Thousands of years ago, humanity discovered that it could forge copper into practical tools. Then, for many years, metalworking used various hardening methods to strengthen them. Today, hardening is popular, but we must know that there are several types of it. Which hardening process gives the best results? Why is vacuum hardening worth noting? We write about it below!
Vacuum hardening – what is it?
The process of hardening metal is aimed at strengthening it. The action itself can be performed in various ways, each having certain advantages and disadvantages. Remember that the hardness of the metal depends not only on its quality, but also on the way it has been hardened. Hardening processes occur when there are differences in temperature. Most of them heat the metal, soak it, and cool it. Each of the above elements has a specific task. For example - heating the metal sometimes actually changes the chemical properties of the metal to achieve the desired results. Sometimes the chemical change only lasts when the metal is hot. "Soaking and soaking" the metal does not actually involve liquids. Instead, it simply means allowing the metal to immerse itself in heat for the appropriate amount of time to achieve specific results. Cooling is the final element that hardens the formed shape.
How does vacuum hardening work?
In the process of vacuum hardening, heat treatment of metal takes place in a vacuum. Why? Because removing the air during hardening can often lead to better and more predictable results. This process usually involves the use of a vacuum pump, which removes the air from the sealed chamber where the heat treatment of the metal is to take place. During the entire process, air does not enter the chamber of the hardened object. In this case, precision and small distortions of the castings are required.
Vacuum hardening used in practice
Of all the ways to harden metal, it's worth focusing on vacuum hardening. Why? Because the air is filled with various elements that can react with different metals in a specific way. In addition to oxygen and carbon dioxide, the air also contains various levels of humidity and other gases, such as hydrogen. Most of the time, these elements do not react with the air - at least not enough for people to see it. When the temperature rises, normal reactions accelerate, yielding much better results. The process of vacuum hardening aims to eliminate these reactions by removing all the air from the heating chamber. Vacuum hardening is the best method, as other solutions only try to reduce reactions, replacing air with non-reactive gases or immersing the metal in a bath of molten salt. In practice, vacuum hardening provides the most controlled possible atmosphere, which often gives the best results. Below we also present a number of other benefits that make vacuum hardening seem like an attractive solution:
Pollution Elimination
Vacuum does not have any contaminants that could cause burning or discoloration of the metal. This is important because discolored or burnt metal often makes products unsuitable for sale or use. Currently, in many heat treatment processes, small trace elements to which the metal is exposed cause harmful reactions. Almost every hardening solution carries the risk of contaminants getting into the object. Vacuum hardening eliminates the above problems.
Oxidation
Most people know that oxidation is often associated with the occurrence of rust. However, during the classic hardening process, oxidation can cause the surface of a metal, hardened object to become rough, matte, and even crack. In short - oxidation weakens the metal. If we use vacuum hardening, such a problem does not exist.
Quality Improvement
In addition to avoiding damage, the vacuum hardening process can also improve many properties of the metal. During vacuum hardening, the metal becomes harder and more resistant to corrosion. Moreover, it has greater hardness, elasticity, and tensile strength. Vacuum-hardened tools are excellent for a wider range of applications.
Vacuum hardening is eco-friendly
Vacuum hardening of metals is one of the most environmentally friendly methods of metal processing. Moreover, such a form of hardening positively affects the workplace and the safety of employees. Remember that metal processing is often a rather dangerous process, vacuum hardening performs tasks where small deformations of castings occur. There are no flammable gases in vacuum hardening and there is no threat to health and life. During vacuum hardening, you do not add new elements, you only remove air. The process does not cause pollution and is quite safe and stable compared to some metal processing methods. It is also very energy efficient.
Speed
Vacuum hardening allows for very rapid heating and cooling, which means you can achieve the desired results faster. Right after the tooling is finished, the tools are ready for the next stage of the forming process. Instead of waiting for the metal to be ready for the next step, you can move on to the final product faster thanks to the vacuum hardening process. Vacuum hardening is used under high pressure and in a vacuum. This means that the heat treatment of foundry products does not corrode quickly and is carried out in a professional manner. Vacuum hardening is used where air supply can have negative consequences. The heat treatment of foundry products using a vacuum in particular makes the metal less prone to corrosion. Depending on what elements we have, how much we care about non-invasive shaping of the product - in the case of some details, a method is required where the vacuum method should be used. The tempering of technological solutions obtained using vacuum hardening seems to be an unattractive solution. For this reason, we recommend using this method!