Click on Yellow Pages Links for a listing of consultants by area of expertise.

The rheology (viscosity) a polymer is a key parameter that affects the extrusion process.  It normally is a function of several variables, and it can be measured in the lab with only a few grams of sample.  However, the measurement process can be quite technical.  Therefore, it is advisable to  have it done by a knowledgeable practitioner.   Dr. Eldridge Mount, III of EMMOUNT Technologies is highly qualified with over 30 years of practical polymer processing experience.  He personally will make detailed measurements of the rheology of your polymer and provide mathematical functions to describe it. 

Click here for a sample report of the results for a rheology test by Dr. Mount.

Slides with notes on kinematics model of solids conveying  The kinematic model for solids conveying uses the solids conveying angle as the constitutive factor instead of friction factors.  The result is a very practical and robust model for calculating solids flow in an extruder.

Calculate the solids conveying angle.  With this spread sheet you can easily calculate the solids conveying angle from the flow rate from any operating extruder.  A great analysis tool to help check the solids conveying of any machine.

Bulk density of several resins as a function of pressure  The bulk density is a needed parameter in the use of the kinematics model.

"Kinematics of  Solids Conveying,"  ANTEC 2003.  The use of the solids conveying angle as the constituitive factor for solids conveying is developed.  The method does not require knowledge or assumptions about friction factors, and cylindrical coordinates are used.

"Kinematics of  Solids Conveying of  LDPE," ANTEC 2004.  The kinematics model based on the solids conveying angle is shown to robustly reproduce solids flow vs pressure for LDPE data very well.   

"Control Volume Analysis of  Solids Conveying"  ANTEC 98.  This paper describes a model for solids conveying that includes heat transfer and the onset of melting.  Cylindrical coordinates are used.

"A Melting Rate Model Based on Extruder Data,"  ANTEC 1999.  Melting rate is found from extrusion data by mathematically isolating the melting section.  Melting rates, melting power, heat transfer, and melt-phase temperature are all found with this model.  An example is shown for LDPE.

"Heat Transfer Coefficients in Extruder Melt Sections,"  ANTEC 96.  A lumped model is used to predict melt temperature development in the melt section of the extruder.  Proper heat transfer coefficients are needed and presented.  A comprehensive plot of melt temperature versus length provides a compete description of melt temperature development in an extruder.  Thermal and shear thinning effects in the channel and flight clearance are included.  See SOFTWARE below to get an up-to-date spread sheet as shown in Figure 1.

"Calculating Power of Extruder Melt Sections,"  ANTEC 97.  The same model as used for ANTEC 96 is used to calculate the power consumed by the metering section of a screw.  The result is a general plot of power versus melt section length.

An Excel Spreadsheet  is given that calculates the melt temperature development according to ANTEC 96, Figure 1, above.  Additionally, power used by the melt pumping section is calculated.  Screw dimensions, process factors, and polymer visosity are needed.  

The Vented Barrier Screw, slides with notes   Presented at ANTEC 2005  The vented barrier screw provides venting while still maintaining the efficiency of the barrier screw design.  Virtually, no screw length is lost with addition of the venting.

"The Vented Barrier Screw,"  ANTEC 2005.  A standard barrier screw was modified to include a vent in the screw root.  Venting was then possible while maintaining the efficiency and rate of the barrier screw.

"Dynamic Torque of a Single Screw Extruder,"  ANTEC 2001.  Screw torque is very dynamic s measured with a strain-gage setup.  Different polmyers and process conditions are shown to greatly affect the frequency and amplitude of torque dynamics.

"Heat Transfer in Extruder Screws,"  ANTEC 2000.  The screw is not adiabatic as is so readily assumed.  The screw is "autogenous" in that equal amounts of heat enter and leave under steady operation.  The heat conduction that occurs within the screw is modeled  here.  

"Stability in Two-Stage Extruder Screws,"  ANTEC 2002.  The stability of a two stage extruder screw depends on the depth of the pumping section (last metering sections.)  A"stepped" pumping section is demonstrated that dramatically improves delivery pressure stability. 

"Calculating Surge Dampening in Melt Delivery Systems,"  ANTEC 97.  The science of hydraulic transients is applied to melt flow piping delivery systems.  The transmission of flow and pressure pulstations from the extruder to the die output is modeled with hydraulic transient modeling theory.  The model not only provides a quantitative measure of the flow dampening, but yields insight into how to best design a delivery system for uniform output at the die.  

A program to calculate sheet cooling is available.  Also, a data file is needed.   This program is based on one-dimensional transient heat conduction in the sheet thickness.  Material properties, initial conditions, and heat zone information on either sideof the sheet are needed.  The program will simlulate the sheet going through up to 50 sequential heat zones.  The program prompts for the needed information. 

0030Edited
0381Edited
0885Edited