Vacuum Extrusion

Air pockets trapped within an extruded material create voids or weak points that can lead to cracking, reduced structural strength, uneven density, or surface defects.

Brick, tile, and ceramic pipe manufacturing rely heavily on vacuum extrusion, along with plastic pipe, profile, and sheet extrusion, food processing applications like sausage casing extrusion, and pottery or ceramic art production. Wintek designs custom vacuum systems that are optimized to support all of these industrial applications.

Clay material is fed into an extruder, often called a pug mill, where it’s mixed and de-aired under vacuum before being forced through a die that shapes it into the desired cross section, such as a standard brick shape, with the vacuum step critical for producing a dense, void free product capable of withstanding the firing process.

Removing trapped air and volatile gases from molten plastic during extrusion helps prevent bubbles, voids, or surface imperfections in the finished product, resulting in more consistent wall thickness, improved mechanical properties, and better overall surface finish compared to extrusion without vacuum de-airing.

Wintek commonly uses liquid ring vacuum pumps in extrusion applications due to their tolerance for moisture, dust, and particulate carryover that can occur when pulling vacuum on clay, ceramic, or certain plastic processing lines. Other types of vacuum pumps routinely experience reliability issues due to the harsh operating conditions in most extrusion processes. Choose from a selection of liquid ring vacuum pumps here.

Deeper vacuum generally removes more entrapped air and produces a denser, more homogeneous material, though the specific vacuum level required depends on the material type, moisture content, and the sensitivity of the final application to any residual air content. Wintek’s systems, which can pull low vacuums to the customers specifications, are perfect for this application.

Common causes include insufficient vacuum level or pump capacity for the material throughput, inadequate residence time in the vacuum chamber section, material moisture content that’s too high or too low for effective air removal, and mechanical issues like worn seals or auger components that allow air to be reintroduced after the vacuum stage. Through the 40+ years of experience Wintek has, we are able to avoid these issues and produce cost-effective vacuum systems.

Regular attention to vacuum pump performance, inspection and cleaning of the vacuum chamber to prevent material buildup or clogging, checking seals and gaskets for air in-leakage, and knockout pot cleaning are important tasks in maintaining a process vacuum system in an extrusion application. Wintek’s process vacuum systems are designed with reliability and maintenance in mind to minimize downtime.

Yes, particularly in plastics extrusion, though recycled material can sometimes contain more contaminants, moisture, or inconsistent composition than virgin material, which may require adjustments to vacuum level, screening, or drying steps beforehand to maintain effective de-airing and consistent product quality.