ExtrusionEXTRUSION LAB
Introduction
Extrusion - a method of forming in which the material is forced
through an opening having a predetermined shape.
Main Types
Extrusion Direction is a variable
considered in this lab experiment
1) Remind students that the topic of extrusion was introduced in
class room lecture yesterday.
Extrusion Lab – Slide *
Structural and Architectural shapes.
Extrusion and examples of products made by sectioning off
extrusions. Source: Kaiser Aluminum.
1) Many actual extrusions were shown in class yesterday.
Extrusion Lab – Slide *
Ram
Die
Billet
Container
Note die and container liner are made of higher quality ( cost and
performance) materials to withstand the temperatures and stresses
of extrusion
Name each of element in the figure.
Extrusion Lab – Slide *
Explain what’s happening.
End of II and Start of III
The first stage is where the billet is being compressed and the
excess air is being pushed out of the chamber.
The second stage is where the force to overcome static friction or
“Sticky Friction”. The end of this stage is marked by the BTF where
extrusion starts to take place.
The third stage is where the steady state extrusion is taking place
and the force required to maintain extrusion is decreasing “ For
forward Extrusion” because the amount of surface area of the billet
contacting the container to which friction is acting on is
decreasing.
The fourth stage is the dead metal zone “DMZ” where extrusion has
taken place and the material is being compressed against the
die.
The BTF is the value estimated from Eq. 15.1 of the text. It is
used to estimate the maximum force in the processes and can be used
to help determine which of several extruders would be used for a
particular extrusion.
Extrusion Lab – Slide *
Today the lab will use Warm Extrusion
Ram Speed (Strain rate sensitivity).
Lubrication
Die Geometry
This variable will be considered in this lab experiment
Lead at room temp (22 °C) To = 22 + 273 T melt = 327 °C + 273 = 600
K
To / T melt = (295) / (600) = 0.5
Warm working 0.3 to 0.5
Extrusion Lab – Slide *
Fluids - no flow across stream lines
Responsible for DMZ
- Elongated grain structure
Extrusion Lab – Slide *
Piping results in less products, more scrap.
DMZ’s don’t contribute to “product”; we want to minimize or
eliminate them.
Chevron failure – discussed in class – not an issue here.
Surface Cracking – discussed in class – not an issue here.
Extrusion Lab – Slide *
Extrusion Experiment
Objectives - To analyze the following variables and their effects
on the extrusion process.
Die Geometry (G)
Lubrication (L)
Qualitative Objectives –The influence of these variables on the
Dead Metal Zone
and the Piping Effect will be visually examined
Quantitative Objectives –Their influence of the extrusion variables
on the magnitude
of the Break Through Force in the extrusion process.
Extrusion Lab – Slide *
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Students should find missing data and fill in table – on lab
computer
Extrusion Lab – Slide *
Procedure
Coat the flat surfaces of the billet half with red layout dye
Use a height gage to scribe cross hatch lines .100” apart
Place the billet in the appropriate die assembly
Have the instructor check set-up and start the extrusion
Stop recording data at 0.8 inches
Record the, approximate BTF from the dial on the Richle
and record on the computer
7) Repeat the steps for all 8 tests
1) Do steps 1 & 2, mostly, before class begins.
