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Before vacuum hardening, a few thousand years ago, humanity discovered that it could forge copper into practical tools. Then, for many years, metalworking has used many different hardening methods in order to increase the sturdiness of metals. Today, hardening is popular, but we need to know that there are several kinds of hardening. Which hardening process produces the best results? Why is vacuum hardening worthy of attention? We’re writing about it below!

What is hardening and vacuum furnace?

The metal hardening process is designed to strengthen the metal. The operation itself can be carried out in different ways, which have certain advantages and disadvantages. Let us remember that the hardness of a metal does not depend solely on its quality, but also on the way it is hardened. The hardening processes occur when temperature differences occur. Most of these processes involve heating the metal, soaking it and cooling it down. Each of the above-mentioned elements has a specific task. For example, metal heating sometimes actually changes the chemical properties of the metal in order to achieve the desired results. Sometimes the chemical change only takes place when the metal is hot. „Soaking” of metal does not in fact include liquids. Instead, this simply means allowing the metal to soak in heat for a proper amount of time to get the desired results. Cooling is the final element, which hardens the produced form.

How does vacuum hardening work?

In the vacuum h. process, the heat treatment of the metal is carried out in a vacuum. Why? As air removal at the time of hardening can often lead to better and more predictable results. Normally, this process consists of using a vacuum pump that removes air from the closed chamber where heat treatment of the metal is to be performed. Air does not enter the chamber throughout the entire process.


Of all the methods of metal hardening, it is worth focusing on hardening v. Why? As the air is filled with different elements that can react in specific ways with various metals. In addition to oxygen and carbon dioxide, air also contains various levels of moisture and other gases such as hydrogen. For most of the time, the above elements do not react with air – at least not enough to allow humans to see it. When the temperature rises, normal reactions are accelerated, which results in much better results. The vacuum hardening process is designed to eliminate these reactions by removing all the air from the heating chamber. Vacuum hardening is the best method because other solutions only try to reduce reactions by replacing the air with non-reactive gases or by immersing the metal in a molten salt bath. In practice, vacuum hardening provides the most controlled atmosphere possible, which often gives the best results. Here are also a number of other benefits that make vacuum hardening an attractive solution:

Removing impurities

Vacuum has no impurities that could burn or stain the metal. This is important because discolored or burned metal often results in products which are not good enough to be sold or used. Currently, in many heat treatment processes, the small trace elements to which the metal is exposed cause harmful reactions. Almost any type of hardening solution carries the risk of impurities entering the workpiece. Vacuum hardening eliminates these problems.


Most people know that oxidation is often associated with rust. However, during a traditional hardening process, oxidation can cause the surface of the metal, to become abrasive and even break. To put it simply, oxidation makes metals more brittle. If vacuum hardening is used, this problem does not exist.

Improving quality

In addition to avoiding damage, the vacuum hardening process can also improve many properties of metal. During vacuum hardening, the metal becomes harder and more resistant to corrosion. It also has greater hardness, flexibility and resistance to stretching. Vacuum-hardened tools are ideal for a wider range of applications.

Vacuum hardening is eco-friendly

Metal vacuum hardening is one of the most environmentally friendly methods of metal treatment. In addition, this form of hardening has a positive impact on the workplace and the safety of workers. Let us remember that metal machining is often a rather dangerous process. There are no flammable gases or health and life hazards in the vacuum hardening process. You do not add new items during vacuum hardening, just remove the air. The process does not cause contamination and is fairly safe and stable compared to some metal machining methods. It is also very energy efficient.


Vacuum h. allows for very fast heating and cooling, which results in achieving the desired results quicker. As soon as processing is complete, 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 towards the final product faster thanks to the vacuum hardening process.

Vacuum furnaces are great for hardening various surfaces and helping heat treated products. They can harden high alloy steels, products with bright surface and many others. With vacuum, we can do oil quenching, water quenching or gas quenching.