TECHNICAL
RUBBER COURSE
Mixing Technology
& Machinery
Robert Dickstein
June 2003
.
Main
Topics
• Commonly used Rubber Compounding machinery
• Basic mixing theory
• Intermeshing and tangential batch mixers
• Practical Aspects of Batch mixer operation
Main
Main
Primary Compounding Machinery
TYPE
General
Advantages
Disadvantages
MILLS
First Rubber
compounding
machine
(not generally a
primary mixer
they are used
as a post mixer
forming device)
-
Very versatile
Broad range of shear capability
accepts all feed forms
good for short production runs
- difficult to control
- difficult to automate
- batch to batch variation ( due to
weighments, feeding ,&heat & shear
history)
- dirty operation
- safety considerations
- low output
- varying power demand
- labor intensive
BATCH MIXERS
Most common
Rubber
compounding
Machinery
-
accepts all feed forms
high output
can be automated
good for short production runs
long life expectancy
broad range of shear capability
- varying power demand
- batch to batch variation
(mixer control & weighments)
- post mixer variable product heat history
- capital intensive
- need post mixer forming
- can be labor intensive
CONTINUOUS
MIXERS
Specialty
applications
- high output
- energy efficient
- ease of process optimization
- easily automated
- uniform product shear & heat
history
- need free flowing feed (particulate
rubber)
- require sophisticated weigh & feed
systems
- not applicable for short runs
- difficult to clean
- capital intensive
- need post mixer forming
TWIN SCREW
EXTRUDERS
Newer
technology
Specialty
applications
-
- need free flowing feed(particulate
rubber)
- require sophisticated weigh & feed
systems
- not applicable for short runs
- difficult to clean
- capital intensive
- configuration changes required
Main
energy efficient
ease of process optimization
easily automated
geometry optimized for use
uniform product shear & heat
history
Compounding’s Quality Objective
QUALITY PRODUCT
PRODUCT POTENTIAL
WHEN PROPERLY FABRICATED THE
PART MUST MEET ALL PHYSICAL
REQUIREMENTS
Main
PROCESSABILITY
THE PRODUCT MIX MUST EASILY
BE FORMED INTO THE FINAL
PRODUCT SHAPE
Process Technology
Compound
Ingredients
Main
Compounding
Machinery
The Mixing Process
Main
Raw Materials
Typical Material Concerns
•Polymer type age, uniformity & purity
•MW & MWD
•entanglements
•thermal &oxidative characteristics
•homogenization of single or multiple polymers
(phase morphological concerns-compatibly)
•environmental and geometric affect of polymers
•filler type( extending,reinforcing,& reactive fillers)
• age,uniformity, purity,reactivity
•particle size and particle size distribution
•requirement to breakdown agglomerates or pellets
• the possible forming of agglomerates
•requirements for efficient filler/polymer interaction
•type of plasticizers ,protective additives,reactive chemicals
•age,uniformity, purity,reactivity
•lubricating affects of liquid and melting additives
•threshold temperature affects for incorporation
•maximum temperature limitations
Main
TYPES OF MIXING
REACTIVE
Main
DISPERSIVE
