Metal Stamping Guide

The Basics

How do metal 3D printers work? What are their main benefits, limitations & applications?

Get instant quote

Metal Stamping Guide

The Basics

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.

The Basics for metal stamping

How do metal stamping work?

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).

Metal stamping basic steps

From here, the specific steps each metal 3D printer follows to manufacture a part vary greatly by technology:

Metal stamping guide - Powder Bed Fusion

Powder Bed Fusion

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 stamping guide - Binder Jetting

Binder Jetting

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

Metal stamping guide - Metal Material Extrusion

Metal Material Extrusion

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 stamping guide - Direct Energy Deposition

Direct Energy Deposition

Metal powder or wire is melted by a high energy source and selectively deposited layerçchining.

Manufacturers: Optomec, Sciaky

Metal stamping guide - Ultrasonic Additive Manufacturing

Ultrasonic Additive Manufacturing

Metal foils are bonded layer-by-layer using ultrasonic welding and then formed to the design shape using CNC machining.

Manufacturers: Fabrisonic

Metal stamping guide - Other processes

Other processes

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...

Metal stamping guide - A brief history of Metal 3D Printing

A brief history of Metal 3D Printing

  • In the late ’80s, Dr. Carl Deckard of the University of Texas developed the first laser sintering 3D printer of plastics. This invention paved the way for metal 3D printing.
  • The first patent of laser melting of metals was filed in 1995 by the Fraunhofer Institute in Germany. Companies like EOS and many Universities lead the development of this process.
  • In 1991, Dr. Ely Sachs of MIT introduced a 3D printing process that is today better known as Binder Jetting. Binder Jetting of metal was then licensed to ExOne in 1995.
  • Metal 3D printing saw slow but steady growth in the ’00s. This changed after 2012 when the original patents started expiring and large investments were made by companies like GE, HP and DM.
  • Today, the Wohler’s report estimates metal 3D printing to be a $720 million market and growing rapidly. In 2017 alone, the sales of metal 3D printers increased by 80%.

Benefits & Limitations of Metal 3D printing

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.

Benefits of Metal 3D Printing

The greatest advantage of metal 3D printing compared to "traditional" manufacturing is its exceptional design flexibility. Since no specific tooling is needed (for example, a mold or a cutting tool), geometries that are impossible to manufacture through other processes are easily 3D printable.

More importantly, increasing the geometric complexity of a part has almost no effect on its manufacturing cost. This means that organic, topology optimized structures can be used with metal 3D printing, to greatly improve the performance of the produced parts.

The great design flexibility of metal 3D printing goes hand in hand with the creation of lightweight structures. In fact, following best design practices for metal 3D printing always gives a lightweight solution.

Typically, advanced CAD techniques, such as topology optimization and generative design, are usually used for this purpose.

This result in parts with both less weight (typically, by 25% to 50%) and higher stiffness. This is key for high-end applications in industries like the aviation and aerospace.

Since tool access is not an issue in metal 3D printing, parts with internal structures can be manufactured.

For example, internal channels for conformal cooling are a great way to increase the performance of a part. Injection molding cores with conformal cooling - manufactured through DMLS/SLM - can reduce injection cycles by up to 70%.

Another example of increased part functionality comes from Metal Extrusion. Using this process, custom jigs and fixtures with complex geometries can be created when needed, increasing the efficiency of operations of other industrial processes on the production floor.

Another great strength of metal 3D printing is its ability to merge an assembly into a single.

This eliminates the need for fasteners and results in parts that can serve multiple functions at once. Also, labor costs and lead times are minimized and maintenance and service requirements are reduced.

As an added benefit, reducing the total part count is another method to create lightweight structures.

Even when a part with complex geometry is manufacturable using "traditional" methods, it can take 20 or more production steps to do so.

In these cases, metal 3D printing should be considered as a valid manufacturing option. Using Binder Jetting, for example, the total number of steps can be reduced to five or less (including post-processing and finishing). This way the complexity of the manufacturing supply chain is greatly reduced.

Contrary to 3D printing of plastics, parts manufactured with DMLS/SLM or Binder Jetting show an isotropic mechanical behavior. Also, their material strength is comparable to the wrought metal (and in some cases even better). For this reason, metal 3D printed parts have found applications in the most demanding industries, like aerospace.

Note, though, that 3D printing parts generally have lower fatigue strength. This is due to their surface roughness and their internal porosity (typically, DMSL/SLM parts have < 0.2% porosity and Binder Jetting parts < 2%).

