Colorant, Thermal & Compositional Melt Homogenization

Extrusion Blow Molding Rod & Tubing Wire & Cable Coatings Cereals and other foods Fibers & Monofilaments INTRODUCTION StaMixCo manufacturers all three commercially proven static mixer designs used for extrusion service (see page 3). As with most pieces of process equipment, each static mixer design has specific advantages and disadvantages that make it more or less suitable for a specific application and installation. The Static Mixer Melt Blender (Figure #1) is installed just in front of the extruder die. It is installed as the last piece of equipment to correct all irregularities created by...

As with most process equipment, there is no one design that is best suited for all applications. Static Mixers are no exception to this general rule. For this reason, StaMixCo manufactures a broad range of static mixer designs of different geometric structures. This allows us to make an unbiased recommendation as to which design is best for a specific application. Below is a short guide that may help you identify the static mixer best suited for your particular application and needs. We have taken the liberty of our previous experience to create the below broad-stroke comparison. If you wish...

HOMOGENEITY REQUIREMENTS FOR EXTRUSION SERVICE In extrusion service, the fundamental purpose of a static mixer is to create a homogeneous polymer melt at the face of the die. This includes: y Temperature Homogenization. y Viscosity Homogenization. y Composition Homogenization of colorants, chemical additives, regrind and fillers. y Self-Cleaning and Homogenization of irregularities created by upstream equipment such as: extruder screw & piping colorant hang-up release material; gear pump teeth footprints; and incorporation of flaked wall-creep degraded polymer hang-up. Achieving the above optimized...

Composition Homogenization & Self-Cleaning There are three fundamental flow regimes associated with the movement of fluids: turbulent, transitional and laminar flow. The flow regime that a fluid in motion falls within is a function of the viscosity, density, velocity and pipe diameter. The movement of low viscosity fluids such as water and gases is normally in the turbulent flow regime where mixing occurs as a result of the pattern of motion of fluids in turbulent flow. Given a long enough length of pipe, fluids traveling in turbulent flow will mix very well. The flow of polymers, resins and...

SMB-R Static Mixer Melt Blender The standard SMB-R static mixer for extrusion service (licensee of Bayer AG, Leverkusen, Germany) contains eight (8) very efficient mixing elements that homogenize the polymer melt as it enters the extruder die. The mixing elements are virtually indestructible due to their monolithic cast construction and create an acceptable pressure drop to fit most installations. Figure #11: The SMB-R mixing elements are extremely strong due to their monolithic cast construction where the mixing bars are joined to each other and to the ring wall via a single molten metal pour....

The proper size SMB-R Melt Blender for a specific application is a function of the available pressure drop; degree of mixing required and polymer flow rate and viscosity at the operating conditions. For most applications, Table #1 provides a conservative estimate of required static mixer size based on extruder screw diameter and high or low viscosity polymer being processed. The standard SMB-R Extrusion Melt Blender contains 8-mixing elements as shown in Figures #13 and #14 with key dimensions shown in Table #1. The mixing elements are made of heat treated high strength 17-4 PH stainless steel...

SMB-GX Static Mixer Melt Blender The standard SMB-GX static mixer for extrusion service contains four (4) very efficient mixing elements that homogenize the polymer melt as it enters the extruder die. The Type SMB-GX static mixer (StaMixCo version of the Sulzer Chemtech SMX Static Mixer)*, is a design that has been in use on extruders for over 25 years. It has the same fundamental crossing-bar structure as the StaMixCo SMB-R static mixer (Figure #11 and #12), but without the support ring around the mixing blade structure which gives the SMB-R its remarkable strength. The SMB-GX mixing grid design...

The proper size SMB-GX Melt Blender for a specific application is a function of the available pressure drop; degree of mixing required and polymer flow rate and viscosity at the operating conditions. For most applications, a conservative estimate of required static mixer size is matching it to the extruder screw diameter. For pressure drop critical applications; the processing of specialty engineering plastics we are not familiar with; or for mixer installations inside of die blocks, we have the know-how to properly size the mixing unit. To perform the necessary design calculations, polymer rheology...

SMB-H Static Mixer Melt Blender The Type SMB-H Helical static mixer (StaMixCo version of the Kenics Thermogenizer Static Mixer)*, is the design that pioneered the static mixing industry and has been used on extruders for over 37 years. The SMB-H helical design is considered a low mixing performance-long length static mixer design (Figure #20) as compared to the later developments of high performance static mixers such as the SMB-R (Figure #12) and SMB-GX (Figure #17) static mixer designs. The SMB-H continues to remain a popular design for simple low-demand applications because it exhibits a low...

The proper size SMB-H Melt Blender for a specific application is a function of the available pressure drop; degree of mixing required and polymer flow rate and viscosity at the operating conditions. For most applications, a conservative estimate of required static mixer size is half the extruder screw diameter. The SMB-H is available in 316L S/S material and is available in standard configurations of: • 6-helical mixing elements with a twist of L/D=1.5 • 9-helical mixing elements with a twist of L/D=1.0 • Any twist L/D is available as tight as approximately 0.7 with the machined version of the...