Optimizing CNC Turret Punch Press Performance: Tips for Effective Mold Use and Maintenance
In the world of plate to stamp metals, CNC turret punch presses have become a vital tool for their rapid stamping speed, high treatment accuracy, and versatility of mold and variety of products. To maximize the performance of these machines, it is crucial to understand the importance of proper mold selection and maintenance. In this blog post, we will explore the key factors to consider when using and maintaining press molds to punch from CNC turret punch presses, including how to ensure the best clearance for your mold, how to prolong its lifespan, and how to eliminate and reduce adhesive materials, prevent leaf deformation, and avoid cutting too narrow strips.
1. Ensuring the Best Clearance for Your Mold
The mold space, also known as the gap between the punch and the lower matrix, is a critical factor in determining the quality of the stamped part. A well-designed mold space ensures that the punch enters the lower sector without interference, resulting in a smooth and consistent stamping process. A suitable mold space is essential, as it affects both the quality of the treated part and the lifespan of the mold.
To ensure the best clearance for your mold, it is essential to check the stamping waste after each production run. This allows you to determine if the mold space is suitable for the specific job. If the space is too large, the waste will have rough and wavy fracture surfaces and smaller shiny surfaces, while a too small space will result in small-angle fractures and larger light surfaces. For unique applications such as groove punching, shearing, or other local stamping, a smaller mold space is required to accommodate the lateral forces that may divert the punch.
The optimal mold space is where the fracture surface and the light surface of the waste have the same angle and overlap, minimizing the infusion force and preventing punching burning.
2. Sharpening: A Key to Prolonging the Life of the Mold
Regular sharpening of the mold is critical to maintaining its performance and extending its lifespan. When the part has excessive burrs or abnormal noise during stamping, it may indicate that the mold needs sharpening. A simple and effective way to prolong the life of the mold is to sharpen it frequently, rather than waiting until it becomes dull. Regular sharpening will not only maintain good room quality and reduce the punching force but also increase the lifespan of the mold by more than double.
To sharpen the mold, it is essential to control the correct hooking method. The proper sharpening procedure involves grinding the punch vertically in the V-groove or magnetic game of the plane crusher, using a fine alumina wheel with a hardness of 46-60, and applying a coolant to prevent overheating and cracking. After sharpening, polish the edge with an oil stone, remove burrs, and grind a rounded corner with a radius of 0.03-0.05 mm to prevent the edge from cracking.
3. Eliminating and Reducing Adhesive Materials
Adhesive materials can occur due to pressure and heat during stamping, resulting in poor punching quality. To eliminate or reduce adhesive materials, it is recommended to polish the mold with a fine oil stone, using the same direction as the punch movement to prevent additional adhesion. Do not use coarse gauze, as this can create a rougher surface and increase the likelihood of adhesion.
4. Preventing Leaf Deformation during Punching of Multiple Holes
When punching multiple holes in a plate, the accumulated shear stress can cause the plate to deform. This is particularly true when punching many small holes, as the material around each hole deforms downward, creating a tensile constraint on the upper surface and compressive stress on the lower surface. To prevent leaf deformation, it is recommended to cut all other holes first, followed by cutting the remaining holes. This reduces stress accumulation during sequential stamping and eliminates the stresses from the front and rear holes, preventing sheet deformation.
5. Avoiding Cutting too Narrow Strips
When cutting leaves with a width smaller than the thickness of the plate, the punch can bend and deform due to lateral forces, resulting in a smaller mold space or severe wear, and potential damage to the upper and lower molds. To avoid this, it is recommended not to cut narrow strips with a width less than 2.5 times the thickness of the sheet. If this cannot be avoided, use a fully guided mold with a support effect of the material retraction plate.
6. Surface Hardening of Punches and Its Scope of Application
While thermal treatment and surface coatings can improve the characteristics of the punch surface, they are not a general solution to solve stamping problems and prolong the lifespan of a mold. In general, thermal treatment and surface coatings are best suited for specific applications rather than being a broad solution for all stamping processes.
In conclusion, maximizing the performance of CNC turret punch presses requires a deep understanding of the importance of proper mold selection and maintenance. By following the guidelines outlined in this blog post, manufacturers can ensure the best clearance for their mold, prolong its lifespan, and eliminate and reduce adhesive materials, prevent leaf deformation, and avoid cutting too narrow strips. By optimizing their processes, manufacturers can achieve improved stamping quality, reduced waste, and increased productivity.
