1. Classification of solidification processes

2. Principle of the process
Structure/Configuration
Process modeling
Defects/quality control
Design For Manufacturing (DFM)
Process variation

3. Shaping Processes For Plastics - Extrusion
1. Introduction
Screen pack

4. Shaping Processes For Plastics - Extrusion
1. Introduction
Extrusion is a process in which the material is forced to flow through a die orifice to provide a long, continuous product whose cross-sectional shape is determined by the shape of the orifice

5. Shaping Processes For Plastics - Extrusion
2. Analysis of Flow Rate

6. Shaping Processes For Plastics - Extrusion
Find the flow rate with respect to various parameters in the system. These parameters include: parameters of the screw, the clearance between the screw and the inner surface of the barrel.

7. The goal of the engineering analysis:
The flow rate or production rate.
The pressure of the or product

8. die Extruder The general idea to meet the goal:
The balance between the two should lead to the flow rate as well as pressure
1. Flow rate inside the extruder and at the die ?
2. Flow rate outside the extruder and at the die ?
die
Extruder

9. Drag flow w Screw surface v d Barrel
Flow rate of the extruder (not including the die)
Drag flow d w v
Screw surface
Barrel

10. d w v dc
(1)

12. Back pressure flow

13. Back pressure flow
(2)

14. Net forward flow Qx
(3)
Linear relation between the net flow rate and head pressure.
Assumption: viscosity is constant.
The structure: extruder only not including die.

15. Shaping Processes For Plastics - Extrusion
The design parameters: those that define the geometry
of the screw and barrel.
The operating parameter: those that can be changed
during the process to affect the output flow
Variable

16. Shaping Processes For Plastics - Extrusion
Maximum head pressure to cause no flow
Maximum pressure and maximum net flow rate

17. Extruder characteristic Qmax
Shaping Processes For Plastics - Extrusion
Extruder characteristic Q
Qmax
pmax p

18. die Shaping Processes For Plastics - Extrusion
Determination of the operating point
Pressure and Flow rate
Die characteristic
die

19. Shaping Processes For Plastics - Extrusion
Determination of the operating point Qx
Die characteristic
Qmax
Operating point
Extruder characteristic
pmax p

20. Example:
Given: diameter D=120 mm
length =3.0 m
channel depth =8.0 mm
pitch = 95 mm
viscosity = 75 pas
head pressure = 4.0 Mpa
Find: the rotational speed of the screw required to
achieve a volumetric flow rate of 90 cm3/s

21. Solution to be filled in the classroom

22. Shaping Processes For Plastics - Extrusion
Discussion
A manufacturing process is to the material to meet requirements.
Requirements: quality, quantity, time, cost, green and sustainability.
Quantity with respect to time is called production rate.
The whole manufacturing system at the equipment level can be viewed as consisting of devices and materials.

23. Shaping Processes For Plastics - Extrusion
Discussion
Both the device and material are under the manipulation from the external system that supplies energy or power and material.
There are several parameters and variables in the manufacturing system: device parameter, process parameter, product parameter.

24. Shaping Processes For Plastics - Extrusion
Discussion
Device parameter also system or design parameter: the one category of parameters that describe the device, e.g., the diameter of the extruder, length of the extruder, etc.
Process parameter also operating parameter: the one category of parameters that describe the process on the material, e.g., the rotational speed of the screw bar, heat energy supply, material supply rate, etc.
Product parameter: the one category of parameters that describe or characterize the product which is the output from a manufacturing system, e.g., the flow rate, etc.

25. Shaping Processes For Plastics - Extrusion
Discussion
Manufacturing system design and control:
Device design: to determine the device parameter.
Process design: to determine the process configuration and parameter.
Product modification: design for process.
Device control.
Process control.
Product quality, quantity, cost, time, green and sustainability