3D Printing: 9 Common Processes

March 10th, 2017

 

You’ve already considered the possibilities for 3D printing. You’ve imagined a not-too-distance future where you can download the file for a car part, remote,  appliance , etc., and print a replacement in just a few minutes from the comfort of your home. Engineer something you’ve been toying with in your head for years. Improve something you already use.

Then there’s what a lot of heavy-hitting groups are experimenting with: printing objects to use as prototypes in aerospace, medical orthopedics, and energy industries.

Besides all the imagined possibilities, there’s sheer excitement around 3D printing and all the things we haven’t thought of just yet. Some technology experts are even going so far to call in-home 3D printing the third industrial revolution.

3D printing is a technology that is, for the hobbyist, still young: only in the last few years have truly affordable options for the weekend inventor sprung up. But we’re almost past the early adopter phase, and there’s plenty of things to learn to make sure you’re on the cutting edge of this new technology.

So, what exactly is it?

3D printing is an additive manufacturing process that makes solid, three dimensional objects from a digital file, often a CAD file. It widens the narrow definition of ‘printing’: instead of using ink to put words on paper, we’re now using materials to make objects. It’s a pretty wide definition, and you may already be thinking of several ways this could work. In fact, there are several ways that already do.

Initially invented in the 1980s, 3D printers were large and expensive. As technology and engineering costs have fallen, more inventors have been able to tweak existing processes or create entirely new processes. The main differences among processes are the materials used and the way layers are deposited and/or built. For instance, some methods melt or soften material to create the layers, while other processes cure liquid material.

We’ve put together a primer on the most common types of 3D printing, including pros and cons. As with any rapidly developing technology, this info isn’t all-encompassing; it’s intended to give you a strong starting point as you enter the world of 3D printing.

Before we jump into the nuts and bolts of each process, consider the reasons 3D printing is being hailed so highly:

  • Rapid prototyping: If your product is easy to test out, you can innovate quickly. Concept to prototype time shrinks. Companies and individuals can understand quickly what works, what doesn’t, and whether their business ideas are viable.
  • On-demand creation: Everything is on demand these days, so why not manufacturing? If companies can produce a product on demand, they don’t have to outsource or over-produce, reducing warehouse space and money spent.
  • Less waste: It’s an additive process, so the object is built up, versus a subtractive process where an object is carved out of raw material. (Less waste can often mean less cost, too.)
  • Accessibility: People living in remote areas now have access to products they may not otherwise be able to get.
  • Potential: 3D printing truly has the potential to change the entire nature of manufacturing. Imagine consumers downloading a file to print the latest device instead of running out or waiting in line at a big box store

Enough with the background, let’s jump into common 3D printing processes. First up, the original:

 

Fused deposition modeling (FDM)

Also known as: fused filament fabrication (FFF), plastic jet printing (PJP)

FDM is one of the original processes, and FDM printers were the first to come to market in the mid-1990s.

How it works: The printer melts a thermoplastic filament, often acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA). A heated extrusion nozzle then deposits the molten filament onto the plate, in X and Y coordinates, as defined by the CAD files. After each layer, the build plate, which serves as the base, lowers down, providing the Z coordinate, for that third dimension.

Depending on the object’s shape, support structures can be inserted during printing, and removed on completion.

  • Pros: At-home options are cheap and easy to find; allows for rapid prototyping for companies and individuals; a huge range of materials can be used.
  • Cons: Structural integrity isn’t the best: small overhangs work, but nothing unsupported.

 

Stereolithography (SLA)

Also known as: optical fabrication, photo-solidification, or resin printing

SA is one of the oldest 3D processes, invented in 1983 by Chuck Hull.

How it works: Like FDM, this is a bottom-up approach, but the material in this process is photosensitive liquid resin. The printer shines a UV laser onto the resin, solidifying anywhere the laser touches. The machine steps down a layer, and continues the next layer. Once the object is complete, it must be rinsed with a solvent, or baked in a UV oven, to de-activate the photosensitivity.

  • Pros: Creates accurate, minute details, perfect for jewelers or cosmetic dentistry
  • Cons: Its high cost (machines are often over $100k) means it’s likely to stay only in the commercial sector

 

Digital light processing (DLP)

DLP is used mostly in commercial industries, though some DIYers are building their own printers, and using smartphones to cure the resin.

