Maguire blenders atop three extruders in a blown film line operated by CFT, South Africa
Gravimetric blenders powered by new LineMaster software from Maguire Products Inc raise extrusion yield control to a new level of simplicity and accuracy and enable processors to enhance product consistency, save on raw material, shorten setup times, and reduce scrap, the company announced recently.
The yield control system has already been used commercially and successfully by Coextruded Film Technologies of South Africa, among other firms.
The new technology makes advanced yield control available without the need for large, complex, and costly hardware systems such as loss-in-weight blenders, according to B Patrick Smith, Maguire’s vice president of marketing and sales. “The simplicity, ease of use, and low cost of this system have made it by far the most widely used blender in the world, yet its precision and reliability also make it eminently suitable for governing the entire extrusion process with unvarying accuracy,” said Smith.
The LineMaster system combines advanced blender controller software with Maguire’s Gravimetric Gateway or “G2” software for integrating blenders in a computer controlled network. This integrated system makes it possible for the blender controller to adjust two critical process parameters simultaneously.
In standard extrusion control, the blender controller automatically adjusts only one parameter - extruder speed - to achieve a manually set target throughput (weight of raw material processed per unit of time). Somewhat more advanced is a basic type of yield control, in which the controller once again automatically adjusts only extruder speed, but does so by first calculating target throughput on the basis of two manually set parameters: target line speed (length of product per unit of time) and target yield (weight per length of extruded product). In contrast with these systems, the LineMaster system simultaneously adjusts both throughput and line speed to achieve target yield, providing complete control of the process.
Three yield-control configurations are possible with the LineMaster system, in each of which 1) the blender is connected to the downstream speed control and automatically adjusts it to maintain line speed; and 2) the desired yield is entered by the operator. The three configurations vary according to which other parameter is to be set as a target by the operator:
