Large Capacity Extrusion Technology for the Next...

September 26-28, 2007 – Boston, MA

Large Capacity Extrusion Technology for the Next Decade

Tom Brown

Director of Sales & Marketing

Cincinnati Milacron Extrusion Systems Business


1000 Pounds /Hr

700 RPM

750 RPM

150 Amps

FASTER!!!

1750 RPM

1500 Pounds/Hr3000 Pounds/Hr

1400 RPM!

5000 Pounds/Hr

350 Amps

Large Capacity Extrusion Technology for the Next Decade

The Trend !

September 26-28, 2007 – Boston, MADrivers for Large Diameter Extruders

Higher Throughput RatesProduct Changeover TimeOptimal Efficiency

UptimeYield Rate Minimal Scrap

Energy Savings Environmental Quality & Consistency of Extruded partRaw Material Cost & Weight Savings

Gravimetric FeedingFoam Coextrusion Processes

Ability to Cool and Pack

September 26-28, 2007 – Boston, MA Applications

(1) Source: Global Industry Analysts Consultancy

GLOBAL USAGE OF PLASTIC PIPE WILL GROW 6.8% ANNUALLY... (1)

This will take usage to 7.3 billion meters (24 billion ft) by 2010

The most important factors in this impressive growth rate are:

Growth in plastic pipe for the natural gas industry and the telecommunications industry

Infrastructure improvements in emerging countries will aid growth, especially for plastic pipe for:

Drinking water

Sewage

Drainage

PVC pipe will enjoy the greatest growth


140mm Parallel Twin for Large Diameter Rigid PVC Pipe

Pipe

Diamond Plastics Corporation


86mm Conical Twin & 2” Single Screw for Co-Extruded PVC based WPC Hand Rail System

WPC Decking & Railing


Coextrusion Systems for Vinyl Fence (140mm Parallel Twin with Two 55mm Conical Coextruders)

Vinyl Fence

September 26-28, 2007 – Boston, MA Foamed & Homogeneous Rigid PVC Sheet

140mm Parallel Twin Screw for 48” wide and up to 25mm Thick Foamed Rigid PVC Sheet


Basic Components of an Extrusion Line

Drive SystemExtruder

Die

CalibrationPullerSawCollection

Feeder

Dump Table

Stacking Table

Pipe Beller

Coiler

Vacuum Calibration

Table

Vacuum Spray Tank

Water Spray Tank

Sheet Roll Stack

Pipe

Profile

Sheet

Coex

Twin Screw

Single Screw

Downstream System(As rate increases, becomes longer or dual or both)

Extruders & Extrusion Systems

Dry Blend from Upstream Material Handling and Blending System

Primary Components & Variables:Raw MaterialsUpstream Material Handling & Blending SystemExtruderToolingDownstream System

Source: Zeus Industrial Products

September 26-28, 2007 – Boston, MAPipe, Profile & Sheet Extrusion Systems


CONICAL

PARALLEL

Application Versatility – Low to Mid Range RateNatural Compression – Large vol. to small vol.

Fixed L/D due to cone angleHigh surface area in feed zone for heat transmission

Tungsten Clad Barrel – Excellent Life/Difficult to rebuildScrews can be rebuilt with Tungsten or Molybdenum

Application Versatility – Mid to High Range RateCan lengthen L/D for process versatility

Low process temps over longer L/D for consistent melt tempConsistent melt flow, screw tips into die

Bimetallic barrels can be re-linedScrews can be rebuilt with Tungsten or Molybdenum

Comparison of Conical & Parallel Twins

September 26-28, 2007 – Boston, MAConical Twin Screws (1) – Range of Technology

96mm Conical Twin for WPC Deck Board

Pipe, Sheet, Siding, WPC, Pelletizing150 - 200Up to 2,80027 – 30 92 – 96

Profile, Pipe, Sheet, Fence, Siding, WPC75 – 125Up to 2,00023 – 2780 – 86

Profile, Pipe, Fence, Siding, WPC, Coex50 – 53Up to 1,21022 – 2465 – 72

Profile, Pipe, Fence, Siding, WPC, Coex40 – 50Up to 70022 – 2355 – 63

Profile, Pipe, Coex17 – 41Up to 50022 – 2440 – 54

Profile, WPC, Coex13 – 20Up to 26423 – 2435 – 39

ApplicationHPOutput

Range (lbs/hr)Flight Length

(D) (3)Front Dia. (2)

Range (mm)

(1) Counter-Rotating Twin Screw Extruders(2) Sources: Am. Maplan; Cincinnati Extrusion; Cincinnati

Milacron; Davis-Standard; Krauss-Maffei; Theysohn(3) Based on front (discharge) diameter


Pipe, Sheet218 - 3114180 – 500022.5 – 28164 – 173

Pipe, Sheet, Fence, Siding, WPC123 – 2501386 – 360026 – 33128 – 140

Profile, Pipe, Fence, Siding89 – 1561210 – 242026 – 36114 – 118

Profile, Pipe, Fence, Siding55 – 125781 – 180021 – 26100 – 110

Profile, Pipe, Fence, Siding Coex50 – 104748 – 165026 – 3690 – 98

Profile, Pipe32 – 68484 – 107823 – 2872 – 88

ApplicationHPOutput

Range (lbs/hr)L / DDiameter (2)

Range (mm)

Parallel Twin Screws (1) – Range of Technology

(1) Counter-Rotating Twin Screw Extruders(2) Sources: Am. Maplan; Cincinnati Extrusion; Cincinnati

Milacron; Davis-Standard; Krauss-Maffei; Theysohn

172mm 26:1 L/D Parallel Twin for RPVC Sheet


Improvements in Formulations

Improvements in Tooling Designs

Improvements in Downstream Capability

Improvements in Gear Box Designs/Thrust Bearings

Improvements in Screw Designs

Ability to add Tungsten Carbide to Screws & Barrel

Gains In “Processing” – Not Just the Extruder


ScrapPoor

OK/MarginalGoodPoor

ScrapPoor

OK/MarginalGoodGood

Poor

ScrapPoor

MarginalGoodPoor

OKPoor

ExcellentGoodGood

Good

Final ProductExtrusion Conditions

Compound FormulationBlend Plant

PVC Twin Screw Matrix


What Determines Output Rate:

Diameter of Screws

Centerline Spacing of Gear Box Shafts

RPM of Screws

Geometry of the Screw Design

Designing The “Next Size Up” Extruder


Feed/Conveying Pre-Heat #1 Pre-Compression Compression Vent Metering Mix Head

Gentle plastification via balance of high surface area (mixing), shear heat (screws) & external heat (barrel) throughout length of processing chamber to achieve fusion of PVC formulation, without reaction of blowing agent until material exits extruder and enters die

Removal of volatiles and entrapped gas in vent zone. This is very critical to the success of PVC foam processes!

Homogenize and smooth out melt in metering zone; Pressurize material to push through die

Additional gentle mixing in Mix Head to 1) disperse melt & eliminate possibility of screw marks in extrudate; 2) If a foam process, react blowing agent as it exits from extruder and enters die

Zone Starts: (3) (6) (3) (2) (2) (2) (6)

Conveying Melting

Melting & Mixing Venting Homogenizing

PressurizingMixing

Parallel Twin Screw Design

High Surface Area

Mixing


Because of the shear sensitivity of PVC, twin screw extruders have dominated the PVC extrusion field.

Screw designs among the major suppliers vary greatly in design

Twin screw extruders rely more on heat transfer and less on shear.

Objective is to increase heat transfer early in the extruder to minimize the need for shear input for melting

Two basic theories to screw design:

Low surface area / High shear

High surface area / Low shear

See graphs of energy input

Counter-Rotating Twin Screw Extruders for PVC


A low surface area design requires high shear to reach ideal melt temperature.

A high surface area design allows the material to reach a higher temperature prior to the compression zone, thus requiring less shear to get the process to ideal temperature.

High Surface Area-Low Shear

Low Surface Area-High Shear

The “Acceptable” Process (Melt) Temperature Range

Process Window for Low Surface Area/High Shear Design

Process Window for High Surface Area/Low Shear Design

High & Low Surface Area Screw Designs

Combination of Heat Transfer & Shear


High Surface Area DesignPressure Drop -

Mixing

High Surface Area / Low Shear Design


Low Surface Area Design

Poor Heat Transfer

Increasing Compression

Leads to High Shear

Low Surface Area / High Shear Design

September 26-28, 2007 – Boston, MAVarious Ways of Measuring L/D

Longer L/D is good – adds more Heat Transfer. Surface area addition with screw design is preferable.

If the screw design is correct you only need 24-28 L/D

High filled formulations, clear semi-rigids, flexibles or wood composite materials require more residence time and work and may require longer L/D to be processed

If L/D is too long, problems can occur:

Twist of screws causes design issues at the exit end of the extruder

Wear and flex failures can be more pronounced necessitating the use of wear resistant materials such as tungsten carbide

Additional length can be obtained through the use of a pre-heater upstream of the extruder to elevate and stabilize the temperature of the raw material feed stream


Torque Master®

Newer 4-shaft gear boxes have been successful in reducing the total torque transferred in one gear stage to 17.5%, whereas traditional 3-shaft gear boxes are at 30% of total torque on one gear.

Allows for a 40%+ higher motor rating, thus helping to meet today’s higher output requirements

Greater stability & reliability

More output per extruder size

Longer service life

Source: Eisenbeiss Torque Master Gear Box 4-Shaft and Gearing Arrangement

Strength in the Gear Box !


The most important technical advances in any extruder continue to be in the ability to reach higher output rates while maintaining melt homogeneity; in the strength of the gear box; and in the quality of the control system.

Pipe, the largest segment user of rigid PVC will continue to increase in diameter and match PE which is already at 72”. The tooling is already developed, and is designed to handle up to 10,000 lbs/hr. The Extruder will need to achieve this too, meaning the technology will advance to the next level.

Extrusion lines will be going faster and faster. In the meantime, many processors are improving their productivity by focusing on improvements to existing equipment and tooling, upstream and downstream systems.

Total cooling length is important. Proper cooling at high throughput rates is absolutely required to maintain the best possible physical properties in all extruded products from PVC.

Power and water consumption will be key issues as costs for power continues to increase and our sources for fresh water become more scarce and difficult to access.

Summary and Conclusions

September 26-28, 2007 – Boston, MASummary and Conclusions

One single large extruder to handle the full range of output

or

Two extruders feeding a reverse Y-Block and combining the outputs of the two to make a single product.

Options Available to Go Bigger & Faster:

September 26-28, 2007 – Boston, MASummary and Conclusions

Alternatives available for continuing to grow:

Maintaining L/D in the 24-26:1 range and incorporating a Pre-Heater OR Extending the L/D and having the extruder handle the full range of output alone

Large Capacity Extrusion Technology for the Next...

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