A mixing study of various single screw mixinng elements using inline melt analysis
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An experimental investigation into solids conveying
1. An experimental study compared the performance of an extruder with a single-piece barrel and integral feedport design to a standard two-piece barrel configuration.
2. Testing was conducted using two resins (HDPE and PP) across a range of screw speeds.
3. Results showed the integral design produced higher output rates and melt temperatures for both resins compared to the standard configuration, with a more significant increase seen for PP.
4. The integral design improved solids conveying by increasing heat transfer to the feed zone, raising temperatures and the coefficient of friction between pellets and barrel wall.
Regrind particle size
Almost all processes, extrusion, injection and blow molding require that regrind be used in the process. Depending on the process greatly determines the amount of regrind that is generated. Some processes produce very minimal amounts of regrind, such as an injection molding process using a hot runner system versus a flat sheet extrusion process producing thermoformed sheet and the entire skeleton has to be fed back into the process or a blow molding process which always generates large amounts of regrind.
6. nanocomposites a single screw mixing study of nanoclay filled polypropylene
6. nanocomposites a single screw mixing study of nanoclay filled polypropyleneR&B Plastics Machinery
Base Lining Your Extruder
When a new extruder is installed, or a new screw mounted in an existing machine, do you know what the expected throughput rate is going to be? You should. If you don’t baseline your extruder, then how are you going to set realistic expectations for its performance? If extrusion screws are designed properly, they typically will be able to withstand the maximum torque available from the extruder and the resin being processed. The extruder should operate at approximately 90% of its full available torque, based on 100% pellet feedstock, which typically will be the worst-case scenario. By using today’s barrier screw technology, higher throughput rates, lower melt temperatures, and better power efficiencies can be obtained. This article will provide some basic insight to help processors to determine if they are obtaining the maximum production rates from their extruders, providing that they have adequate downstream cooling and handling equipment in the extrusion system.
A mixing study of various single screw mixing elements using inline melt anal...
A mixing study of various single screw mixing elements using inline melt anal...R&B Plastics Machinery
A mixing study of various single screw mixing elements using inline melt analysisAn Empirical Study on Barrier Flight
An Empirical Study for the Optimization of the Barrier Flight Clearance for Single Stage Extrusion Using Design of Experiment
Over-hung Loads
Recently a processor installed a new screw into their 6” x 32:1 L/D extruder. Within a few weeks the hard facing that had been welded on the flight OD started to pop off. (As shown in the attached photo) The flight failure was in an isolated area, so it was then assumed that the failure was due to a poor weld bond. The screw was ultra-sonically inspected and the remaining flights showed good bore, but the entire screw was rebuilt and returned to the customer.
Buying a used extruder
When buying a used extruder, it is important to carefully inspect the gearbox, feed throat, and barrel for excessive wear. Additionally, the extruder must have adequate torque for the intended application. Over time, advances in screw design have allowed for higher throughput rates but require more torque. A typical older 3.5" extruder from the 1960s-1970s with a 75hp motor could produce 700-750 lb/hr of PVC but only 400-450 lb/hr of HDPE. Modern 3.5" extruders require a minimum of 125hp and can produce 650-700 lb/hr of HDPE with a 150hp motor and updated screw design. Make sure a used extruder has the
Recommended
An experimental investigation into solids conveying
1. An experimental study compared the performance of an extruder with a single-piece barrel and integral feedport design to a standard two-piece barrel configuration.
2. Testing was conducted using two resins (HDPE and PP) across a range of screw speeds.
3. Results showed the integral design produced higher output rates and melt temperatures for both resins compared to the standard configuration, with a more significant increase seen for PP.
4. The integral design improved solids conveying by increasing heat transfer to the feed zone, raising temperatures and the coefficient of friction between pellets and barrel wall.
Regrind particle size
Almost all processes, extrusion, injection and blow molding require that regrind be used in the process. Depending on the process greatly determines the amount of regrind that is generated. Some processes produce very minimal amounts of regrind, such as an injection molding process using a hot runner system versus a flat sheet extrusion process producing thermoformed sheet and the entire skeleton has to be fed back into the process or a blow molding process which always generates large amounts of regrind.
6. nanocomposites a single screw mixing study of nanoclay filled polypropylene
6. nanocomposites a single screw mixing study of nanoclay filled polypropyleneR&B Plastics Machinery
Base Lining Your Extruder
When a new extruder is installed, or a new screw mounted in an existing machine, do you know what the expected throughput rate is going to be? You should. If you don’t baseline your extruder, then how are you going to set realistic expectations for its performance? If extrusion screws are designed properly, they typically will be able to withstand the maximum torque available from the extruder and the resin being processed. The extruder should operate at approximately 90% of its full available torque, based on 100% pellet feedstock, which typically will be the worst-case scenario. By using today’s barrier screw technology, higher throughput rates, lower melt temperatures, and better power efficiencies can be obtained. This article will provide some basic insight to help processors to determine if they are obtaining the maximum production rates from their extruders, providing that they have adequate downstream cooling and handling equipment in the extrusion system.
A mixing study of various single screw mixing elements using inline melt anal...
A mixing study of various single screw mixing elements using inline melt anal...R&B Plastics Machinery
A mixing study of various single screw mixing elements using inline melt analysisAn Empirical Study on Barrier Flight
An Empirical Study for the Optimization of the Barrier Flight Clearance for Single Stage Extrusion Using Design of Experiment
Over-hung Loads
Recently a processor installed a new screw into their 6” x 32:1 L/D extruder. Within a few weeks the hard facing that had been welded on the flight OD started to pop off. (As shown in the attached photo) The flight failure was in an isolated area, so it was then assumed that the failure was due to a poor weld bond. The screw was ultra-sonically inspected and the remaining flights showed good bore, but the entire screw was rebuilt and returned to the customer.
Buying a used extruder
When buying a used extruder, it is important to carefully inspect the gearbox, feed throat, and barrel for excessive wear. Additionally, the extruder must have adequate torque for the intended application. Over time, advances in screw design have allowed for higher throughput rates but require more torque. A typical older 3.5" extruder from the 1960s-1970s with a 75hp motor could produce 700-750 lb/hr of PVC but only 400-450 lb/hr of HDPE. Modern 3.5" extruders require a minimum of 125hp and can produce 650-700 lb/hr of HDPE with a 150hp motor and updated screw design. Make sure a used extruder has the
Instrument Calibration
1) The author was asked to investigate screw design problems at a sheet extrusion facility with issues on all 5 of its lines.
2) To begin, the author measured the thermal expansion of one extruder barrel according to theoretical calculations and found it was within 0.030 inches, showing around 0.750 inches of expansion as expected. Wear patterns on screw flights were also consistent.
3) Process data gathered revealed the screw speed readings were miscalibrated, with one reading 24% too low and another 23% too high compared to actual counts, indicating the importance of verifying instrument readings.
Oversize Screw and Barrel
I have written in the past about screw/barrel wear and also screw rebuilding, but there are some screw and barrel shops that offer an alternative for excessive barrel wear and that is honing the barrel oversize and then rebuilding the screw oversize also to fit.
An experimental investigation into melt pump performance
This document summarizes an experimental investigation into melt pump performance using three different resins. Key findings include:
1. Melt pump efficiency and output decreased as discharge pressure increased, and efficiency was higher for stiffer resins which experienced less backflow. Stiffer HDPE had the highest efficiency while softer PS had the lowest.
2. Higher discharge pressures and pump speeds increased melt temperature. PP had the highest melt temperatures, followed by HDPE then PS.
3. Stiffer resins and higher pressures led to higher motor amperage requirements. Pump sizing should account for resin properties and system pressure differentials.
Gross Versus Net
Several years ago, a customer had ordered a new screw for their thin sheet process. They requested a throughput rate of 1600 lb/hr...
Solids conveying consistency
The material handling of the feedstock is a very critical part of the extrusion process. If the feedstock is not introduced to the feedsection of screw in a smooth and uniform matter, then the likelihood of a stable and consistent output is unlikely. This is the reason why it is very important that if regrind is added to the virgin feedstock, it must be done very consistently and uniformly. It should also be mentioned here that a very important part of the extrusion equipment is the hopper and feedthroat section. If the hopper and feedthroat sections are not designed properly, inconsistent material flow to the screw can take place. For example, if the conical section of the hopper (see figure) does not have the proper transition, the resin will not flow smoothly into the feedthroat of the extruder.
