WEXCO BO-22 Corrosion-Resistant Injection and Extrusion Barrels

WEXCO "BO-22" Barrels

High-Performance Injection and Extrusion Barrels

Simply our best corrosion-resistant bimetallic plasticating barrels
for processing highly corrosive resins, including Fluoropolymers!

Primary Applications:

For Molding Medical Products and Insulated Wire & Cable using Corrosive Polymers

The “technical stuff”:

WEXCO “BO-22” (pronounced "bee-oh 22") injection and extrusion barrels are specifically designed and manufactured to withstand highly corrosive processing environments, such as when molding products using Fluoropolymers.

Such polymers emit acidic gases during the molding process that may dissolve oxide coatings that protect nickel chrome or nickel cobalt bore inlays (typically used in “standard” bimetallic barrels). Fluoropolymers can quickly ruin any “standard” bimetallic, nitrided, or tool steel barrel, especially if resins are allowed to dwell in the machine.

In contrast, WEXCO’s BO22 barrels have a protective layer in the bore and all surrounding areas exposed to corrosive gases. This bore protection is a nickel-rich boron base alloy containing 12% molybdenum and a matrix rich in complex borides and carbides. These elements allow the protective layer to maintain its high temperature hardness. It has a Rockwell hardness from HRC 50 to HRC 55 at 700° F.

After machining the basic shape of the barrel, the BO22 bore protection is added by using a Hot Isostatic Pressing (HIP) process that creates a non-porous bore lining. The molybdenum and its alloying elements found in WEXCO BO22 bore protection are far superior in corrosion resistance against halogen containing elements. This substantially reduces acid attack when compared with conventional nickel-cobalt base alloy, e.g., WEXCO “555”, or similar protective bore linings produced by competing manufacturers.

As an extra measure of protection against acidic corrosion of barrel surfaces that cannot be protected as part of the “BO22” HIP process, such as the barrel discharge end, transducer holes, or flange surfaces, WEXCO adds acid-resistant Inconel material to these areas.

When to select WEXCO BO22 highly corrosion-resistant barrels

When Iron-absorption is a problem in molded parts:
When molding medical and other critical plastic products that cannot have traces of iron in their makeup, WEXCO BO22 barrels, when used with corrosion-resistant screws, will substantially reduce the absorption of iron particles from the barrel bore to the melted polymer.
If you are processing Fluoropolymers, or other similar highly corrosive resins, or medical products requiring reduced iron contamination, then WEXCO "BO22" barrels are the choice of experts.

As can be expected, the much more costly manufacturing processes that yield the highly corrosion-resistant and extremely “low-iron” attributes of the WEXCO BO22 barrel come with higher price tag than ordinary barrels. However, as Fluoropolymer processors are discovering the benefits of choosing WEXCO BO22 barrels in fewer machine teardowns for barrel changes, and cleaner, more consistent product, the demand for WEXCO BO22 barrels has increased substantially during the past year.

For processing polymers that are less corrosive than Fluoropolymers, lower cost WEXCO 555 barrels with added Inconel protection may suffice. To choose the most cost-effective corrosion-resistant WEXCO barrel for your particular processing application, be sure to discuss your particular application with our Technical Sales staff.

CLICK HERE to link to an article on BO22 barrels in "Plastics Machinery and Auxiliaries" magazine