Direct Metal Laser Sintering

Question 1

Direct Metal Laser Sintering - Principle/Method?

Answer 1

• Scanning and Sintering metallic powder using a focus laser beam (fibre laser) that causes the powder to winter (fuse or melt) and solidify in the shape of a layer of the prototype.
• Use of true production material, near- net shape process.

Question 2

DMLS - Category

Answer 2

Power Bed Fusion

Question 3

DMLS - Process Characteristics

Answer 3

• 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 the laser
• Temperature of Build chamber up to 200 degrees Sintering is achieved with power laser (200W-1kW)

• Requires Support structure which acts as support and to take heat away from the workpiece.

Question 4

DMLS - Process Characteristics

Answer 4

• Surface finish and accuracy
  • Good surface finish - ARA 4-20um
  • High accuracy - 20-50um
  • Recommend Wall thickness (min) 0.3mm

- Easily Machinable 
• Spark- Erosion
• Welding
• Shot-Peening, polishing, coating
• Heat treatment

Question 5

DMLS - Materials

Answer 5

• Aluminium
• Stainless and managing steel
• Cobalt chromium alloys
• Nickel alloys
• Titanium
• Bronze

• Powder size (particle size)

36-65um

Question 6

DMLS - Applications

Answer 6

• Functional Prototypes
• Series- Production Parts
• Tooling
• Aerospace, Motorsport, medical (dental, implants etc)

Question 7

DMLS - Advantages

Answer 7

• Recyclable material - Metal powder that is not sintered can be reused.
• Strong, functional parts: Properties of a finished part are comparable to a part cast In the same material.
• Variety of materials: Between DMLS and SLM, a wide range of metal and metal alloy powders are available, including steels and stainless steels and aluminium.
• Parts are made directly with no pre mould fabrication in traditional methods.

Question 8

DMLS - Limitations

Answer 8

• High Pricing: machines and materials are expensive and process is slow.
• Porous Parts: Finished DMLS Parts are porous relative to the metal part. Porosity can be controlled but not eliminated in the process or during post processing.
• Small Parts: Most DMLS Printers have relatively small build volumes.