How do metal 3D printers work? What are their main benefits, limitations & applications?
How do metal stamping work? What are their key benefits & limitations? How is metal stamping used in the industry today?
In this section, we will answer these questions and we will learn more about the basic mechanics of each metal stamping process. Through a comparison with "traditional" manufacturing, you will you gain a deeper understanding of the current state of metal stamping and its great potential.
Similar to all other 3D printing processes, metal 3D printers build parts by adding material a layer at a time based on a digital 3D design - hence the alternative term Additive Manufacturing.
This way, parts can be built with geometries that are impossible to manufacture with "traditional" subtractive (CNC machining) or formative (Metal Casting) technologies, and without the need for specialized tooling (for example, a mold).
From here, the specific steps each metal 3D printer follows to manufacture a part vary greatly by technology:
A high-power laser (in DMLS/SLM) or an electron beam (in EBM) is used to selectively bond metal powder particles together, layer-by-layer forming the metal part.
Manufacturers: EOS, 3D Systems, Renishaw, SLM Solutions, Concept Laser, Arcam
Metal powder particles are bound together with an adhesive layer-by-layer, forming a “green” part that needs to be thermally post-processed (sintered) to remove the binder and create a fully-metal part.
Manufacturers: Desktop Metal, ExOne, Digital Metal, HP
A filament or rod consisting of polymer and heavily loaded with metal powder is extruded through a nozzle (like in FDM) to form the “green” part that is post-processed (debinded and sintered) to create a fully-metal part.
Manufacturers: Desktop Metal, Markforged
Metal powder or wire is melted by a high energy source and selectively deposited layerçchining.
Manufacturers: Optomec, Sciaky
Metal foils are bonded layer-by-layer using ultrasonic welding and then formed to the design shape using CNC machining.
Other metal 3D printing systems have been developed over the years based on established plastic 3D printing technologies (such as Material Jetting or SLA).
3D printing has also been used to create tooling for “traditional” metal manufacturing, such as sand casting or investment casting.
Manufacturers: XJet, ExOne
Today, the most used metal 3D printing process are Direct Metal Laser Sintering (DMLS) / Selective Laser Melting (SLM), followed by Binder Jetting and Metal Extrusion.
If you want to dive deeper into the basic mechanics, particular benefits and limitation, and capabilities of each of these technologies, jump directly to the next part of this guide.
For the rest of this section, we will focus on the general aspects of metal 3D printing that apply to all processes. We will also explore how they compare with "traditional" manufacturing processes. This way you will gain a broader understanding of how to get the most out of this unique manufacturing technology. But first, a short history lesson...
It is important to understand that metal 3D printing is a powerful tool that comes with many unique benefits. Yet, its current limitations do not always make it the best option when it comes to manufacturing of metal parts.
Here we summarized the most important advantages and disadvantages of metal 3D printing. Use them to understand where metal 3D printing stands today and where it is headed in the near future.
Here we collected examples of key industrial applications of metal 3D printing. They illustrate some of the main benefits and limitations of the technology. Use them to better understand why engineers chose metal 3D printing for their particular application.
Creating lightweight structures is of paramount importance for the space industry. The current cost of launching a kilogram of payload into space is approximately $10,000 to $20,000. So, metal 3D printing of topology optimized parts has great potential here.
Optisys, for example, is a provider of micro-antenna products. They used DMLS/SLM to reduce the number of discrete pieces of their tracking antenna arrays from 100 to only 1. With this simplification, Optisys managed to reduce the lead time from eleven months to two, while achieving a 95% weight reduction.
The ability to create organic structures, personalized to the anatomy of every individual, makes metal 3D printing a very appealing solution for the medical industry. Today, medical implants from biocompatible materials (such as titanium) are one of the major uses of metal 3D printing.
Back in 2007, Dr. Guido Grappiolo was the first surgeon to implant a 3D printed hip cup implant. With the help of LimaCorporate and Arcam, he designed the Delta-TT Cup, a titanium implant with a lattice structure that accelerates patient rehabilitation and bone growth. A decade later, more than 100,000 of these hip cups have been implanted successfully to patients.
The adoption of metal 3D printing as a manufacturing option for end parts in the automotive industry is increasing rapidly. For the time being, high-performance and racing are the main applications of metal 3D printing.
The TU Delft Formula Student team, one of the most successful teams in the history of the sport, used DMLS to manufacture their topology optimized bracket for their formula car. This bracket is the main connection point between the wheel and the chassis and it is designed to withstand forces up to 400 kg. The re-designed titanium bracket has half the weight and twice the strength of an equivalent part machined out of steel.
