An oem would classify this machine as a flighted length f. The length of the cooling hole and the flow rate of water are used to maintain the screw tempera ture in an optimal range. Other authors adopted a statistical analysis for screw design purposes. In junes column, we simplified extruder screw output using the dragflow equation for a. The extruder screw rpm is independent from the feed rate and is used to optimize compounding efficiencies. Handson examples and case studies hanser publications. To calculate the throughput of an extrusion system you must know a number of values related to the system pressure, the dimensions of the extruder and. Advancements in screw design technology for the blown. There are several advantages of the modern extrusion process 1. Plastic extrusion screw design and types of extrusion. Alternatively, the decision maker can apply equation 2 to. Hot endextruder combos can only flow so much material before they start skippingetc.
Screw wear should be measured and the results recorded on a screw inspection report print sample pdf at right in the following manner. By using a grooved feed throat, the output of the extruder is increased compared to a machine with. You can improve the accuracy of the calculation by entering the specific gravity of your. Jim frankland is a mechanical engineer who has been involved in all types of extrusion processing for more than 40 years. Motor size and thrust bearing life 2 5 6 9 17 22 26 29 1.
If an oven is used to clean the screw, take care to avoid temperatures higher than 800f. The capacity of the extrusion conveyor and its power requirement were respectively, 18. By contrast, our extrusion guide book egb is intended to provide practical down to earth answers to. There are a number of respected publications on the market devoted to the extrusion process but many focus on the theory, rather than the reality, which makes them impractical for operators or too academic for educational and training purposes. Understanding plastics engineering calculations hanser. The formula based on heating the polymer is only an estimate of potential output. The effect of changing the ld ratio can be summarized in the following manner the larger the ratio longer flighted length, the. Plastics extrusion is a highvolume manufacturing process in which raw plastic is melted and formed into a continuous profile. Analyzing and troubleshooting singlescrew extruders. The region of the barrel under the hopper zone 0 should. Singlescrew extrusion the extruder characteristic drag flow the couette.
January 12, 2011 extrusion is a production process that uses a screw to force material through a pressurized system. However, to understand the basics of singlescrew performance requires only a simple handheld calculator. The water then flows back out of the screw through a section of cast pipe. Thermoset screws processing considerations to maximize processing performance 18 19. January 31, 2011 determine the productivity of your workshop extruder by calculating its flow rate. The material used in the tests consisted of a blend of 45% 1. Screw rpm 80 root temperature 50 c screw diameter 63. How to calculate extruder throughput by dan howard, ehow contributor updated. The shaft diameter and screw geometry, which includes screw pitch and angle, were 20 and 56 mm, and 16. The calculation is based on standard extruder screw geometry. To be an expert takes some very specialized training and experience. Adiabatic extruder for sheet extrusion uses 10% less specific energy the extruder can be used to process pp, ps, apet, cpet, pla, pe and also pc. Extrusion produces items such as pipetubing, weatherstripping, fencing, deck railings, window frames, plastic films and sheeting, thermoplastic coatings, and wire insulation.
The mechanism of operation is most easily appreciated by considering that the screw is stationary and that the barrel rotates. Doboczky found that the ratio of observed to theoretical output varied from roughly 50 to 90%, with 70% being a mean value. By including the cold zones or weld zones, the formula will. It was also possible to calculate the mass flow rate and the velocity drop. The ld ratio for extrusion screws generally range from 24. The programmable calculator a tool for measurement of. In order to minimize the residence time and maximum output, the screw speed must be increased during the compounding. The abovementioned parameter represents the basic criterion for purchasing new expensive equipment for extrusion technology. This is an extrusion rate calculator for flighted feed screws used in thermoplastic melt processing. Classification of extrusion processes the two basic types of extrusion are direct and indirect, which are commonly used in aluminum industries as shown in fig.
Extrusion extrusion is used for processing most types of thermoplastics and rubbers. The design of a screw for plasticating polymer extrusion based on scientific. The plastic extrusion screw model is shown in figure 3. The design of screw is important for plastic processing. Max impact screws are designed to provide the maximum output at the maximum value. To be able to predict the throughput of a singlescrew extruder or the metering time of an injection moulding machine for a given screw geometry, set of processing conditions and polymeric material is important both for practical and designing purposes. Oct 26, 2012 the effects of torque and ld require screw design smarts in order to be properly estimated. Dsbm davis standard barrier maddock ssmm single stage maddock mixing ssm single stage metering extrusion output rates. D ld because that is the actual amount of machine work which the screw manufacturer must do to complete the product. Extruders channel materials, such as dough or clay, though a rigid tube. The extruder showing the hopper, the barrel with heating zone. The geometry of screw extruders is characterized by one or multiarchimedean screws housed in a heated barrel with a lengthtodiameter ratio ld typically of 1550.
