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Additive and Subtractive Manufacturing

Manufacturing can be broken into two main technologies – additive manufacturing and subtractive manufacturing. The additive manufacturing process builds a part from scratch, layer by layer, until the part is complete. Using only the material that is needed to create the part (with minimal support structures), this process results in little to no waste. 3D printing is the most common form of additive manufacturing.


This process typically starts with a 3D model of the part that is generated utilizing computer-aided drafting (CAD) software.  The CAD model is processed by slicing software that will give the 3D printer the instructions needed to produce the part layer by layer. Metal 3d printing service providers are often used to help incorporate this technology into companies’ manufacturing workflows.

Traditional subtractive manufacturing process produces parts by removing unneeded material from a larger solid piece of stock. This process inherently results in a good deal of waste.

While some subtractive manufacturing processes are done manually, many are semiautomated using computer numerical control (CNC) machining. This process results in a high level of accuracy and allows for repeatability.

Similar to additive manufacturing, the subtractive process when utilizing CNC starts with a 3D model of the part generated with CAD software. The CAD software is then used to export CNC files that will be used to manipulate the tools within the CNC machines to produce the final part.

Balancing Both Technologies When Producing Metal Parts

When it comes to producing metal parts, additive and subtractive technologies both have advantages and disadvantages. While certain types of parts or circumstances may call for one process over another, many times a balance between the two can provide greater flexibility and increased proficiency.

For example, metal 3D printing can produce very complex geometric parts, but at times, it can be a fairly slow process. In contrast, CNC machining can offer a less time-consuming process but is much more limited when it comes to complex part geometry.

As stated above, material waste is also a consideration for both technologies. This is an important factor to consider in terms of total material costs.

In terms of manufacturing runs of multiple differing parts, some parts may better lend themselves to one process over another.  However, some parts may require the use of both processes.

For example, some parts produced via metal 3D printing may need a secondary CNC process to apply reams, bores, tapped threads, or milled surfaces. Also, many metal 3D printed parts require secondary processes to remove support material or apply the desired final surface finish utilizing subtractive manufacturing processes.  These additional steps are referred to as post processing.

Careful planning is a must when considering whether to utilize one process over another, or a combination of the two should be used. Required accuracy, precision, tolerances, surface finish, as well as weight reduction, topographical optimization, and part complexity are all important factors that need to be considered when choosing the appropriate method. Material preferences, availability, and cost are additional factors to consider. Metal 3D printing service providers are well versed in helping clients through this decision process.


The design flexibility of 3D metal printing, along with the ability to produce highly complex geometry, make additive manufacturing a perfect technology to pair with the increased accuracy and superior surface finish abilities of subtractive manufacturing’s CNC process.

The metal 3d printing service providers at GPI Prototype and Manufacturing Services are here to help you decide how to balance these two processes for your next metal 3d printing project. Give us a call (847-615-8900) or LiveChat us to discuss your metal manufacturing questions and challenges.  

conformal cooling tooling

DMLS 3D Metal Printing

Metal 3D printing is becoming more and more commonplace in today's design and production workflows. This additive manufacturing process can produce prototypes, end-use parts, strong but lightweight structures, and complex shapes that can’t be accomplished by using traditional manufacturing processes, all with little to no waste. There are many different types of metal 3D printers on the market today, however, most of them fall into one of four categories: powder bed fusion, direct energy deposition, material extrusion, and binder jetting.

Direct Metal Laser Sintering (DMLS) was the first type of metal 3D printing that a patent was filed for. DMLS 3D printing falls under the powder bed fusion category and is a very popular technology for a variety of reasons - such as its ability to generate complex parts, strong fully dense parts with good mechanical properties, as well as lighter parts through topology optimization. The printing process works by using a laser to selectively melt metal powder particles together (into a melt pool) on a build plate, layer by layer. After the first layer is melted together, the build plate lowers and a new layer of powder is spread across the build plate with a recoater blade. The process continues, layer by layer, until the part is complete.

