In those documentaries on the animals of the desert, at some point they always say something like “the harsh environment shapes desert dwellers into uniquely strong and beautiful creatures.” The same is true for our tech startups. “6 things that make the Arizona technology startup community unique” takes a look at this environment and what we need to do to take advantage of it.
Numerical simulation has been the bulk of my career for 30 years now. I love simulation. It has had a huge positive impact on product development as well as many other industries. In “What is numerical simulation? And why should I care?” I evangelize a bit about my professional passion.
When you think about high-tech in Arizona, what comes to mind? We have it all here. However, the one tech industry that supports and enables many of the others is microelectronics. In “Let’s focus on microelectronics for a bit” we go over a few of the reasons why Microelectronics are so important to Arizona.
One of the more difficult things about being at the Additive Manufacturing Users Group (AMUG) is dealing with the fact that there is more to do than you can hope to accomplish in four and a half days. So I decided to focus on two themes: laser-based metal additive manufacturing (AM); and design & simulation for AM. In this post, I focus on the former and try to distill the trends I noticed across the laser-based metal AM system manufacturers that were present at the conference: Concept Laser, SLM, Renishaw, EOS and 3D Systems (listed here in the decreasing order of the time I spent at each supplier’s booth). While it is interesting to study how 5 different suppliers interpret the same technology and develop machines around it, it is not my objective to compare them here, but to extract common trends that most suppliers seem to be working on to push their machines to the next level. For the purposes of this post, I have picked the top-of-the-line machine that each supplier offers as an indication of the technology’s capabilities: they span a range of price points, so once again this is not meant to be a comparison.
As a point of observation, the 5 key trends I noticed turned out to be all really aspects of taking the technology from short run builds towards continuous production. This was not my intent, so I believe it is an accurate indication of what suppliers are prioritizing at this stage of the technology’s growth and see as providing key levers for differentiation.
1. Quality Monitoring
Most customers of AM machines that wish to use it for functional part production bemoan the lack of controls during manufacturing that allow them to assess the quality of a part and screen for excursionary behavior without requiring expensive post-processing inspection. Third party companies like Sigma Labs and Stratonics have developed platform-independent solutions that can be integrated with most metal AM systems. Metal AM suppliers themselves have developed a range of in-situ monitors that were discussed in a few presentations during AMUG, and they generally fall into the following categories:
- Input Monitors:
- Laser: Sensors monitor laser powder as well as temperature across the different critical components in the system
- Oxygen Level: Sensors in the build chamber as well as in sieving stations track O2 levels to ensure the flushing of air with inert Argon or Nitrogen has been effective and that there are no leaks in the system
- Output Monitors:
- Live video: simple but useful, this allows users to get a live video stream of the top layer as it is being built and can help detection of recoater blade damage and part interaction
- Meltpool: Concept Laser showed how its Meltpool monitoring system can be used to develop 2D and 3D plots that can be superimposed with the 3D CAD file to identify problematic areas – the video is also on YouTube and embedded below. SLM and EOS offer similar meltpool monitoring solutions.
- Coater consistency: Concept Laser also described a monitor that captures before and after pictures to assess the consistency of the coater thickness across the build area – and this information is fed forward to adjust subsequent coater thicknesses in an intelligent manner.
Quality monitoring systems are still in their infancy with regard to what is done with the information generated, either in terms of feed forward (active) process control or even having high confidence in using the data to validate part quality. A combination of supplier development and academic and industry R&D is ongoing to get us to the next level.
2. Powder Handling
In a previous post, I touched upon the fire and explosion risks posed by metal powder handling. To lower the bar for an operator to gain access to a metal AM machine, one of the considerations is operator safety and the associated training they would need. Suppliers are constantly trying to improve the methods by which they can minimize powder handling. For a mechanical engineer, it is intriguing to see how reactive metal powders can be moved around in inert atmospheres using different strategies. The SLM 500HL uses a screw system to move the powder around in narrow tubes that stick out of the machine and direct the material to a sieving station after which they are returned to the feed area. The Renishaw RenAM 500M on the other hand uses a pneumatically driven recirculation system powered by Argon gas that is well integrated into the machine frame. Concept Laser also offers automated powder handling on the XLine 2000R, while EOS and 3DSystems do not offer this at the moment. Figure 2 below does not do justice to the level of complexity and thought that needs to go into this.
