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hardening process

Around the year 7,000 BC, people discovered that they could hammer copper into useful shapes for tools that lasted longer than stone.

In the millennia that followed, metal-working has come a long way. Today, you need to choose everything from the right metal to the best hardening process to get the results you want. 

Which hardening process results in the best metal tools? Each process has its pros and cons. But if you want minimal warping and many other benefits, you'll want vacuum-hardened tools.

In this guide, we'll take a close look at everything that makes this hardening process superior -- keep reading to learn more.

What Is the Hardening Process?

The metal hardening process simply makes the metal stronger. However, there are many different ways to do this, and some are better than others.

We generally think of metal items as hard and able to stand up to lots of rough use. But this property often comes from the way the metal was hardened, rather than the metal itself. 

Hardening processes use temperature to make the metal easier to use and more durable. Most of these processes heat the metal, then soak it, and then cool it. 

Each step has a different purpose. For example, heating metal sometimes actually changes the chemical properties of the metal to get the desired results. Sometimes, the chemical change only lasts while the metal is hot. Other times, it's permanent.

"Soaking" the metal doesn't actually involve liquid. Instead, it just means letting the metal soak in the heat for the proper amount of time to get results.

Finally, the metal gets cooled down to reach its final, hardened form.

How Vacuum Heat Treatment Works

With the vacuum hardening process, the heat treating for the metal happens in a vacuum.

Removing air from the environment during the hardening process can often lead to better, and more predictable, results. Usually, the process involves using a vacuum pump to remove the air from a sealed chamber where heat treating will happen. Careful maintenance ensures air won't leak into the chamber during treatment. 

Benefits of Vacuum Hardening

Of all the ways to harden metal, what makes vacuum hardening ideal?

The air is filled with different elements that can react with different metals in certain ways. In addition to oxygen and carbon dioxide, air also contains varying moisture levels and other gases, like hydrogen.

Most of the time, these elements won't react with air -- at least, not in a big enough way for people to see. But when the temperature goes up, the normal reactions get accelerated for much bigger results.

A vacuum hardening process seeks to eliminate these reactions by taking out all the air from the heat chamber. Other methods try to reduce reactions by replacing the air with non-reactive gases, or by submerging the metal in a bath of molten salt.

However, vacuum hardening offers the most controlled possible atmosphere, which often gives the best results. Let's take a closer look at the benefits.

1. No Discoloration

In a vacuum, there aren't any impurities that can cause the metal to get scalded or discolored. 

Discolored or scalded metal often results in unsellable or unusable products. This can become incredibly costly for a business. With many heat treating processes, the small trace elements the metal gets exposed to create damaging reactions.

Even in molten salt or non-reactive gas, small impurities can sneak in. But in a vacuum, you've completely eliminated the sources of scalding and discoloration.

2. Avoid Oxidation

Most people are familiar with oxidation as the cause of rust. However, oxidation during a non-vacuum hardening process can make the surface of the metal become duller, rougher, and have soft spots or cracks.

Oxidation makes metal weaker. With a vacuum heat treatment process, the hot metal doesn't come into contact with any damaging oxygen. 

3. Improve Multiple Properties

In addition to avoiding damage, a vacuum hardening process can also improve many properties of your metal.

When you treat metal with the vacuum process, it comes out harder and resists corrosion better. It also has more tensile strength, shear strength, ductility, and elasticity. 

This means metal tools that have been vacuum hardened are great for a wider variety of purposes and can stand up well to more use. This method is great for making tools for new purposes where these properties are especially important. 

4. Environmentally Friendly

Vacuum metal hardening is one of the most environmentally friendly ways to treat metal. Some buyers today care about environmentally friendly sources, and this also means employees get to have a safer work environment.

Metal treatment processes often come with lots of danger. But vacuum heating doesn't use any flammable gases or any health hazards. 

With a vacuum, you're not adding new elements, just taking out the air. The process doesn't result in pollution, and it's quite safe and stable compared to some methods for treating metal. It's also very energy efficient. 

5. Faster Results

The vacuum method allows for very fast heating and cooling, so you can get the results you want faster. As soon as the treatment is over, the parts or tools are ready for the next step in the forming process.

Instead of waiting for the metal to be ready for the next step, you can move forward to the final product faster with the vacuum hardening process. 

Interested in Vacuum Hardening Solutions?

If you want to try the vacuum hardening process, but can't invest in the space and equipment needed, we can help. As the largest Slovenian provider of heat treatment, we offer a complete production process from start to finish. 

In addition to vacuum hardening, we have many other heat treating options to meet your needs. Find out more here.

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