Also, it may be of interest to clarify the inherent misnomer/confusion in considering DMLS as a form of “sintering”.   Check out this post to better understand DMLS vs. DMLM.

DMLS 3D Design Considerations – A Different Way of Thinking

To get the most out of DMLS 3D printing, it’s important to understand the different design considerations that will allow you to get the most out of the capabilities this technology brings to the table. Considerations such as supports, post-processing, surface finish, and tolerances all need to be considered in the design process. Careful DMLS 3D metal printing design considerations can improve part manufacturability, increase part aesthetics and, importantly, lower production times and costs.

DMLS 3D Printing Guidelines

  • Here are some guidelines and best practices that will help to produce the most optimal parts at the lowest cost possible. These guidelines are especially critical when using a metal 3D printing service, as 3D print service providers typically don’t offer design services and are actually not allowed to make any design changes, due to various reasons, including maintaining certifications in certain industry sectors. Wall Thickness: Too thin of walls can cause unstable parts, while too thick of walls can lead to part stress and cracking. A good rule of thumb is to use minimum wall thicknesses of 0.4 mm to add stability, and if you are designing much thicker walls, consider using internal honeycomb structures to eliminate part stress.
  • Support Structures: Are required for features such as overhangs, angles, and holes. (But don’t worry about it – we take care of it). Supports enable the printing of features that are not directly touching the build plate, by printing a structure that provides a platform for that feature to be printed on once that layer is reached. When we design your support structure, we try to minimize the areas where the support touches the actual part, as this will lead to less post-processing and an improved surface finish.
  • Overhangs: If you are designing a part with overhangs or cantilevers of more than 1 mm, we will need to add support under those areas in order for them to print successfully.
  • Part Orientation: It’s best to orient parts so that the need for support structures is minimized. You’ll also want to keep in mind the surface finish. Upward facing features will result in the best surface finish.
  • Channels and Holes: When designing channels and holes into parts, 0.4 mm is the minimum size that can be produced with DMLS 3D Printing. Likewise, holes and channels larger than 10 mm will require support.

At GPI Prototype, we can recommend design guidelines to our customers, but it is up to the customer to implement those guidelines before submitting them to DMLS 3D printing RFQ’s to GPI. We do provide all support structure and orientation recommendations to fit your needs.

How Does DMLS Work

Metal 3D Printing

While metal 3D printing may be relatively new to the additive manufacturing industry, the technology’s evolution since its inception has been remarkable. Metal 3D printing, in a very short time, has added value to a wide range of industries from manufacturing to medical, automotive to aerospace and everything in between. The technology is being used to aid in product development workflows, rapid prototyping, tooling, education and the creation of fully-functional end-use parts. 

Despite the evolution of metal 3D printing technologies, or even the emergence of new ones, the tried and true technology of direct metal laser sintering (DMLS) continues to be a popular solution when it comes to metal additive manufacturing solutions. So, let’s take a more detailed look at direct metal laser sintering, how it works and some of its advantages.

What Is Direct Metal Laser Sintering?

Actually, there is no such thing as thing as Direct Metal Laser Sintering!

EOS coined (trademarked) the term DMLS as ‘Direct Metal Laser Sintering’, undoubtedly in an attempt to brand their technology.  Unfortunately, this was a misnomer, and remains very misleading.  When using EOS default parameters, a melt pool is formed and a fully-dense structure equivalent to wrought, results.  

This is identical to processes referred to as DMLM (Direct Metal Laser Melting) and, thus, we will refer to the process as Direct Metal Laser Solidification for the remainder of this article, as per EOS’ subsequent statements. Read our more in-depth clarification of these two terms. 

Direct metal laser solidification (DMLS), aka DMLM, is considered a metal powder bed fusion (MPBF) technology, meaning that parts are printed in a build area (bed) containing finely powdered metal particles that are melted together layer by layer using a laser, to form the finished part. Depending on the specific 3D printer, layer heights on average run between 20 – 60 microns. 

