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How to use the punch press tooling correctly
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How to use the punch press tooling correctly

Views: 0     Author: Site Editor     Publish Time: 2023-11-23      Origin: Site


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This article mainly shows the problems that often occur in the use of CNC turret punch tooling, and proposes corresponding technical points and precautions for tooling maintenance and maintenance in response to these problems.

Scrap rebound is the biggest killer of the tooling. The influencing factors are: (1) The sharpness of the cutting edge of the tooling. The larger the rounded corner of the cutting edge, the more likely it is to cause the scrap to rebound; (3) Whether the gap of the tooling is reasonable; (4) Whether there is more oil on the surface of the processed sheet; (5) The spring of the tooling is fatigued and damaged; (5) Poor lubrication.

Tooling centering

In the use of the tooling, there will be a phenomenon of uneven wear on each side of the die punch. Some parts have larger scratches and wear faster, while some parts wear more slowly, especially on narrow rectangular toolings. This situation is particularly obvious. The main reasons for this problem are as follows: (1) The design or machining accuracy of the machine tool turret cannot meet the requirements, especially the poor alignment of the tooling mounting seat of the upper and lower turntables; (2) The design or machining accuracy of the tooling cannot meet the requirements; (3) Tooling The accuracy of the guide sleeve of the punch is not up to standard; ⑷The tooling gap is too large or too small; ⑸Due to long-term use and wear, the center of the tooling mounting seat or the tooling guide sleeve is not good.

Tooling spring fatigue damage

In use and maintenance, CNC turret punch tooling springs are often easily overlooked. Different punch equipment and toolings correspond to different spring specifications. Different springs have different performance and service life. Therefore, the springs need to be maintained or replaced regularly. . Otherwise, it is easy to cause tooling material problems or cause greater losses such as damage to toolings and guide sleeves.

The technical points of correct use of CNC punch tooling

Optimal tooling clearance

Die gap refers to the sum of the gaps on both sides of the punch entering the lower die. The choice of die gap depends on the plate thickness, material and stamping process. Different plate thickness or material should choose the corresponding die gap. If the gap is too small or too large, it will damage the die and affect the punching quality. If the tooling gap is selected appropriately, it can ensure good punching quality, reduce burrs and collapse, keep the sheet flat, effectively prevent stripping, and extend the service life of the tooling. The judgment of the tooling gap is mainly by checking the stamping waste. If the scrap has rough and undulating fracture surfaces and smaller shiny surfaces, it means that the gap is too large. The angle formed by the fracture surface and the bright surface is proportional to the gap. The larger the gap, the curling and fracture will be formed when punching, and even a thin edge protrusion will appear.

Ways to eliminate and reduce sticky materials

Due to the pressure and heat generated during stamping, the small particles of the sheet material will stick to the surface of the punch, thereby affecting the quality of the punch. Generally, lubrication is used to prevent overheating and at the same time reduce friction. If lubrication is not possible or the scrap material rebounds, the punches of the same size can be alternately used for punching. Multiple punches can be punched in turn to allow each punch to have a sufficient cooling time before use. To remove the sticky material on the punch, it can be polished with fine oil stone to avoid the production of further sticky material. The polishing direction should be consistent with the direction of the movement of the punch. Avoid using coarse emery cloth for sanding to prevent the surface of the punch from becoming rougher and sticking to the material again.

Measures to prevent sheet deformation when punching many holes

If many holes are punched on a board, the board will be deformed. This is due to the accumulation of punching stress every time a hole is punched, the material around the hole will deform downwards, tensile stress appears on the upper surface of the sheet, and compressive stress appears on the lower surface. When few holes are punched, this punching stress will not affect the quality of the sheet, but when many holes are punched, the tensile and compressive stresses on the upper and lower surfaces of the sheet will continue to accumulate at a certain point, which will cause the material to be uneven , Deformation. The method to prevent this kind of deformation is to change the punching sequence of the holes, punch every other hole, and then return to punch the remaining holes. This can effectively reduce the stress accumulation during sequential punching in the same direction. Although this punching method will also produce stress, it will cancel the stress of the two sets of holes before and after each other, thereby preventing the deformation of the sheet.

