Nitride plasticating barrels are manufactured typically from AISI 4140 HT or similar steels with elements to enhance nitride depth. The barrel is treated using either a gas-nitride or ion-nitride process. Gas-nitride is the more common method. It is less expensive than the ion process. The typical gas-nitride barrel bore has a shallow case hard depth of about .002 - .004 inch, while the typical ion-nitrided bore is hardened to a depth of about .015 inch. Hardness and wear resistance diminishes with depth and wear rate accelerates with operation time. This causes other components such as the feed screw to wear at a faster rate as well. The depth of wear protection for a bimetallic barrel is .050-.062 inch.
Nitride barrels have a low cost
Easy to manufacture
Nitriding can be used for complex geometries such as ID grooves, twin bores and auxiliary components.
Thin layer of wear protection
Short peak performance life
Low wear resistance
Not cost effective
Wexco produces nitrided cylinders, when the cylinder wall is too thin for the spin-casting process. Also for complex geometries such as grooved liners, certain twin bore barrels, feed and end components. We prefer to supply the superior wear resistance of bimetal construction whenever possible.
4-10 times thicker wear resistant bore inlay
High wear resistance
Long peak performance life
More cost effective
More complex to manufacture (The process does not lend itself to complex geometries)
The "bottom line" of Nitride vs. Bimetallic Plasticating Barrels:
Bimetallic barrels have over 30 years of proven history sustaining peak performance up to ten times longer than nitride barrels.