Update of K-Tron Loss-in-weight

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Update of K-Tron Loss-in-weight Feeding
Technology
12th Continuous Mixer and Extruder Users
Conference Indian Head Division Presented By Jim
Rutter Ron Letizia K-Tron America
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Overview

• Review of Loss-in-weight Feeders
• Choosing the Proper Feeder
• Advances in Loss in Weight Feeders for
• Enhanced Performance
• Getting Valuable Data From Your Feeders

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Loss-in-weight Principle
Feeder and material are continually weighed, and
metering speed is controlled to maintain desired
discharge rate.
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Theory of Operation of a Loss-in-weight Feeder
WEIGHT
SPEED (RPM)
SETPOINT
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Choosing the Proper Feeder For Your Application
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Material - Physical Properties- Handling
Characteristics- Rate
Feeder - Operating Principle- Weighing System-
Control System - Mechanical System
Environment - Vibration- Temperature
ACCURACY - User Specified- Required Quality-
Minimum Cost
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Determine the Process Performance Requirements

• Repeatability
• Linearity

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Linearity
Linearity is a measure of flow rate error over
the full operating range
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Repeatability
Repeatability describes flow rate variability at
a given rate setting
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Other Considerations

• Feedrate
• Material Properties
• Refill Method
• Environment
• Control Integration

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Designs for All Applications
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Performance Timescales
ACCURACY
Momentary - Selection/Sizing- Weighing
Resolution- Control Response - Environment
Steady State - Measurement Stability -
Maintenance
Refill Phase - Refill Performance- Refill
Frequency
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Advances in Loss-in-Weight Technology to Meet
High Performance Demands
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Improved Load Cell Technology

• Higher Sampling Rates (112 samples/sec)
• Vibration - Digital Filtering
• Temperature Compensation

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Vibration Filtering vs. Non-Vibration Filtering
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SFT Load Cells
SFT II 200 - 1000 kg
SFT II 18 120 kg
SFT III 60 1000 N
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Screw Speed Modulation

• Improved Short Term Accuracy
• 2 Sigma at 10 Seconds Improved
• Tremendously
• Steady Material Output
• Ideal for Low Feed Rates

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Initial Situation
In general, an attempt at aggressive control
will fail and increase the mass flow variations.
Additionally, during volumetric phases, such as
refill or pert, the speed remains constant.
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With Screw Speed Modulation
The periodic pulsation of material is measured
and screw speed is adjusted. The Speed Modulation
Algorithm learns when and how much the mass flow
changes periodically, and then changes the
screw speed just before there will be an
error. It continues modulation during
volumetric phases such as refill or pert.
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Connectivity Options

• Options to Meet Any Plant Network Demands
• Ethernet Compatibility
• Wireless Capability

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Getting Valuable Data From Your Feeder

• The Communications Link
• Collecting Data

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Communication LinkData Concentrators
Host Computer or PLC
High Speed Network
Display/Data Concentrator
Local Display
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Communication LinkGateways
Host Computer or PLC
High Speed Network
GATEWAY
GATEWAY
GATEWAY
Local Display
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Communication LinkDirect Connection To Feeder
TREND

• No Bottlenecks
• Less Components

Host Computer or PLC
High Speed Network
Local Display
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Direct Connection To Your Feeder
Whats Important?
CONTROLLER

• Ease of Setup
• Reliability
• High Speed/Data Throughput
• Deterministic
• Supports large data transfers

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What Protocol To Use?

• Modbus RTU / ModbusPlus
• AB DF1, Siemens 3964R
• Profibus DP
• DeviceNet / ControlNet
• Ethernet-Modbus / TCP
• Ethernet-Ethernet / IP

CONTROLLER
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Ethernet For Control TREND

• High Speed
• Proliferation of Products
• Open Fieldbus Standards
• Modbus/TCP (Modbus over Ethernet)
• Ethernet/IP (DeviceNet over Ethernet)
• Reliability?
• Deterministic Question?

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Ethernet Determinism

• Ethernet does not provide consistent latency due
  to arbitration
• algorithm called Carrier Sense Multiple Access
  with Collision
• Detection (CSMA/CD).

Delays Due To CSMA/CD Two Node Packet
Collision BandWidth 100 Mbits/sec, 1000
packets/sec 128 byte packet 99 sure will run
1140 years without gt 1 msec delay 1024 byte
packet 99 sure will run 2 years without gt 1
msec delay (Source Can Ethernet Be Real
Time, Real-Time Innovations, Sunnyvale, CA)
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Ethernet Determinism

• Switches vs. Hubs
• Switches virtually eliminate all collisions
• by buffering packets
• Max delay can be calculated
• Slower on lightly loaded networks due
• to imposed delays.

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Collecting Data

• Who uses the data?
• (Operations, Maintenance Personnel, Quality
  Control)
• Can the communications link eliminate I/O?
• Can the data help determine end product quality
  and help with end product validation?
• What control functions are required?

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Collecting Data
Advanced feeders provide a wealth of information

• Real-time access to all process data and
  parameters
• Access to diagnostic and service related
  information
• Provides data and control functions for other
  feeder related components (such as pre-feeders
  and loaders)
• Quick start built-in configurations to reduce
  learning-curve
• Flexibility in configuration

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Customizing Data Collection
PC based tools help determine what parameters and
data types will be exchanged.
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Using Feeder Data
Process data can be used to predict
end-product quality problems or equipment
failures before they occur.

• Periodic catch samples validate feeder operation.
  Periodic end-product analysis validates the
  product.
• Proactive approach may include collecting data in
  real time and statistically comparing it to
  known-good data to determine if run is likely
  to produce good end-product.

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Conclusions

• Trends toward direct feeder communications with
  high speed protocols
• Industrial Ethernet gaining acceptance
• Important to have access to all data with easy
  customization
• Advantages to integrating feeder related
  equipment
• Real-time data can be useful to predict problems
  and ensure end product quality

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