Machining started to come to the fore with the wood industry in the 18th century, and then it became popular and widespread in the 20th century by using it in iron forming processes. There are different machining methods that vary according to the process to be applied, the shape to be given and the material.
What is Machining?
In its most general definition, machining is the process of forming by removing machining from a material. It is a manufacturing method by removing a layer from the surface with sharp-edged tool pieces so that a raw material can be processed in a determined shape and size. The pieces that separate from the surface of the main material are called chips. The tips used in shaping the material are called tools. Each operation is performed on machine tools. There are different machine tools according to the machining method. In today’s modern technologies, these processes are done on CNC machines. The process applied in machining is also called by expressions such as abrasion and chipping.
While a single machining method can be used to shape a material, more than one method can be used together. This situation varies according to the process to be applied and the form to be given to the material. The main machining methods are as follows:
- Turning: It is generally used in the manufacture of cylindrical parts. For example, screws and bolts are among the parts produced by this method. The chip removal process is applied by applying rotational motion to the workpiece. Longitudinal turning can be done along the length of the workpiece, as well as transverse machining. Transverse machining is also called face turning. The main operations with turning are grooving, threading, screwing, drilling, curved, angled, conical, part cutting, knurling, internal and external turning. Shaping is carried out by using cutting tools suitable for the operation to be performed.
- Milling: It is the machining process that is done by keeping the workpiece fixed with the cutting tools rotating around its own axis. In some operations, both the workpiece and the cutting tools may be moving. Grooving, gear cutting, hole enlargement, stepped or angled machining, gears, flat and curved surfaces are the main operations. Milling machines are of two types, horizontal and vertical. Different milling cutters are used according to the process to be performed.
- Planing and Shaping: Horizontal, vertical and angled chip removal operations with linear cutting motion are called planing and shaping. Both are similar to each other. The difference between them is that in planing, the feed movement is provided by the piece and the cutting movement is provided by the tool. In the shaping process, on the other hand, the opposite progress is made with the tool and the cutting movement with the piece. Although the speed in this process is low, the length of the application area offers the advantage of removing more metal in one go.
- Drilling: Drilling machines are used in these processes. However, this process can be done according to the material to be processed in CNC turning and milling machines with a hole drilling apparatus. Spiral, blunt, perforated and stepped drills are used according to the application area. Reaming is applied when needed to smooth the part after drilling. In addition, more than one drill type can be used depending on the type of operation to be performed.
- Grinding: Chip removal is performed with an abrasive tool. It enables the grinding wheels to take the excess on the workpiece surface with the rotation and advancement movement. Profile, plunge, cylindrical and flat surface treatments are the main methods made by grinding. It is used in processes that require a small amount of metal removal and on very hard surfaces.
- Reaming: It is a smoothing process applied to obtain smoother and cleaner surfaces after drilling. There are two types as cylindrical and conical reaming.
- Broaching: The metal removal method performed with a linear moving rod-shaped cutting tool is called broaching. Both coarse and fine stock removal can be done with this method. There are two types, internal and external broaching.
- Honing: It is a low-speed chip removal process with coarse-grained stones called honing stones, with forward and rotational movement.
- Lapping: Applied on ground surfaces. This process is used to make the surface smooth. It is a second process for parts that need precision and fine processing.
What is the Difference Between Machining and Chipless Manufacturing?
Production methods are generally mechanical, physical and chemical types. Machining and chipless manufacturing methods are included in the mechanical production type. However, the two methods have differences in procedure. In machining, the shaping process is done by machining. In chipless manufacturing, the materials are shaped while they are molten, instead of the machining process. Both manufactures have different methods within themselves. In chipless manufacturing, methods such as casting, forging, cold or hot drawing, welding, riveting, brazing and melting are applied. There is no change in material mass in chipless manufacturing. In machining, there is surface abrasion, that is, the mass changes as a result of the process.
What are the Advantages of Machining?
- Machining methods allow different materials to be processed. For this reason, all kinds of materials such as wood, metal and plastic can be processed with machining.
- It is also used in the production of small parts, as it can be formed in desired dimensions.
- It has the advantage of giving the desired geometric shape to the material. Holes, screws, rounded and angular parts are produced by machining.
- The flexibility it provides in the production of different sizes and shapes is advantageous in the processing of difficult parts.
- Clean and smooth surfaces are obtained in machining.
- The desired shape can be given to the material as well as the desired shine can be given to the surfaces.
- Preparing the desired shape in digital environment eliminates the cost of molds.
- Another advantage of not requiring a mold is that machining methods can be used easily in cases where a small number of prototype products are required.