Limitations of Metal 3D printing

Compared to traditional manufacturing methods, the cost of metal 3D printing today is considerable. On average, a typical DMLS/SLM part will cost you approximately $5,000 to $10,000 to 3D print and finish. So, it is important to keep in mind that the use of metal 3D printing makes economic sense only if it is connected with considerable improvement in performance.

There is a demand for affordable metal 3D printing solutions though. The new benchtop Metal Extrusion systems and production Binder jetting systems could fill this gap in the near future.

Another limitation of metal 3D printing is that it cannot compete yet with traditional manufacturing when it comes to larger volumes.

The lack of custom tooling means that start-up costs are low, but also that the total manufacturing costs are not significantly affected by the volume of production. In other words, the unit price is almost unchanged at higher quantities and economies of scale cannot kick in.

Yet, the industry is working towards metal 3D printing systems that can streamline production. For example, DMLS/SLM machines with multiple lasers and Binder Jetting systems capable of continuous production are currently entering the market.

Designing parts for metal 3D printing follows a different set of rules than "traditional" manufacturing. This often means that existing designs have to be re-designed.

Moreover, the tools provided by older CAD software may not be enough to take full advantage of the benefits of metal 3D printing. For an extensive introduction to the main design consideration, advanced CAD tools and design rules for metal 3D printing, jump to the last section of this guide.

Almost every metal 3D printed part will need some post-processing before it is ready to use. This adds to the overall cost and delivery time.

Independent of the selected technology, combinations of thermal treatments, machining, polishing, and other finishing methods are almost always required to produce the final part. We will see more details on the necessary post-processing steps for each technology in later sections.

Applications of metal 3D printing

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.

Space

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.

3DP 101 - applications - space

Healthcare

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.

DMLS/SLM hip implant

Automotive

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.

Automotive

Industrial Tooling

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.

Industrial Tooling

Product Development

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.

Product Development

Materials for Metal 3D printing

The number of metal material available for metal 3D printing is growing rapidly. Engineers can today select from alloys including:

  • Stainless steels
  • Tool steels
  • Titanium alloys
  • Aluminum alloys
  • Nickel-based superalloys
  • Cobalt-chrome alloys
  • Copper-based alloys
  • Precious metals (gold, silver, platinum...)
  • Exotic metals (palladium, tantalum...)

For more information on the characteristics and applications for the most common metal 3D printing alloys, follow the links:

Stainless steel

Stainless steel is a metal alloy with high ductility, wear and corrosion resistance that can be easily welded, machined and polished.

Metal Stamping Materials in Stainless steel

Aluminum

Aluminum is a metal with good strength-to-weight ratio, high thermal and electrical conductivity, low density and natural weather resistance.

Metal Stamping Materials in Aluminum

Titanium

Titanium is a metal with an excellent strength-to-weight ratio, low thermal expansion and high corrosion resistance that is sterilizable and biocompatible.

Metal Stamping Materials in Titanium

Cobalt-chrome

Cobalt-chrome (CoCr) is a metal super-alloy with excellent strength and outstanding corrosion, wear and temperature resistance.

Metal Stamping Materials in Cobalt-chrome

Nickel alloys

Nickel alloys (Ni) have excellent strength and fatigue resistance. Can be used permanently at temperatures above 600°C.

Metal Stamping Materials in Nickel alloys

The Cost of metal 3D printing

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.

Production step Operation 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.

The speed of metal 3D printing

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).

Metal 3D printing vs traditional manufacturing

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
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:

  • DMLS/SLM is the best solution for parts with high geometric complexity (organic, topology optimized structures) that require excellent material properties for increasing the efficiency of the most demanding applications.
  • Binder Jetting is the best solution for low-to-medium batch production that cannot justify the large economic investment of a formative method and for parts with geometries that cannot be efficiently manufactured with a subtractive method.
  • Metal Extrusion is the best solution for metal prototypes and one-off parts with geometries that would otherwise require a 5-axis CNC machine to manufacture.

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:

Quantity Low complexity Header Header
< 10 parts CNC machining Metal extrusion
CNC machining
DMLS/SLM
< 100 parts CNC machining Binder Jetting
CNC machining
Binder Jetting
DMLS/SLM
< 1,000 parts CNC machining
Metal casting
Binder Jetting
CNC machining
Binder Jetting
1,000+ parts Sheet Metal
Metal casting
Metal casting -