Many people know that in the production of metal stamping dies, the machinery requires maintenance and careful inspection to extend die life and thereby improve production efficiency. In the following sections, we will focus on the four major maintenance precautions for progressive metal stamping dies.
I. Maintenance of the punch and die.
1. When disassembling the punch and die, care should be taken to preserve the original state of the die so that it can be easily restored during subsequent die installation. If shims or spacers are present or have shifted, the thickness of the shims must be engraved on the parts and recorded.
2. When replacing a punch, test whether the stripper insert slides smoothly into the die and whether the clearance between the insert and the die is uniform. When replacing a die, also test whether the clearance between the insert and the punch is uniform.
3. Considering that the punch becomes shorter after grinding, shims may need to be added to achieve the required length; check whether the effective length of the punch is sufficient. When replacing a damaged punch, the cause must be identified, and the corresponding die should be checked for edge chipping and whether the cutting edge requires grinding.
4. When assembling the punch, check whether there is sufficient clearance between the punch and the retainer or punch plate. If a pressure block is used, check whether there is any allowance for movement. The assembled die should be placed horizontally, then a flat steel block should be placed on the die surface and lightly tapped into position with a copper rod. Do not place it at an angle or force it. The bottom of the die should be chamfered. After installation, check whether the die face is level with the mold surface.
5. After the punch, die, and die core are assembled, a necessary inspection of the guide strips should be carried out to see whether any parts are installed incorrectly or reversed. Check whether the die and die pad are installed backward, whether the piercing holes are blocked, and replace them with new ones if necessary. Check whether parts need to be stolen, whether sufficient material is stolen, and whether the parts that need to be locked are locked.
6. Pay attention to confirming the locking of the stripper plate screws. When tightening, balance the force and lock crosswise from the inside out. Do not lock one screw completely before locking another, as this may cause the stripper plate to tilt, leading to punch breakage or reduced die precision.
II. Maintenance of the Stripper Plate.
1. When disassembling the stripper plate, first use two screwdrivers to pry it up evenly, then use both hands to remove it with balanced force. If difficulty is encountered during disassembly, check whether the interior of the die is clean, whether all locking screws have been removed, and whether the die has been damaged due to material jamming. Identify the cause, then take appropriate action. Do not handle it blindly.
2. When installing the stripper plate, first clean the punch and the stripper plate, apply lubricating oil to the guide posts and the punch entry points, position it evenly, then press it into place with both hands, repeating several times as needed. If it is too tight, investigate the cause (whether the guide posts and guide bushings are aligned properly, whether any parts are damaged, whether the new punch can pass through the stripper plate smoothly, and whether the position is correct), then take appropriate action.
3. If there are pressure blocks on the fixed plate, check whether there is sufficient space on the stripper backing plate. During prolonged stamping operations, the contact surface between the stripper plate and the material will develop indentations. Severe indentations can affect the material pressing accuracy, causing abnormal and unstable product dimensions. The stripper inserts and the stripper plate need to be inspected, repaired, or reground.
4. The accuracy of the equal-height sleeves should be checked. If the heights are not equal, it will cause the stripper plate to tilt, compromising its precise guiding and smooth downward pressing functions, which must be maintained.
III. Adjustment of Die Clearance.
1. The die core locating holes may wear out due to frequent die core assembly, resulting in excessive clearance after assembly (looseness after assembly) or uneven clearance (positioning deviation). This can cause changes in the cross-sectional shape after stamping. If poor, the punch can easily break, producing burrs, etc. You can inspect the cross-section condition after punching and make appropriate clearance adjustments.
2. When the clearance is small, there will be fewer burnish zones. When the clearance is large, there will be more burnish zones and larger burrs. A reasonable clearance can be achieved through adjustment. After adjustment, proper records should be made, and markings can also be placed on the side of the die to facilitate subsequent maintenance operations.
3. In daily production, attention should be paid to collecting and preserving the optimal state of the original die strip. If subsequent production goes poorly or the die undergoes variation, it can serve as a reference for die repair.
4. Additionally, auxiliary systems should be inspected and maintained, such as whether the ejector pins are worn, whether they can eject properly, and whether the guide pins and bushings are worn.
IV. Inspection of guide components.
1. Check the clearance between the guide pillar and guide bushing for any signs of burning or wear, and verify whether the lubrication supply to the die guide is normal.
2. Wear and loss of precision in guide components will reduce the accuracy of the die, leading to problems in various parts of the die. Proper maintenance and periodic replacement are necessary. Check the accuracy of the guide components. If the guide pins are worn and have lost their correct guiding precision and function, they must be replaced. Inspect the condition of the stripping springs and ejector springs to see if they are broken, or if they have become fatigued after prolonged use without breaking, losing their original strength. They must be regularly maintained and replaced. Otherwise, this can cause die damage or result in production difficulties.
The above are the four major maintenance considerations for progressive metal stamping dies. I hope that, in addition to following operating procedures, all metal die operators can correctly perform daily maintenance on their dies, thereby saving costs for die manufacturing enterprises.