One of the limitations of automating powder handling is the ability to change materials, which is very hard to impossible to do with high enough confidence with these systems. As a result, their use is limited to cases where one machine can be dedicated to one material and efficiency gains of powder handling can be fully realized. The jury is still out on the long term performance of these systems, and I suspect this is one area that will continue to see improvements and refinements in subsequent model releases.
3. Multi-Laser Processing
In the quest for productivity improvement, one of the biggest gains comes from increasing the number and power of available lasers for manufacturing. In my previous experience with laser based systems (albeit not for this application), an additional laser can increase overall machine throughput by 50-80% (it does not double due to steps like the recoater blade movement that does not scale with the number of lasers).
The suppliers I visited at AMUG have very different approaches to this: SLM provides the widest range of customizable options for laser selection with their 500HL, which can accept either 2 or 4 lasers with power selection choices of 400W or 1000W (the 4 laser option was on display, YouTube video from the same machine in action is below) – the lasers of different powers can also be combined to have two 400W and two 1000W lasers. Concept Laser’s XLine 2000R allows for either 1 or 2 1000W lasers and their smaller, M2 machine that was showcased at AMUG has options for 1 or 2 lasers, with power selection of 200W or 400W. EOS, Renishaw and 3D Systems presently offer only single laser solutions: the EOS M 400 has one 1000W laser, Renishaw’s RenAM 500M has one 500W laser and the ProX DMP 320 from 3D Systems has one 500W laser.
There are a few considerations to be aware of when assessing a multi-laser machine: Each laser drives an increase in machine capital cost. But there is another point of note to remember when using multi-laser systems for manufacturing that centers around matching process outputs from different lasers: laser-to-laser variation can be a dominant source of overall process variation and can drive a need to calibrate, maintain and control both lasers as if they were independent machine systems. Additionally, development of a process on one particular laser power (100W, 400W, 500W, 1000W) may not scale easily to another and is something to remember when developing a long term strategy for metal AM that involves different kinds of machines, even if from the same supplier.
4. Software Integration
Renishaw spent a significant amount of time talking about their easy-to-use QuantAM software which is designed to integrate Renishaw process parameters and part processing information more tightly and allow for seamless process parameter development without needing third part software like Magics. Additive Industries announced in their presentation at AMUG that they had just signed an agreement with 3DSIM to integrate their support design software solution into their MetalFab1 machine. Software integration is likely to be an increasing trend especially around the following areas:
- Improving support design methods and reducing its empirical nature and reducing the material, build time and support removal costs associated with them as well as eliminating the need for iterative builds
- Increasing process options available to the user (for example for the outer skin vs the inner core, or for thick vs thin walls)
- Simplifying the development of optimized process parameters for the user working on new materials
- Integrating design and process optimization to increase effective part performance
In a future blog post, I will look specifically at the many design and simulation tools available around AM and how they are connected today even if not well-synergized.
5. Modular System Architectures
In a list of mostly evolutionary changes, this is the one area that struck me as being a step-change in how this technology will make an impact, even if it will be felt only by larger scale manufacturers. Concept Laser and Additive Industries are two companies that delivered presentations discussing how they were approaching the challenge of revolutionizing the technology for true production and minimizing the need for human touch. Common to both is the notion of modularity, allowing for stacking of printing, powder removal, heat treating and other stations. While Additive Industries are developing a flow resembling a series production line, Concept Laser have taken the more radical approach of having autonomous vehicles delivering the powder bed to the different stations, with travel channels for the vehicles, for the operator and for maintenance access (Figure 3). Both companies expect to have solutions out by the end of this year.
It is an interesting time to be a manufacturer of laser-based metal 3D printers, and an even more interesting time to be a consumer of this technology. The laser-material interaction fundamentals of the process are now fairly well-established. Competitors abound both in existing and emerging markets with machines that share many of the same capabilities. Alternative technologies (E-Beam melting, deposition and jetting) are making strides and may start to play in some applications currently dominated by laser-based technologies. A post early-adopter chasm may be around the corner. This will continuously drive the intense need to innovate and differentiate, and possibly also lead to a merger or two. And while most of the news coming out of conferences is justifiably centered around new process technologies (as was the case with Carbon’s CLIP and XJET’s metal nanoparticle jetting at AMUG this year), I think there is an interesting story developing in laser-based powder bed fusion and can’t wait to see what AMUG 2017 looks like!