To calculate the throughput of an extrusion system you must know a number of values related to the system pressure, the dimensions of the extruder and the properties of the material that you are extruding. Unless specially designed, there is little backmixing in standard screw extruders. Extrusion parameters such as barrel zone temperatures and screw speed can be utilized to increase the tensile strength of the composite matuana and li, 2004. If a threezone screw is not capable of completing the melting process and higher output rates are required, a barrier screw can be employed. Different types of polymer will have different screw designs. The control on the linemaster hopper monitors weight while reading and updating. Extrusion flowrate calculator by luckypants thingiverse. Report two or three times, to check output consistency. This will be the output rate of the extruder in lbshr or kghr. Measuring screw and barrel wear reiloy westland corporation. Special attention needs to be taken into account while designing screws for the film extrusion process, particularly for multilayer barrier film extrusion, due to. Hsei twinscrew extruders are starve fed with the output rate determined by the feeders.
Extrusion is a production process that uses a screw to force material through a pressurized system. A simple way to evaluate your screw performance, part 2. Depending on the type of extruder, the output is determined either by the geometry of the solids. Depending on the material, the 34dlong single screw extruder with a screw diameter of 75 mm, operating at screw speeds. Jun 04, 2010 extruder feedscrew design, more than any other part of an extrusion system, determines the productivity and quality of the extruded product. That is why the problem of determining the extrusion force is given special attention in the referential literature. This article mainly focuses on the extrusion of thermoplastic products due to their.
Extrusion output of hot feed screw designsextrusion output of hot feed screw designs source. In general, the cooling hole is drilled into the screw up to. Doboczky also argued that the output of a twin screw extruder is about three times as high as that of a single screw extruder of a similar size and screw speed. Excursions were held to a couple of big industries in. Hsei twin screw extruders are starve fed with the output rate determined by the feeders. In hot extrusion, the billet is preheated to facilitate plastic deformation. L p tan e d q l t p s g 12 2 3 l p tan e d l p sin dh q d hn sin cos t p s g t p s s t t 2 12 12 1 23 2 in our analysis we neglect this term 0 note. Extrusion can be cold or hot, depending on the alloy and the method used. Feeders meter solids pelletsfillers, and so on or liquids into the hsei twin screw extruder. For example, the simultaneous optimization of the channel depth and helix angle for melt conveying in order to maximize the output can be carried out. Classification of extrusion processes the two basic types of extrusion are direct and indirect, which are commonly used in aluminum industries as shown in. In june, we also showed the full formula if the pitch is other than standard. The pressure is generated from the action of screw rotation against barrel wall.
Initially the calculation assumes a specific gravity of 1. The mechanism of operation is most easily appreciated by considering that the. The programmable calculator a tool for measurement of extruder performance vol. Drag flow mechanism down channel velocity component vz v cos. Feeders meter solids pelletsfillers, and so on or liquids into the hsei twinscrew extruder. Understanding screw design for film extrusion process macro. All the screws were equipped with a maddock type mixer on the discharge end of the screw with approximately the same mixer undercut clearance of. A handheld calculator and some basic equations can help. The extruder characteristic for a newtonian fluid is a linear relation between q and. Pdf design of single screw extruder for homogenizing bulk. Pdf the design of a screw for plasticating polymer extrusion based. A too high or too low output results when the dimensions.
Pdf design of single screw extruder for homogenizing. A simple model of throughput calculation for single screw. To calculate the throughput of an extrusion system you must know a number of values related to the system pressure, the dimensions of the extruder and the properties of the material. This screw has a secondary flight barrier flight in the channel which is undercut and permits the passage of only fully molten plastic.
How to calculate extruder flowrate by william hirsch, ehow contributor updated. Screw designers are constantly asked to improve output quantity without sacrificing qualityor to improve both at the same time. Checking extrusion output rates without the use of a. Clean the screw, while hot, with a soft wire brush and copper or brass gauze and allow to cool to room temperature. Pdf a simple model of throughput calculation for single screw. Linemaster extrusion control linemaster automatically regulates the drive speeds of an extrusion line to ensure the correct amount of material is used and excess material is eliminated.