3D FEM Analysis of a Wave Type Screw Channel
The paper presents a fundamental study of the polymer flow within a “wave” type screw channel. The analysis is performed on an “unwrapped” form of a conventional screw channel and a “wave” type channel of similar size. A 3D Finite Element Method
(FEM) simulation was used to simulate the flow field and flow characteristics of the wave channel are compared relative to the plain channel.
New and Improved Screw Technology for Processing INGEO™ PLA
Since the early 1990’s INGEO™ resins have made enormous improvements in the process ability of their bio-polymer resins. In the early days, when the resin was first being manufactured at pilot plant levels, extrusion processing of INGEO™ was very difficult.
Today, natural additives are being used to improve the process ability of these resins. Several new lubricant additive packages were tested to determine which package produced the best overall performance and process improvements. The process data was used to quantify the process ability of the various additive packages.
The data was then compared to the internal pressure data that was collected to analyze and determine the best overall additive package.
Extruder Screw Cooling
There are basically three Coefficients of Friction (Figure 1) that take place in the feed section of the screw, (1) between the barrel and the pellet, (2) between pellet to pellet, and (3) between the root of the screw and the plastic pellet.
Comparison of two different cooling methods for extrusion
1. The study compared the power consumption of air cooling versus water cooling for an extrusion process using four different resins.
2. Water cooling used slightly more energy than air cooling for all resins, with the greatest difference seen in PET where water cooling used 80% more energy.
3. Air cooling is recommended for dedicated processes as it provides sufficient cooling with less energy use than water cooling, however the screw design must match the resin to avoid excessive heating or cooling needs.
General Extruder Audit Information
From time to time it is necessary to do a complete an audit on the condition of an extruder to make sure that it is operating in top condition for maximum effectiveness and efficiency. The following some general information that should be considered to accomplish a good Extruder Audit.
The effects of running different barrel temperature profiles for various resins
The effects of running different barrel temperature profiles for various resinsR&B Plastics Machinery
Differences in solids conveying, screw pressure profile generation, output, motor energy required, will vary between resins, barrel temperature profiles, and resin preheat temperatures, on a single stage low compression barrier screw design.A Method for Purging and Cleaning an Extruder Screw and Barrel
1) The best way to clean a screw and barrel is to remove the screw from the machine and clean it outside using brass tools and stearic acid rather than applying direct heat, which can damage the metal.
2) To purge the system, use HDPE plastic at 200C while slowly rotating the screw until the extrudate fully changes from the processing resin to HDPE.
3) Clean the screw using brass tools and stearic acid while exposing sections, then clean the barrel bore using a wire brush coated in copper gauze and stearic acid.
Empirical evaluation of different groove feed screw geometries
Plasticization rates can be greatly increased with the use of grooved feed extrusion. Grooved feed extruders can be used in a wide range of extrusion processes for higher output rates. This technology has doubled plasticization rates for some resins and processes as compared to smooth bore extruders.
This paper will compare the performance of three different screw geometries while processing fractional melt HDPE. One of the main methods of evaluation will be the comparison of internal pressure profiles over the entire length of the screw at eleven different locations down the length of the barrel at two L/D apart.
Screw and barrel wear
Screw and barrel wear is critical in all plasticating applications whether it is extrusion, injection molding, and blow molding, plus twin screw extrusion. Excessive screw and barrel wear can cause instable throughput or recovery on reciprocating screws, increased melt temperature and reduced plasticating rates.
Extruder or Injection Molding Machine Startup and Shutdown Article
Many companies have their own procedure for starting up and shutting down an extruder or injection molding machine and, depending on the process, there may be reasons for the specific method. But from the point of view on the effect of the screw itself, the following procedure will produce the best overall results.
Extrusion Screws for Thermoplastic Composites
There are two different areas of screw design for thermoplastic composites: the screw
design which is being used to make the thermoplastic compound and the screw
design which is used to process the compounded thermoplastic. This paper
mainly discusses the latter of the two types, but many of the issues are pertinent to both.