Shut up and listen. Easy to say, hard to do. every day in a ton of different ways, we are asked to listen to what other people are saying, and the reality is that not a lot of us do. In this post, “Why you should learn to shut up and listen” I go over why the problem causes real issues in business, and some suggestions on being a better listener.
Overcoming convergence difficulties in nonlinear structural problems can be a challenge. I’ve written a couple of times previously about tools that can help us overcome those difficulties:
- Overcoming Convergence Difficulties in ANSYS Workbench Mechanical, Part I: Using Newton-Raphson Residual Information
- Overcoming Convergence Difficulties in ANSYS Workbench Mechanical, Part II: Quick Usage of Mechanical APDL to Plot Distorted Elements
I’m pleased to announce a new tool in the ANSYS Mechanical tool belt in version 17.0.
With version 17.0 of ANSYS we get a new meshing option for structural simulations: Nonlinear Mechanical Shape Checking. This option has been added to the previously available Standard Mechanical Shape Checking and Aggressive Mechanical Shape Checking. For a nonlinear solution in which elements can become significantly distorted, if we start with better-shaped elements they can undergo larger deformations without encountering errors in element formulation we may encounter fewer difficulties as the nodes deflect and the elements become distorted. The nonlinear mechanical setting is more restrictive on the element shapes than the other two settings.
We’ve been recommending the aggressive mechanical setting for nonlinear solutions for quite a while. The new nonlinear mechanical setting is looking even better. Anecdotally, I have one highly nonlinear customer model that reached 95% of the applied load before a convergence failure in version 16.2. That was with the aggressive mechanical shape checking. With 17.0, it reached 99% simply by remeshing with the same aggressive setting and solving. That tells you that work has been going on under the hood with the ANSYS meshing and nonlinear technology. By switching to the new nonlinear mechanical shape checking and solving again, the solution now converges for the full 100% of the applied load.
Here are some statistics using just one measure of the ‘goodness’ of our mesh, element quality. You can read about the definition of element quality in the ANSYS Help, but in summary better shaped elements have a quality value close to 1.0, while poorly shaped elements have a value closer to zero. The following stats are for tetrahedral meshes of a simple turbomachinery blade/rotor sector model (this is not a real part, just something made up) comparing two of the options for element shape checking. The table shows that the new nonlinear mechanical setting produces significantly fewer elements with a quality value of 0.5 or less. Keep in mind this is just one way to look at element quality – other methods or a different cutoff might put things in a somewhat different perspective. However, we can conclude that the Nonlinear Mechanical setting is giving us fewer ‘lower quality’ elements in this case.
|Shape Checking Setting||Total Elements||Elements w/Quality <0.5||% of elements w/Quality <0.5|
Here are images of a portion of the two meshes mentioned above. This is the mesh with the Aggressive Mechanical Shape Checking option set:
The eyeball test on these two meshes confirms fewer elements at the lower quality contour levels.
And this is the mesh with the Nonlinear Mechanical Shape Checking option set:
So, if you are running nonlinear structural models, we urge you to test out the new Nonlinear Mechanical mesh setting. Since it is more restrictive on element shapes, you may see longer meshing times or encounter some difficulties in meshing complex geometry. You may see a benefit in easier to converge nonlinear solutions, however. Give it a try!
Many of you may have seen the recent launch of an Atlas V rocket from United Launch Alliance (ULA). We are honored to have lent our expertise to ULA’s 3D Printing efforts that resulted in the use of parts on that rocket made with additive manufacturing. We will be talking about that and other ways we help the Aerospace Industry at the 32nd Space Symposium this week in Colorado Springs Colorado. Please stop by!
Getting a product from idea to the market is a lot of work. Much effort and attention is focused on figuring out the idea, but the part after that is usually portrayed as some romantic quest involving coffee, colocation spaces, and long hours. In this article, “So, you have an idea for a product, what next?” we offer up some practical advice on the steps you need to take to get going.
The development of small modular nuclear reactors, or SMR’s, is a complex task that involves balancing the thermodynamic performance of the entire system. Flownex is the ideal tool for modeling pressure drop [flow] and heat transfer [temperature] for the connected components of a complete system in steady state and transient, sizing and optimizing pumps or compressors, pipes, valves, tanks, and heat exchangers.
