Jar Hing Products Analyze the Cause of Mold Burst

1. The mold material is not good and is prone to cracking during subsequent processing

2. Heat treatment: deformation caused by improper quenching and tempering process

3. Insufficient flatness of mold grinding, resulting in bending deformation

3. Design process: The strength of the mold is insufficient, the spacing between the cutting edges is too close, the mold structure is unreasonable, and the number of template blocks is not enough without a base plate or foot pad

4. Improper handling of wire cutting: the gap is incorrect due to wire cutting, and the corners are not cleaned

5. Selection of punching machine equipment: The tonnage of the punching machine is insufficient, and the punching force is not enough, and the mold is adjusted too deeply

6. Unsmooth material removal: No demagnetization treatment or material return tips before production; During production, there are stuck materials such as broken needles and springs

7. Uneven material discharge: there is no leakage or rolling blockage during the assembly of the mold, or the foot pad is blocked

8. Production awareness: lamination stamping, inadequate positioning, no use of air guns, and continued production despite cracks in the template

Die failure form

The main forms of die failure are wear failure, deformation failure, fracture failure, and bite failure. However, due to different stamping processes and working conditions, there are various factors that affect the lifespan of the stamping die. The following is a comprehensive analysis of the factors affecting the lifespan of the stamping die in terms of design, manufacturing, and use, and proposes corresponding improvement measures.

1 Stamping equipment

The accuracy and rigidity of stamping equipment (such as presses) have a crucial impact on the lifespan of stamping dies. The precision and rigidity of stamping equipment are high, and the service life of the stamping die is greatly improved. For example, the complex silicon steel sheet stamping die material is Crl2MoV, which is used on ordinary open press machines with an average regrinding life of 10000 to 30000 times. However, when used on new precision press machines, the regrinding life of the stamping die can reach 60000 to 120000 times. Especially for small clearance or no clearance stamping dies, hard alloy stamping dies, and precision stamping dies, it is necessary to choose a press with high precision and good rigidity. Otherwise, the lifespan of the mold will be reduced, and in severe cases, the chess equipment will be damaged.

2 Mold Design

(1) The precision of the guiding mechanism of the mold. Accurate and reliable guidance is highly effective in reducing the wear of mold working parts and avoiding the impact of convex and concave mold scratches, especially for blank and small gap punching molds, composite molds, and multi-station progressive molds. To improve the lifespan of the mold, it is necessary to correctly select the guiding form and determine the accuracy of the guiding mechanism based on the requirements of process properties and part accuracy. In general, the accuracy of the guide mechanism should be higher than the fit of the convex and concave molds.

(2) Geometric parameters of the cutting edge of the mold (convex and concave molds). The shape, fit clearance, and fillet radius of convex and concave molds not only have a significant impact on the forming of stamping parts, but also have a significant impact on the wear and service life of the mold. The fit gap of the mold directly affects the quality of the punched parts and the lifespan of the mold. For those with high accuracy requirements, smaller clearance values should be selected; On the contrary, the gap can be appropriately increased to improve the lifespan of the mold.

3 Stamping process

(1) Raw materials for stamping parts.

In actual production, due to the thickness tolerance of raw materials for external pressure parts exceeding the tolerance, material performance fluctuations, poor surface quality (such as rust) or unclean (such as oil stains), etc., it can cause adverse consequences such as increased wear of mold working parts and susceptibility to blade breakage. Therefore, attention should be paid to: ① using raw materials with good stamping process as much as possible to reduce stamping deformation force; ② Before stamping, the grade, thickness, and surface quality of the raw materials should be strictly checked, and the raw materials should be wiped clean. If necessary, surface oxides and rust should be removed; ③ According to the stamping process and the type of raw materials, softening treatment and surface treatment can be arranged if necessary, as well as selecting appropriate lubricants and lubrication processes.

(2) Layout and edging.

Unreasonable reciprocating feeding and layout methods, as well as excessively small edge values, often result in sharp wear of the mold or gnawing of the convex and concave molds. Therefore, while considering improving the utilization of material judgment, it is necessary to choose a reasonable layout method and edge value based on the processing batch size, quality requirements, and mold fit clearance of the parts, in order to improve the mold life.

4 Mold Materials

The impact of mold materials on the lifespan of molds is a comprehensive reflection of various factors such as material type, chemical composition, organizational structure, hardness, and metallurgical quality. The lifespan of molds made of different materials often varies. Therefore, two basic requirements are proposed for the materials of stamping die working parts: ① the material's performance should have high hardness (58-64HRC) and high strength, as well as high wear resistance and sufficient toughness, with small heat treatment deformation and a certain degree of thermal hardness; ② The process performance is good. The manufacturing process of stamping die working parts is generally complex, so it is necessary to have adaptability to various machining processes, such as malleability, machinability, hardenability, hardenability, quenching crack sensitivity, and grinding workability. Usually, mold materials with excellent performance are selected based on the material characteristics, production batch size, precision requirements, etc. of stamping parts, while considering their processability and economy.

5 Hot working process

Practice has proved that the Hot working quality of the die has a great influence on the performance and service life of the die. According to the analysis and statistics of Failure cause of dies, the "accidents" of die failure caused by improper heat treatment account for more than 40%. The quenching deformation and cracking of the working parts of the die and the early fracture in the use process are all related to the Hot working technology of the die.

