IPI Technical Presentation Compounding Basics - Requirements of Feeding, Dosing & Mixing Srikanth, 10.04.13, mc India
Extrusion & Compounding Srikanth, 10.04.13, mc India
Principle of “ Extrusion ” & “ Compounding ” Meat grinder principle
Different types of extruders Extruder Single Screw Co-rotating Twin Screw parallel Counter-rotating Co-kneader conical Internal mixer (e.g. banbury mixer) Planetary Roller Different extruder types are leading to different: � types of potential material supply Ring Extruder � necessary dosing principles � controls
Definition of Extrusion � Extrusion � a continuous, multi-stage manufacturing process � for producing thermoplastic parts with a fixed cross-sectional profile
Definition of Compounding � Compounding � a continous, multi-stage process for the production of plastic compounds � formulations are done by mixing polymers and additives in a molten state using twin screw extruders
Typical Products in “ Compounding ” Products Compound Masterbatch
Definition of “ Compound ” � Compound � Lower concentrated composite. Compound is used 100% in the end product !!!
Definition of “ Masterbatch ” � Masterbatch � Higher concentrated composite. Masterbatch is diluted in the endproduct with raw polymer (base resin) !!!
Requirements of Dosing & Feeding Srikanth, 10.04.13, mc India
Dosing processes in SSE / Counter-TSE and Co-TSE Dosing process Counter-rotating Co-rotating Twin Screw Single Screw Twin Screw Extruder Extruder (Co-TSE) Extruder (SSE) (Counter-TSE) flood fed starve fed
Definition of “ Flood Fed ” � Flood Fed (SSE, Counter-TSE) � At all times of the process, the extruder is flooded with material � the extruder screw chamber is overfilled!!! � Viewing the extruder main port from top, you cannot not see the screw of the SSE and Counter-TSE � Increasing the screw speed of the extruder always leads to increased throughput rates � Throughput rate is defined by the screw speed of the extruder and the throughput of the dosing unit has to follow � The SSE and Counter-TSE are production lines for endproducts (products are e.g. pipes, profiles, films and sheets) � The SSE and Counter-TSE can build up pressure in the direction to the downstream equipment (use of melt pumps not necessary)
Definition of “ Starve Fed ” � Starve Fed (Co-TSE) � The dosing units are dosing max. the amount of material which is necessary in the chamber of the twin screw to a max. 100% � no overfilling of the extruder screw chamber!!! � Viewing the extruder main port from top, you can always see the screw of the Co-TSE � Increasing the screw speed of the extruder never leads to increased throughput rates � Throughput rate is defined only by the throughput rate of the dosing unit � Throughput and screw speed of the extruder are independently set from each other � The Co-TSE is more a continous mixing device than a production line for endproducts (products are pellets e.g. Masterbatches or Compounds) � The Co-TSE can not build up high pressure in direction to the downstream equipment (often the use of melt pumps is necessary)
Dosing Principle, Devices & Process Integration Twin Screw Extruder dosing principle volumetric gravimetric dosed dosed dosing device synchronous synchronous dosing units dosing units (loss-in-weight) process integration starve fed
Feeding, Dosing & Mixing „ consistent defined premix throughput per unit of time “ Srikanth, 10.04.13, mc India
Feeding, Dosing & Mixing In the game of Chess, a „ good formation “ is important to achieve a winning result, since pieces in isolation cannot perform. Courtesy: „ The Extruder Times – Steer Consultancy Services “ Srikanth, 20.04.13, mc India
Feeding, Dosing & Mixing Technical Concepts Srikanth, 10.04.13, mc India
Materials Management – Dosing & Mixing What are the goals of Dosing & Mixing? � Defined material throughput per time unit with a dosing unit � To guarantee quality constancy with controlled material throughput � To guarantee a homogeneous mixture of all materials � To guarantee process safety � Cost optimization in regards of prime material consumption � Process documentation (e.g. medical technology, automotive , etc.)