To highlight this power and capability, PADT and Flownex will be exhibiting at the 2016 SMR conference in Atlanta where we will be available to discuss exciting new Flownex developments in system and subsystem simulations of SMRs. If you are attending this year’s event, please stop by the Flownex booth and say hello to experts from M-Tech and PADT.
If you are not able to make the conference or if you want to know more now, you can view more information from the new Flownex SMR brochure or this video:
Why is Flownex a Great Tool for SMR Design and Simulation?
These developments offer greatly reduced times for performing typical design tasks required for Small Modular Nuclear Reactor (SMR) projects including sizing of major components, calculating overall plant efficiency, and design for controllability
This task involves typical components like the reactor primary loop, intermediate loops, heat exchangers or steam generators and the power generation cycle. Flownex provides for various reactor fuel geometries, various reactor coolant types and various types of power cycles.
Flownex can also be used for determining plant control philosophy. By using a plant simulation model, users can determine the transient response of sensed parameters to changes in input parameters and based on that, set up appropriate pairings for control loops.
For passive safety system design Flownex can be used to optimize the natural circulation loops. The program can calculate the dynamic plant-wide temperatures and pressures in response to various accident scenarios, taking into account decay heat generation, multiple natural circulation loops, transient energy storage and rejection to ambient conditions.
This is the first of what we hope to be a monthly posting here on our blog, reviewing PADT events happening in the next 5 or 6 weeks and reviewing activities over the previous month.
Upcoming Events, Seminars, and Gatherings
April 5-7: AMUG Annual Meeting
St. Luis, MO
This annual meeting of the Additive Manufacturing Users Group has been a long time favorite of PADT. Everyone involved in making and running industrial 3D Printers will be in St. Luis this year. PADT’s Dhruv Bhate will be given two presentations and we will be hanging out in the exhibit hall. Look for anyone in a PADT shirt and say hi!
April 7: Seminar: Additive Manufacturing and the Navy SBIR Program With RevAZ/AZ Commerce
PADT Tempe, AZ
Learn more about the Navy Sea SBIR Program from Jonathan Leggett, the NAVSEA SBIR Program Manager, about how AZ Manufacturers can use SBIR Grants to assist in funding R&D early stage innovation. Jonathan will also review the Navy’s roadmap on additive manufacturing and 3D printing.
April 11-14: Space Symposium
Colorado Springs, CO
This premier event for the entire Space industry is a favorite of PADT’s We will be there in force in our own both, and with Stratasys, talking about how Additive Manufacturing is changing many aspects of space hardware. Look for Mario, Norm, Anthony, James, and Renee. We expect to catch up with our customers and if we don’t know you, stop by and introduce yourself.
April 13, 11:30 – 1:00: AZTC Lunch-n-Learn
Innovation is easier said than done: Why skipping product simulation is no longer an option
PADT will be presenting results from a recently released study on how the use of simulation has a significant and measurable impact on top line revenue for companies who make products. Lunch is included in this free event. Come back for a link in a day or so.
April 14-15: International SMR and
Advanced Reactor Summit
Flownex and PADT will be attending this meeting, the premier event for Small Modular and Advanced Reactor design. Flownex is the leading tool for modeling fluid flow in and around reactors of all types, and is helping to drive the development of this new generation of nuclear power. Look for us in the Flownex booth.
PADT’s Dhruv Bhate will be discussing his career as an Engineer with High School students. He will also share with them his latest career change in to the exciting world of 3D Printing.
April 21: AZBio Expo 2016
PADT will be attending this key Bioscience industry event with a booth and by attending sessions. Stop by and learn the latest about how PADT helps medical device companies make their innovation work. We will of course be talking about 3D Printing and simulation as well.
May 12, 2016: Design for 3D Printing
Talk at Digital Manufacturing 2016 Conference
This conference is focused on 3D Printing and Additive Manufacturing with a focus on inkjet technologies. PADT’s Eric Miller will be sharing his thoughts on design considerations for those who wish to use 3D Printing to manufacture their parts.
May 16-19: RAPID Show
The other big Additive Manufacturing show in the US is Rapid, held in Orlando, FL this year. PADT will be presenting at least one, and perhaps two times at this event. We will also be hanging out with Stratasys and other partners in the exhibit area.
March Events in Review
March was a busy month for events, with a couple of special opportunities to reach new audiences and learn more.
