The forms and factors affecting the service life of cold stamping molds

Cold stamping die refers to a process equipment that processes materials (metal or non-metal) into parts (stamped products) or semi-finished products in cold stamping processing. The lifespan of molds can generally be divided into design lifespan and service lifespan. In the mold design stage, it is necessary to clarify the production batch type or total quantity of mold production parts that the mold is suitable for, that is, the design life of the mold. Under normal circumstances, the service life of the mold should be greater than the design life. The service life of cold stamping molds is directly related to the quality and efficiency of product processing, and is an important factor affecting the economic cost and benefits of product processing. It is also an important indicator for measuring the low manufacturing cost of cold stamping molds.

1、 Several forms that affect the service life of cold stamping molds

The number of products processed before the cold stamping die is scrapped due to wear or other forms of failure is called the service life of the cold stamping die.

1. Fracture

The phenomenon of breakage and cracking of convex and concave molds during use. Due to the fact that the convex and concave molds of the mold are the parts that bear a large amount of punching pressure during stamping work, the convex and concave molds of the mold may break during the stamping process.

2. Deformation

The convex and concave molds have undergone shape deformation during use, causing changes in the geometric shape of the processed product parts, which in turn affects the dimensional accuracy and shape requirements of the processed parts.

3. Wear and tear

Wear caused by prolonged and frequent friction between convex and concave molds and the processed material.

4. Bite the blade

The adjustment of the clearance between the convex and concave molds is uneven, and the adjacent edges of the convex and concave molds bite each other, causing damage to the cutting edges of the convex and concave molds.

2、 The main factors affecting the service life of cold stamping molds

In order to improve the service life of stamping molds, analyze the expired molds, understand and master the causes of failure and the main factors affecting mold service life.

1. The influence of cold stamping die materials

(1) The influence of mold material properties. The hardness, properties, strength, plastic deformation resistance, fracture resistance, and thermal fatigue resistance of various mold materials vary. The strength of the materials can meet the specific usage requirements of the mold to avoid early failure.

(2) The impact of metallurgical quality on mold steel. If the steel contains non-metallic inclusions with low strength and poor plasticity, it is easy to form crack sources and cause early fracture failure of the mold. When there are too many carbides in the steel, forming a network, large block or strip segregation, it will seriously reduce the impact toughness and fracture resistance of the steel, causing fracture, fragmentation and cracking of the mold.

2. The influence of cold stamping die structure

(1) The influence of mold geometry. The geometric shape of the mold has a significant impact on the flow and forming force of the blank during the forming process, thereby affecting the lifespan of the mold.

(2) The impact of mold gaps. The working clearance between the convex and concave molds not only affects the quality of the workpiece, but also affects the lifespan of the mold. For example, if the gap between the deep drawing die is too small, it will increase frictional resistance, easily scratch the surface of the workpiece, and increase the wear of the mold. The gap between the punching die is too small, which will exacerbate the wear of the convex and concave dies and reduce the service life of the mold.

(3) The influence of structural form. The unreasonable structural form of the mold will lead to stress concentration and fracture failure.

3. The influence of cold stamping mold manufacturing process

(1) The influence of forging technology. If the forging process is not reasonable, it will reduce the performance of the steel, cause forging defects, and create hidden dangers that lead to early failure of the mold. Common surface defects of forgings include cracks, folds, pits, etc.

(2) The impact of processing technology. The rough surface, uneven geometric shape changes at the connection, or sharp corners and machining tool marks in cutting processing will initiate fatigue cracks and cause fatigue failure of the mold. Excessive feed rate and insufficient cooling during grinding can easily lead to grinding cracks and reduce the fatigue strength and fracture resistance of the mold.

4. The influence of working conditions and maintenance of cold stamping molds

(1) The impact of processed materials. The higher the strength and thickness of the processed material, the greater the force that the mold can withstand, resulting in a relatively lower lifespan of the mold. If the material being processed has a high affinity with the mold material, it will adhere and wear to the mold during the stamping process, reducing the lifespan of the mold.

(2) The influence of stamping equipment characteristics. The stiffness and accuracy of stamping equipment have an impact on the lifespan of molds. If the open press machine is a C-shaped frame and uses an unguided mold, it is prone to deformation under the action of punching force, resulting in misalignment of the center lines of the upper and lower molds, uneven working clearance of the molds, and even blade biting and chipping.

(3) The influence of lubrication conditions. Good lubrication conditions can reduce friction, frictional heat, and impact force, and minimize mold wear.