What Is Outgassing And Why Must I Be Concerned With It?

Also known as off-gassing, outgassing is a term that has been dominating many household and industrial conversations. You may have heard it being associated with inefficient satellite equipment, poorly manufactured plastics and other items, poor industrial performance and high maintenance costs during the injection molding process or malfunctioning vacuum electronic equipment.

It’s true that off-gassing is not a positive term. It is the reason why, today, more and more industries are producing way less than their potential capacity, and why industrial processes are becoming more expensive. Understanding outgassing or off-gassing is important to help you appreciate its negative role in normal industrial operations to enable you to curb it. It is also necessary as it can help you come up with a better vacuum system.

What is off-gassing?

Off-gassing is the process by which gases and chemicals are released from different materials that we usually have in our industries. More precisely, the emissions occur when the source is exposed to high temperature or low external pressure — or both. The process can cause many problems in the semiconductor industry. For instance, it can lead to the contamination of the vacuum chamber that requires an ultra-high vacuum. Generally, in high and ultra-high vacuum systems, the gas load mainly comes from the released gases from the surface of the vacuum.

Why does it matter?

In an industrial context, any manufacturer creating equipment intended to be used in a high-vacuum environment has to consider off-gassing. This is because the effects of this process can affect many electronic application areas. These involve things like satellites, medical systems and space-based equipment.

For instance, a typical space equipment may release trapped gas. This gas may condense on other critical components and damage them or affect their performance in some way. In a hospital setting, outgassing can impede the maintenance of a sterile environment that is necessary for smooth medical operations.

Unfortunately, that’s not the only way trapped gas affects normal operations. One of the most important operations in most industries today is the injection molding that is used for the mass production of items, especially plastics. During the injection molding cycle, trapped gas usually leads to different problems, including short shots, part burns, clogged vents and unsightly blemishes and voids. Moreover, the trapped gas can lead to higher maintenance or cleaning costs. This usually occurs when it leads to a buildup of residue in the vented pins, creating the need for many interruptions in the production process to clean the tool.

The process can even lead to the corrosion of the tool steel; this increases the cost of maintaining the tool. The biggest problem, generally, is that even when these plastics are produced through the injection molding processes, they carry tiny pockets of gas while solidifying. Factors like sunlight, time and heat lead to the expansion of these gas bubbles. Consequently, microscopic holes are blown in the surface of the plastic, releasing the gas in offices, schools, homes and other places where the items end up. Here are two examples:

Electronics: Items like computers typically emit gases, such as ozone. They are usually produced by photocopiers and laser printers during the printing process.

Particleboard and plywood: These items contain a glue that holds them together; this glue contains a compound known as formaldehyde. It is one of the many carcinogens we have.

Other sources include:

• Porous metals
• Elastomers
• Lubricants
• Porous metals
• Heat transfer greases

In an ultra-high vacuum system’s upper reaches, the stainless steel that manufacturers use to create the chamber itself is known to outgas a level of carbon monoxide and hydrogen. Similarly, there are certain gases that have been identified as the most predominant ones that outgas from different surfaces. They include:

• Oil
• Water vapor
• Solvents
• Organic materials
• Grease vapor

How can you prevent its effects?

There are many ways to avoid off-gassing. In injection molding processes, we need to have proper venting to avoid air and gas being trapped in the mold.

One of the proposed ways involves giving the gas a little more time to disperse by slowing down the initial stage fill time. But as you can imagine, that’s costly; it increases the overall cycle time. The best way is conducting vacuum venting. This method removes the gas from the mold while it’s getting filled. It’s simple: the trapped gasses dissipate from the mold as soon as the vacuum is activated.

In an industrial setting, it is also important to maintain cleanliness to minimize or avoid off-gassing. You can achieve high vacuum levels efficiently by reducing the effective surface areas to reduce the effect the emission. Usually, the higher the surface area, the greater the impact; therefore the more the resulting pressure in the system.

Secondly, you need to select the right pump technology. This is important as it would assist you achieve HV or UHV vacuum levels efficiently and effectively. Although you can get a good pump from a reputable source, such as High Vac Depot, you have to select the right pump type based on your objectives. For instance, turbomolecular pumps are low maintenance, easy to operate, don’t require regeneration and offer that desirable hydrocarbon-free operation. However, they have low pumping speeds for the lighter gases, and are sensitive to particulate contamination. On the other hand, the ion getter pumps require nearly zero maintenance, they are made up of radiation tolerant material, and they can be baked to as high as 4500C. However, they have low pumping efficiency when it comes to handling noble gases. They also have a low pumping speed while in HV/UHV applications.

As this is just an example, the point is to ensure you select the right pump technology based on your applications to make sure you prevent the amount of particles being released through the surfaces. Just make sure to accompany the technology with high-quality vacuum valves and gauges, such as those from High Vac Depot for optimal results. You can chat with an expert today by contacting us online or giving us a call at 1-800-289-6945.