How it works:  Similar to SA, DLP uses a photosensitive polymer as the material. Instead of using UV beams, however, a special projector projects light that cures the resin. The projector comprises a grid of micro-mirrors, laid out on a semiconductor chip controlled by a computer. The mirrors tilt: one angle produces light and creates a bright pixel; the other angle turns the pixel dark. The projector then hardens the polymer layer by layer. Any remaining liquid polymer is drained away.

  • Pros: The speedy projectors print highly-accurate, layers in just seconds.
  • Cons: Structural integrity can be a little iffy on unsupported structures.

 

Selective laser sintering (SLS)

SLS dates back to the mid-1980s at University of Texas, and it’s used mostly for prototyping development pieces.

How it works:  This technique uses powerful UV beams, similar to SLA, but the material is powdered. The UV laser sinters, or heats without melting, a layer of powdered granules, binding the material together. As long as the material is powdered, the printer can handle plastic, metal, glass, or ceramic. Once formed, the object must cool in the printer.

  • Pros: Wide range of usable materials; remaining powdered material can be recycled.
  • Cons: The high-powered lasers are expensive, so SLS remains mostly a commercial process.

 

Selective laser melting (SLM)

Can be considered a subset of SLS

SLM’s ability to handle heavy metals make it perfect for the aerospace and medical industries that are pioneering its use.

How it works:  Unlike SLS, the laser in this process must entirely melt the metallic powders, so SLS is uses for heavy-duty metals like titanium, stainless steel, aluminum, and cobalt chrome.

  • Pros: SLM offers large-scale and detailed structures.
  • Cons: Using these heavy metals is risky, and it’s prohibitively expensive, so it’s resigned to commercial industries like aerospace, energy, and medical orthopedics.

 

Electron beam melting (EBM)

This technology is being used in the medical implant and energy markets. GE has invested heavily, especially for developing turbine blade.

How it works:  This is a larger, more intense version of SLS. EBM uses metal powders, but the UV beam is replaced by a computer-controlled electron beam and a high vacuum. This metallic melting point can get as hot as 1000° Celsius.

  • Pros: There’s a lot of potential.
  • Cons: It’s expensive and slow.

Laminated objects manufacturing (LOM)

LOM works a bit differently than the ones we’ve talked about so far.

How it works:  The printer starts with layers of adhesive paper, though plastic and metal laminates are possible, too. The printer heats and presses the layers, fusing them together. Then, a computer-controlled laser or knife cuts the object’s shape, piece by piece. Depending on the design, some printers can machine and drill the object, too. Once the excess material is cut away, the object can be sanded or sealed with paint.

  • Pros: Really affordable, especially when using paper; can make larger-scale objects, pretty quickly, too; full-color options are available
  • Cons: Dimensional accuracy isn’t great; the technology is still being developed

 

Binder jetting (BJ)

Also known as: multi-jet modeling, powder bed printing, inkjet 3D printing, drop-on-powder printing

Chalk this up to the engineers at MIT who invented binder jetting. It’s perfect for prototyping and short-run manufacturing, especially in medical, automotive, and aerospace industries. Keep an eye on this process, as its full potential is still being explored.

How it works:  This process uses two materials: a powder based (often gypsum) and a bonding agent. The bonding agent adheres the layers of powder together. After each layer is complete, the build plate lowers, and the process repeats.

  • Pros: The big pro here is BJ offers full-color printing, just by adding pigments to the binding agent (typically CMYK); there’s a lot of investment in this process, with HP developing ‘multijet fusion’ to improve detailed output
  • Cons: The structural integrity isn’t great (yet), so don’t expect super high-res prints

 

Material jetting (MJ)

Also known as: wax casting

This is the people’s 3D print technology. There’s no specific inventor, because the casting part of this process has been used by jewelers for centuries to create high-quality, customized jewelry in various metals. Technology has innovated this process by automating the wax casting.

