Vacuum Bagging Process for Vacuum Bonding - in Parts Manufacture

Vacuum Bagging Process for Vacuum Bonding

Vacuum Bagging and Vacuum Bonding

  • Sketch of Equilibar EVR used in vacuum bonding

The technique of vacuum bagging is used in the construction of engineered materials and parts that need to be bonded together with adhesives. Vacuum bonding is another name for this process used to keep a part under pressure as the adhesive cures. The part is enclosed in an airtight “bag”, then a vacuum is applied to remove the air inside the vacuum bag. Pressure is applied evenly at perpendicular angles to all surfaces of the part inside the vacuum bag, resulting in excellent adhesion even with unusual geometry. Common parts manufactured using vacuum bonding include composite parts for airplanes and boats, carbon fiber aerospace parts, laminated flooring, touchscreen display bonding and many others.

The bonding process typically requires precise pressure control for a long duration across a large area. The specifications for a vacuum bagging process can be very detailed and in many cases data will be collected during the process for quality control. During this time, there is a chance the vacuum pump could experience spikes or dips. The use of an Equilibar® vacuum regulator (EVR) is an excellent solution in vacuum bagging systems to avoid disturbances in pressure over time. The EVR responds instantaneously to changes in pressure and adjusts accordingly to keep a precise vacuum setpoint regardless of perturbations in the vacuum. Another advantage of using an Equilibar EVR in this instance is that it can be designed using a variety of chemically compatible elastomers and metals.

Sketch of Equilibar EVR used in vacuum bonding

Equilibar EVR with manual control used for precision vacuum control in vacuum bagging process

Automated Vacuum Bonding

For vacuum bagging applications that require automation for ease of use on the shop floor, the Equilibar EVR is very easy to automate. Instead of using a manual pilot regulator to control the setpoint of the EVR, an electronic vacuum regulator can be installed. A vacuum setpoint can be dictated by an external supervisory control device sending a 4-20mA or 0-10V signal to the electronic vacuum regulator. The EVR will keep precised control at the pressure sent through the electronic E/P vacuum regulator. See schematic below.

Sketch of Equilibar EVR used in automated vacuum bonding

Electronic pilot control of an Equilibar EVR assists with automation

GSD4 vacuum regulator

Stainless Steel Equilibar EVR-GSD6 with manual pilot controller

 

photograph of Equilibar vacuum regulator with QPV electronic pilot regulator

Anodized Aluminum Equilibar EVR-GSD6 with a QPV electronic pilot controller

Application Spotlight: Vacuum Bonding for NASA

The NASA contractor building the Orion spacecraft uses a vacuum bonding process to secure all the Thermal Protection System (TPS) to the aeroshell of the craft. The aeroshell protects the vehicle and crew from thermal loads during reentry. Every tile and Avcoat block is vacuum-bonded onto the Artemis 1 and Artemis 2 spacecrafts. They use Equilibar EVR regulators because of their ability to maintain bonding pressures within tight engineering tolerances. These EVR regulators play a critical role in TPS processing. The largest bonding surface is just over 16 feet in diameter. The NASA contractors build a vacuum bag across the entire 16 foot surface, so it’s a challenging application. Read more about the use of Equilibar EVR for the NASA Artemis program in the feature article to the right.

 

 

Equilibar article in Hendersonville Times News

Feature Article: Equilibar Technology for NASA

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