One of the main keys to DMLS/DMLM, and how it differs from other similar technologies, is in the melting itself, where high temperatures are used to bring the metal particles to their melting point to fuse them together into a fully-dense piece. 

How Does It Work

The first step in any 3D printing project is creating a digital 3D model of the part that is to be printed. Digital 3D models can be created using computer-aided design (CAD) software to model the part from scratch, or if a physical part already exists, a 3D scanner can be used to create a 3D model by generating a digital point cloud or triangular mesh of the part. 

The digital model is then loaded into a slicing program that will analyze the model and create the instructions that the 3D printer will use to build the finished part layer by layer. Once the slicing operation is complete, and the file is sent to the 3D printer, the process is fairly automated, other than some general setup.

Once the print run is initiated, a thin layer of powder is then dispersed across the build area. Next, the laser is projected onto the material and then it follows the path for that layer based on the results of the slicing program. 

Only the particles in the path of the laser are melted together. This process is repeated layer upon layer, until the part has been completely printed. After a cooling period, the powder that was not melted can be cleared from the build area, and the part can be removed.

Advantages of Direct Metal Laser Solidification/Melting 
  • Minimized Waste: Additive manufacturing only uses the material required to build the part, so there is minimal waste and decreased material costs.
  • Stronger Parts with Reduced Weight: Metal is inherently stronger than plastic and the DMLS/DMLM process can lead to topology optimization and reduced weight.
  • Complex Geometries: DMLS/DMLM can create complex geometric parts and assemblies that would not be possible by using traditional manufacturing methods.
  • Potential for Fewer Parts: DMLS/DLML leave open opportunity to create fully-formed parts in one pass, whereas conventional methods might require several steps/pieces or sub-assemblies which then must be assembled together to form the final part.
  • Wide Range of Metallic Materials to Choose From 
  • Turnaround Time: Unlike traditional manufacturing methods, there is no tooling to be created or equipment setup, which leads to quicker turnaround times.

The team at GPI Prototype and Manufacturing Services can help with any and all aspects of your metal 3D printing projects. Contact them today to see how direct metal laser solidification/melting can add value to your operations.

Metal 3D Printing

Metal 3D printing is rapidly being adopted by companies of all types and sizes. The technology is being incorporated into design and product development workflows, alongside, and in some instances, even replacing traditional manufacturing processes altogether. Prototypes, as well as end-use production metal parts, can be created with metal 3D printing. The process works by using a laser to selectively fuse/melt together powder that contains small metal particles. 

Unlike traditional manufacturing processes that are mostly subtractive and inherently include a high amount of waste, metal 3D printing is an additive manufacturing process that only uses the amount of material that is needed to build the part, so there is little to no waste. 

Metal 3D printing can be cost-prohibitive though when considering whether to bring the process in-house, due to the capital cost of equipment, its installation, materials, and training. That’s why outsourcing additive manufacturing to companies that specialize in metal 3D printing services makes sense for many companies. 

If you’re considering incorporating metal 3D printing into your prototyping or product development process, here are some tips.

Explore Potential Advantages Over Traditional Manufacturing Methods

One big advantage of using a metal 3D printing service in your product design workflow is the fact that it can decrease the time it takes to get a part from the design stage, through prototyping and testing, to the production of the final part, when compared to traditional processes. This also means that there may be more time to try additional design iterations of a part. 

Cost savings from having little to no waste in the process is another reason to consider metal 3D printing. Subtractive processes inherently have a high amount of waste as material needs to be removed from larger stock parts, whereas additive manufacturing adds only the material that is needed, layer by layer. 

Weight lossing and part reduction are also potential advantages. Complex assemblies can be printed as one part with metal 3D printing, while traditional manufacturing would normally require multiple parts, processes, and fastening/joining methods.

Potential for Varied Materials and Processes

In addition to the advantages discussed above, utilizing a metal 3D printing service gives you access to all the various materials and processes that they have in-house. Many metal 3D printing services offer metal alloys such as stainless steel, cobalt chrome, maraging steel, aluminum, nickel alloy, titanium, and more. Multiple finishing options are typically available as well, including everything from a raw finish to a shot blast finish, to a shiny mirror-polished finish. 

