Common problems and solutions in mold maintenance for plastic mold manufacturers 123
Date: September 20, 2024
We often encounter customers saying that there are problems with your mold, but they only mention the quality of your mold without reflecting on whether there are any problems during use. Below, the editor of Donglai Plastic Mold Factory shares some common solutions to mold maintenance problems.
Molds play a crucial role in the production process, but customers often complain about problems with the molds and accuse them of poor quality. However, few people reflect on whether there are problems during use. The quality issues of molds may lead to low production efficiency, unstable product quality, and even safety hazards, so mold maintenance is crucial. Below, I will share some solutions to common problems in mold maintenance.
Common problems and solutions in mold maintenance for plastic mold manufacturers 123
1. Several key points need to be noted before using the punch. Firstly, clean the punch with a clean cloth to ensure that the surface is clean and free of impurities. Secondly, check if there are scratches, dents, or other damages on the surface of the punch. If there are, use an oilstone to remove them. Thirdly, timely apply oil and rust prevention to the punch to maintain its smooth surface and extend its service life. Finally, be careful when installing the punch to ensure that it does not tilt and can be gently tapped with a soft material tool. Only after the punch is correctly positioned can the bolt be tightened to ensure safety and stability.
2. The installation and debugging of the punching die are also crucial steps. The installation and calibration of stamping dies must be particularly careful, especially for large and medium-sized stamping dies. The cost of stamping dies is expensive and heavy, and it is difficult to move them in small amounts, so personal safety should always be the top priority. During the installation process, the stroke of the press slide should be selected according to the process documents and die design requirements, and it should be ensured that the mold is correctly aligned with the mold handle hole and reaches the appropriate mold installation height. When fixing the punching die, the lower die should be fixed first, then the upper die, and a suitable torque wrench should be used to tighten it to ensure consistent pre clamping force. This can effectively prevent malfunctions during the stamping process caused by manually tightening the threads.
Common problems and solutions in mold maintenance for plastic mold manufacturers 123
Before trial molding, the mold should be thoroughly lubricated and prepared with normal production materials. Start the punching die 3-5 times in the empty stroke to confirm that the mold is operating normally before conducting a trial punching. During the trial molding process, it is necessary to adjust and control the depth of the convex mold entering the concave mold, check and verify the performance and operational flexibility of the die guidance, feeding, pushing, side pressure, and spring pressure mechanisms and devices, and make appropriate adjustments to achieve the best technical state of the mold. For different specifications of stamping dies, different quantities of trial stamping and initial inspection should be carried out to ensure that the quality meets the requirements before production.
Stamping technology plays a crucial role in the manufacturing process. However, there may be some problems during the stamping process, such as stamping burrs, jumping waste, pressure marks, scratches, and external surface abrasions of the workpiece after bending. The emergence of these problems not only affects the quality of the product, but may also lead to a decrease in production efficiency and waste of resources. Therefore, timely and effective resolution of these issues is crucial for ensuring smooth production and improving product quality.
3. Stamping burrs are a common problem. The causes of stamping burrs may include excessive or uneven clearance between molds, improper mold material and heat treatment, stamping wear, etc. To solve this problem, measures such as readjusting the mold gap, selecting materials reasonably and conducting appropriate heat treatment, grinding the punch or insert, adjusting the depth of the convex mold entering the concave mold, and standardizing the operation of the punching machine can be taken.
4. Jumping waste is also a common problem. Jumping waste may be caused by factors such as large gaps between molds, short convex molds, high stamping speed, excessive viscosity or droplets of stamping oil, and scattered debris generated by stamping vibration. To solve the problem of jumping waste, some measures can be taken, such as adjusting the sharpness of the cutting edge, increasing the complexity of the waste, increasing the depth of the mold, using vacuum adsorption, demagnetizing the punch, insert, and material.
5. The issues of pressure and scratches also need to be taken seriously. These problems may be caused by oil stains, debris, uneven mold surfaces, insufficient hardness of parts surfaces, material strain and instability in the material strip or mold. To solve these problems, it is possible to wipe off oil stains and remove debris, improve the surface smoothness of the mold, perform surface treatment, adjust spring force, modify or lower mold positioning, etc.
6. Scratching the outer surface of the workpiece after bending is also a problem that needs to be solved. This may be caused by the rough surface of the raw materials, waste materials in the formed blocks, uneven formed blocks, too small bending radius of the convex mold, and too small bending gap of the mold. To solve this problem, cleaning, leveling materials, removing debris, electroplating, polishing formed blocks, increasing the bending radius of convex molds, adjusting the bending fit gap between upper and lower molds, etc. can be used.
7. In the case of missed punching holes, it is generally caused by factors such as punch breakage not being detected, missed punch installation after mold repair, and punch sinking. After mold repair, first piece confirmation should be carried out to compare with the sample and check for any omissions. If the punch sinks, the hardness of the upper mold pad should be improved.
