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3D printing doesn’t refer to one kind of manufacturing or technological process and therefore a well-rounded understanding requires an in-depth look into all available 3D printing systems.
While it’s not exactly easy to bundle 30+ years of manufacturing advancements into a succinct article, we’ve taken on the challenge because we want to help you make informed and grounded decisions on how, where and when to implement 3D printing into your own business operations or even daily life.
3D printing refers to any manufacturing process which additively builds or forms 3D parts in layers from CAD data.
The technology is significant because it offers direct manufacturing, meaning a design goes directly from you to physical product through a computer and a printer. Let’s break it down further.
3D printing starts with a digital file derived from computer aided design (CAD) software. Once a design is completed, it must then be exported as a standard tessellation language (STL) file, meaning the file is translated into triangulated surfaces and vertices.
The STL file then has to be sliced into hundreds – sometimes thousands – of 2-D layers (Fig.1).
A 3D printer then reads the 2-D layers as building blocks which it layers one atop the other, thus forming a three dimensional object. All design files, regardless of the 3D printing technology, are sliced into layers before printing.
Layer thickness – the size of each individual layer of the sliced design – is determined partly by technology, partly by material, and partly by desired resolution and your project timeline; thicker layers equates to faster builds, thinner layers equate to finer resolution, less visible layer lines and therefore less intensive post-processing work (Fig.2).
After a part is sliced, it is oriented for build.
Orientation refers to how and which direction a part is placed on the 3D printing build platform. For example, a part may be oriented at an angle, or lying flat/standing vertical.
Similar to CNC machining, orientation factors into the outcome of surfaces and details on a 3D printed part. Because 3D printing builds one 2-D layer at a time, the individual lines appear as ribbed surfaces on parts.
Downward facing surfaces usually reveal more layer lines. Certain build orientations are better for curved or square features while delicate features require special consideration.
Technologies with higher instances of warp (or material deformation) must account for large flat surfaces during build orientation.
It is critical to consider these factors because how a part is oriented determines where supports are added – or needed – within the build. Supports are a huge factor for 3D printing, and can affect material finish and accuracy of a 3D printed part.
Most 3D printing processes require support structures to act as “scaffolding” for features that can’t be built above open air, such as overhangs, undercuts, holes, cavities, etc.
Where supports are required largely depends on the material, build process (3D print technology) and build resolution (layer thickness), among other factors.
Support structures are usually made using the same or similar material as the final build and are removed after the model cures.
We will delve deeper into why technologies require supports – and which ones do not – once we break out into individual 3D printing processes.
Let’s recap: 3D printing, regardless of process, takes a 3D CAD file, slices it into 2-D layers, and additively builds up a part 2-D layer by 2-D layer. 3D printing is significant because it changes the way we think about manufacturing.
We’ve detailed why 3D printing is viewed as a game-changer for manufacturing in the next section, including how 3D printing has changed prototyping and production through cost, lead time and design freedom.
3D printing brings a revolutionary approach to manufacturing through three key advantages: Shorter lead time, design freedom, and lower costs.
In today’s on-demand ecosystem of Netflix and Amazon (and Starbucks online ordering, for that matter), it’s a little hard to appreciate manufacturing before 3D printing.
The way we have approached prototyping for the past three decades might even be considered a luxury when compared with prototyping prior to 3D printing.
Today, 3D printing an early phase design and re-printing it overnight is feasible and affordable thanks to rapid prototyping or 3D printing platforms like PolyJet and Stereolithography.
3D printing a final product in just one to two days is feasible with multiple 3D printing technologies, such as Laser Sintering, Fused Deposition Modeling and Direct Metal Laser Sintering.
However, prior to these quick-turn prototyping and production manufacturing processes, bringing an idea into physicality was an involved and costly process and there often wasn’t room or time to re-prototype frequently or make multiple design adjustments.
Let’s look at a fairly common example. Rewind to 1985: You’re a design engineer bidding on a new product. It’s a dream project; you already have an idea of the design.
Where do you start? First, you head to the drafting room (AutoCAD, the earliest computer aided design software (CAD), has only been out two years – too early for your company to have fully adopted it just yet).
You develop a design, hand drawing details and carefully measuring out dimensions via ruler and pencil. Once the design is finalized, you meet with your model shop or an outside modeling firm.
The shop can machine the model manually - adding in features and details, with painstaking hand labor and fabrication - or the shop can create a prototype tool and cast a plastic or metal part, which will add another 2-4 weeks to your project.
You choose CNC machining. Machine drafters help translate your design into instructions a machinist can use to build the part and your design is manually translated into a lengthy program (known as RS-274 or simply g-code) for the machine to read and execute code line by line.
The design undergoes further configurations as you figure out what can and can’t be built given your timeframe and the constraints of the manufacturing process. By now, more than a month has passed and your model is still in early production stages.
Fast forward to 2005. You are offered the chance to bid on a new product. It’s a dream project; you’ve had a rough idea of the design for years.
You draft out a rough sketch before moving to 3D CAD, easily plugging in dimensions and executing the design in the 3D software (you’re a CAD modeling pro!).
