Machining plays a vital role in the vast field of mechanical engineering. Machining is the process of changing the dimensions or properties of a workpiece with the help of mechanical equipment. In the production process, the process of changing the shape, size, location and nature of the object of production into a finished or semi-finished product is known as a process, which is a key part of the production process. Processes include casting, forging, stamping, welding, machining, assembly, etc., of which the mechanical manufacturing process is generally the sum of parts machining process and machine assembly process, the rest of the transportation, storage, power supply, equipment maintenance, etc. are auxiliary processes. Moreover, the process is composed of one or more sequential processes, a process contains a number of steps.

Common machining process introduction

Turning

Turning is divided into external turning, internal turning, turning plane, turning threads and other types. When turning, the workpiece rotates to form the main cutting motion, and different tool movements can form different shapes. For example, the tool moves parallel to the axis of rotation to form internal and external cylindrical surfaces, and moves along the inclined line intersecting the axis to form a tapered surface, and feeds along the curve to form a specific rotating surface on an imitation lathe or CNC lathe, and uses a molding tool to feed transversely to process rotating surfaces, and also processes threaded surfaces, end planes and eccentric shafts, etc. The machining accuracy is generally ITC (IT), which is the highest. Turning accuracy is generally IT8 - IT7, surface roughness 6.3 - 1.6 μm, fine turning up to IT6 - IT5, roughness 0.4 - 0.1 μm. Turning productivity is high, the cutting process is smooth and simple tools.

Milling

Milling is cutting material on the surface of the workpiece by rotating the tool, which can make plane, concave and convex surfaces, gears and other complex shapes of parts, including plane milling, vertical milling, end milling, gear milling, contour milling and other ways. The main cutting motion is tool rotation, horizontal milling plane is formed by the milling cutter external circular edge, vertical milling plane is formed by the milling cutter end face edge. Increasing the rotational speed of the milling cutter can increase the cutting speed and productivity, but the milling cutter teeth cutting in and out will produce impacts, easy to vibrate, limiting the surface quality enhancement, but also aggravate the tool wear. According to the main movement speed direction and workpiece feed direction relationship is divided into smooth milling and reverse milling. Shun milling, milling force horizontal force and workpiece feed direction is the same, easy to make the workpiece and table tampering, hit the knife, processing of hard-skinned workpiece exacerbated tool wear; reverse milling can be avoided to avoid tampering, but the cutting edge will be in the processed surface extrusion slide, accelerate the tool wear, and milling force is easy to make the workpiece uplift, produce vibration. Milling accuracy can generally reach IT8 - IT7, surface roughness 6.3 - 1.6μm, CNC milling machine for processing complex workpieces of great significance.

Drilling

Drilling is the use of rotary drill bit in the workpiece cutting material to form holes, widely used in manufacturing, construction and maintenance fields, can be divided into conventional drilling, center drilling, deep hole drilling, multi-axis drilling and so on. Conventional drilling uses spiral cutting edge drills for small holes and general drilling; center drilling drills small holes on the surface of the workpiece and then uses a large drill to ensure that the position of the large holes is accurate; deep hole drilling requires special drills and cooling technology to process deep holes; and multiaxial drilling uses multiple drills to drill multiple holes at the same time.

Grinding

Grinding is the use of abrasives to cut or grind away the surface material of the workpiece to obtain the desired shape, size and quality, commonly used in high-precision and high surface quality requirements of the parts, such as molds, precision mechanical parts, tools and so on. Grinding is categorized into flat grinding, cylindrical grinding, internal grinding and contour grinding. Surface grinding processing flat workpiece surface, external grinding processing cylindrical workpiece outer circle, internal grinding processing hole surface, contour grinding processing complex contour shape.

Boring

Boring is used to process the internal circular hole of the workpiece by rotating the tool to cut in the existing hole, unlike drilling. It is divided into manual boring and CNC boring. Manual boring is suitable for small batch production and simple tasks, while CNC boring realizes automated high-precision machining through programming.