We started with the 2016 Aerospace, Defence, and Manufacturing Conference put on by the Arizona Technology Council on March 3rd. Dhruv Bhate gave a talk about Additive Manufacturing in the state and made a call to action for more cooperation. Our booth was well attended.
March 23rd was a busy day, with the SEMI Arizona presentation of the GPEC study: “Microelectronics: An Economic Pillar for Arizona” at breakfast. We learned a ton about the importance of this sector to the state and where it is headed. This was followed by a sad event, a going away party for Jeff Saville as he departs CEI and spends some time in industry.
Meanwhile, up in Utah, our team was at the Wasatch Front Materials Expo. This event has always been well attended and a chance for us to meet with existing customers and get in front of others who are interested in ANSYS and Stratasys.
The next night saw a well attended event at The Perch in Chandler for the Chandler Innovations Connector. The east valley tech startup community is booming and we were able to visit with many entrepreneurs and mentors.
On March 29th PADT’s Eric Miller was invited to be on a panel to discuss innovation in the Bioscience industry in Arizona. The event focused on an update for the Flinn Foundation’s Bioscience Roadmap project. What an amazing panel and it was good to see the progress, and work still to be done, to build more momentum around this critical industry.
Three events in support of government R&D finished up the last week of the month. The Utah crew attended the Hill Air Force Base Technology Expo on March 30th, an annual event where vendors can share how they help the research going on at the base.
Meanwhile, we were holding a seminar at Los Alamos National Labs on Optimization with ANSYS products and how it can drive the use of Additive Manufacturing. That same presentation was repeated at Sandia National Labs on the 31st.
The final event of the month was a fantastic presentation on Infrared sensors in Albuquerque, NM. This was the first event that we have attended put on by the New Mexico Technology Council, or NMTC. Made some great connection and we are looking forward to more interaction with them.
Adding Complexity and Moving
After playing with that block it seems like it may be time to try a more complex geometry. For business banking, I’ve got this key fob that generates a number every thirty seconds that I use for security when I log in. Might as well sort of model that.
So the first thing I do is start up a new model and orient myself on to the sketch plane:
Then I use the line and arc tools to create the basic shape. Play around a bit. I found that a lot of things I had to constrain in other packages are just assumed when you define the geometry. A nice thing is that as you create geometry, it locks to the grid and to other geometry.
I dragged around and typed in values for dimensions to get the shape I wanted. As I was doing it I realized I was in metric. I’m old, I don’t do metric. So I went in to File and selected SpaceClaim options from the bottom of the window. I used the Units screen to set things to Imperial.
This is the shape I ended up with:
I took this and pulled it up and added a couple of radii:
But if I look at the real object, the flat end needs to be round. In another tool, I’d go back to the sketch, modify that line to be an arc, and regen. Well in SpaceClaim you don’t have the sketch, it is gone. Ahhh. Panic. I’ve been doing it that way for 25 some years. OK. Deep breath, just sketch the geometry I need. Click on the three point arc tool, drag over the surface, then click on the first corner, the second, and a third point to define the arc:
Then us pull to drag it down, using the Up to icon to lock it to the bottom of the object.
Then I clicked on the edges and pulled some rounds on there:
OK, so the next step in SolidEdge would be to do a thin wall. I don’t see a thin wall right off the top, but shell looks like what I want, under the Create group on the Design tab. So I spinned my model around, clicked on the bottom surface I want to have open and I have a shell. A thickness of 0.035″ looks good:
My next feature will be the cutout for the view window. What I have not figured out yet is how to lock an object to be symmetrical. Here is why. I sketch my cutout as such, not really paying attention to where it is located. Now I want to move it so that it is centred on the circle.
Instead of specifying constraints, you move the rectangle to be centered. To do that I drag to select the rectangle then click Move. By default it puts the nice Move tool in the middle of the geometry. If I drag on the X direction (Red) you can see it shows the distance from my start.
So I have a couple of options, to center it. The easiest is to use Up To and click the X axis for the model and it will snap right there. The key thing I learned was I had to select the red move arrow or it would also center horizontally where I clicked.
If I want to specify how far away the edge is from the center of the circle, the way I did it is kind of cool. I selected my rectangle, then clicked move. Then I clicked on the yellow move ball followed by a click on the left line, this snapped the move tool to that line. Next I clicked the little dimension Icon to get a ruller, and a small yellow ball showed up. I clicked on this and dragged it to the center of my circle, now I had a dimension from the circle specified that I could type in.