You finalize your design with your project leader, upload your 3D CAD file to Stratasys Direct Manufacturing and select PolyJet prototyping.
The next afternoon, you’re showing your physical model to your team. They immediately point out a flaw – hey, nobody’s perfect – and you head back to the 3D drawing board.
A few prototypes later and you and your team land on it, the perfect model. You order a new print – this time, you need it to be functional and cosmetically finished. Your trusted 3D printing partner, Stratasys Direct Manufacturing, prints up your part in Fused Deposition Modeling, hand sands it down and ships it back to you all in the span of five business days.
It’s only been four weeks since you started prototyping. It only took you roughly one month to get your finalized idea into the bidding room. That’s the difference 3D printing has made—from weeks to days. From “no, we can’t make that” to “yes, we can build it”.
And today, 3D printing isn’t just used for prototypes and models. 3D printing includes:
It’s a matter of knowing which technology is good for what application, and when to use one over the other. But lead time is just one small piece of the 3D printing solutions puzzle.
Perhaps the most revolutionary advantage 3D printing offers is its inherent design freedom.
Traditionally, designers and engineers have relied heavily on the manufacturing process to dictate the end design.
Involved conventional manufacturing processes like CNC machining have inherent strict limitations on assembly rules, manufacturability and overall feasibility.
Stepping outside of design practices for these conventional manufacturing processes directly results in increased cost and labor.
However, sticking to the design rules of the past inevitably results in stunted innovation growth.
Additive manufacturing, or 3D printing, has opened doors previously unimaginable to designers and engineers because it doesn’t rely on the same design and manufacturing constraints as conventional manufacturing.
Through 3D printing, free-flowing, organic and intricate designs are seamlessly executed while maintaining strength in ways impossible via any other manufacturing process.
In the images below, we’ve laid out some of the more beautifully complicated designs built using a 3D printing process called Laser Sintering. These 3D printed designs are involved, and yet the part can be built in a consolidated unit.
Attempting to machine parts like these would be either very expensive or even impossible. There are designs only 3D printing can execute, and without 3D printing they simply wouldn’t be feasible.
An excellent case example of the design freedom of 3D printing comes straight from NASA.
NASA’s Marshall Space Flight Center was able to transform a part that previously contained 150+ parts and, through 3D printing, consolidated the whole design into one continuous unit!
Design freedom in 3D printing is considered “zero-cost” because of the layering process.
Design features are seamlessly integrated within each cross-section as the part builds, eliminating the need for tooling, labor intensive assembly, and reducing time and part count to result in significant cost savings.
3D printing reduces manufacturing/production costs through a variety of advances that can be boiled down to three key advantages: Zero tooling, zero-cost complexity, reduced labor.
These three advantages ultimately result in shorter lead times, which additionally relates to cost savings. We’ve defined these three cost savers below and how 3D printing accomplishes them.
Tooling is required in a variety of production processes, from lost wax tooling for investment casting to steel tooling for injection molding. Tooling typically involves machining an A and B side of a design.
Tool designs must take into account design features such as release points, to actually get the molded part out of the tool; holes and angles, which can become difficult to execute given that the tool can’t have floating interior features unattached to the tool itself and features can’t inhibit the release of the molded part; and typical features like wall thickness, which usually can’t vary because varying wall thicknesses can harden at different times which even on a small scale effects the accuracy of the part.
There are many design and manufacturability constraints inherent to tooling, which is why 3D printing is such a game changer. 3D printing builds parts from the bottom up and doesn’t require any tooling to execute complicated designs.
By eliminating tooling, 3D printing removes the cost and labor of building tools. Plus, 3D printing frees up designs for a much broader range of geometric capabilities – like interior floating parts!
We covered this idea in the above section, but it’s worth reiterating. With tooling or machining, achieving an interior floating part, for example, would require a lot of extra labor.
It would require pins and manual pin extraction, in terms of tooling and molding, or multiple coding and re-orienting of a part in terms of machining.
Overall, such an interior feature would be so cost prohibitive to produce, it would most likely not be considered for a final design. Thanks to 3D printing, interior, no access features are seamlessly executed without increased labor, time or design finagling.
While 3D printing requires manual labor to remove build supports or smooth surfaces, it reduces manual labor in many ways when compared to conventional processes.
As we mentioned above, because 3D printing doesn’t require tooling, it is able to significantly reduce labor associated with tooling production.
3D printing also reduces labor by consolidating multiple part assemblies into one single unit. Eliminating assembly is a huge cost saver. 3D printing further reduces labor through automation.
Preparing a part for a build is largely automated with some manual interaction to perfect part orientation or support creation.
Unlike machining, which typically requires a manual programmer to execute the lines of code necessary to machine a part, 3D printing software automates the creation of line by line information to build a part one layer at a time.
While some may disagree on whether or not 3D printing is truly revolutionary for manufacturing, its cost, time and labor reductions positively transform the production landscape in a way not seen since the industrial revolution.
It’s a great time to be in the industry, as further materials developments and process controls evolve to further automate and perfect 3D printing for use in thousands more applications.
To see where businesses are implementing 3D printing in their practices today and in the future, download our industry report of 700 professionals.