Planing

Planing is the use of planing knives to cut the surface of the workpiece to obtain a flat surface, accurate size and quality, commonly used in processing larger workpieces flat surface, such as the base, bed, etc.. Divided into roughing and finishing stages, roughing depth of cut is large, finishing depth of cut is small. There are two types of planing, manual and automatic. Manual is used for small quantities and simple tasks, while automatic controls the movement of the planing tool through the machine tool. The speed of planing is limited by the reciprocating linear motion of the tool, and the productivity is low, but it is smoother than milling, and the machining accuracy is generally up to IT8 - IT7, with surface roughness Ra6.3 - 1.6μm, and the planing flatness can be up to 0.02/1000, with surface roughness 0.8 - 0.4μm.

Interpolation

The insertion of cutting tools with insertion gradually deepen the cutting, manufacturing internal complex contours, commonly used in processing workpiece contours, grooves, holes and other complex shapes, can obtain higher accuracy and quality, suitable for high precision and good surface quality parts, divided into plane insertion, contour insertion, groove insertion, hole insertion and other types of different types have different applications.

Specialty Machining

Specialty machining is a method different from traditional cutting, including chemical machining (CHM), electrochemical machining (ECM), electrochemical machining (ECMM), electric discharge machining (EDM), electrical contact machining (RHM), ultrasonic machining (USM), laser beam machining (LBM), ion beam machining (IBM), electron beam machining (EBM), plasma machining ( PAM, electrohydraulic machining (EHM), abrasive flow machining (AFM), abrasive jet machining (AJM), hydrodynamic machining (HDM), and various types of complex machining.

Electrical Discharge Machining

EDM utilizes an instantaneous spark discharge between the tool electrode and the workpiece electrode to melt the surface material of the workpiece at a high temperature. The machine consists of a pulse power supply, an automatic feeding mechanism, the machine body and a circulating filtration system for the working fluid. Workpiece fixed in the worktable, pulse power supply, two poles close to the spark discharge, workpiece surface material due to high temperature melting, vaporization is eroded, the working fluid circulation system to exclude the products of galvanic corrosion, multiple discharges after the tool electrode contour “copy” to the workpiece. Can be processed hard, brittle, tough, soft and high melting point conductive materials, semiconductors and non-conductive materials, a variety of holes, curved holes, micro holes and three-dimensional curved cavities, but also can be used to cut off, cutting, surface enhancement, inscribing, printing nameplates and markings.

Electrolytic machining

Electrolytic machining utilizes the principle of anodic dissolution of metal in electrolyte. Workpiece connected to the positive pole of the DC power supply, the tool connected to the negative pole, electrolyte from the narrow gap high-speed flow through the cathode of the tool to the workpiece feed, the workpiece surface metal according to the cathode shape dissolution, electrolysis products are taken away by the electrolyte, tool shape “copy” on the workpiece. Characterized by small operating voltage, current, a complex surface or cavity processing, processing difficult to process materials, high productivity, processing without mechanical cutting force and heat, suitable for easy deformation or thin-walled parts, but more ancillary equipment, large footprint, high cost and electrolyte corrosion and pollution problems, mainly used in the processing of holes, cavities, complex surfaces, small-diameter deep holes, rifling, deburring, engraving and so on.

Laser processing

Laser processing is accomplished by laser processing machine, including laser, power supply, optical system and mechanical system. The laser converts electrical energy into light energy to produce a laser beam, which is focused by the optical system to irradiate the workpiece. The workpiece is fixed on a three-coordinate precision table, which is controlled and driven by a numerical control system to complete the feeding movement. Laser processing without processing tools, high power density, can be processed almost all difficult to process materials, is non-contact processing, the workpiece is not deformed by the force, punching, cutting speed is high, thermal deformation is small, the slit is narrow, the edge of the quality is good, and is widely used in a variety of materials, small holes in the processing and cutting.

Ultrasonic processing

Ultrasonic machining is the use of ultrasonic frequency vibration of the end face of the tool impact working fluid in the suspension of abrasive, abrasive impact grinding workpiece surface to achieve processing. Ultrasonic generator will be converted to ultrasonic frequency alternating current oscillation, through the transducer into mechanical vibration, amplitude expansion rod amplification displacement amplitude, drive the tool vibration impact abrasive. Processing of difficult-to-cut materials is often compounded with other processing methods, can improve processing efficiency, precision and surface quality.