High shear
DISTRIBUTIVE
Batch Mixing Technology
Main
Basic Components of The Batch Mixer
AIR or HYDRAULIC
CYLINDER
(ram actuator)
HOPPER
HOPPER COVER
ASSEMBLY
RAM
CHAMBER
ROTORS
(Tangential or Intermeshing)
Mixer motor drive
& reduction set
Main
Batch discharging
mechanism
DROP DOOR
THERMOCOUPLE IN
DROP DOOR OR END FRAME
(indicated mix temperature)
Batch Mixing
Technologies
Intermeshing
Intermix® “Mark 5”
Main
Tangential
Banbury® F series “ST”
Machinery in Application
AREAS O F APPLICATIO N
% O F INTERM IX®
BATCH M IXERS IN
APPLICATIO N
% O F BANBURY® BATCH
M IXERS IN APPLICATIO N
TIRE CO M PO UNDS
5
57
TECH NICAL RUBBER G O O DS
ie,SEALS,H O SE , AND CUSTO M
M IXING
79
23
W IRE AND CABLE
7
3
3
4
6
13
FLO O RING
PLASTICS CO M PO UNDING
Main
Areas of mixer application
Intermix ®
&
Banbury®
-medium viscosity formulations
-general rubber goods
Intermix ®
Banbury ®
-specialty rubber goods
(low temperature compounding )
-extreme quality applications
-high volume applications
-easy to mix formulations
-sticky materials
•reactive mixing applications (high viscosity)
•single step mixing applications
•multiple step mixing applications
(especially final mix of high
viscosity compounds)
Main
Selected Items of Comparison
Mechanical
INTERMESHING ROTOR DESIGN
TANGENTIAL ROTOR DESIGN
• Ram actuation
(HYDRAULIC OR PNEUMATIC)
• Hopper door
• Ram or weight design
• Mixer sides
• Mixer rotor end plates
• Mixer rotors
• Drop door design
• Drop door latch mechanism
• Dust stops
Main
Main
1
Hydraulic hopper Actuation
Potential Benefits
•Eliminates compressed air
requirements
•Efficient application of high
batch pressure
•Potential Increase of process
repeatability due to the
elimination of the variations in
the plant air supply
•Potential reduction in plant
operating expenses
• it allows position control and
variation of pressure on the
batch during the mixing cycle
Main
Batch & Cylinder Pressure
CYLINDER AIR PRESSURE
- air pressure applied to the
piston in the cylinder forcing
the weight down
BATCH or RAM PRESSURE
- pressure applied by the
bottom of the weight
on the batch
Main
Batch & Cylinder Pressure
Cylinder Vs Batch Pressure
(F-270 - 22 inch diameter air cylinder)
70
Batch
PSI
60
50
40
30
20
10
0
10
20
30
40
50
60
70
Air cylinder PSI
Main
80
90
100
Batch & Cylinder Pressure
(hydraulic system for F-270 mixer)
Main
“BATCH” AND “CYLINDER”
PRESSURE
PSI T
(PSI ABOVE PISTON)
BATCH PSI = f (PSI T - PSI B) x AREA PISTON
AREA WEIGHT
MIXER AIR CYLINDER PERFORMANCE
(assume area of piston = area of weight)
( Batch pressurization time)
PSI B
90
( PSI BELOW PISTON)
80
PSI
(CYLINDER)
70
AIR PRESSURE ABOVE PISTON
IN CYLINDER
60
BATCH PSI
50
( EFFECTIVE PRESSURE
ON BATCH)
40
RESIDUE
PSI
AIR PRESSURE
BELOW PISTON BLOCKAGE
SLOW PRESSURIZATION
BATCH
30
PRESSURIZATION
IN CYLINDER
20
10
0
0
15
20
30
TIME (SECONDS)
Main
40
50
60
“BATCH” AND “CYLINDER”
PRESSURE
PSI T
(PSI ABOVE PISTON)
BATCH PSI = f (PSI T - PSI B) x AREA PISTON
AREA WEIGHT
MIXER AIR CYLINDER PERFORMANCE
Increased pressurization time
PSI B
Legend
PSI(top)
PSI(B)
PSI (B res.)
