From ceramics used in construction to hydraulic systems installed in airplanes and cars, many products we use today are made through sintering. The manufacturing industry relies on this process to transform porous raw materials into sturdy components.
There are multiple sintering techniques depending on the furnace atmosphere used to heat materials. One example is vacuum sintering, which is often used by aviation, medical equipment, and additive manufacturing industries.
In vacuum sintering, materials are heated to the point of melting to transform them into different properties. When done right, this process offers many advantages that can help streamline the work of industrial manufacturers.
If you want to learn more about vacuum sintering, use this article as your guide in understanding this technique and choosing the right gasses and furnaces for it.
What is Vacuum Sintering?
Vacuum sintering is the process of melting metallic powder materials into dense material in a vacuum environment. As you heat these materials with pressures ranging between 10-2 and 10-4 millibar, they transform into different properties.
Metals prone to absorption or dissolution in the atmosphere, such as tantalum, niobium, titanium, and zirconium, typically undergo this process.
Vacuum sintering often comes after another process called debinding, which involves removing “binders” or impurities developed during injection-molding processes. It’s similar to cleaning meat and vegetables before cooking so that they’re free from dirt and germs.
Without debinding, the impurities can contaminate the binding process. However, when debinding is done poorly, component surfaces will develop blisters or forms that cannot be removed during the sintering phase.
Advantages of Vacuum Sintering
Vacuum sintering offers many advantages for industrial manufacturers, such as:
- Reduces machining processes
Vacuum sintering helps manufacturers create special-shaped components, so the output is already close to the end product’s final shape. This minimizes the need for post-machining processes, saving you time and labor.
- Prevents atmosphere contamination
This process involves gasses that help deoxidize and remove non-metallic substances from raw metals. This process prepares materials for assembly, heat treatment, densification, and finishing.
- Cleans and brightens components
By cleaning and deoxidizing raw metals, both the debinding and vacuum sintering processes help create brighter and purer materials by removing defects, surface flaws, and dimensional inconsistencies.
Picking the Right Process Gas
You’ll need different gasses to deoxidize materials during the sintering process. When it comes to vacuum sintering, the three primary gasses used to process materials are nitrogen, argon, and hydrogen.
Nitrogen is the most used gas for sintering because it’s less expensive than other gasses. It also provides more flexibility to sintering atmosphere systems, making it easier to turn furnaces on and off and keep them idled under protective environments.
Argon is more expensive compared to nitrogen and is only used as an inert gas when the workpiece material is sensitive to nitrogen. It also helps protect molten and heated metals as they’re processed.
Hydrogen is used as a reducing agent in the sintering process. It helps protect sintered metals from oxidation and decarburization and enables consistent performance throughout the process. However, it comes with a hefty price, like argon.
How to Choose a Vacuum Sintering Furnace
Aside from gasses, furnaces also play a crucial role in vacuum sintering. Before you select one, make sure to consider the following factors.
- Cleaning process
Since metals have to undergo the debinding process before being placed in a vacuum atmosphere, you must determine whether you need separate furnaces to handle each treatment or just one to handle both.
Vacuum sintering requires metals to be clean, meaning it needs a furnace that’s also free from substances that can negatively affect the product’s characteristics. If your binder is difficult to use or your application requires a higher-than-average purity, you may need to use separate furnaces for debinding and vacuum sintering.
Meanwhile, if you plan to use a single lab furnace for both treatments, make sure it uses gas-flow distribution with a box separating the binders from sintering powders.
- Fragility of parts
Choose a furnace capable of reaching the required temperature for pre-sintering, as this process can help strengthen materials after the debinding process. Debinded materials become fragile and at risk of breaking when moved from one furnace to another.
If you’re short of workers, a single furnace for debinding and vacuum sintering may work in your favor. Using a furnace for both treatments can help you meet high production requirements where you may need to work overnight to process raw materials.
Many factors come into play when choosing a furnace based on your capacity. Do you have high or low production requirements? How long do both the debinding and vacuum sintering processes take? How many loads would you usually transfer from one sintering furnace to another?
Answering these questions can help determine if you need a separate furnace for each treatment or if a single one will do.
- Energy consumption
Minimizing energy consumption is an important part of any manufacturing process today as it helps reduce costs and save the environment. If saving energy is part of your goals as a manufacturer, you may want to consider getting a single furnace for debinding and vacuum sintering.
However, remember that the amount of energy used for debinding can be different from that for vacuum sintering. Make sure to research how much energy each treatment uses to determine the right furnace for your needs.
High-Quality Lab Furnaces
Choosing the right furnace with the right features and settings is an integral part of the vacuum sintering process. It helps manufacturers save time and costs and even improve the quality of their products.
However, selecting the right furnace can often be a difficult task. If you need assistance in choosing vacuum sintering equipment, look no further than AIl Furnaces. We offer vacuum tube furnaces that can effectively heat metals to very high temperatures and conduct processes like sintering with high consistency and low contamination.