
Finally, we conclude that there are different types of machines for metal machining, and many processes are involved in it. After reading this complete article, you now have a thorough understanding of several machining processes and the processes involved in metal machining.
Various types of tools and tooling techniques have also been discussed in this article. Meanwhile, mechanical, abrasive, thermal, and chemical machining methods can help achieve the desired product design.
If you are a beginner in this field, the article will help you in the material and process selection of metal machining. There are still so many things that you need to understand, and consulting a metal machining expert will help you a lot in designing your desired product.