Avoid punching narrow strips

When the die is used to punch a sheet with a width less than the thickness of the sheet, the punch will bend and deform due to lateral force. On the other side, due to the small gap, the wear will be aggravated, and the lower die will be scratched or scratched in severe cases. At the same time, the upper and lower toolings are damaged. In addition, when a narrow strip is cut, the sheet often will not be completely cut off, but will tend to bend into the opening of the lower die, or even wedge the side of the die. The way to avoid this kind of tooling wear is to try to avoid narrow strips with too small nibbling width, especially for sheets less than 2.5 times the thickness of the sheet. If it is impossible to avoid narrow material punching, it is recommended to use a stripper or use a fully guided die.

Different material toolings should be used for different material plates

The surface hardening of the punch usually uses titanium plating, nitriding, etc. The surface hardening layer of the punch is not only a surface coating, it is a part of the punch matrix and a molecular structure with a thickness of 12 to 60 μm. Through surface hardening, the wear of the tooling will be reduced when punching special materials such as stainless steel plates, but the surface hardening of the tooling cannot extend its service life. Through the surface hardened punch, the maintenance method is still proper lubrication, timely sharpening and Operate according to procedures and other conventional methods. The surface-hardened tooling can still be sharpened in the usual way. Surface hardened punches can be used in the following situations: punching soft or viscous materials (such as aluminum); punching thin abrasive materials (such as glass epoxy sheet); punching thin hard materials (such as stainless steel); frequent nibbling; Abnormal lubrication.

Maintenance knowledge

Maintenance in use

⑴The tooling should be cleaned and lubricated regularly or in time, and the tooling should be strictly inspected before installation and use to remove the dirt. During production, add lubricating oil or stamping oil to the corresponding sliding parts and cutting edges of the tooling at regular intervals; after the end of production, the tooling should be thoroughly inspected and cleaned. After cleaning, the anti-rust lubricating oil should be applied in time, and sealed and stored to ensure The tooling is cleaned to facilitate normal use in the future.

⑵When installing the male and female toolings on the turret(turntable), install them in strict accordance with the installation process of the tooling to avoid inconsistent installation of the male and female toolings. For those toolings with installation direction requirements, be cautious to avoid installation errors. accident.

⑶ The operating tool for installing the tooling should be made of softer metal, such as aluminum or copper. If the operating tool is too hard, the tooling may be damaged due to knocking or smashing during the installation process. During transportation, protect the tooling, handle it with care, and avoid damage to the cutting edge and guide. When changing toolings and sharpening, pay attention to safety before and after starting the equipment to prevent damage to equipment, toolings, and personnel.

Maintenance after use

⑴ Timely sharpening: The amount of sharpening of the cutting edge of the punch die is limited. When the cutting edge is worn, it should be sharpened in time. If it is continued to be used, it will accelerate the cutting edge wear, thereby reducing the quality of the punching and shortening the service life of the tooling. Practice has proved that it is very important to grasp the appropriate timing of sharpening. Don’t wait until sharpening is necessary. Regular micro-sharpening can not only reduce the punching force and ensure good workpiece quality, but also double the length of the tooling. Service life. In addition, mastering the correct sharpening method also contributes to the improvement of the service life of the tooling. In order to prevent the tooling from cracking or annealing due to overheating, the high-quality coolant required by the manufacturer should be added during sharpening; after sharpening, the burrs on the cutting edge should be removed with oilstone, and the cutting edge should be polished to a radius of 0.03~0.05mm. The rounded corners are flattened, so that you can prevent the cutting edge from chipping. In addition, the cutting edge surface cannot be magnetized and must be demagnetized to prevent material blocking; the punch is demagnetized and sprayed with lubricating oil to prevent rust.

⑵Replace the spring in time: In the tooling maintenance process, springs and other elastic parts are most easily overlooked, but the springs often break and deform. The damaged spring must be replaced in time, and the spring of the same specification and model should be used to avoid the use of the tooling or the damage to the tooling due to the mismatch of the parts.

⑶Check whether the fasteners are loose or the parts are damaged at any time, check the relationship between the parts of the tooling installation base and other parts and whether there is damage at any time, find and solve them in time to avoid loosening and displacement, causing damage to the tooling and other accidents.

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