Outsourcing to a metal 3D printing service that offers multiple materials means that you can have greater design flexibility in terms of the look, feel and strength of your part. Likewise, having more than one metal 3d printing process to choose from will give you additional ways to explore part functionality. 

Here we need to do a bit of clarification in process terminology. While many believe that DMLS and DMLM (Direct Metal Laser Melting) are different processes that turn out different results, that is inaccurate.  Actually, there is no such thing as thing as Direct Metal Laser Sintering! They are both the same thing, but why is that?

EOS coined (trademarked) the name DMLS, which they called ‘Direct Metal Laser Sintering’, undoubtedly in an attempt to brand their technology.  Unfortunately, this was a misnomer, and is very misleading.  When using EOS default parameters, a melt pool is formed and a fully-dense structure, equivalent to wrought, results.  This is identical to processes referred to as DMLM.  

In a statement intended to clarify, EOS recently stated that, going forward, they would prefer the word ‘solidification’ (as opposed to ‘sintering’) be used in describing their DMLS (Direct Metal Laser Solidification) process.

There are sintered-based 3D printing technologies out there as well, but EOS is not one of them – EOS is melt-pool based. Other equipment makers do use sintering - but as a secondary step in their process – heating the printed part in an oven to harden it and reduce its porosity.

All this is to say that you might need some guidance from the experienced metal 3D printing technicians at GPI Prototype and Manufacturing Services to see how they can help you successfully incorporate metal 3D printing into your next product design project. At GPI – We build the part with you, NOT apart from you.


The confusion that exists between DMLS and DMLM needs to be addressed.  This article is intended to clarify an aspect of metal 3D printing terminology that is commonly misunderstood and often used incorrectly.


DMLS = DMLM because they are identical in value!

To understand the basis for this statement, here is a simple analogy.

Visualize a bucket of ice cubes on your conference table.

If left to sit for a short while at room temperature, the individual cubes will soon stick to each other, such that if you try to pull out one cube you will most likely get a random glob of multiple cubes stuck together.  This fusing of cubes together is analogous to the most common interpretation or use of the word ‘sintering’. Note that the properties of the glob of cubes may or may not resemble the properties of an individual cube as there will likely be pockets of air, or different density ice, interspersed within the mass of ice.

If you left this same bucket of ice cubes out on the table long enough for all the cubes to melt, you would have a bucket of water.  If you put that bucket of water back in the freezer it would solidify into effectively one large homogenous and fully dense piece of ice.  This is analogous to what happens in DMLM and DMLS 3D printing with metals.  

The laser provides enough heat (energy) to melt the metal particles the laser is directed at and then, as the laser moves on, the melt pool rapidly solidifies into a fully dense homogenous structure.   Note in this case that the properties of this new block of ice exactly resemble the properties of the individual ice cubes we started with and do not have air, or different density ice, interspersed within the mass.

So sintering is not melting.  

Sintering Does Have Its Place

Note that in traditional sintering of powder metal all kinds of processes were developed to address the porosity or fill the interstitial spaces between particles – like infiltration and hipping.  These processes are not needed with DMLS or DMLM as the resultant structure is fully-dense as produced.

If you actually needed a portion of a part to be sintered within a DMLM part, let’s say the center, it is possible to change the power of the laser for that defined area of the part, and then turn it back up to complete the rest of the part, resulting in a part with a less dense/solid center.  Kind of like a piece of hard candy with a soft, chewy core.   

EOS Terminology Change

EOS coined (trademarked) the name DMLS, undoubtedly in an attempt to brand their technology.  Unfortunately, this was a misnomer, and very misleading.  When using EOS default parameters, a melt pool is formed and a fully-dense structure, equivalent to wrought, results.  This is identical to processes referred to as DMLM.  

In a statement intended to clarify, EOS recently stated that, going forward, they would prefer the word ‘solidification’ (as opposed to ‘sintering’) be used in describing their DMLS (Direct Metal Laser Solidification) process.