Screw and Barrel Inspection
Screw and barrel inspection plays a very important part in achieving exceptional production performance. The screw and barrel are major components of extrusion, injection molding and blow molding processes, and should be measured for wear at least once a year (preferably twice a year). Many U.S. companies schedule preventive maintenance (PM) during the week of Independence Day and again during the week of Christmas.
Barrel temperature profiles for barrier type screw
This document discusses recommended barrel temperature profiles for barrier type extrusion screws. It recommends:
1) Setting the die and adapter zones to the resin manufacturer's recommended melt temperature.
2) Setting the feed throat section 10-20°F warmer than ambient to preheat the material without causing bridging.
3) Installing screw cooling in the feed section to reduce friction and optimize solids conveying.
4) Evenly spacing the remaining zone temperatures between the feed and metering sections to gradually melt the resin using increased energy input.
Starting temperature profiles are provided for example resins to process them less stressfully and reduce wear on the screw and barrel.
A method for purging and cleaning a screw and barrel
This document provides guidance on properly purging and cleaning screws and barrels for extrusion and injection molding machines. It recommends using HDPE as a purging compound and rotating the screw at 15-20 rpm to purge the system. Direct heat from an acetylene torch should never be used, as it can damage screw tolerances and properties. Instead, simple hand tools like brass brushes and putty knives should be used to manually clean screws once removed from the machine. The document aims to help companies improve changeover and maintenance procedures in a safe and cost-effective manner.
Things Your Extruder Screw Designer Never Told You About Screws - Slideshow
This document provides an overview of screw design concepts for plastic extrusion. It discusses common screw nomenclature and sections including flighted length, diameter, feed, transition, and metering. Key concepts covered include length to diameter ratio, coefficient of friction, solids conveying theory, drag and pressure flow, and how viscosity affects pumping. Different screw technologies like barrier screws and two-stage screws are also summarized. The presentation emphasizes providing screw manufacturers with resin data and understanding screw mechanics to ensure optimal screw design.
Basic Screw Geometry: Things Your Extruder Screw Designer Never Told You Abou...
Basic Screw Geometry: Things Your Extruder Screw Designer Never Told You Abou...R&B Plastics Machinery
This document provides an overview of basic screw geometry for single screw extruders. It defines key terms like flighted length, screw diameter, and L/D ratio. It describes the different sections of the screw - feed, transition, and metering - and factors that influence their design like material properties, length, and compression ratio calculations. The document also discusses two-stage vented screw designs and how to calculate compression ratios and pumping capacities for different screw configurations.More Related Content
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Instrument Calibration
1) The author was asked to investigate screw design problems at a sheet extrusion facility with issues on all 5 of its lines.
2) To begin, the author measured the thermal expansion of one extruder barrel according to theoretical calculations and found it was within 0.030 inches, showing around 0.750 inches of expansion as expected. Wear patterns on screw flights were also consistent.
3) Process data gathered revealed the screw speed readings were miscalibrated, with one reading 24% too low and another 23% too high compared to actual counts, indicating the importance of verifying instrument readings.
Oversize Screw and Barrel
I have written in the past about screw/barrel wear and also screw rebuilding, but there are some screw and barrel shops that offer an alternative for excessive barrel wear and that is honing the barrel oversize and then rebuilding the screw oversize also to fit.
An experimental investigation into melt pump performance
This document summarizes an experimental investigation into melt pump performance using three different resins. Key findings include:
1. Melt pump efficiency and output decreased as discharge pressure increased, and efficiency was higher for stiffer resins which experienced less backflow. Stiffer HDPE had the highest efficiency while softer PS had the lowest.
2. Higher discharge pressures and pump speeds increased melt temperature. PP had the highest melt temperatures, followed by HDPE then PS.
3. Stiffer resins and higher pressures led to higher motor amperage requirements. Pump sizing should account for resin properties and system pressure differentials.
Gross Versus Net
Several years ago, a customer had ordered a new screw for their thin sheet process. They requested a throughput rate of 1600 lb/hr...
