Methods and apparatus for plugging honeycomb structures

A method of inserting plugging material into a ceramic honeycomb structure comprised of a plurality of walls defining a plurality of cells, the method comprising:

• placing a container proximate the honeycomb structure, the container containing a charge of the plugging material;
• providing an extrusion mask provided with a plurality of extrusion holes;
• providing an annular flow plate disposed directly adjacent the extrusion mask, the annular flow plate being provided with a plurality of restrictor holes which are diametrically smaller than the extrusion holes, the annular flow plate having an inner annular edge defining a central opening;
• axially aligning select cells to the restrictor holes of the flow plate and the extrusion holes of the extrusion mask prior to discharging the plugging material;
• discharging from the container a discharge of the plugging material comprised of at least a portion of the charge, and
• passing the discharge through an extrusion mask and then through the annular flow plate disposed directly adjacent the extrusion mask, wherein the annular flow plate restricts flow of an outer portion of the discharge more than an inner portion of the discharge, wherein the discharge is divided into a plurality of slugs of the plugging material, and the slugs are injected into respective cells of the honeycomb structure to form shots of the plugging material in the respective cells.