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Systematic Molding. Use right arrow to advance Slides. MOLDING: Art or Science?. Injection Molding Approaches. Traditional Molding (Art) Decoupled Molding (Science). Traditional Molding. Fill & Pack on first stage - PowerPoint PPT Presentation
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Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 1
Systematic Molding
Use right arrow to advance Slides
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 2
MOLDING:
Art or Science?
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 3
Injection Molding Approaches
Traditional Molding (Art)
Decoupled Molding (Science)
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 4
Traditional Molding
Fill & Pack on first stage
Use only enough first stage pressure to pack the mold
Subject to large shot to shot variation
Shorts, flash, warp, dimensional issues
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 5
thick
thinvi
scos
ity
flow rateslow fast
As speed increases, the plastic gets thinner and easier to push
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 6
thick
thinvi
scos
ity
flow rateslow fast
High sensitivity to fill speed variation
Low sensitivity to fill speed variation
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 7
Decoupled Molding
A method of process control that minimizes variation in parts by:
separating the filling stage from pack & hold
Utilizing the machine controls to manage fill, pack & hold
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 8
Decoupled Molding
Set first stage hydraulic pressure control “high”
Allow machine to provide whatever pressure needed to deliver constant fill speed
Set first stage velocity for constant and fast fill speed
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 9
Decoupled Molding
Separate the filling (velocity) phase from packing phase
Transfer to pack at ~ 95% of full shot (by position)
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 10
Benefits of Decoupled Molding
Fast fill at constant speed
Reduce part variations due to material viscosity variations
Won’t flash
Pack consistently
Gives the most robust, repeatable process
Reduces cycle time, improves quality
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 11
Philosophy of molding from the plastics point of view
Non-Newtonian
Flow rate, temperature, pressure, cooling rate
Use optimum constant flow rate
Separates fill from pack and hold
Cavity pressure controls process
Systematic Decoupled Molding
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 12
Total Process Control
Flow Rate
Temperature
Pressure
Cooling Rate
PROCESS VARIABLES
Material Viscosity
EXTERNAL VARIATION
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 13
Rigorous methodology to launch a new part
Arrives at the optimum process
Drives the set-up sheet
Should be done at prototype
Systematic Decoupled Molding
Process Optimization
Oct. 18, 2003 WINWARD TECHNOLOGIES, LLC 14
Total Process Control
Dimensions
Surface
Structure
Correlates: PART CHARACTERISTICS
To: PROCESS PARAMETERS