Materials Management – Dosing & Mixing Process types: Continuous Discontinuous -Cyclical process interruption -Continuous mass flow of material (kg/h) (parts per hour) -Discontinuous mass flow of material with finite resolution � Extrusion, Compounding � Injection moulding
Materials Management – Dosing & Mixing Dosing unit types: Cone dosing Synchronous Asynchronous -Batch dosing -No process interruption -Cyclical process interruption -Throughput indication in kg/h, etc. -Throughput indication in kg/batch/time � Discontinuous mass flow � Continuous mass flow
Materials Management – Dosing & Mixing Dosing methods: Gravimetric dosing Volumetric dosing Dosing without weighing Dosing with weighing
Materials Management – Dosing & Mixing Dosing methods: Gravimetric dosing Volumetric dosing Synchronous Asynchronous Synchronous Asynchronous -Theoretical control of material throughput -Control of material throughput by -Simple control mechanism weighing detection in combination with -No complex measurement and control closed loop control necessary (Loss In Weight or Gain In Weight) -No process controlling necessary -High process safety -Economic in purchasing -Process logging & documentation possible -Expensive in purchasing
Materials Management – Dosing & Mixing Extrusion Dosing Blow Blown Flat- and HT-sheet and Sheet, procedure moulding Fibre Cable Profil Pipe film strech film HT-film Cast film Asynchronous volumetric Synchronous volumetric Asynchronous gravimetric Synchronous gravimetric In-Line Compounding processes Dosing procedure Engineering- Cable Masterbatch Masterbatch Metal- Natur. fibre PLA- Conti. Disconti. Compound Comp. (Monobatch) (Tailor made) Comp. compound Comp. Asynchronous volumetric Synchronous volumetric Asynchronous gravimetric Synchronous gravimetric Not suitable Technically possible Typical application
Feeding, Dosing & Mixing Methods Srikanth, 10.04.13, mc India
Materials Management – Dosing & Mixing Dosing methods: Volumetric dosing 3. Manual adjustment of the control Control 2. n Manual 1. measurement Measuring: with common Manual lab scale measurement with Quantity of dosed volume in measuring bin relation to speed and time. � Bulk density and throughput Controlled by: may change … Motor speed controller
Materials Management – Dosing & Mixing Gravimetric Dosing methods: Gain-In-Weight-Principle + Δ m Measurement: Quantity gain; Δ m/ Δ t Typical for: Discontinuous processes, e.g. batching
Materials Management – Dosing & Mixing Gravimetric Dosing methods: Loss-In-Weight-Principle - Δ m Measurement: Quantity throughput; Δ m/ Δ t Typical for: Continuous processes � Independently from the weight measuring method a control and regulation loop is necessary !
Materials Management – Dosing & Mixing Gravimetric Dosing methods: Gravimetric dosing (LIW) Loss In Weight processor Load cell � Automatic calibration through Loss In Weight control and scale + system n � Compensation of bulk density Control changes Measuring: Throughput measurement (mass flow) MINICOLOR G SPECTROCOLOR G Controlled by: GRAVIPLUS Differential quotient of mass and time
Materials Management – Dosing & Mixing LIW process: High resolution load cell − ∆ m t m t m ( ) ( 1 ) = − i i − ∆ t t t − i i 1 Settle down Refilling phase phase Gravimetric dosing phase
Materials Management – Dosing & Mixing LIW process: Refill+settle down time must be less than 10% of total dosing time! Refill complete Refill window Refill request
Materials Management – Dosing & Mixing Dosing methods overview: Automatic Material conveying Material storage Automatic refilling W Dosing bin with S Agitator (if necessary) Load cell S Dosing module with Controlled drive Filling level sensor technology Collecting bin and agitator (if necessary) Vibration damper Volumetric Gravimetric
Feeding, Dosing & Mixing Products Srikanth, 10.04.13, mc India
Materials Management – Dosing & Mixing Classifying the flowing characteristics (DIN ISO 3435): • Classifying: 45° 30° α • Free flowing material: angle of repose α : 0 - 30 ° • Normal flowing material: angle of repose α : 30 - 45° • Non free flowing material: angle of repose α : 45 - 60° • Clumpy material: angle of repose α : > 60° • Non-gliding material: sticking, bridge-building, difficult to separate
Materials Management – Dosing & Mixing Gravimetric dosing stations: Cone/Screw Screw Dosing & mixing station dosing & mixing station for granules, powders, dosing & mixing station for granules fibers & liquids for granules Gain-In-Weight Blender Loss-In-Weight Dosing Unit Loss-In-Weight Dosing Unit GRAVICOLOR SPECTROCOLOR G GRAVIPLUS
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