Melt Pressure Measurement

section view of plastics extruder
Section view of basic plastic extruder
The manufacture of plastic parts, extrusions, and films are all similar in that they involve the melting of solid plastic, then the forming of it into some output product. In a common extrusion process, dry solid base material, plastic flakes, pellets, powder, or granules, is fed into a screw. The screw is within a tubular housing called a barrel and is driven rotationally by a motor. The machining of the screw, and its rotation, forces the plastic material into an continually decreasing volume as it moves along the length of the screw/barrel assembly. The friction and pressure induced upon the plastic, as well as some carefully controlled heating along the barrel, melt the plastic in a predictable fashion. The melted plastic is forced through a breaker plate supporting screens that serve as filters to retain particulate contaminates from the liquid plastic. The liquified plastic, called a "melt", is driven by the screw motion out the end of the machine and into a forming stage of the process.

Producing melt with the proper characteristics for the forming stage involves careful measurement and control of temperature along the barrel. Multiple PID controllers and heaters typically create several heat zones along the screw length. Monitoring the melt pressure is also an important element of process control.

One company, GP:50 Melt Pressure, manufactures temperature sensors, pressure transducers, and other measurement equipment specifically tailored for the plastics industry. The company's sharpened focus on a single industry has produced a range of specialized products that meet specific application requirements and interface well with the machinery and systems used in plastics forming. Pressure and temperature sensors and transmitters are configured with options that reflect the requirements of plastic forming operations, a reflection of the company's extensive experience in this arena.

Share your plastics forming requirement and challenges with a product specialist, combining your process knowledge with their product application expertise to develop effective solutions.
melt pressure and temperature sensors for plastic forming

Load Cell Application in Process Measurement

force weight load cell process instrument
The Model G5 can process signals from mulitple
load cells
Courtesy BLH/Nobel
In industrial application of process measurement and control, principles of the physical sciences are combined with technology and engineering to create devices essential to modern high speed, high accuracy system operation. Years of research, development, and the forward march of humanity’s quest for scientific knowledge and understanding yields packaged devices for process measurement that are easily applied by system designer and operators.

Load cells are the key components applied to weighing component or processed materials in modern industrial operations. Load cells are utilized throughout many industries related to process management, or just simple weighing operations. In application, a load cell can be adapted for measurement of items from the very small to the very large. 

In essence, a load cell is a measurement tool which functions as a transducer, predictably converting force into a unit of measurable electrical output. While many types of load cells are available, one popular cell in multiple industries is a strain gauge based cell. Strain gauge cells typically function with an accuracy range between 0.03% and 0.25%. Pneumatically based load cells are ideal for situations requiring intrinsic safety and optimal hygiene. For locations without a power grid, there are even hydraulic load cells, which function without need for a power supply. These different types of load cells follow the same principle of operation: a force acts upon the cell (typically the weight of material or an object) which is then returned as a value. Processing the value yields an indication of weight in engineering units. 

For strain gauge cells, deformation is the applied operational principal, where extremely small amounts of deformation, directly related to the stress or strain being applied to the cell, are output as an electrical signal with value proportional to the load applied to the cell. The operating principle allows for development of devices delivering accurate, precise measurements of a wide range of industrial products. 

Load cell advantages include their longevity, accuracy, and adaptability to many applications, all of which contribute to their usefulness in so many industries and applications. A common place to find a strain gauge load cell in use is off a causeway on a major highway at a truck weigh station. Through innovation, load cells have been incorporated in an efficient measuring system able to weigh trucks passing through the station, without having each stop. Aircraft can be weighed on platform scales which utilize load cells, and even trains can be weighed by taking advantage of the robust and dependable nature of the transducers. 

Thanks to their widespread incorporation and the sequential evolution of technology, load cells are a fantastically useful tool in process measurement and control. Share your process weighing challenges with application experts, combining your own process expertise with their product knowledge to develop an effective solution.

Hile Adds New Programmable Automation Controller

modular programmable automation controller
One version of the Eurotherm T2750
Programmable Automation Controller
now offered by Hile Controls of Alabama
Hile Controls of Alabama recently added the Eurotherm T2750 line of programmable automation controllers to its already broad offering of Eurotherm process recorders and controllers.

The T2750 is a high performance modular control unit that provides redundancy and capability that are unmatched in a consolidated single unit. The controller backplane, of which there are several variants to accommodate the scope of I/O needed for a process, can be populated from an extensive array of I/O and function modules providing a customized setup that closely matches project requirements.

Unit functionality includes:

  • I/O Block
  • Communications
  • Signal Conditioning
  • Control
  • Timing
  • Logic
  • Math
  • Valve and Motor Control
  • Diagnostics
  • Recorder
  • More
There is much more to learn about the highly capable T2750 Programmable Automation Controller. A datasheet is included below, but your interest will be best served by contacting a product application specialist and sharing your process control challenges. The combination of your process knowledge and their product application expertise will develop effective solutions.

PLC Enhanced With Integrated HMI, PID, Recording, and More

PLC programmable logic controller with touchscreen HMI PID and recorder
E+PLC100 Precision PLC
Courtesy Eurotherm
Industrial process control applications can present multi-faceted challenges to those responsible for designing them. There can be many small operations that must coordinate and combine into a larger one. Selecting and configuring hardware to develop the necessary inputs, execute control functions, and connect with machinery via controller outputs may prove to be only one layer of several that comprise a well functioning online process operation.

For smaller scale projects, Eurotherm has developed a product that integrates many of the functions needed to develop and execute a process control operation. The E+PLC100 bundles multiple necessary hardware components into a compact unit.
  • PID control function
  • Touchscreen display
  • On board process recording
  • Analog inputs
  • Digital inputs
  • Relay outputs
  • Digital outputs
One can think of the unit as a PLC with built-in PID control and recording, or as a PID controller with logic control and recording. Whatever the case, it can simplify the hardware configuration for a project immensely. Instead of researching and specifying separate controllers, HMI, PLC, I/O, and recording devices and getting them all connected, powered, and coordinated, just configure and program the E+PLC100 with all the functions needed in a single unit. Space savings are substantial, as well as cost, by eliminating much of the time for design, assembly, and configuration of multiple hardware units.

The programming of the unit is intuitive, executed on a PC using the companion software. There is benefit to having the whole program for the process on a single need to coordinate the programming or operation of multiple hardware units.

There is much more to learn about the value and features of this truly capable precision PLC. A product brochure is included below, but best results will come from sharing your ideas and process control challenges with a product application specialist. Combining your process knowledge with their product application expertise can streamline your project completion time and move quickly toward an effective solution.