How it works:  The printer melts the wax, then several nozzles sweep back and forth, depositing the wax into an aluminum build plate in layers. As the wax touches the plate, it cools and solidifies. A different wax with a lower melting point serves as structural support, and it is deposited below and of the object’s structural overhangs. When finished, a heated bath melts away the support wax.

  • Pros:  Don’t need to buy a 3D printer to use this technology – companies like Shapeways and Sculpteo offer printing on their machines.
  • Cons: Castable wax is fragile; with only a few degrees separating soft wax from molten wax, you have to work fast.

Today, these are the 9 most common 3D printing processes. Of course, if you’re into experimenting, a lot of people are making their own processes, simply by modifying a standard inkjet printer and using a wide range of materials. You could even use a 3D printer to make modification to your self-styled printer.

 

References

https://en.wikipedia.org/wiki/3D_printing

http://www.pcmag.com/article2/0,2817,2394720,00.asp

https://all3dp.com/types-of-3d-printer-technology-explained/

 

Project of the Month: A coffee cup that put all others to shame!

February 20th, 2017

You’ve had some experience doing some 3D modeling in ViaCAD and want to take your design skills to the next level. This project combines many of ViaCAD’s adaptable 3D tools to produce an impressively useful result: a coffee cup!

In the video, we see that the first step is to pull the Subdivision toolset into the work area.

 

 

This is important because the bulk of the work in creating the coffee cup will be done using these tools – having them at the ready makes the process much faster.

Bonus Tip: In the ‘View’ dropdown menu, you will see the following viewpoints – Right Side, Front, Top, Left side, Back, Bottom, Isometric, and Trimetric. This ‘Cup’ project uses a variety of views but it primarily starts in the ‘Isometric’ view and the ‘Right Side’ view.

Designing the Cup

To create the base of your coffee cup, select the center point circle tool and click the intersection of the x, y, and z axes, expanding it until the diameter reaches 3.5 inches, which can be specified in the data entry window.

 

 

 

 

Next, select the “Extrude Mesh” tool in the subdivision pallet. Making sure the circle is highlighted, select a point along the z axis that is slightly distant from the base. In the data entry window, you can change the length of your extruded mesh to however tall you want your coffee cup to be. For the sake of the video change the length to 4.5 inches.

 

 

 

 

In the same data entry window change the number of distributions around the circle from four to 15.

You should now see a cylinder with openings on each end. To close those openings, use the ‘Fill Hole’ tool, again located in the subdivision tool pallet.

 

 

 

 

With the ‘Fill Hole’ tool selected, make sure the drop down menu in the top bar says ‘close edge’ NOT ‘close all’. This will ensure that the ‘Fill Hole’ centers in the middle of the circle rather than on one of the sides. On the top and bottom of the cylinder select one of the sides and the ‘Fill Hole’ tool will do the rest.

At this point you can choose what will be the top of your coffee cup and angle it out. You can do this by selecting all the vertices on the top face and scaling them out using the gripper tool.

 

 

 

 

 

 

 

 

Once you’re satisfied with the basic shape of your cup you can use the ‘Add Loop’ tool and the gripper to cut out the center. Focusing on the top of your cup (the end you extended using the gripper tool), select the ‘Add Loop’ tool, select a triangle at the top of the cylinder, and then select the distance from the edge which will represent the thickness of your cup. This should create a loop around the inside of the top surface of the cylinder.

Use the ‘Deep Select’ tool to select each of the triangles on the top of the cylinder – holding shift as you click each shape. With each shape selected, you can now use the gripper tool to push them into your 3D model. Hold the ‘alt’ key on mac, or the ‘ctrl’ key on PC, click the Z arrow of the gripper tool, and push it down into the cup.

In the video, the view is changed to ‘Wire Frame’ so the modeler can inspect the inside of the cup and make sure the thickness of the walls and base are even.

 

 

 

Deselect the wire frame so you can view your 3D model. You’ve finished the rough body of your coffee cup!

Smoothing it Out

In the video the model is subdivided twice to smooth out a lot of the shapes. After you subdivide your design you will see some of the edges still have some geometrical sharpness. A great trick to eliminate this, which the video goes over, is using the ‘Add Loops’ tool near the edges of the modes to smooth them out.