Metal 3D printing is used today to create industrial tools with added functionality. These advanced tools can greatly increase the productivity of other proceses.
For example, metal molds with internal conformal cooling channels can be manufactured using DMLS/SLM 3D pritning. These cooling channels can be printed to any shape and closer to the part than subtractive methods can accomplish. A printed metal mold can cost about $10,000, which is considerable compared to the $4,000 that the same mold would cost if it was CNC machined. The increased cost brings significant performance improvements. Users reported injection cycles that are shorter by 60% to 70% with almost no scrap.
The main applications of Metal Extrusion today is the manufacture of metal prototypes. When compared to other in-house solutions, the time savings offered by Metal Extrusion can greatly reduce the time-to-market of new engineering products.
Lumenium is a start-up that develops innovative internal combustion engines. They were seeking a faster and more cost-effective approach to prototyping their engine parts. Traditionally, their development cycle is approximately 3.5 years. By incorporating Metal Extrusion in their workflow, they estimated that they reduced their development time by 25% to 2 years and 9 months.
The number of metal material available for metal 3D printing is growing rapidly. Engineers can today select from alloys including:
For more information on the characteristics and applications for the most common metal 3D printing alloys, follow the links:
Stainless steel is a metal alloy with high ductility, wear and corrosion resistance that can be easily welded, machined and polished.
Aluminum is a metal with good strength-to-weight ratio, high thermal and electrical conductivity, low density and natural weather resistance.
Titanium is a metal with an excellent strength-to-weight ratio, low thermal expansion and high corrosion resistance that is sterilizable and biocompatible.
Cobalt-chrome (CoCr) is a metal super-alloy with excellent strength and outstanding corrosion, wear and temperature resistance.
Nickel alloys (Ni) have excellent strength and fatigue resistance. Can be used permanently at temperatures above 600°C.
The cost of a metal 3D printer varies greatly between technologies. The selling price of a DMLS/SLM printer averages at $550,000 and can reach $2 million USD. Metal Binder Jetting systems cost approximately $400,000. A Metal Extrusion printer will cost you around $140,000 including the post-processing units.
The manufacturing cost of a typical DMLS/SLM part is approximately $5,000-$10,000 (including finishing). For Binder Jetting and Metal Extrusion, the cost per parts can be up to 5-10 times lower than that of DMLS/SLM parts. At the time of writing though, it is still early to assess the full operational cost of these systems.
The table below is a break down of the average costs of different manufacturing steps for DMLS/SLM. Notice that the material cost, as well as the cost of post-processing, contribute considerably to the overall cost.
|Manufacturing||Material cost||$200 - $500 per kilogram|
|DMLS/SLM cost||$2,000 - $4,000 per build †|
|Post-processing||Stress relief||$500 - $600 per build †|
|Part/supports removal||$100 - $200 per part|
|Heat treatment / HIP||$500 - $2,000 per build †|
|CNC machining||$500 - $2,000 per part|
|Surface treatments||$200 - $500 per part|
† Typically, six to twelve parts can fit on the same build plate.
Independent of the process, a metal 3D printed part requires at least 48 hours and an average of 5 days to manufacture and finish.
About 50% of the total production time is allocated to printing. This, of course, depends on the volume of the part and the need for support structures. For reference, the current production rate of modern metal 3D printing systems varies between 10-40 cm³/h.
The remaining production time is related to post-processing and finishing requirements. Thermal treatments contribute significantly to the total production time: a typical thermal cycle lasts 10 to 12 hours. Mechanical surface finishes can also be a time-consuming step as they need input from an expert (5-axis CNC machining) or manual labor (hand polishing).
Always begin with a Cost vs Performance analysis, when you are choosing between a metal 3D printing and a subtractive (CNC machining) or formative (metal casting) technology.
Generally speaking, the manufacturing cost is mainly connected to the production volume, while the performance of a part depends greatly on its geometry.
The key strength of metal 3D printing is its ability to create parts with complex & optimized geometries. This means that it is ideal for manufacturing high-performance parts. On the other hand, it does not scale as well as CNC machining or metal casting at higher volumes.
Typical unit cost vs quantity for additive, subtractive and formative technologies
As a rule of thumb:
The high cost of metal 3D printing can be only financially justified if it is connected to a significant increase in performance or operational efficiency.
Of course, each metal 3D printing process meets different industrial requirements. Use the tips below as general guidelines to understand which process is the most suitable for you:
The table below is a Volume vs Part Complexity matrix, showing the areas that each manufacturing process (additive, subtractive or formative) performs at its best. Use it as a quick reference:
|< 10 parts||CNC machining||
|< 100 parts||CNC machining||
|< 1,000 parts||