Stamping is a forming process in which external force is applied to sheets, strips, tubes, and profiles through a press and die, causing plastic deformation or separation to obtain workpieces of the required shape and size. Depending on the process conditions, stamping can be classified in different ways. Below, Fangchuan Lubrication Technology Co., Ltd. briefly introduces the types of stamping processes:
- Classification by finished workpiece.
Based on the finished workpiece, stamping processes can be broadly divided into two categories: separation processes and forming processes (which are further divided into bending, deep drawing, and forming).
(1) Separation processes involve separating the stamped part from the blank along a specific contour line during stamping, and the quality of the separated cross-section must also meet certain requirements.
(2) Forming processes involve plastic deformation of the stamping blank without damage, reshaping it into the required finished product shape while also meeting requirements such as dimensional tolerances.
Second, classification by temperature during the stamping process.
Based on the temperature during the stamping process, there are two methods: cold stamping and hot stamping. This depends on the material's strength, plasticity, thickness, degree of deformation, and equipment capacity, while also considering the material's original heat treatment state and final service conditions.
(1) Cold stamping is the processing of metal at room temperature, generally suitable for blanks with smaller thicknesses. Advantages include no heating, no scale formation, good surface quality, easy operation, and low cost. Disadvantages include work hardening, which in severe cases can cause the metal to lose its ability to undergo further deformation. In most cases, cold stamping requires the use of stamping oil to improve the process. Additionally, the blank thickness must be uniform with a small variation range, and the surface must be clean, free of spots, and free of scratches.
(2) Hot stamping is a method in which the metal is heated to a certain temperature range before stamping. Advantages include eliminating internal stress, avoiding work hardening, increasing material plasticity, reducing deformation resistance, and lowering equipment power consumption. - Classification by die structure:
A stamping die is a tool used to separate or deform metal sheets. It consists of an upper die and a lower die. The shank of the upper die is fixed to the slide of the press and moves up and down with it, while the lower die is fixed to the worktable of the press. It is an indispensable tool in stamping production. According to the die structure, the processes can basically be divided into three types: simple stamping, progressive stamping, and compound stamping.
(1) Simple stamping refers to a stamping process that completes only one operation during a single stroke of the press. This is a simple die blanking or punching operation. When the punch moves downward, the stamped part (or scrap) enters the die opening, and the strip clamps the punch and moves upward with it.
(2) Progressive stamping refers to completing several stamping operations simultaneously at different stations of the die during a single stroke of the press. It is carried out in one cycle, with the feed distance for each stroke controlled by stop pins.
(3) Compound stamping involves completing several stamping operations simultaneously on the same part of the die within a single stroke. The most notable feature of compound stamping is that the die contains both a punch and a die. When the slide moves downward with the punch, the strip is first blanked between the punch and the blanking die. The blanked portion is resisted by the drawing punch in the lower die, and as the slide continues to move downward, the die moves downward accordingly to perform the drawing operation. Compound dies are suitable for stamping parts with high production volumes and high precision.
4. Classification by basic process.
According to the main basic stamping processes, there are several fundamental operations, including blanking, punching, bending, and drawing.
(1) Blanking and punching are operations that separate the blank. The process of blanking and punching is exactly the same, but the purpose differs. In blanking, the separated portion is the finished product, and the remaining periphery is scrap. In punching, the goal is to create holes; the sheet after punching is the finished product, and the separated portion is scrap. Blanking and punching are collectively referred to as blanking. The punch and die of a blanking die have sharp edges, and there is a clearance between the punch and die to ensure a clean cut with minimal burrs.
(2) Bending is used to give the workpiece various angles and shapes. The working part of the bending die must have an appropriate fillet radius to prevent the workpiece from cracking during bending.
(3) Drawing is the process of forming a flat blank into a cup-shaped or box-shaped part. The edges of the punch and die in a drawing die should be rounded to prevent the workpiece from being torn. There should be a clearance slightly larger than the sheet thickness between the punch and die to reduce friction. To prevent wrinkling, a blank holder is used to press down on the edges of the blank. - Classification by the material of the stamped part.
Common sheet metals include low-titanium alloy, carbon steel, stainless steel, aluminum, copper, and their alloys. These materials offer high plasticity and low deformation resistance, making them suitable for cold stamping processes.
(1) Copper, aluminum, and their alloys possess excellent ductility and superior electrical conductivity. As a result, stamping processes using these materials are widely employed in the production of internal components for electrical equipment.
(2) Stamping processes for carbon steel and stainless steel are commonly used to manufacture equipment housings, structural parts, enclosures, and similar items. However, due to their higher rigidity, stamping oils are typically applied to improve the process.
(3) Titanium alloy stamping is primarily applied in scenarios requiring lightweight yet high-strength components, such as large equipment, aircraft, ships, and satellites. The processing techniques are technically challenging and costly. Therefore, when stamping titanium alloys, specialized stamping oils must be used to enhance the process to a professional level.