 

 

 

 

You can add as many loops as you feel is necessary, but we recommend loops close to the edge of the open side of the cylinder, as well as the bottom (as demonstrated in the video).

Making a Handle

To add a handle on the outside of your cup, use the ‘Add Loop’ tool on the outside of the cylinder, creating two pairs of loops – one toward the top and one toward the bottom.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

With the ‘Deep Select’ tool click on one of the rectangles created by the ‘Add Loop’ tool. When the gripper tool appears, ‘alt’ or ‘ctrl’ click on the Z arrow and extrude the rectangle from the cylinder about an inch. Do the same with the bottom rectangle.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tilt the extruded facets toward each other by 45 degrees – precisely specifying using the data entry window.

To finish the handle, use the bridge tool to connect the two extruded facets. Simply click on the first side, and then on the second and the ViaCAD will do the rest.

Bonus Tip: To eliminate any possible frustrations with the ‘Bridge Tool’, make sure you have selected ‘facet’ and not ‘edge’ in the drop down window. Doing this should make the process a breeze.

You can subdivide your mesh one more time and there you have it – your own coffee cup!

*The remainder of the video goes into tools that are only available in Shark products.

CAD Drafting Tip of the Month: Draw View

February 2nd, 2017

Do you create architectural drawings in ViaCAD? If so, adding the ‘Draw View’ tool to your design arsenal will help make your designs accurate and faithful to your original concept, and will ensure a seamless transition from drafting to printing floorplans and designs.

If you have never used the ‘Draw View’ tool before, we recommend working through the steps of this tutorial video, while also trying features that the video does not discuss. Doing this will make you more comfortable with the tool and will help you master Architectural drafting with ViaCAD faster.

With the Draw View tool, you can manipulate the properties of your architectural floorplans, isolate its different layers, and create printable, sharable documents for the building part of your projects.

To help demonstrate the power of this architectural drafting tool the video below uses a floorplan preloaded onto ViaCAD Pro 10 , but this can be done with any floorplan that you create in ViaCAD or import from another software.

Opening up the preloaded floor plan

  1. Select ‘File’
  2. Select ‘Open Examples’
  3. Select ‘ViaCAD Files’
  4. Open ‘floorplan.vc3

We recommend that you look through the different preloaded objects and plans that ViaCAD offers to see the different kinds of things you can create, and possible starting points for future projects.

Creating the Draw View

  1. Once your floorplan is up, pull out the Draw view pallet from the toolbar.
  2. Using the dynamic pan and zoom tools, offset the floorplan slightly to the left (leaving the same amount of space on the right).
  3. In the toolset, click Draw View and create a box around the floorplan. Once you’ve done that you can drag that box to the right and you will see an identical image.

Note: You might run into a snag if you click and drag the Draw View box over the floorplan. Instead, click to select one corner of your box, and click again once you’ve moved your mouse to the opposite corner, making sure the box that appears covers up the entire plan.

When your floorplan is in the draw view you can manipulate a variety of its properties using the rectangle in the top left corner of the Draw View box. The video demonstrates the scale being changed, but there are a variety of other properties you can manipulate including edges and pen styles.

You can also make changes and add things to the original drawing (as long as those changes are in the draw view area) and they are reflected in Draw View – just deselect the draw view box and edit the original plan. This is useful if you’ve already made several property changes with Draw View but want to change the source material.

Selecting Layers

  1. Click on the rectangle in the top left corner of the Draw View
  2. Select layers. In this window you can see the list of viewable layers.
  3. To isolate a layer, simply click on it and make sure it’s the only thing highlighted. (If you’re following along with the video you will see four layers all selected).
  4. The same goes for isolating select layers – use the shift key and select the layers you want to see.

The video goes further with layer manipulation and how it can be used with Draw View.

You can select your draw view box and then go to the ‘edit’ tab, click ‘change layers’, create a new layer and make it ‘Layer One’. Next, we see the video go to ‘Concept explorer’ under the ‘Window Tab’, then go to layers and isolate layer one – which is done by right clicking the layer and selecting ‘isolate layer’.

Once you’ve completely isolated your Draw View layer you can do things like add mechanical symbols or title bars so you can create a more printable document with in depth measurements and information.