Mechanical parts machining is the core process of transforming raw materials into parts with definite shapes, dimensions, and performance. Its working principle is rooted in the comprehensive application of materials mechanics, geometry, and manufacturing technology. It aims to achieve controlled material removal, plastic forming, or layer-by-layer deposition through external force and energy transfer, thereby meeting the multiple requirements of mechanical systems for the function and precision of parts. Although different machining methods have different process paths, their underlying logic revolves around "material state change" and "geometric shape shaping," forming unique operating mechanisms.
Removal machining processes use "cutting" as their core principle, with typical examples being turning, milling, drilling, and grinding. Their working mechanism utilizes the relative motion between the tool and the workpiece, applying shearing force to the surface material of the workpiece through the tool's cutting edge, causing excess material to separate along a specific direction to form the desired contour. Turning, through the coordination of workpiece rotation and linear tool feed, machines the surface of rotating bodies; milling, relying on tool rotation and multi-directional workpiece movement, generates planes, grooves, or complex curved surfaces. This process requires precise control of cutting speed, feed rate, and depth of cut to balance material removal efficiency with tool wear and surface quality. Essentially, it converts mechanical energy into kinetic energy for material separation, achieving a gradual approximation of the desired shape.
Forming processes are based on the principles of "plastic deformation" or "solidification forming," encompassing casting, forging, stamping, and injection molding. Casting involves injecting molten metal or plastic into a mold cavity, then cooling and solidifying to obtain a blank consistent with the cavity. Its principle is that the material retains shape memory during the phase transition from liquid to solid. Forging applies pressure to a solid metal blank, forcing it to undergo plastic flow and volume transfer, filling the mold gaps and forming a dense structure. Its core lies in utilizing the ductility of metal at high temperatures to achieve shape reconstruction. Stamping uses the high-speed impact of a press and a die to change the shape of sheet metal during drawing, bending, or blanking, relying on the material's plastic deformation limits and the constraint of the die. The key to these processes is controlling the material flow characteristics and the geometric accuracy of the die to ensure defect-free and dimensionally stable parts.
Additive manufacturing processes overturn the traditional "subtractive" thinking, with "layer-by-layer deposition" as their core principle. Their working mechanism involves using 3D model slice data to stack materials layer by layer along a predetermined path through methods such as laser sintering, fused deposition modeling, or photopolymerization, ultimately solidifying them into a solid part. For example, selective laser melting (SLM) uses a high-energy laser beam to melt metal powder point by point, solidifying layer by layer to form a dense structure; fused deposition modeling (FDM) heats and extrudes thermoplastic filaments, cooling and solidifying them through layer-by-layer stacking. This principle overcomes the limitations of traditional processing on the geometric complexity of parts, and is particularly suitable for the direct forming of complex structures such as internal hollowing and topology optimization. Its core lies in the precise control of the spatiotemporal matching of energy input and material supply, ensuring interlayer bonding strength and overall accuracy.
Regardless of the processing method, measurement and feedback are indispensable components of the working principle. By employing technologies such as coordinate measuring machines (CMMs), laser scanning, or image inspection, the dimensions, geometric tolerances, and surface quality of machined parts are quantitatively evaluated. This data is then fed back to the machining system, driving dynamic adjustments to process parameters or toolpaths, forming a closed-loop control system of "machining-inspection-optimization." This is the core guarantee for achieving precision machining and stable quality.
In summary, the working principle of mechanical parts machining is an engineering integration of principles from multiple disciplines: eliminating machining reliance on shearing and separation, forming based on plastic or solidification, and additive manufacturing utilizing layer-by-layer deposition. These three aspects, through energy transfer and material state control, jointly construct the transformation path from raw materials to precision parts. A deep understanding and flexible application of this principle are fundamental prerequisites for improving machining efficiency, ensuring parts quality, and promoting manufacturing technology innovation.