Finally, note that there are sintered-based 3D printing technologies out there as well, but EOS is not one of them – EOS is  melt-pool based. These other equipment makers do use sintering - but as a secondary step in their process – heating the printed part in an oven to harden it and reduce its porosity.  

The expert metal 3D printing technicians at GPI Prototype and Manufacturing Services can help you successfully incorporate metal 3D printing into your next prototyping, manufacturing or product design project. At GPI – We build the part with you, NOT apart from you. 

eos eosint m 280GPI Prototype, located in Lake Bluff, IL, recently announced the completion of a facility expansion to double office space, accommodating new staff brought in to handle the rapid growth experienced at GPI.  In addition, existing warehouse space has been remodeled to accommodate six more direct metal machines.

Historically focused on building metal prototypes, GPI has been growing the portion of its business dedicated to additive manufacturing.  In preparation for this strategic commitment, GPI added two key individuals to its production and engineering departments in 2014.  The team was strengthened by the addition of a metallurgical engineer as well as a metals applications engineer.  This engineering strength is spearheading R&D and production capabilities on all DMLM machines.

To further support the growth of its metal additive manufacturing services, GPI has been adding to its production capacity.  In 2014, GPI acquired two new direct metal machines.  These machines are dedicated to the production of aluminum parts.  Growth continues for GPI, especially with the scheduled delivery of a new EOS M290 in June.

In response to increased opportunities from the aerospace and medical industries, GPI recently went through the rigor of certification for AS9100:2009 Rev C, ISO 13485:2003, ISO 9001:2008 and is a registered ITAR facility.  These certifications provide GPI with the standardized processes used to create quality products and meet regulatory requirements.  During the course of certifications, GPI created an Internal Management System, providing assurances in all manufacturing processes.  Requirements include internal audits, recordkeeping, process procedures and monitoring, management reviews and corrective and preventative action plans.

In more recent news, GPI is making a change in upper management.  Scott Galloway, Founder and President, will take on the new role of CEO.  Adam Galloway, has been promoted from VP Sales and Marketing and has assumed the role as President of GPI.  Adam joined the company in 2003 and has been an integral member of the management team at GPI for the past eight years.  “It is exciting to be part of a company that is not afraid to take risks and realize when diversification is necessary to sustain strong growth.  GPI started out specializing in prototypes.  As we’ve continued to make giant steps forward, the production capabilities we offer today continue to allow GPI to reach higher levels within the AM industry,” – Adam Galloway.

3 eos dmls machines

GPI Prototype announced that it has completed the installation of a third DMLS machine from EOS. The additional EOSINT M 270 joins the EOSINT M270 & M280 machines currently being used at GPI to build metal parts additively. The addition of a third machine establishes GPI as a leader in metal rapid prototyping and expands their DMLS material selection to include aluminum.

DMLS offers many advantages vs traditional tooling including the ability to manufacture complex geometries and shapes not possible with CNC machining. Conformal cooling channels can also be integrated into designs to dramatically reduce injection molding cycle/lead times and lower costs. GPI offers 6 material choices for DMLS including Stainless Steel (GP1 & PH1), Titanium (Ti64), Cobalt Chrome (MP1), Maraging Steel (MS1) & Nickel Alloy (IN718). GPI is in the testing phase for aluminum and will be dedicating the EOSINT M 280 machine to aluminum parts in the next month.

GPI is also proud to announce that they have received their International Traffic in Arms Regulations (ITAR) Registration. ITAR regulates the export and import of U.S. military and defense related equipment and information. Companies receiving this certification have corporate procedures and controls in place to ensure compliance. The ITAR Registration allows GPI to support military and defense-related projects in the United States.

