Additive Manufacturing Powder

Overview

Additive manufacturing (AM), also known as 3D printing, utilizes metal powders to construct components layer by layer based on digital models. The powder acts as the feedstock and is selectively melted, sintered, or bound by precision heat sources guided by the CAD geometries.

Popular AM processes for metals include binder jetting, directed energy deposition, powder bed fusion, and sheet lamination. Each technique requires powder with specific characteristics to achieve optimal density, surface finish, dimensional precision, and mechanical properties in the printed parts.

This guide provides an in-depth look at metal powder for AM, including alloy options, production methods, key powder properties, applications, specifications, suppliers, and purchasing considerations when sourcing material. Helpful comparison tables summarize technical data to assist with powder selection and qualification.

Sourcing optimized AM powder enables manufacturers to improve print quality, reduce defects, and fully leverage 3D printing benefits like design freedom, faster iteration, and part consolidation. Connecting with knowledgeable suppliers simplifies raw material qualification.

Alloy Options for AM Powder

A wide range of metals and alloys are available as optimized powder feedstock for 3D printing processes:

Common Alloy Systems for Additive Manufacturing Powder

• Stainless steels
• Tool steels
• Titanium and titanium alloys
• Aluminum alloys
• Nickel superalloys
• Cobalt-chrome alloys
• Precious metals like gold, silver
• Exotic alloys like copper, tantalum, tungsten

Both standard and custom alloys can be sourced to meet specific needs in terms of corrosion resistance, strength, hardness, conductivity, or other properties.

Metal Powder Production Methods for AM

Additive manufacturing utilizes metal powder produced through:

Typical Metal Powder Manufacturing Methods for AM

• Gas atomization
• Water atomization
• Plasma atomization
• Electrolysis
• Carbonyl iron process
• Mechanical alloying
• Metal hydriding/dehydriding
• Plasma spheroidization
• Granulation

Spherical atomized powders provide optimal flow and dense packing required for most AM processes. Some techniques allow nanoscale or customized alloy particles.

Key Characteristics of AM Metal Powder

Critical powder characteristics for AM include:

Metal Additive Manufacturing Powder Properties

Characteristic	Typical Values	Importance
Particle size distribution	10 to 45 microns	Affects densification, surface finish
Particle shape	Spherical	Improves powder flow and packing
Apparent density	2 to 4 g/cc	Influences powder bed density
Tap density	3 to 6 g/cc	Indicates compressibility
Hall flow rate	25-50 s/50g	Ensures smooth powder spreading
Loss on ignition	0.1-0.5%	Low moisture content improves printing
Oxygen content	<0.1%	Minimizes defects from oxides

Precisely controlling characteristics like particle size, shape, and chemistry is critical to achieving fully dense AM parts with desired properties.

Applications of AM Metal Powder

Additive manufacturing enables complex geometries impossible through conventional techniques:

Metal Additive Manufacturing Applications

Industry	Uses	Benefits
Aerospace	Turbine blades, structures	Design freedom, weight reduction
Medical	Implants, prosthetics, instruments	Customized shapes
Automotive	Lightweighting prototypes and tools	Rapid iteration
Defense	Drone parts, protective structures	Quick prototypes and short runs
Energy	Heat exchangers, manifolds	Part consolidation and topology optimization
Electronics	Shielding, cooling devices, EMI	Complex enclosed structures

Lightweighting, part consolidation, and high-performance alloys for extreme environments provide key advantages over traditional manufacturing methods.

Specifications for AM Metal Powder

International specifications help standardize AM powder characteristics:

Metal Powder Standards for Additive Manufacturing

Standard	Scope	Parameters	Test Methods
ASTM F3049	Guide for characterizing AM metals	Sampling, size analysis, chemistry, defects	Microscopy, diffraction, SEM-EDS
ASTM F3001-14	Titanium alloys for AM	Particle size, chemistry, flow	Sieving, SEM-EDS
ASTM F3301	Nickel alloys for AM	Particle shape and size analysis	Microscopy, image analysis
ASTM F3056	Stainless steel for AM	Chemistry, powder properties	ICP-OES, pycnometry
ISO/ASTM 52921	Standard terminology for AM powders	Definitions and powder characteristics	Various

Compliance with published specifications ensures repeatable, high quality powder feedstock for critical applications.

Global Suppliers of AM Metal Powder

Leading international suppliers of AM-optimized metal powders include:

Metal Powder Manufacturers for Additive Manufacturing

Supplier	Materials	Typical Particle Size
Sandvik	Stainless, tool steel, nickel alloys	15-45 microns
Praxair	Titanium, superalloys	10-45 microns
AP&C	Titanium, nickel, cobalt alloys	5-25 microns
Carpenter Additive	Cobalt chrome, stainless, copper	15-45 microns
LPW Technology	Aluminum alloys, titanium	10-100 microns
EOS	Tool steel, cobalt chrome, stainless	20-50 microns

Many focus on fine spherical powders specifically engineered for common AM methods like binder jetting, powder bed fusion, and directed energy deposition.

Purchasing Considerations for AM Metal Powder

Key aspects to discuss with suppliers:

• Desired alloy composition and properties
• Target particle size distribution and shape
• Envelope density and hall flowability
• Allowable impurity levels like oxygen and moisture
• Required testing data and powder characterization
• Available quantity range and lead times
• Special handling precautions for pyrophoric alloys
• Quality systems and powder origin traceability
• Technical expertise in AM powder requirements
• Logistics and delivery mechanisms

Work closely with suppliers experienced in AM-specific powders to ensure ideal material selection for your process and components.

Pros and Cons of AM Metal Powder

Benefits vs Limitations of Metal Powder for Additive Manufacturing

Advantages	Disadvantages
Allows complex, customized geometries	Higher cost than conventional materials
Shortens development time dramatically	Powder handling precautions required
Simplifies assemblies and lightweights	Post-processing often needed on as-printed parts
Achieves properties nearing wrought materials	Size and build volume constraints
Eliminates expensive tooling	Thermal stresses can cause cracking and distortion
Enables parts consolidation and topology optimization	Lower production volumes than traditional methods
Improves buy-to-fly ratio greatly	Requires rigorous powder characterization and parameter development

When used appropriately, metal AM provides game-changing benefits but requires expertise to implement successfully.

FAQs

How small can particle size be for metal additive manufacturing?

Specialized atomization techniques can produce powder down to 1-10 microns, however most metals printers work best with minimum size around 15-20 microns for good flow and packing.

What causes poor surface finish in printed metal parts?

Surface roughness arises from partially melted powder adhered to surfaces, spatter, staircase stepping, and suboptimal melt pool characteristics. Using finer powders and dialing in ideal processing parameters smoothens finish.

Do all metal 3D printing methods work with the same powders?

While there is overlap, binder jetting generally uses a broader powder size distribution than powder bed fusion. Some processes are limited to certain alloys based on melting points or reactivity.

How are mixed or bimetallic powders made?

Prealloyed powders ensure uniform properties but for composites, physical powder blending or specialized atomization techniques provide custom blended elemental powder mixes.

How long does it take to change powder material in a metal printer?

A full purge and changeover between significantly different alloys requires 6-12 hours typically. Quick changes between similar materials can be under an hour.

Conclusion

Optimized metal powders enable additive manufacturing processes to construct complex, robust metal components with superior properties. Matching alloy chemistry and powder characteristics to the printing method and component performance requirements is critical to high quality results. By partnering with experienced powder suppliers, end users leverage expertise in both powder production and 3D printing processes to develop parts faster and more reliably. Continued advances in metal powders help drive increased adoption of additive techniques across critical industries.

know more 3D printing processes