PSI (EFF.-1)
PSI (EFF-res)
90
( PSI BELOW PISTON)
80
PSI
(CYLINDER)
70
60
BATCH PSI
50
( EFFECTIVE PRESSURE
ON BATCH)
40
RESIDUE
PSI
SLOW PRESSURIZATION BLOCKAGE
FAST
30
PRESSURIZATION
20
10
0
0
15
20
30
TIME (SECONDS)
Main
40
50
60
Selecting a
Hydraulic or Pneumatic
actuated ram
Topics to be addressed
• Tangential
Vs Intermeshing rotor mixer
• Consistency of air pressure to mixer
• Quality & quantity of supplied air
• Operating cost
• Environmental considerations
• System Maintenance costs
• Capitol investment
• Knowledge of system operating characteristics
Main
Selected Items of Comparison
Mechanical
•
•
•
•
•
•
•
•
•
TANGENTIAL ROTOR DESIGN
Ram actuation
Hopper door
Ram or weight design
Mixer sides
Mixer rotor end plates
Mixer rotors
Drop door design
Drop door latch mechanism
Dust stops
Main
Main
INTERMESHING ROTOR DESIGN
1
Intermix® full down weight position
The ram when full down is an
extension of the body bore
( the bottom becomes a working surface)
Main
Banbury® full down weight position
The ram full down position is
elevated.The Elevated Position
is necessary for efficient venting
and material flow within the
mixing chamber
Main
Selected Items of Comparison
Mechanical
•
•
•
•
•
•
•
•
•
TANGENTIAL ROTOR DESIGN
Ram actuation
Hopper door
Ram or weight design
Mixer rotors
Mixer rotor end plates
Mixer sides
Drop door design
Drop door latch mechanism
Dust stops
Main
Main
INTERMESHING ROTOR DESIGN
1
Intermix ®
Dispersive and Distributive Mixing
Dispersive Mixing
Distributive
Mixing
Main
Intermix rotor designs
(increased fill factor and shear flow)
NR 5
Main
NR 2
Mixing Action “Banbury ®”
Distributive
Dispersive
Even speed or friction operation
Main
F-Series Banbury Mixers
(tangential mixers)
Even speed Rotor
Alignments
Main
F-Series Banbury® Mixers
(tangential mixers)
F series Banbury rotor types
ST™ / SN4T
4 wing / SK
WFT
Main
2 wing
Feeding Efficiency
Intermix ® Vs. Banbury ®
Main
Selected Items of Comparison
Mechanical
•
•
•
•
•
•
•
•
•
TANGENTIAL ROTOR DESIGN
Ram actuation
Hopper door
Ram or weight design
Mixer rotors
Mixer rotor end plates
Mixer sides
Drop door design
Drop door latch mechanism
Dust stops
Main
Main
INTERMESHING ROTOR DESIGN
1
Drop door designs of the
Intermix ® Vs. Banbury ®
a full extension of the body
bore for maximum shear work
and heat transfer
Intermix ®
Main
Contoured to be an extension of
the body bore and relieved to permit
material transfer
Banbury ®
Mixer Metal Temperature
Temperature Control
- Maximum Productivity
- Optimum Quality
Heat Transfer
Main
Optimum Material Flow
(Stick-Slip)
Intermix® Chamber Water Cooled Cavities
TEMPERATURE CONTROLLED
WEIGHT STANDARD
HIGH EFFICIENCY
TEMPERATURE CONTROLLED
SIDES
HIGH EFFICIENCY
TEMPERATURE CONTROLLED
ROTORS
TEMPERATURE CONTROLLED
ROTOR END PLATES STANDARD
TEMPERATURE CONTROLLED
DOOR TOP
Main
Intermix ® Rotor Cooling
Enhanced spiral cooling passages over whole length of rotor body
Enhanced cooling of Nog
Main
NR5 Rotor Spiral Cooling
Main
Banbury ® Mixer Heating / Cooling
“OPTIONAL” CORED WEIGHT
FOR TEMPERATURE CONTROL
HIGH EFFICIENCY
TIP COOLED ST ROTORS
“OPTIONAL” TEMPERATURE
CONTROLLED ROTOR END
PLATES AND DUST STOPS
Main
HIGH EFFICIENCY
TEMPERATURE CONTREOLLED
SIDES
TEMPERATURE
CONTROLLED
DOOR TOP
Banbury® Rotor Cooling
(Tip Cooled Design)
conventional rotor cooling
Main
ST™ rotor cooling
Typical Ram Action and Power Demand
Banbury ® Ram Action
and Power Demand
Intermix ® Ram Action
and Power Demand
Mixer
power
Main
Mixer
Power
PRIMARY VARIABLES AFFECTING BATCH MIXERS
•
•
•
•
•
•
•
•
Main
Main
compound formulation
batch weight / fill factor
mixing steps and procedures
mixer applied batch pressure
mixer rpm
mixer temper ( metal temperature control )
compound component considerations
environmental effects
1
Batch Size Calculation
BATCH SIZE
(THEORETICAL)
batch wt. = (net mixer volume)
(density compd.)
