Stamping is one of the practical processes for mass production of parts. In the stamping production process, the mold has the most problems and is the most important factor in the entire stamping production process. Directly affecting production efficiency and costs. Affects the delivery cycle of the product. Mold problems mainly focus on mold damage, product quality defects, and mold grinding, which have long plagued industry production. Only by correctly handling these key points. Stamping production can proceed smoothly.  

1 Mold malfunction

   Mold failure is the most common problem in stamping production, often causing production downtime and affecting the product production cycle. Therefore, it is necessary to quickly identify the cause of the mold malfunction and carry out reasonable repairs.  

1.1 Mold damage

   Mold damage refers to the cracking, breakage, expansion, etc. of the mold. To deal with mold damage, it is necessary to find the cause from the design, manufacturing process, and use of the mold. Firstly, it is necessary to review whether the manufacturing materials of the mold are suitable and whether the corresponding hot burial process is reasonable. Usually, the heat treatment process of mold materials has a significant impact on them. If the quenching temperature of the mold is too high, the quenching method and time are unreasonable, and the tempering frequency, temperature, and elbow spacing are not selected properly, it will all lead to damage of the mold after entering the stamping production. Insufficient size or depth design of the feeding hole can easily block the slot and cause damage to the feeding plate. If the spring force design is too small or the height of the sleeve is not equal, it will cause the spring to break, the material dropping plate to tilt, resulting in overlapping impact and damage to the parts. Improper fixation of the punch or insufficient screw strength can cause the punch to fall or break. When using the mold, there may be installation errors in the position and direction of the parts or poor bolt tightening. The working height adjustment is too low and the guide column lubrication is insufficient. Malfunctions in the feeding equipment and abnormalities in the press can cause damage to the mold. If there are foreign objects entering the mold, overlapping parts, or blockage of waste materials, they should be dealt with in a timely manner and continued to be processed and produced. It is easy to damage the falling plate, punch, lower template, and guide column of the mold.  

1.2 Card mold

   During the stamping process, if the mold is not flexible or even stuck, production must be stopped immediately to identify the cause of the stuck mold and troubleshoot. Otherwise, it will escalate the malfunction and cause damage to the mold. The main reasons for mold jamming are poor mold orientation and tilting. Or there may be foreign objects between the templates, making it impossible to stick them flat; Insufficient mold strength design or uneven force distribution. Causing deformation of the mold, such as the hardness and thickness design of the mold seat and template being too small, making them susceptible to external impact and deformation; The installation of the mold position is inaccurate, and the positioning error of the upper and lower molds exceeds the tolerance. Or the accuracy of the press is too poor, causing interference in the mold; The strength of the punch is insufficient, and the position of the punch is too close, resulting in an imbalance of lateral force on the mold. At this point, the strength of the punch should be increased to enhance the guidance and protection of the discharge plate.  

1.3 Mold damage and repair

   The cost of stamping production molds is high. Usually, mold costs account for 1/5-1/4 of the total cost of the parts. This is because, in addition to the difficulty and high cost of mold manufacturing. The cost of mold repair and blade grinding maintenance after production is also high, and the original cost of the mold only accounts for about 40% of the total mold cost. Timely maintenance of molds to prevent damage can greatly reduce the cost of stamping production molds After the mold is damaged, there is still a choice between repair and scrapping. Generally speaking. Non natural wear and tear failure of stamping dies, such as damage to non critical components. As well as faults such as small punch breakage, punch upsetting becoming shorter, concave template cracking, and punching blade cracking, most of them can be fully restored to normal state through maintenance methods and put back into stamping production. But. When the key components of the mold are severely damaged, sometimes both the convex and concave molds are damaged at the same time. The one-time repair cost exceeds 70% of the original cost of the stamping die, or the mold life is approaching. The significance of maintenance is not significant, and in this case, scrapped molds should be considered: except for large molds and continuous molds with complex structures. When the mold maintenance technology is too complex, the cost of repairing the mold is too high, and the difficulty is too great, it will inevitably lead to a long maintenance cycle, seriously affecting the normal production of stamping. Therefore, early failure and scrapping should be chosen, and the mold should be remanufactured. Under normal circumstances, the main form of failure for stamping dies is excessive wear and tear. Deliver from new mold manufacturing for use. Until the burrs on the punched parts exceed the standard, the dimensions and positional accuracy of the parts exceed the tolerance, and the mold cannot be repaired or has no repair value at all, then the mold can only be scrapped. From the use of new molds to their failure and scrapping. Generally, it requires multiple repairs and sharpening.  