After playing around a bit, if found a second, maybe more general way to do this. I clicked on the line I want to position. One of the icons over on the left of my screen is the Move Dimension Base Point icon. If you click on that you get another one of those small yellow balls you can move. I dragged it over to the center of the circle and clicked. then I can specify the distance as 0.75″
I’ve got the shape I want, so I pull, using the minus icon to subtract, and I get my cutout:
If you look closely,you will notice I put rounds on the corners of the cutout as well, I used Pull again.
The last thing I want to do is create the cutout for where the bank logo goes. It is a concentric circle with an arc on the right side. Saddly, this is the most complex thing I’ve ever sketched in SpaceClaim so I was a bit afraid. It was actually easy. I made a circle, clicking on the center of the outside arc to make them concentric. The diameter was 1″. Then I made another circle of 2″ centered on the right. To get the shape I wanted, I used the Trim Away command and clicked on the curves I don’t want. The final image is my cutout.
Now I can do the same thing, subtract it out, put in some rounds, and whalla:
Oh, and I used the built in rendering tool to quickly make this image. I’ll have to dedicate a whole posting to that.
But now that I have my part, it is time to play with move in 3D.
Moving in 3D
Tyler, who is one of our in-house SpaceClaim experts (and younger) pointed out that I need to start thinking about editing the 3D geometry instead of being obsessed with controlling my sketches. So here goes.
If I wanted to change the size of the rectangular cutout in a traditional CAD tool, I’d go edit the sketch. There is no sketch to edit! Fear. Unknown. Change.
So the first thing I’ll do is just move it around. Grab one of the faces and see happens.
It moves back and forth, pretty simple. The same tools for specifying the start and stop points are available. Now, if I ctrl-click on all four surfaces the whole thing moves. That is pretty cool.
Note: I’m using the undo all the time to go back to my un-moved geometry.
Another Note: As you select faces, you have to spin the model around a lot. I use the middle mouse button to do this rather than clicking on the spin Icon and then having to unclick it.
That is enough for this post. More soon.
Learning More About Pulling
As I explored ANSYS SpaceClaim in my first try, it became obvious that a lot of capabilities that are in multiple operations in most CAD systems, are all combined in Pull for SpaceClaim. In this posting I feel like it would be a really good idea for me to really understand all the things Pull can do.
Start with the Manual
Not very exciting or adventurous. But there is so much in this operation that I feel like I will miss something critical if I don’t read up first. It states:
“Use the Pull tool to offset, extrude, revolve, sweep, and draft faces; use it to round, chamfer, extrude, copy, or pivot edges. You can also drag a point with the Pull tool to draw a line on a sketch plane.”
Let’s think about that for a second. What it is basically saying is if I pull on an object of a given dimension, it creates an object that is one higher dimension. Point pulls to a curve, a curve pulls to a face, and a face pulls to a solid. Kind of cool. The big surprise for me is that there is no round or fillet command. To make a round you pull on an edge. This is change.
Pull some Stuff
I started by reading my block with a hole back in.
This fillet pull thing scares me so I thought I’d confront it first. So selecte Pull, and selected an edge:
Then I dragged it away from the block. Nothing. You can’t create a surface that way. Then I dragged in towards the center. A round was created.
If anything, too simple. Back in my day, adding a round to an edge took skill and experience!
So next I think I want to try and change the size of something. Maybe the diameter of the hole. So I select the cylinder’s face. Is shows the current radius. I could just change that value:
Instead I drag, and while I do that I noticed that there are two numbers, the current radius and the change to the radius! Kind of cool. No, really useful.
You use tab to go between them. So I hit tab once, typed 3 then tab again (or return) and I get a 8 mm diameter. I like the visual feedback as well as the ability to enter a specific change number.
Next thing that I felt like doing was rounding a corner. Put a 5mm round on the corner facing out:
So I grabbed the point and dragged, and got a line.
Remember, it only goes up one entity type – point to curve. Not point to surface. So I ctrl-clicked (that is how you select multiple entities) on the three curves that intersect at the corner:
Then I dragged and got my round.
Pulling Along or Around Something
This are all sort of dragging straight. After looking at the manual text it seems I can revolve and sweep as well with the Pull operation. Cool. But what do I revolve or sweep around and along? Looking at the manual (and it turns out the prompt on the screen) I use Alt-Clicking to define these control curves. Let’s try it out by revolving something about that line I mistakenly made.