Solids conveying consistency
The material handling of the feedstock is a very critical part of the extrusion process. If the feedstock is not introduced to the feedsection of screw in a smooth and uniform matter, then the likelihood of a stable and consistent output is unlikely. This is the reason why it is very important that if regrind is added to the virgin feedstock, it must be done very consistently and uniformly. It should also be mentioned here that a very important part of the extrusion equipment is the hopper and feedthroat section. If the hopper and feedthroat sections are not designed properly, inconsistent material flow to the screw can take place. For example, if the conical section of the hopper (see figure) does not have the proper transition, the resin will not flow smoothly into the feedthroat of the extruder.
3D FEM Analysis of a Wave Type Screw Channel
The paper presents a fundamental study of the polymer flow within a “wave” type screw channel. The analysis is performed on an “unwrapped” form of a conventional screw channel and a “wave” type channel of similar size. A 3D Finite Element Method
(FEM) simulation was used to simulate the flow field and flow characteristics of the wave channel are compared relative to the plain channel.
New and Improved Screw Technology for Processing INGEO™ PLA
Since the early 1990’s INGEO™ resins have made enormous improvements in the process ability of their bio-polymer resins. In the early days, when the resin was first being manufactured at pilot plant levels, extrusion processing of INGEO™ was very difficult.
Today, natural additives are being used to improve the process ability of these resins. Several new lubricant additive packages were tested to determine which package produced the best overall performance and process improvements. The process data was used to quantify the process ability of the various additive packages.
The data was then compared to the internal pressure data that was collected to analyze and determine the best overall additive package.
Extruder Screw Cooling
There are basically three Coefficients of Friction (Figure 1) that take place in the feed section of the screw, (1) between the barrel and the pellet, (2) between pellet to pellet, and (3) between the root of the screw and the plastic pellet.
Comparison of two different cooling methods for extrusion
1. The study compared the power consumption of air cooling versus water cooling for an extrusion process using four different resins.
2. Water cooling used slightly more energy than air cooling for all resins, with the greatest difference seen in PET where water cooling used 80% more energy.
3. Air cooling is recommended for dedicated processes as it provides sufficient cooling with less energy use than water cooling, however the screw design must match the resin to avoid excessive heating or cooling needs.
General Extruder Audit Information
From time to time it is necessary to do a complete an audit on the condition of an extruder to make sure that it is operating in top condition for maximum effectiveness and efficiency. The following some general information that should be considered to accomplish a good Extruder Audit.
The effects of running different barrel temperature profiles for various resins
The effects of running different barrel temperature profiles for various resinsR&B Plastics Machinery
Differences in solids conveying, screw pressure profile generation, output, motor energy required, will vary between resins, barrel temperature profiles, and resin preheat temperatures, on a single stage low compression barrier screw design.A Method for Purging and Cleaning an Extruder Screw and Barrel
1) The best way to clean a screw and barrel is to remove the screw from the machine and clean it outside using brass tools and stearic acid rather than applying direct heat, which can damage the metal.
2) To purge the system, use HDPE plastic at 200C while slowly rotating the screw until the extrudate fully changes from the processing resin to HDPE.
3) Clean the screw using brass tools and stearic acid while exposing sections, then clean the barrel bore using a wire brush coated in copper gauze and stearic acid.
Empirical evaluation of different groove feed screw geometries
Plasticization rates can be greatly increased with the use of grooved feed extrusion. Grooved feed extruders can be used in a wide range of extrusion processes for higher output rates. This technology has doubled plasticization rates for some resins and processes as compared to smooth bore extruders.
This paper will compare the performance of three different screw geometries while processing fractional melt HDPE. One of the main methods of evaluation will be the comparison of internal pressure profiles over the entire length of the screw at eleven different locations down the length of the barrel at two L/D apart.
Screw and barrel wear
Screw and barrel wear is critical in all plasticating applications whether it is extrusion, injection molding, and blow molding, plus twin screw extrusion. Excessive screw and barrel wear can cause instable throughput or recovery on reciprocating screws, increased melt temperature and reduced plasticating rates.
Extruder or Injection Molding Machine Startup and Shutdown Article
Many companies have their own procedure for starting up and shutting down an extruder or injection molding machine and, depending on the process, there may be reasons for the specific method. But from the point of view on the effect of the screw itself, the following procedure will produce the best overall results.