The problem of abnormal material detachment is a common challenge during mold processing. When the detachment plate is too tightly matched with the convex mold, the detachment plate is tilted, the height of the equal height screws is not uniform, or other detachment devices are not in place, it can lead to abnormal detachment. To solve this problem, it is necessary to repair the detachment parts and use a combination of detachment screws, sleeves, and internal hexagonal screws. In addition, a small gap between the molds can also lead to abnormal material detachment, as the punch is detached from the material
A large demolding force is required, causing the punch to be bitten by the material. The solution is to increase the gap between the lower molds. If there is a reverse cone in the concave mold or if the material dropping hole of the concave mold is not aligned with the material leakage hole of the lower mold seat, it can also cause material detachment problems. It is necessary to repair the concave mold and the material leakage hole. It is also important to check the condition of the processed materials, as dirt adhering to the mold can cause the punch to be bitten by the material and unable to be processed. In addition, the passivation of the edges of the punch and lower mold should be sharpened in a timely manner to ensure that the mold can smoothly process the desired product.
The problem of uneven bending edges and unstable dimensions also needs to be taken seriously. Methods such as increasing the pressure line or pre bending process, increasing the pressing force, adjusting the clearance between the convex and concave molds to make it uniform, polishing the rounded corners of the convex and concave molds, and ensuring that the height dimension cannot be less than the minimum limit dimension can all help solve this problem. In addition, attention should be paid to the thinning of extruded materials on curved surfaces. Small rounded corners of concave molds and small clearances between convex and concave molds can lead to such problems, which need to be corrected in a timely manner.
It is very important to apply high-quality forming lubricant to the material in advance when dealing with stainless steel flanging deformation. This can help the material to be better separated from the mold and move smoothly on the lower mold surface during forming, avoiding deformation and wear.
The material is twisted and punched with a large number of holes, resulting in poor flatness of the material, which may be caused by the accumulation of stamping stress. When punching a hole, the material around the hole is stretched downwards, causing an increase in tensile stress on the upper surface of the board, and the downward punching motion also leads to an increase in compressive stress on the lower surface of the board. For punching a small number of holes, the results are not obvious, but as the number of punching holes increases, the tensile and compressive stresses also increase exponentially until the material deforms. One method to eliminate this deformation is to punch every other hole and then return to punch the remaining holes. Although this generates the same stress on the board, it breaks down the accumulation of tensile/compressive stress caused by continuous punching in the same direction. This also allows the first batch of holes to share the partial deformation effect of the second batch of holes.
The mold is severely worn. ① Replace the worn mold guide components and punches in a timely manner. ② Check if the gap between the molds is unreasonable (too small) and increase the gap between the lower molds Try to minimize wear, improve lubrication conditions, lubricate plates and punches. The amount of oil and the number of oil injections depend on the conditions of the processing material. Cold rolled steel plates, corrosion-resistant steel plates and other rust free materials need to be oiled into the mold, with the oiling points being the guide sleeve, oiling port, lower mold, etc. Use light engine oil. For materials with rust deposits, during processing, the rust micro powder will be sucked into the space between the punch and the guide sleeve, generating dirt that prevents the punch from sliding freely inside the guide sleeve. In this case, if oil is applied, the rust deposits will be more easily attached. Therefore, when punching this material, the oil should be wiped clean instead, decomposed once a month, and the dirt on the punch and lower mold should be removed with gasoline (diesel) oil. Before reassembling, it should be wiped clean again. This can ensure that the mold has good lubrication performance Improper grinding method can cause annealing of the mold and exacerbate wear. Soft abrasive grinding wheels should be used, with small cutting amounts, sufficient coolant, and regular cleaning of the grinding wheels.
Preventing stamping noise is a crucial and essential equipment in the sheet metal processing industry. Punching machines generate mechanical transmission noise, stamping noise, and aerodynamic noise during operation. The high value of this noise can reach 125dB (A), which greatly exceeds the noise index requirements of 85dB (A) and below specified by national standards. Therefore, it causes extremely serious harm and pollution to operators and the surrounding environment (such as offices, residential areas, conference rooms, etc.). Effectively managing this noise has become an urgent problem to be solved. Especially with the implementation of China’s first Noise Law, the scale of environmental protection industrialization is increasing, which has accelerated the urgency of noise control. Starting from the noise sources of punching machines and the structure of molds,
To reduce noise, attention should be paid to the following points:
① Pay attention to mold maintenance and cleaning, and keep the cutting edge sharp.
② The shape, quantity, material, and length of the cutting edge of the mold should not be too large in contact with the part. The punch should be used for oblique blade step punching, so that the mold can be cut into different depths at different positions. The entire process achieves true cutting, rather than synchronous extrusion.
③ The cutting edge of the mold must be perpendicular to the installation surface, and the clearance between the convex and concave mold cutting edges should be reasonable. When unloading is difficult, the clearance between the lower mold can be increased, and the unloading force can be increased by using soft surface unloading plates and other methods.
④ The precision of coordination between various work templates and the processing of some exhaust grooves Change the stop plate to a small piece assembly, and change the stripping plate and lower template to an embedded type to reduce the impact area.
⑥ The source of the ejector pin for the stripping plate has been changed to a T-shaped ejector pin, with the spring installed on the upper mold seat and matched with the ejector pin to ensure that the stripping plate still has a certain degree of free movement in the open mold state.
⑦ Maintain good lubrication, no interference with the mold, and smooth operation Aluminum plates are placed on the surface of the upper and lower mold seats to cushion the impact force After the mold is debugged, install a soundproof cover or sponge board on the punching machine for sound insulation treatment Improve the precision of the punching machine,