DED

Question 1

What is the primary difference between DED and Powder Bed Fusion (SLM/EBM)?

Answer 1

In DED, the material (feedstock) is delivered directly into the melt pool as it is being melted, rather than being spread over a bed beforehand.

Question 2

Name three unique advantages of the DED process.

Answer 2

Ability to repair damaged components (e.g., turbine blades).
Ability to create functionally graded materials by changing composition during the build. (Man kan till exempel börja med 100 % stål i botten och sakta öka mängden titan tills toppen består av 100 % titan.)
Ability to process very large build volumes (>1000 $mm^3$).

Question 3

What happens if the Global Energy Density (GED) is too high or too low in DED?

Answer 3

Too low GED: Leads to lack of fusion (insufficient bonding with the substrate).
Too high GED: Leads to keyhole porosity (excessive material vaporization).

Question 4

How does the Scanning Speed in DED compare to SLM?

Answer 4

Scanning speed in DED is typically 10 to 100 times lower than in SLM. However, productivity remains high because the melt pool and layer thickness are much larger.

Question 5

What are the three main types of power sources used in DED?

Answer 5

Laser (LMD/Laser Cladding).

Electron Beam (EB-DED).

Arc Plasma (Wire Arc AM / WAAM).

Question 6

Råmaterial exempel DED

Answer 6

Vanligaste materialen:
Rostfritt stål: Exempelvis 316L (vanligt i WAAM/Arc-DED).
Nickel-baserade legeringar: Inconel 625, 718 och Hastelloy X.
Titanlegeringar: $Ti$-$6Al$-$4V$ och $Ti$-$15Mo$.
Verktygsstål: Exempelvis H13.
Specialitet:Multimaterial: DED kan blanda olika pulver under processens gång för att skapa komponenter med varierande kemisk sammansättning.

Question 7

DED: Main consequence of high powder feed rate with low laser power

Answer 7

Increased fusion of defects

Question 8

DED: hög lasereffekt (High Laser Power) men låg pulvermatning (Low Powder Feed Rate)

Answer 8

Keyholing/Evaporation: Materialet förångas, det sprutar gnistor (stänk) och geometrin förstörs.

Tenta-tips: Kom ihåg att i DED fungerar pulvret som en “kylare” som tar upp laserenergin. Utan pulver blir lasern som en skärbrännare istället för ett byggverktyg.