(fill factor)
Fill factor (Intermix) = 0.85 (fill factor(Banbury))
Main
Main
1
BANBURY® Mixer
Net Chamber Volume& Rotor Type
(liters)
NET MIXER VOLUME “ LITERS “
Main
rotor type
2 wing
4wing ST™
Br- 1600
1.6
-
rotor type
2 wing
4 wing
4 wing ST™
F-80
80
70.5
70.5
1D
16.5
-
F-200
200
156
156
F-50
50
F-270
270
257
257
F-370
----414
414
F-620
---652
704
Intermix ® Mixer
Net Chamber Volume (nr-5) rotors
(liters)
Net Mixer volume “liters”
Machine size K-0
NR-2 rotors 1.64
NR-5 rotors 1.82
Main
K-1
5
5.5
K-2 K-2A
18
44
20
49
K-4
82
91
K-5
126
140
K-6 K-6A K-7
185 231 330
205 257 330
K-8
436
484
K-10
783
870
Intermix ® Vs Banbury ®
Batch Weight & fill Factor
Banbury ® ST equipped mixer @ 50 psi batch pressure
Intermix ® NR5 equipped mixer @ 75 psi batch pressure
160
140
120
ML 4
@
100 C
100
Legend
Tangential
Intermeshing
80
60
40
20
0
0.5
0.55
0.6
0.65
0.7
0.75
FILL FACTOR
Main
0.8
0.85
0.9
BANBURY®
BATCH WEIGHT & FILL FACTOR
APPLIED BATCH
PRESSURE
Main
BANBURY®
Batch Pressure & Viscosity
APPLIED
BATCH
PRESSURE
( PSI )
Main
Optimum fill factor
(Banbury)
% FILL VS PRODUCT VISCOSITY
50
48
PRODUCT
MOONEY
ML4
46
44
42
PROPRIETARY
NR SINGLE STEP
MIX
105° C DISCHARGE
25 RPM
25 PSI BATCH
Main
67
69
% FILL
74
80
“RPI” DATA
(Banbury Data)
1A
ram position Vs time
small batch weight
Main
1B
ram position Vs time optimum
batch weight
1C
ram position Vs time
large batch weight
Typical Ram Action and Power Demand
Banbury ® Ram Action
and Power Demand
Intermix ® Ram Action
and Power Demand
Mixer
power
Main
Mixer
Power
“RPI” SYSTEM
signal conditioner
RECORDER
Main
Mix Topography &
Process Optimization
INDICATED MIX TEMPERATURE
MIXER POWER
RAM POSITION
Main
Banbury Mixer RPM &
Mix time
Main
Mixer RPM & CB
Dispersion
%
CB
DISP.
100
98
96
94
OPERATING
WINDOW
92
90
88
86
84
82
30
35
40
45
55
60
F-270 MIXER RPM
Main
65
70
75
80
Mixer RPM,TCU settings &
Mooney Viscosity
100
Mixer rpm, Mixer temperature, Mooney
Viscosity, & Cycle time
90
90
80
80
70
Legend
cycle time 100%=10 minutes
Mooney 0-90 ML4
std deviation 100% = +/- 66.7
70
% of full
scale
60
70 F mixer
50
50
40
40
90 F mixer
30
30
20
20
140 F mixer
10
10
0
28
3D mixer 2 wing rotor
100 lb. #4SS Natural
43 PSI batch pressure
uniform feed @ approx. 10 Lb.
chunks
70 F feed temperature
discharge @ 285 -300F
Main
60
56
84
mixer rpm
0
112
mooney
ML 4
Mix Cycle and Mixer
RPM
MIX CYCLE FUNCTION DISTRIBUTION
(POLYMER)
loading
4%
low speed breakdown
16%
( TO PREVENTcooling
60%
STICKING ON
THE MILL)
( FILLERS)
Legend
loading
low speed breakdown
high speed mixing
ram bump
cooling
Main
ram bump
1%
high speed mixing
20%
Mixer Metal Temperature
Temperature Control
- Maximum Productivity
- Optimum Quality
Heat Transfer
Main
Optimum Material Flow
(Stick-Slip)
Metal Temperature & Interfacial
friction effects
Main
SBR mixing,TCU settings
& mix efficiency
Main
Mixing Action “Banbury ®”
Distributive
Dispersive
Even speed or friction operation
Main
ST Rotor Performance
Cure Uniformity and Rotor Temperature
Tread Compound - Final Mix
F-270 4wST
mixer body @49 C (120 F)
mixer door @ 27 C (81 F)
fill factor @ 75%
batch Pressure @ 4.1 bar (60 psi)
mixer @ 30 rpm
70 sec rm dn mix time
rotor water @ 71 C (160 F)
rotor water @ 60 C (140 F)
Main
rotor water @ 49 C (120 F)
Temperature Control Unit
“TCU”
Main
Banbury® Water Flow Rates
( for maximum heat transfer)
Main
Banbury® TCU settings
(starting points)
Main
COMPONENT CONSIDERATIONS
“Feed Form”
(kW)
(NR)
(410)
(298)
(336)
LBS. (50.9Kg)
(298)
PSI
(261)
(224)
(32 ‘C)
(121 ‘C)
(149’C)
(186)
(149)
(112)
(0.045)
(0.136)
(0.455)
(4.55)
AVERAGE WEIGH OF RUBBER FEED UNIT - LBS.
