Additive Manufacturing - Direct Metal Laser Sintering

Question 1

DMLS Method

Answer 1

• Scanning and sintering metallic powder using a focused laser beam (fibre laser) that causes the powder to sinter and solidify in the shape of a layer of the prototype
• Use of true production material, near-net shape process

Question 2

DMLS Process Characteristics

Answer 2

• Layer thickness 0.02-0.04mm
• Process takes place in an inert nitrogen atmosphere <1% oxygen to stop the metal powder oxidising when heated by laser
• temperature of build chamber up to 200°C (sintering is achieved with high power laser (200W-1kW)
• Requires support structure which acts as support and to take heat away from the workpiece

Surface finish and accuracy

• good surface finish - Ra 4-20µm
• high accuracy - 20-50µm
• recommended wall thickness (min) 0.3mm

Easily machinable

• spark-erosion
• welding
• shot-peening, polishing, coating
• heat treatment

Question 3

DMLS- Materials

Answer 3

• Aluminium
• Stainless and maraging steel
• Cobalt chromium alloys
• nickel alloys
• titanium
• bronze
• powder size (particle diameter) between 36-65µm

Question 4

DMLS- Applications

Answer 4

• Functional Prototypes
• Series-production parts
• Tooling
• Aerospace, motorsport, medical (dental, implants etc)

Question 5

Pros of DMLS

Answer 5

• All metals are recyclable, only use what you sinter
• Near net-shape process, producing parts with high accuracy and detail resolution
• Good surface quality and excellent mechanical properties
• constant development and release of new materials onto the market

Question 6

Cons of DMLS

Answer 6

• More complex process than SLS with regards to designing support structure and orientation
• Parts need to be cut from the steel place (using Wire-EDM); increase to cycle time and labour costs