(1) Forging process is an important link in the manufacturing process of mold working parts. For high alloy Tool steel dies, technical requirements are usually put forward for metallographic structures such as carbide distribution of materials. In addition, it is necessary to strictly control the forging temperature range, develop correct heating specifications, use the correct forging force method, and slow cooling or timely annealing after forging.

(2) Prepare for heat treatment. Preparation heat treatment processes such as annealing, normalizing, or quenching and tempering should be used according to the different materials and requirements of the working parts of the mold, in order to improve the structure, eliminate the structural defects of the forging blank, and improve the processing technology. High carbon alloy die steel, after appropriate preliminary heat treatment, can eliminate network secondary cementite or chain shaped carbides, spheroidize and refine carbides, and promote the uniformity of carbide distribution. This is beneficial for ensuring the quality of quenching and tempering, and improving the lifespan of the mold.

(3) Quenching and tempering. This is a key link in mold heat treatment. If overheating occurs during quenching and heating, it not only causes significant brittleness of the workpiece, but also easily causes deformation and cracking during cooling, seriously affecting the lifespan of the mold. Special attention should be paid to preventing oxidation and decarburization during quenching and heating of stamping dies. The heat treatment process specifications should be strictly controlled, and vacuum heat treatment can be used if conditions permit. After quenching, timely tempering should be carried out and different tempering processes should be adopted according to technical requirements.

(4) Stress relieving annealing. The working parts of the mold should undergo stress relieving annealing treatment after rough machining, with the aim of eliminating the internal stress caused by rough machining to avoid excessive deformation and cracks caused by quenching. For molds with high precision requirements, stress relieving tempering treatment is also required after grinding or electric machining, which is beneficial for stabilizing mold accuracy and improving service life.

6. Machined surface quality

The quality of the working parts and surface of the mold is closely related to the wear resistance, fracture resistance, and adhesion resistance of the mold, which directly affects the service life of the mold. Especially the surface roughness value has a significant impact on the lifespan of the mold. If the surface roughness value is too large, stress concentration will occur during operation, and cracks can easily occur between its peaks and valleys, affecting the durability of the mold. It also affects the corrosion resistance of the workpiece surface, directly affecting the service life and accuracy of the mold. Therefore, the following precautions should be taken: ① During the processing of mold working parts, it is necessary to prevent grinding and burning the surface of the parts, Strictly control the grinding process conditions and methods (such as grinding wheel hardness, particle size, coolant, feed rate, and other parameters); ② During the machining process, macro defects such as knife marks, interlayers, cracks, impact marks, etc. should be prevented on the surface of the working parts of the mold. The existence of these defects can cause stress concentration, become the root cause of fracture, and cause early failure of the mold; ③ By using precision machining such as grinding, grinding, and polishing, a smaller surface roughness value can be obtained and the service life of the mold can be improved.

7 Surface strengthening treatment

In order to improve the performance and service life of molds, the application of surface strengthening treatment for mold working parts is becoming increasingly widespread. Common surface strengthening treatment methods include liquid carbonitriding, ion nitriding, boronizing, vanadizing and electric spark strengthening, as well as chemical vapor deposition (CVD), Physical vapor deposition (PVD) and carbide dipping on the workpiece surface in salt bath (TD). In addition, the use of high-frequency quenching, hydraulic pressure, shot peening and other surface strengthening treatments can generate compressive stress on the surface of the working parts of the mold, improve its fatigue strength, and is conducive to improving the lifespan of the mold.

Control of metamorphic layer in 8-wire cutting

The cutting edge of stamping dies is often processed by wire cutting. Due to the thermal and electrolytic effects of wire cutting machining, a certain thickness of metamorphic layer is formed on the surface of the mold, resulting in a decrease in surface hardness and the appearance of micro cracks. This leads to early wear of the wire cutting machining die, directly affecting the maintenance of the die cutting gap and the tendency of the blade to collapse, shortening the service life of the mold. Therefore, in online cutting processing, reasonable electrical standards should be selected to minimize the depth of the metamorphic layer as much as possible.

9. Correct use and reasonable maintenance

In order to protect normal production, improve the quality of stamping parts, reduce costs, and extend the service life of stamping dies, it is necessary to use and maintain the dies correctly and reasonably, strictly implement the "three inspections" system of stamping dies (pre use inspection, during use inspection, and post use inspection), and do a good job in stamping and maintenance maintenance maintenance work. Its main work includes the correct installation and debugging of molds; Strictly control the depth of the convex mold entering the concave mold; Control and correct the extension of the bottom dead center of the upper mold in processes such as bending, cold extrusion, and shaping; Timely regrind and polish the edges of chess tools; Pay attention to maintaining the cleanliness and proper lubrication of chess equipment. The correct use and reasonable maintenance of molds are crucial for improving the lifespan of molds.

In short, in the entire process of mold design, manufacturing, use, and maintenance, the application of advanced manufacturing technology and the implementation of comprehensive quality management are effective guarantees for improving the lifespan of molds. We are committed to developing professional production and strengthening mold standardization work. In addition to part standardization, there are also standardization of design parameters, combination forms, and processing methods, continuously improving the level of mold design and manufacturing, Beneficial for improving mold life.