Metal 3D Printing: A Guide to Metal Additive Manufacturing

Metal 3D printing, also known as metal additive manufacturing, is revolutionizing what engineers and designers can achieve.

What is metal additive manufacturing - A Brief Introduction

Metal additive manufacturing (MAM), also known as metal 3D printing, refers to a set of technologies that can build fully dense metal parts by adding layer upon layer of material. Parts are fabricated directly from 3D model data, allowing for geometries and designs not possible with traditional manufacturing methods.

Additive Manufacturing vs Traditional manufacturing processes

Additive Manufacturing (AM) technologies allow designers and engineers to overcome many of the constraints imposed by both traditional formative and subtractive manufacturing processes for large metal components.

While subtractive methods like machining are limited by the geometries they can produce, formative processes like forging, casting and molding impose additional constraints related to the tooling and dies required. Formative manufacturing often restricts design complexity in order to accommodate the molds and to facilitate easier part removal.

In contrast, AM techniques like selective laser melting (SLM) use a layer-by-layer approach to build up fully dense metal parts directly from 3D model data. This enables the fabrication of components with optimized designs, complex geometries and lattice structures - features that are difficult or impossible with both subtractive and formative manufacturing.

AM processes also eliminate the need for tooling or molds, leading to reduction in material waste and scrap, and improved material yield.

Let us now compare metal AM with a prevalent subtractive manufacturing process for metals — computer numerical control (CNC) machining — to examine their key differences in detail.

Metal 3D Printing vs CNC: Pros and Cons

CNC machining is a type of subtractive manufacturing process, in which material is removed from a bulk workpiece to create a part. “CNC” stands for computer numerical control.

Complexity

• Metal 3D printing can produce parts with highly complex geometries, optimized lattice structures and precise internal features. This level of complexity is very difficult or impossible for CNC machining.

• However, CNC machining can produce simple to moderately complex shapes more precisely and at lower costs.

Material Usage

• Metal 3D printing utilizes a higher percentage of input materials since there is minimal machining waste in the form of chips and scraps.

• In contrast, CNC machining involves significant material loss from machining operations, resulting in lower material efficiency.

Costs

• Metal 3D printing is well suited for low to medium volume production of complex parts due to lower tooling costs.

• However, CNC machining is often more economical for higher volume production of simple parts due to lower material and setup costs.

Surface Finish

• The surface finish of metal 3D printed parts is generally rougher and requires post-processing for some applications.

• CNC machined parts typically have a smoother surface finish and tighter dimensional tolerances.

Material Choice

while CNC machining can process essentially any metal that can be cut or abraded, the range of metal powders and alloys that can currently be used for metal 3D printing is more constrained. However, the variety of viable metal powders for additive manufacturing is growing rapidly as the technology continues to advance.

Types of Metal Additive Manufacturing

A variety of metal AM technologies exist that can be categorized according to ASTM F42 standards as follows:

Binder jetting: Processes that deposit a binder into a bed of metal powder to selectively bind the powder together layer-by-layer. The part is then infiltrated and sintered to achieve full density.

Powder bed fusion: Processes that melt and fuse metal powder by applying thermal energy, including selective laser melting (SLM) and electron beam melting (EBM). Parts are build layer-by-layer from metal powder that is selectively fused using a laser or electron beam.

Sheet lamination: Processes that bond sheets of metal together through welding, interfusion or adhesion, such as ultrasonic additive manufacturing (UAM). Parts are built up layer-by-layer from metal foils.

Direct energy deposition: Processes that fuse materials by applying focused thermal energy directly to the part, including laser-based and electron beam-based methods. Parts are built up directly using wire or powder feedstock.

Metal 3D Printing for specific industries

• Aerospace - Weight savings, material choice, part consolidation and design complexity are enabling metal AM applications in aircraft components, space technology and drone manufacturing.

• Automotive - Lighter metal components, optimized cooling, mass customization and design flexibility are driving metal AM adoption in the auto industry for applications like engine parts.

• Medical - Properties like biocompatibility, precision and design freedom are enabling metal 3D printing of prosthetics, implants and surgical guides.

• Consumer products - Mass customization, reduced lead times and whole-part manufacturing are benefiting consumer electronics, sports equipment and other products using metal AM.

Challenges and limitations

• Part size constraints - Available build volumes for metal 3D printers limits the maximum part size that can be produced, though this is improving over time.

• Surface finish issues - Metal AM parts often require post-processing to achieve smooth surface finishes required for some applications.

• Material properties - Properties of metal AM parts like fatigue resistance and durability are still inferior to traditional manufacturing in some cases.

• Cost - Despite advantages for low-volume production, the costs of metal 3D printers and materials remain relatively high, limiting adoption. Read our article to gain insights into cost of 3D printing.

Future trends and developments in metal 3D printing

• New materials - More metal alloy powders will become available for 3D printing, including superalloys, refractory metals and rare earth materials. New metal composites will also emerge.

• Multi-material printing - The ability to print different metal and non-metal materials within the same part will enable production of components with tailored properties and functional gradients.

• Printed electronics - Integration of conductive materials within 3D printed metal structures will create opportunities for customized electronic components.

• Industry adoption curves - Widespread adoption of metal AM for end-use production across industries like aerospace, automotive and medical is likely to accelerate as technology improves and costs decrease.

As these capabilities are realized, metal 3D printing will increasingly move from prototyping to production applications. Overall, the future of metal AM remains extremely promising.

Unionfab - China's Leading Metal 3D Printing Company

Metal additive manufacturing is rapidly evolving to enable unprecedented design freedoms, part performance and material efficiencies for metal components.

At Unionfab, we're committed to helping our customers pioneer this technological transformation and unlock new possibilities for their businesses.

Metal Additive Manufacturing Materials

Unionfab supports a wide range of the most common metal additive manufacturing materials, including:

Unionfab metal 3D printing material options

With over 800 additive manufacturing systems spread across more than 6 factories, Unionfab offers comprehensive capabilities to serve customers across the entire product development lifecycle. Whether you need a single prototype within days or thousands of end-use parts per month, our experts can help accelerate your time to market.

Get an instant quote now to start your metal 3d printing project!