I click on one of the curves on the round. then Alt-Click the line – It turns blue. So there is a nice visual clue that it is different than the source curve. Now I’ve also got spinny icons around the curve rather than pull icons.
So I drag and… funky revolved surface shows up. I had to spin the model to see it clearly:
Let me stop and share something special about this. In most other CAD tools, this would have involved multiple clicks, maybe even multiple windows. In SpaceClaim, it was Click, Alt-Click, Drag. Nice.
Using the Pop=up Icons
As you play with the model you may start seeing some popup icons near the mouse when you select geometry while using pull. The compound round on the block is complicated, so I spun it around and grabbed just one edge and pulled it in to be a round. Then I clicked on it and got this:
Not only can I put a value in there, I can drop ones I use a lot. I can also change my round to a chamfer, or I can change it to a variable radius. This is worth noting. In most other CAD tools you pick what type of thing you want to do to the edge. Here we start by dragging a round, then specify if it is a chamfer or a variable.
The variable radius is worth digging more in to. I clicked on it and it was not intuitive as to what I should do. Let’s try help. Search on Variable Radius… duh. Click on the arrow that shows up and drag that. There are three arrows. The one in the middle scales both ends the same, the one on either end, well it sets the radius for either end.
Clicking on a control point and hitting delete, gets rid of them.
That’s just one icon that pops up. Playing some more it seems the other icons control how it handles corners and multiple fillets merging… something to look at as I do more complex parts.
The other popup I want to look at is the Up To one. It looks like an arrow on a surface. In other tools I extrude, cut, revolve all the time to some other piece of geometry. This is the way to do it in Space Claim. Let’s say I want to pull a feature to the middle of my hole. First I sketch the outline on a face:
That is enough for pulling and for today. In the next session it may be time to explore the Move command.
This post is a table of contents to a series about ANSYS SpaceClaim. After over 31 years of CAD use, it has become difficult for me to learn new tools. In this series I will share my experience as I explore and learn how to use this fantastic tool.
One of the first concepts you come across in metal 3D printing is the notion of reactivity of the powder metal alloys – in this post, I investigate why some of these powder alloys are classified as reactive and others as non-reactive, and briefly touch upon the implications of this to the user of metal 3D printing tools, scoping the discussion to laser-based powder bed fusion. Ultimately, this boils down to a safety issue and I believe it is important that we, the users of these technologies, truly understand the fundamentals behind the measures we are trained to follow. If you are looking to get something chemical etched visit https://interplex.com/technology/process-capability/chemical-etching/.
Figure 1 below is indicative of the range of materials available currently for the laser-based powder bed fusion process (this selection is from Concept Laser). I have separated these into non-reactive and reactive metal alloys. The former includes steels, Inconels, bronze and CoCrW alloys. The reactive metal alloys on the other hand are Aluminum or Titanium based. The question is: what classifies them as such in the context of this process?
Reactivity in this process really pertains to the likelihood of the alloy in question serving as a fuel for a fire and/or an explosion, which are two related but distinct phenomena. To truly understand the risk associated with powder metals, we must first understand a few basic concepts.
1. Fire and Explosion Criteria
Figure 2 is a commonly used representation of the criteria that need to be met to initiate a fire (fuel, oxygen and an ignition source) and an explosion (the same three criteria for a fire, plus a dust cloud and confined space). When handling reactive metal alloy powders, it is important to remember that two of the three requirements for a fire are almost always met and the key lies in avoiding the other criterion. When not processing the powder in the machine, it is often subject to ambient oxygen content and thus all precautions are taken to prevent an ignition source (an ESD spark, for example). When the metal is being processed with a high power laser, it is done in an inert atmosphere at very low Oxygen levels. This thought process of appreciating you are one criterion away from a fire is useful, if sobering, to bear in mind when working with these powders.
2. Terms Used to Describe Fire and Explosion Risk
There are several terms used to describe fire and explosion risk. I have picked 5 here that tie into the overall “index” I will discuss in the following section. All these parameters are in turn functions of the material in question, both with regard to its composition and its size distribution and are co-dependent. These definitions are adapted from Benson (2012) and Prodan et al. (2012).
- Fire Related: These two terms describe the sensitivity of a metal dust cloud to ignition.