(KG)
Main
(45.5)
COMPONENT CONSIDERATIONS
“environmental effects”
NAT,L RUBBER MASTICATION
100
80
* TEMPERATURE
AVG POWER
* HUMIDITY
MOONEY REDUCTIION RATE
% of
scale
range
60
40
MIX TIME
Legend--scale range
mix time 0-10 min.
avg kw 0-200
mooney reduction rate 0-10 M/min.
20
0
-10
(14 F)
4
(40 F)
21
(70 F)
RUBBER FEED TEMPERATURE DEGREES CENTIGRADE
Main
32
(90 F)
Mixing Parameters, Steps and Procedures
“The Art of Mixing Rubber”
I MIXING STEPS
III MIXER OPERATING PARAMETERS
SINGLE STEP MIX
- conventional single step
- upside down single step
- process specific single step
MULTIPLE STEP MIX
- premastication (optional )
- masterbatch
-simple single step mix
-process specific single step mix
- remill (optional )
- final mix
- % fill(batch weight)
- temper
- ram pressure
-
mixer speed
II MIXING PROCEDURES
- order of additions
- number of additions
- number of ram cleanings (brushes)
- discharging procedures
- rpm and batch pressure settings
- means of control
Main
CYCLE CONTROL
-time
- indicated temperature
- energy (kwh)
- torque (power hp or kw )
Mixer Power
Indicated Mix Temperature
Mixer Motor Power
90 sec.
START
225 F
175 F
Time (min)
180 sec.
END
• Indicated Mix Temperature
(end frame or drop door T.C.)
Mixer Power
•Time
Time (min)
5 hp-hr
•Mix Energy (hp-hr)
Mixer Power
10 hp-hr
(Power x time)
(area under the power Vs time curve)
Time (min)
•Mixer Motor power
Mixer Power
125 hp
100 hp
(mixer motor torque)
Tim e (m in)
Main
Single step mixing
Event
1
2
3
4
5
Description
load polymer,all black,chemicals ,oils ,fillers ,cures
ram down mix to 175 F
raise ram and brush
ram down mix to 225 F
discharge batch- float ram open, drop door& dwell 15 sec
close drop door and raise ram
Event 5
(discharge & make
ready)
rpm
10
50
30
25
30
time (sec.
17
50
20
30
30
147
Kwh
0.09
2.66
1.01
1.87
0.00
5.72
Event 1
(loading)
Event 2
Event 4
(ram down mixing)
(ram down mixing)
Event 3
(Brush-clean ram)
Event 5
Event 1
Event 4
Event 2
Event 3
Main
batch PSI
up
50
up
30
up
The End
Main
Banbury® Technical Data
Banbury®
designation
Br
00C
1D
F-50
Net Chamber 1.57 4.24 18.7
volume (liters)
47.4
Rotor type
ST
Main
2w
2w
2w
F-80
F-120
F-200
F-270
F-370
80 /70
124 / 106
220 / 200
270 / 257
414
2w/4w&ST 2w/4w
2w/4w&ST
F-620
650 / 711
2w/4w&ST 4w & ST 4w / ST
Intermix ® Technical Data
Capacities with the NR5 Rotors (liters)
Main
Intermix
type
K0 K1
K2
K2A K4 K5
Net
Chamber
volume
(liters)
1.8
20
49
5.5
K6
K6A K7
91 143 206 257
306
K8
K10
484
870