Additional services include Stereolithography (SLA), Selective Laser Sintering (SLS), 3D Printing (3DP), Fused Deposition Modeling (FDM), Room Temperature Vulcanization (RTV), Investment Casting, Tooling, CNC Machining, Finishing, Painting and Laser Scanning. These services are priced very competitively in the industry while providing the best in quality and customer service.

eosint m 280 dmls machine

GPI Prototype announced that it has completed the installation of a EOSINT M 280 machine from EOS. The EOSINT M 280 is an updated version of the EOSINT M 270 currently being used at GPI to build metal parts additively. The addition of a second machine establishes GPI as a leader in rapid prototyping and expands their DMLS material selection to include aluminum and titanium.

GPI is committed to showcasing their additive technology at industry events and informing customers of the benefits and cost savings of additive manufacturing vs traditional machining. On September 14th-15th, 2011 at the ODT Conference & Exhibition in Fort Wayne, Indiana, GPI will be showcasing parts made via DMLS at booth #803. GPI will also be exhibiting at Design & Manufacturing Midwest on September 20-22, 2011 in Chicago, IL at booth 2234. GPI has established a foothold in a variety of markets including medical, aerospace, automotive & consumer products.

DMLS offers many advantages vs traditional tooling including the ability to manufacture complex geometries and shapes not possible with CNC machining. Conformal cooling channels can also be integrated into designs to dramatically reduce injection molding cycle/lead times and lower costs. GPI offers 8 material choices for DMLS including Stainless Steel, Cobalt Chrome, Maraging Steel, Bronze Alloy, Titanium Alloy, Aluminum & Nickel Alloy. Parts can be built in 20 micron layers with a turnaround time of a few days.

Top-quality, accurate, clean prototypes can be built in hours and shipped to the customer in a few days.

Additional services include Stereolithography (SLA), Selective Laser Sintering (SLS), 3D Printing (3DP), Fused Deposition Modeling (FDM), Room Temperature Vulcanization (RTV), Investment Casting, Tooling, CNC Machining, Finishing & Painting, Laser Scanning & Packaging solutions.

The University of California, San Diego chapter of Students for the Exploration and Development of Space conducted two hot-fire tests of their second 3D printed rocket engine on April 18, 2015 at the Friends of Amateur Rocketry test facility in the Mojave Desert.

The rocket engine, named Ignus, was sponsored by GPI Prototype and metal 3D printed at their facilities in Lake Bluff, IL. The rocket engine utilized liquid oxygen and kerosene as its propellants and was designed to achieve 750 lbf of thrust, a stepping stone in the club’s goal of producing larger and more powerful rocket engines.

“We aim to align our research so it is compatible with the needs of the aerospace industry. 3D printing has significant benefits including huge cuts to the cost, time to fabricate, and weight of rocket engines”, said Deepak Atyam, Club President and Gordon Fellow.

The SEDS chapter conducted this research with the support of various organizations including GPI Prototype, NASA’s Marshall Space Flight Center, Lockheed Martin, the Gordon Engineering Leadership Center, and XCOR Aerospace.

Ignus is the first engine that was tested in a series of hot fires of different engine designs that the club plans to do in a lead up to their eventual rocket launch later this year at the Intercollegiate Rocket Engineering Competition. The competition will be held in Green River, Utah June 24-27, 2015. That rocket, named Vulcan1, would be one of the first rockets powered by a 3D printed engine in the world.


University of California San Diego Students for the Exploration and Development of Space (SEDS UCSD) announced that they successfully launched the Vulcan-1 rocket on May 21st at the Friends of Amateur Rocketry (FAR) site in Mojave, CA.

Some delays were initially experienced, but the 3d printed rocket engine was launched successfully in windy conditions. This achievement makes them the first university group to design, create, and launch a rocket powered by a completely 3D printed engine.

Vulcan-1 is 19 feet long, 8 inches in diameter, and capable of producing 750 lbs of thrust. The rocket was powered with a combination of liquid oxygen (LOx) and refined kerosene and used a cryogenic, bi-propellant, liquid-fueled blow down system. The rocket engine was sponsored by GPI Prototype & Manufacturing Services and 3D printed in inconel 718 at their facilities in Lake Bluff, IL.

