Stamping die is the main equipment used in the metal forming process. They are used to press sheet metal into the desired shape and size. The quality of stamping die directly affects the quality of products. In order to improve the wear resistance of stamping die, some measures must be taken.
The stamping die is made of steel alloy. However, high volume production runs can wear out.
Rapid wear and tear, which leads to increased costs due to replacement and downtime. Thankfully, there are ways to extend the life of the stamping die, such as hardening, and other ways to improve the wear resistance of the stamping die.
Extending the life of stamping die has the following benefits.
Reduce the cost
Extending the life of the die reduces overall operating costs because the die is replaced less frequently. This brings the added cost saving advantage of reduced downtime.
There are fewer defects
Stamping dies that resist wear also produce parts with fewer defects.
By increasing the life of the stamping die, there are fewer inconsistencies in the stamping part because the stamping pressure changes slightly each time the stamping part is used. Taking steps to extend the life of the mold can minimize this problem and result in more consistent results.
The following eight hardening tips will help you improve the wear resistance of your stamping die.
Die heat treatment
Deep Draw Stamping dies need heat treatment to keep them sharp and resistant to wear. Heat treatment at temperatures of 500 to 600 degrees Celsius produces martensite in steel alloys, which is a very hard form of steel crystal structure. The tiny crystals formed during this process have strong anti-corrosion properties, preventing rust and increasing hardness. In order for this process to work smoothly, you must quench the stamping die in oil using a water vaporization device. If this step is skipped, the wear resistance of the stamping die will be reduced.
Hard enamel coating
A hard enamel coating on the surface of the die will cover up any pores and pits on its surface, giving it a smooth, shiny appearance. This makes it harder for the material to adhere to the die surface during stamping and alleviates pitting problems.
Hard enamel coatings can be applied in two different ways, 1) by mechanical spraying or 2) by chemical vapor deposition (CVD). Mechanical spraying is the less costly method, but has the disadvantage that the coating can be reapplied to the mold only a limited number of times. CVD is the better choice because it doesn't have this limitation. However, the cost of CVD is much higher than mechanical spraying.
Vapor deposition method
The metal is heated in a vacuum until it reaches a gaseous state. This vapor coats the surface of the steel alloy. This reduces wear because the parts do not stick to the die surface after this process. The coating also prevents rust.
This method is less expensive than the CVD option, but more expensive than the mechanical spray option. Your choice depends on the requirements of your application. For example, if only a few dies are used in the stamping process, CVD may not be considered.
Wear resistant coating
The wear-resistant coating is applied to a hard enamel coating, so that all parts of the surface of the die have been covered. The wear-resistant coating can prolong the service life of steel alloy die and greatly improve its performance. In addition, less pressure is required to press the assembly because the part does not stick to the die surface. This results in fewer defects, greater efficiency, and lower costs. It also makes the whole process more reliable and consistent.
This is a less costly option than the other methods mentioned earlier. However, it does not last long and needs to be reapplied frequently. That said, it's better than not using any wear protection at all.
Carburizing, also known as surface hardening, surface hardening, or carburizing, increases the carbon content of the alloy, thereby increasing the surface hardness. There are various methods, such as gas carburizing or liquid carburizing, all of which have advantages and disadvantages.
Gas carburizing is the less expensive option, does not require specialized equipment, and can be performed at most stores. The downside is that it can only be used in small molds and takes longer to complete.
Liquid carburizing is the more expensive option, but it can be used on any mold size and is faster than gas carburizing.
Nitriding is a heat treatment process that diffuses nitrogen onto a metal surface to form a hardened surface. This process is most commonly used for low alloy steels. It can also be used in titanium, aluminum and molybdenum. Nitriding is a heat treatment often used in stamping dies to increase their wear resistance. The nitriding process involves heating a steel alloy to a point where nitrogen reacts with the metal to form a layer of nitride on its surface. This layer increases wear resistance, which may be beneficial if the stamping die is to be used in wet or corrosive environments.
The disadvantage of nitriding is that it can only be applied once and takes a long time to complete, so it is not suitable for some applications. This process is expensive, so it's not the best option in many cases.
Ceramic coatings are commonly used in stamping die to protect them from wear and tear. The coating is made of a variety of materials, such as silicon carbide, alumina and titanium nitride, all of which have their own advantages and disadvantages.
Silicon carbide is the most common type of ceramic coating because of its very high wear resistance. However, its lack of corrosion resistance makes it unsuitable for wet environments.
Although alumina does not wear as well as silicon carbide, it is more resistant to corrosion. It is a good choice for applications where stamping dies are used in humid environments. It is also cheaper than silicon carbide.
Titanium nitride is the most corrosion-resistant of all ceramic coatings, but it is also the least wear resistant. It is best used as a coating for molds designed to produce small parts.
The thermal spraying
Thermal spraying deposits a layer of material on the surface of the stamping dies to protect them from wear. They combine various materials, such as metal, ceramic or plastic, each with its own advantages or disadvantages.
Metals are commonly used in thermal spray coatings because of their high wear resistance. However, they are the most expensive options and can be difficult to apply.
Ceramics are cheaper than metals and wear better than plastics, but they are not as tough as metals.
Plastic is the cheapest option, but it also wears the least well.
The use of high quality lubricant can reduce the wear of stamping die. The role of lubricants is to reduce friction between the die surface and the workpiece, thereby reducing the amount of wear and tear.
There are many lubricants available, each with its advantages and disadvantages. Common types include oil-based lubricants, water-based lubricants, and dry-film lubricants.
Oil-based lubricants are the most common and have high viscosity, which makes them very effective in reducing friction. However, they can be cumbersome to use and can also cause mold corrosion, depending on the metal the mold is made of.
Water-based lubricants are not as dirty as oil-based lubricants, but they do not last long and need to be reapplied frequently. Dry film lubricants are also dirty and must be reapplied more frequently, but they last longer and therefore have less down time while lubricating the stamping die.
Regardless of the process, the stamping die must be in good condition. Corrosion can cause them to crack or shatter, permanently ending their use. Therefore, they must always be thoroughly cleaned and protected, but this is not always sufficient. The best way to ensure that the stamping die continues to work for as long as possible is to treat it with one of the various coatings we discussed above.