Design Parameters
The following major factors should be considered in the detailed development of an aluminum extrusion design:
.Shape configuration/constraints
.Circumscribing circle size
.Functionality
.Tolerances
.Surface finish
.Alloys & Tempers
.Dies & Tooling
Types of Extrusion Defects
Surface Cracking
High Extrusion Temperature
High Ram Speed
High Friction
2. Piping Defect
Non-uniform Flow of Metal.
3. Internal Cracking
Central part with low speed
while outer part have high speed.
Avoid high tongue ratios(better within 16) (width of fin vs. height). Where possible, reduce deep narrow "tongues" by redesigning the profile. Also, keep somewhat balanced wall thicknesses.
Good Aluminum Extrusion Design Practices
. Balanced walls
. Avoid/minimize hollows
. Generous tapers
. Practice symmetry/minimize asymmetrical detail
. Use grooves, webs and ribs
. Minimize perimeter/cross-section ratio
Die Tongue Ratios
Steel tongue in the die that create a slot in the extrusion
2. Depth of slot divided by gap of slot in the die
3. The smaller the gap, the less steel support in the die, which creates more variation in the fins and
higher chance of die breakage.
4. The base of the fins will have the metal variation. the top of the fins is where the die will break.
5. Consult your extruder for ratios above 8:1
6. Even flow and alloy is key to higher ratios, avoid unequal metal mass on sides of tongue and
hard pushing alloys.