The Vulcan-1 project began in 2014 and quickly grew into a team of over 60 student engineers. The team fabricated and tested the rocket at Open Source Maker Labs, which provided equipment and support for the project.  SEDS UCSD also received mentor support from NASA, XCOR, Open Source Maker Labs, and many other groups in the space industry.

“This sort of technology has really come to fruition in the last few years.  This is proof of concept that if students at the undergraduate level could drive down the costs of building these engines, we could actually fly rockets and send up payload that is cheaper and more efficient,” said Darren Charrier, the group’s incoming president.  “One day, we’d like to see this technology being implemented on large-scale rockets, which means that we could send satellites to provide internet for developing countries, we could mine asteroids, perhaps even go colonize Mars.”


The photos below show a guitar tailpiece we 3d printed in metal using direct metal laser melting (DMLM). The project is a great example of high-end 3d printed guitar parts that can be created using this unique metal 3d printing technology.

The design for the tailpiece was inspired by the front grille of a 1937 Delahaye 135MS Roadster. Two versions of this part were created, one as a completely 3d printed piece and another where just the frame was 3D printed and vertical rods were added separately. The project illustrates how just because something can be 3d printed, for some parts 3d printing better complements existing fabrication techniques.

Looking for a custom guitar? Visit Mark Lacey Custom Guitars for more information about this guitar and other guitar projects.

Car Photo By Rex Gray [Creative Commons Attribution 2.0 Generic]

One of the many benefits of using additive manufacturing, commonly referred to as 3D printing, to produce consumer goods is that it offers the opportunity for mass customization.  Mass customization is the ability to produce personalized products that meet customer specified needs, at or near mass production pricing.

The major limiting factor in bringing mass customized products to market is the expensive tooling required to produce these parts, and the large minimum order quantities required to make that tooling economical.  Enter in Additive Manufacturing (AM).

Additive manufacturing produces anything from one off prototypes to production parts without the need for expensive tooling.  Due to the layer based nature of the processes, additive manufacturing allows one to print multiples of the same part, or multiple variations, at one time.  In product development, this reduces time to market by shortening the prototyping cycle. In production, additive manufacturing enables one to print customized products specifically tailored to an individual.

GPI Prototype & Manufacturing Services completed the first set of custom bike lugs and drop outs for Jamie White of Métier Vélo. Métier Vélo, which translates to "craft bicycle" or "professional bicycle", is a custom bicycle design and fabrication shop based out of Salt Lake City, Utah.

Producing these parts in Titanium Ti-6Al-V4 (Ti64) additively allows Jamie to build bikes designed specifically for the individual fit of each rider; meaning no two Métier Vélo bicycles are the same.

Metal additive manufacturing produces part geometries not possible through subtractive or cast methods.  Métier Vélo's lugs are completely hollow featuring complex internal geometries, internal cable routing, and custom mounts. For easy repair the lugs and drop outs can be un-bonded from their carbon fiber tubes if the tubes become damaged. Not to mention they look amazing!

This is the questions I hear the most...Well how does DMLS work?

Are you familiar with stereolithography (SLA)? Well they are very similar processes, but DMLS does it in metal.

What makes SLA and DMLS similar is that fact that both build with supports, SLA builds with supports and so does DMLS. This means that any bottom surface must be supported to the build plate. The easiest way to explain this is that if you were to slice the part into a bunch of layers then take those layers and start from the bottom and work your way to the top, you then have to stack these layers one on top of the other right? So, you have to build from something, one layer must build on top of something else whether it be a support or another layer it just cannot be free floating in air like the SLS process is.

I hear a lot well isn't it like SLS and it doesn't require supports? Nope, this is much different, the reason being is that there is stress involved, just like traditional machining there is some warping and stress. Each layer is melted locally using a fibre optic laser, so that layer can become very hot and the laser isn't zapping the whole part at once (which may be worst).

