small diameter single shaft is located on top to perform the mixing as well as a small amount of cook and water absorption.

The slower, large diameter single shaft located at the bottom of the assembly is designed to provide higher retention times to encourage thermal transfer and liquid absorption.

Nontraditional dual shaft

The nontraditional dual shaft, typically called a differential diameter conditioner, or DDC, initially follows the same philosophy of a traditional dual shaft as seen with the Extru-Tech, Inc. (ETI) family of dual conditioning cylinders, or DCCs, with some minor differences (see Figure 6).

For example, neither the paddle cross-sectional areas

Figure 6 The nontraditional dual shaft initially follows the same philosophy of a traditional dual shaft with some minor differences.

Figure 7 The traditional dual shaft features two parallel, counter-rotating shafts with intermeshing beaters.

nor shaft speeds are identical. That speed relationship between the shafts never changes. It is always 5 to 1 with the smaller shaft turning faster.

Also, the base speed is not variable. The shafts are parallel and counter-rotating, and the paddles intermesh for excellent mixing capability.

The traditional dual shaft shown in Figure 7, also identified as the ETI DCC, features two parallel, counter-rotating shafts with intermeshing beaters. The shaft and beater footprints are identically sized and symmetrical.

The two shafts, driven by a single variable speed motor, can be modulated (in terms of speed) to vary the retention time as well as reversed for an accelerated clean-out. ■

NEW PRODUCT!

September 2007 Extru-Technician 6