2. Quality defects in the components

   The most common quality defect of components is product size deviation. Only a few products have surface quality issues.  

2.1 Size out of tolerance

   Dimensional deviation is a serious defect in stamped parts. Firstly, it is necessary to check and verify the design of the mold to eliminate any design or manufacturing issues. If the dimensions exceeding the tolerance are related to the thickness of the material, the thickness, material, and hardness of the stamping material should be tested. During the stamping production process, dimensional deviations are mainly caused by mold wear, poor positioning and guidance, and deformation of the parts. The wear of the cutting edge of the mold can cause burrs to become too large or the cutting dimensions to increase, guide pins or other positioning devices to not work, the feeding machine to not relax, the wear of the positioning block to make the feeding distance too long, the length of the guide plate to be incorrect, or the gap between the guide plates to be too large. The deformation of the workpiece during production is mainly caused by impact deformation, such as excessive blowing pressure or heavy impact caused by falling of the product; deformation caused by compression or crushing during discharge, the discharge position should be cleaned in a timely manner or the discharge space should be increased; deformation caused by improper ejection. For example, if the top material pin is not properly prepared, the spring force is not appropriate, or the ejection is too long, the elasticity should be adjusted or the position or number of pins should be changed; Deformation during cutting. Partial bent parts cannot allow material overlap and must be dropped each time. When disc-shaped strain occurs, pressure pads can be used to eliminate it; Shear deformation is mainly caused by material distortion and unevenness. Size increase or center asymmetry; Floating debris extrusion deformation is caused by the upward movement of waste materials, the retention of fine debris on the mold surface, or the extrusion deformation of foreign objects.  

2.2 Unqualified surface quality

   The surface quality problem of stamped parts is mainly due to excessive burrs. The first reason for excessive burrs on the workpiece is the wear of the mold edge, which should be re ground (as described below) to ensure a sharp edge. Secondly, the interval between convex and concave molds is unreasonable. If the gap is too large, most of the side surfaces will be wiped with light. If the gap is too small, secondary shear surfaces will occur. If the material hardness is too high, the material should be replaced or the gap should be increased. When the punching edge size is too small or the cutting material is too little, the material will be pulled into the gap of the mold and become burrs. At this point, it is necessary to increase the edge size or cutting allowance for punching.  

Blade mold for 3 molds

   Reasonable grinding of molds in stamping production. It can effectively improve the service life of the punching die, save mold costs, and significantly reduce the wear of the cutting edge of the product. When the originally sharp cutting edge becomes dull to a certain extent, it will cause excessive burrs on the punched parts, and the dimensional and positional accuracy will decrease. Therefore, the mold must be sharpened to restore its sharp cutting edge. Reduce punching burrs and dimensional and positional deviations, and improve the surface quality of formed parts. If the mold is not sharpened in a timely manner, delaying the sharpening time will result in severe friction of the already worn thick burrs, forming a vicious cycle of excessive wear on the mold. This will require several times the amount of sharpening to restore the sharpness of the blade, greatly shortening the life of the mold. When the burrs on the workpiece are about to exceed the allowable burr height, production should be stopped immediately and the mold should be sharpened. In practical production, on-site workers are accustomed to determining the size of burrs on the workpiece and determining the timing of grinding based on their hand feel, which results in significant operational errors. It is best to detect the height and thickness of burrs on the workpiece, the uniformity of burr distribution, the size and positional accuracy of the punched part, and the quality of the punched surface to grasp the wear of the cutting edge and determine the optimal grinding time for the mold.

   The amount of mold grinding must be determined based on the actual wear of the cutting edge face and side, in addition to considering factors such as material thickness, concave mold shape and structure, and grinding sequence. After multiple grinding processes, the size of the concave die will change, especially for punching dies designed with small upper and large lower conical concave die openings. Due to the outward inclination of the concave die edge wall, the horizontal size of the die will inevitably increase after grinding the upper surface of the die. Therefore, before grinding, the calculation should be based on the angle of the cone. During grinding, attention should be paid to measuring the size of the workpiece to prevent excessive size increase due to multiple grinding, which may cause the product to exceed the tolerance.

   The efficiency and cost of stamping production are highly dependent on molds. For mold failures that occur during the production process, specific problems should be analyzed and correct maintenance plans should be developed. Timely resolution of mold damage is necessary to reduce downtime for mold repairs, shorten production cycles, and ensure the normal operation of stamping production.

If you need mold products, please contact: 0555-6971767/6970850