- Ignition Temperature: This is the lowest surface temperature capable of igniting a powder or dust dispersed in the form of a dust cloud
- Minimum Ignition Energy: This measures the ease of ignition of a dust cloud by electrical and electrostatic discharges.
- Explosion Related: These terms describe the severity of an explosion arising from a fire once ignited.
- Minimum Explosion Concentration (MEC): This is the smallest amount of dust which when suspended in air, under a set of test conditions, will initiate an explosion and propagate even after the action of the ignition source has ceased.
- Maximum Explosion Pressure: This is a measure of the highest pressure that occurs during of an explosion of a flammable mixture in a closed vessel.
- Maximum Rate of Pressure Rise: This is the maximum slope of the pressure/time curve during a flammable mixture explosion in a closed vessel.
3. Index of Explosibility
Having defined these terms, the question is how they can be tied together to give some sense of the hazard associated with each metal powder. I came across a 1964 US Bureau of Mines study that defined an Index of Explosibility as a measure of the hazard risk posed by powder metal alloys. The index represents both the sensitivity of the powder to ignition, and once ignited, the severity of the resulting explosion. Since this is a subjective metric, it is normalized by comparison against a “standard”, which was selected as Pittsburgh coal dust in the 1964 study. Importantly though, this normalization enables us to do qualitative comparisons between metal powders and have some sense of the hazard risk posed by them. Figure 3 is the equation reproduced from the original 1964 report and shows how this term is estimated.
The study also showed how the index was a direct function of particle size. Most powders for 3D metal printing are in the 20-100um range, and as shown in Fig. 4 for atomized Aluminum, the risk of an explosion increases with reducing particle diameter.
The authors tested a range of metals and computed the different variables, which I have compiled anew in the table in Figure 5 for the ones we are interested in for metal 3D printing. The particle sizes in the 1964 study were ones that made it through a No. 200 sieve (less than 75 microns), but did not include sub-micron particles – this makes it an appropriate comparison for metal 3D printing. It is clear from the Index of Explosibility values, as well as the Cloud Ignition Temperatures in the table below why Aluminum and Titanium are classified as reactive metals requiring special attention and care.
4. Implications for Metal 3D Printing
So what does this mean for metal 3D printing? There are three things to be aware of that are influenced by whether you are working with non-reactive or reactive alloys – I only provide a general discussion here, specific instructions will be provided to you in supplier training and manuals and must be followed.
- Personal Protective Equipment (PPE): There are typically two levels of PPE: standard and extended. The standard PPE can be used for non-reactive alloy handling, but the reactive alloys require the more stringent, extended PPE. The main difference is that the extended PPE requires the use of a full bunny suit, ESD grounding straps and thermal gloves.
- Need for Inert Gas Handling: Many tasks on a metal 3D printer require handling of powder (pouring the powder into the chamber, excavating a part, cleaning the chamber of powder etc.). Most of these tasks can be performed in the ambient for non-reactive metal alloys with standard PPE, but for reactive alloys these tasks must be performed in an inert atmosphere.
- Local authority approvals: It is important that your local authorities including the fire marshall, are aware of the materials you are processing and review and authorize their use in your facility before you turn on the machine. Local regulations may require special procedures be implemented for preparing the room for use of reactive metal alloys, that do not apply to non-reactive metals. It is vital that the authorities are brought into the discussion early on and necessary certifications obtained, keeping in mind that reactive metal alloy use may drive additional investment in safety measures.
Safe operation of metal 3D printers requires installation of all the necessary safety equipment, extensive hands-on training and the use of checklists as memory aides. In addition to that, it helps to connect these to the fundamental reasons why these steps are important so as to gain a clearer appreciation of the source of the hazard and the nature of the risk it poses. In this article I have tried to demonstrate why reactivity in metal 3D printing matters and what the basis is for the classification of these metal alloys into reactive and non-reactive by leveraging an old 1964 study. I wish to close with a reminder that this information is meant to supplement formal training from your equipment supplier – if there is any conflict in the information presented here, please revert to your supplier’s recommendations.
Thank you for reading; stay safe as you innovate!
If you are like me, you are in a tech business because you love science. But who has time to learn about all the new an exciting discoveries out there. Even reading is something we often don’t have time for. So I’ve started listening to science podcasts and it has been a fantastic way to stay on top of things, and get reminded about the things I’ve forgotten.
In “Best way to stay science educated: Podcasts” I go over the three that are worth following regularly and talk about more about why it is important.