How to treat the surface of stamping die to prevent deformation?

The key to the surface treatment of stamping die to prevent deformation is to select the appropriate surface treatment method and strictly control the process parameters. The following is a concrete introduction:

Select the appropriate surface treatment method.

nitrogen treatment

Principle: Nitrogen atoms penetrate into the surface of the die to form a nitrided layer with high hardness and good wear resistance, which improves the wear resistance, corrosion resistance and bite resistance of the die, thus reducing the wear and deformation of the die during stamping.

Advantages: the nitriding temperature is relatively low, generally around 500-600℃, and the thermal stress generated by the mold during the treatment is small, which is not easy to cause deformation. At the same time, the nitrided layer has good hardness and toughness, which can effectively improve the service life of the die.

Application scenario: It is suitable for all kinds of stamping dies, especially dies with high requirements on wear resistance and corrosion resistance, such as stamping dies for automobile panels and precision electronic parts.

Hard chromium plating treatment

Principle: A layer of hard chromium is plated on the surface of the die by electroplating. The hard chromium layer has the characteristics of high hardness, high wear resistance and low friction coefficient, which can improve the surface hardness and smoothness of the die, reduce the friction between the material and the die during stamping, and reduce the wear and deformation of the die.

Advantages: the hardness of hard chromium plating layer can reach HV800-1200, which can significantly improve the wear resistance and scratch resistance of the mold. At the same time, the chromium plating layer has good corrosion resistance, which can prevent the mold from being corroded in the process of use and affect the accuracy and life.

Applicable scene: It is often used for stamping dies with high requirements on surface smoothness and wear resistance, such as drawing dies and bending dies. In some stamping processes that need high precision forming, hard chromium plating can effectively ensure the dimensional accuracy and surface quality of the die.

Electroless nickel plating

Principle: A Ni-P alloy layer was deposited on the surface of the mold by chemical reduction. The electroless nickel plating layer has uniform thickness, good wear resistance, corrosion resistance and low friction coefficient. It can form a dense protective film on the surface of the die to reduce the friction and wear between the die and the workpiece during stamping, thus preventing the die from deformation.

Advantages: The hardness of electroless nickel plating layer is generally between HV 500 and 1000, and it has good toughness and fatigue resistance. Compared with hard chromium plating, the thickness of electroless nickel plating is more uniform, and it is not easy to be too thick or too thin locally, which can better ensure the dimensional accuracy of the mold. In addition, the electroless nickel plating process has little restrictions on the shape and size of the mold, and is suitable for all kinds of complicated molds.

Application scenario: it is suitable for some small and medium-sized stamping dies with high requirements on corrosion resistance and wear resistance, such as plastic molding dies and metal stamping dies. In some occasions that require high surface quality of dies, electroless nickel plating can provide good surface smoothness and uniform coating thickness, which is helpful to improve the quality of stamping parts.

Controlling surface treatment process parameters

Treatment temperature: Different surface treatment methods have different suitable temperature ranges. If the nitriding temperature is too high, the mold will produce greater thermal stress, leading to deformation; If the temperature is too low, the hardness and thickness of the nitrided layer will not meet the requirements. In the process of hard chromium plating and electroless nickel plating, temperature control is also very important. If the temperature is too high, it may affect the quality and performance of the coating and even lead to mold deformation. If it is too low, it will slow down the plating speed and reduce the production efficiency.

Treatment time: Treatment time directly affects the thickness and quality of surface treatment layer. Taking nitriding treatment as an example, the treatment time is too short and the nitrided layer is too thin to provide enough wear resistance and corrosion resistance; Too long time will not only increase the cost, but also make the nitride layer loose and other defects, which will affect the performance of the mold. When plating hard chromium and electroless nickel, the treatment time should also be reasonably determined according to the material, size and thickness of the required coating, so as to ensure that the coating is uniform and dense, and the mold will not be deformed or its performance will be degraded due to excessive plating.

Other parameters: In the nitriding process, parameters such as gas flow and pressure will also affect the nitriding effect. Appropriate gas flow and pressure can ensure that nitrogen atoms penetrate into the surface of the die evenly and form a nitride layer with good quality. In the process of hard chromium plating and electroless nickel plating, bath composition, pH value, current density and other parameters play a key role in the quality and performance of the coating. It is necessary to regularly detect and adjust the parameters of the plating solution to ensure that the plating solution is in a good working state, so as to obtain stable coating quality and prevent uneven surface treatment of the mold due to parameter fluctuation, which will lead to deformation.

Before surface treatment, the mold needs to be thoroughly cleaned and degreased to ensure good adhesion between the surface treatment layer and the mold matrix. At the same time, after surface treatment, it is necessary to carry out appropriate post-treatment on the mold, such as tempering and polishing, to eliminate the residual stress generated during surface treatment and improve the surface quality and performance of the mold.