Here is how the whole DMLS process starts:

1) You start with a CAD file that is sliced into 20 or 40 micron layers using a specialized software called Magics. There is a lot more that goes into just taking the CAD file, for instance each part must be orientated to build the best way. I can't give away all the secrets right?
2) Take the sliced file and input it into the EOS software and depict the best angle for this part to be facing the recoater blade (the blade that sweeps new powder over each layer).
3) Output job file.
4) Add powder and level build plate inside the equipment.
5) Install Job parameters for the EOS equipment via the EOS software.
6) Input job file to the EOS equipment computer.
7) Let oxygen levels get to a safe amount.
8) Hit GO!
9) Take build plate out of EOS equipment.
10) Cut parts off the build plate (typically a 2-4 mm support structure under the part is cut close to the plate).
11) Remove support material with a variety of tools and/or CNC equipment.
12) Finish said parts to desired finish level.
13) Pack and send.

I made that seem very simple, however there is much more that is involved. Removing the supports isn't always the easiest thing in the world, as the support material is the same material that the part is created in. I know I am missing a ton of information but this is the easiest way to teach you how the actual process works. Stay tuned for more blog posts.

The million dollar question right...is it really worth prototyping the exotic metals using DMLS rather than machining them. I guess it is really going to depend on your time frame and geometry. The thing about DMLS is, its super fast, on top of that it can create really complex geometries. Would it be worth a one off CNC of a titanium or aluminum part if you have to create work-holders and buy a lot of material to do just one part, probably not. Let me talk a little about each of the exotic materials.


Since DMLS is an additive technology, it drastically reduces material waste in comparison with traditional processes. Investment casting of titanium is difficult and often has a high scrap rate. Currently, many titanium aerospace components are machined from solid stock, often cutting away 90% or more of the original material. This becomes a time consuming, costly operation that is completely eliminated with titanium DMLS, not to mention much lower labor costs.

Some of the characteristics that make titanium ideal for aerospace applications also make it difficult to machine. Its hardness and low heat conductivity reduce tool speeds and life, require a great deal of liquid cooling during machining, and limit the productivity of certain shapes, such as thin walls. Laser-sintered titanium retains the beneficial properties of the metal and involves no tool-wear or coolant costs. In addition, nearly any geometry, including thin walls, can be created with laser-sintering. - Nextbigfuture.com

Typical Applications:

- Direct manufacture of functional prototypes, small series products, individualized products-
- Spare parts requiring good corrosion resitance properties

- Parts requiring a combination of high mechanical properties and low specific weight

- Structural and engine components for aerospace and motor racing applications, etc.


EOS Aluminium AlSi10Mg is a master alloy aluminium- powder. AlSi10Mg is a typical casting alloy with good casting properties and is used for cast parts with thin walls and complex geometry. The alloy combination silicon/magnesium results in a significant increase in the strength and hardness. It also features good dynamic properties and is therefore used for parts subject to high loads.Standard building parameters completely melt the powder in the entire part.

Parts made of EOS Aluminium AlSi10Mg can be machined, wire eroded and electrical discharge machined,welded, micro-blasted, polished and coated. Unexposed powder can be re-used.

Typical applications:

- Direct manufacture of functional prototypes, small production runs, user-specific products or spare parts
- Parts that require a combination of good thermal properties with low weight


Machining Inconel 718 is tough and nobody likes to do it. The DMLS process allows you to produce Inconel parts quick, while being affordable.

This material is ideal for many high temperature applications such as gas turbine parts, instrumentation parts, power and process industry parts etc. Material also possesses excellent cryogenic properties and potential for cryogenic applications.

Standard processing parameters use full melting of the entire geometry, typically with 20 µm layer thickness. Parts built from EOS NickelAlloy IN718 can be easily post-hardened to 40-47 HRC (370-450HB) by precipitation-hardening heat treatments. In both as-built and age hardened states the parts can be machined, spark-eroded, welded, micro shot-peened, polished and coated if required. Unexposed powder can be reused.

Typical applications:

- Aero and land based turbine engine parts
- Rocket and space application components
- Chemical and process industry parts
- Oil well, petroleum and natural gas industry parts

Contact Us

940 North Shore Drive
Lake Bluff, IL 60044
Phone Number

(262) 563-5555


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