Extrusion Screws for Thermoplastic Composites
There are two different areas of screw design for thermoplastic composites: the screw
design which is being used to make the thermoplastic compound and the screw
design which is used to process the compounded thermoplastic. This paper
mainly discusses the latter of the two types, but many of the issues are pertinent to both.
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An experimental investigation into melt pump performance
An experimental investigation into melt pump performance
New and Improved Screw Technology for Processing INGEO™ PLA
New and Improved Screw Technology for Processing INGEO™ PLA
Comparison of two different cooling methods for extrusion
Comparison of two different cooling methods for extrusion
The effects of running different barrel temperature profiles for various resins
The effects of running different barrel temperature profiles for various resins
A Method for Purging and Cleaning an Extruder Screw and Barrel
A Method for Purging and Cleaning an Extruder Screw and Barrel
Empirical evaluation of different groove feed screw geometries
Empirical evaluation of different groove feed screw geometries
Extruder or Injection Molding Machine Startup and Shutdown Article
Extruder or Injection Molding Machine Startup and Shutdown Article
More from R&B Plastics Machinery
Screw and Barrel Inspection
Screw and barrel inspection plays a very important part in achieving exceptional production performance. The screw and barrel are major components of extrusion, injection molding and blow molding processes, and should be measured for wear at least once a year (preferably twice a year). Many U.S. companies schedule preventive maintenance (PM) during the week of Independence Day and again during the week of Christmas.
Barrel temperature profiles for barrier type screw
This document discusses recommended barrel temperature profiles for barrier type extrusion screws. It recommends:
1) Setting the die and adapter zones to the resin manufacturer's recommended melt temperature.
2) Setting the feed throat section 10-20°F warmer than ambient to preheat the material without causing bridging.
3) Installing screw cooling in the feed section to reduce friction and optimize solids conveying.
4) Evenly spacing the remaining zone temperatures between the feed and metering sections to gradually melt the resin using increased energy input.
Starting temperature profiles are provided for example resins to process them less stressfully and reduce wear on the screw and barrel.
A method for purging and cleaning a screw and barrel
This document provides guidance on properly purging and cleaning screws and barrels for extrusion and injection molding machines. It recommends using HDPE as a purging compound and rotating the screw at 15-20 rpm to purge the system. Direct heat from an acetylene torch should never be used, as it can damage screw tolerances and properties. Instead, simple hand tools like brass brushes and putty knives should be used to manually clean screws once removed from the machine. The document aims to help companies improve changeover and maintenance procedures in a safe and cost-effective manner.
Things Your Extruder Screw Designer Never Told You About Screws - Slideshow
This document provides an overview of screw design concepts for plastic extrusion. It discusses common screw nomenclature and sections including flighted length, diameter, feed, transition, and metering. Key concepts covered include length to diameter ratio, coefficient of friction, solids conveying theory, drag and pressure flow, and how viscosity affects pumping. Different screw technologies like barrier screws and two-stage screws are also summarized. The presentation emphasizes providing screw manufacturers with resin data and understanding screw mechanics to ensure optimal screw design.
Basic Screw Geometry: Things Your Extruder Screw Designer Never Told You Abou...
Basic Screw Geometry: Things Your Extruder Screw Designer Never Told You Abou...R&B Plastics Machinery
This document provides an overview of basic screw geometry for single screw extruders. It defines key terms like flighted length, screw diameter, and L/D ratio. It describes the different sections of the screw - feed, transition, and metering - and factors that influence their design like material properties, length, and compression ratio calculations. The document also discusses two-stage vented screw designs and how to calculate compression ratios and pumping capacities for different screw configurations.More from R&B Plastics Machinery (6)
Barrel temperature profiles for barrier type screw
Barrel temperature profiles for barrier type screw
A method for purging and cleaning a screw and barrel
A method for purging and cleaning a screw and barrel
Things Your Extruder Screw Designer Never Told You About Screws - Slideshow
Things Your Extruder Screw Designer Never Told You About Screws - Slideshow
Basic Screw Geometry: Things Your Extruder Screw Designer Never Told You Abou...
Basic Screw Geometry: Things Your Extruder Screw Designer Never Told You Abou...