Creature Design Enabled by 5-Axis CNC

Details on the product design and build process are rarely presented in the comprehensive, concise fashion of this video from John Cox’s Creature Workshop. Sure, he’s building limited run sculptures for the entertainment industry but the process of sculpting, scanning, processing, machining, and assembling is common to many design industries. Plus, I love seeing practical applications of 5-axis CNC machining.

Here are some photos of the process:

Sculpture Scanning
Scanning

Processing
Processing

Machining
Machining

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Beautiful Deconstruction

Photographer Todd McLellan takes the product take-apart to a new level by artistically arranging the parts and photographing them, then photographing the parts, presumably, being tossed into the air.

The products he takes apart are a few technological generations old but it is still insightful to see how they look on the inside and marvel at the complexity. Younger engineers will be amazed at the level of detail achievable in the pre-CAD era.

More at http://www.toddmclellan.com/; click the “New Work” link on the left and have a look at the video of the deconstruction and photography process.

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Moldflow and FEA

Moldflow Algor Interop

I’ve said it before and I’ll say it again, there’s nothing like having a prototype to evaluate (The Value of Physical Prototypes & Moldflow and Part Visualization). This is mostly due to the fact that simulations that represent real-world performance are timely and costly to develop. I can’t remember an instance when I relied on FEA alone without empirical testing to establish actual performance of the simulation.

Autodesk is getting closer to bridging this gap between simulation and the real world by integrating key features of its large software portfolio. The first thing they did that impressed me was their integration of Moldflow and Showcase to aid in the visualization of cosmetic defects on plastic parts (re-link: Moldflow and Part Visualization).

Even more interesting and, in my opinion, useful, is their interoperability between Moldflow and Algor (FEA/mechanical simulation) which addresses the issue of simulated material properties vs. real-world material properties. Typically material properties are applied to FEA models with the assumption they are isotropic. But most injection molded plastics are anisotropic. The real material properties of injection molded plastic parts are dependent on many factors. Flow of material through the mold is an important one since it is the material flow that determines fiber and molecular orientation. This is especially important in the case of glass-filled resins; the strength in the direction of the glass fibers is greater than in the transverse direction. The magic bit of the Autodesk offering is that Moldflow results can be imported into Algor where they are used to calculate material properties at each point in the FEA mesh, better representing the plastic part coming out of the mold. Different gate locations and process parameters can be simulated through both Moldflow and Algor to determine how to maximize the performance of the part in critical areas.

Moldflow Algor Interop

It’s not going to eliminate the need for empirical testing of final parts but it definitely helps in optimizing designs early in the process.

{Update February 22, 2011: Thanks to Bob Williams (@ADSKsimulation) for the link to the video}

Have your say in the forums

The Value of Physical Prototypes

I watched the first 4 installments of BBC’s Design for Life on a plane over the Pacific and found the last 2 episodes on Vimeo. The show is pretty much The Apprentice with Philippe at the helm. Plus I think the show illustrates how truly difficult it is to conceive and develop a product from a blank slate. Week after week young designers struggle to prove their design prowess to Philippe and usually fall short by under-delivering or missing the point completely. One week Philippe sent 4 designers packing.

The most profound moment of the show happened in episode 5. After weeks of failing to convince Starck that her new standing/walking aid for the elderly had merit, contestant Ilsa Parry presented the prototype. After merely looking at the proto Philippe’s attitude changed completely. After trying the product for himself he was sold.

Great that Ilsa persevered and continued to drive the vision of her product. Great that the rest of us can witness the power of the prototype in a real-world situation.

The entire series is available on Vimeo:

Design for Life Episode 1
Design for Life Episode 2
Design for Life Episode 3
Design for Life Episode 4
Design for Life Episode 5
Design for Life Episode 6

Design for Life | Episode 5 from designforlife on Vimeo.

Comment now in the Form Loves Function Forum.

Moldflow and Part Visualization

For a while now Autodesk has been talking about digital prototyping as a means to save on costs of real, physical prototypes. True that their portfolio is quite comprehensive but there is nothing like a real, physical model for testing and evaluation. More often than not I have been able to build, test, and tweak a prototype more quickly than setting up a simulation and waiting for it to run. That said, simulations have their place in the design process and Autodesk worked out an interesting integration between 2 seemingly disparate products.

Moldflow is a great tool for evaluating plastic parts and the associated tooling and processing during the execution stage of the design cycle. Showcase is a rendering/visualization tool used primarily by upstream industrial designers. Autodesk has put together a great workflow allowing users to extract geometry from the Moldflow package and visualize it within the Showcase environment. It’s not quite as good as cutting steel and shooting parts, but definitely more cost effective.

Moldflow Insight

Comments are happening on the new Form Loves Function Discussion Forum.

Nexus One Design Videos

These are a bit heavy on the marketing-speak and not as deep into the details as I like to get, but there are a few interesting bits making these videos worth posting; hardware and software designed in conjunction, optimization of the 3D engine, and insight into the magnitude of physical testing going into design validation.

Episode 1: Concept & Design

Episode 2: Display and 3D Framework

Episode 3: Testing

Episode 4: Manufacturing

Episode 5: Day One (all marketing here, but kinda cool to see all the pieces in action together)

I’d love to see how they make that sheetmetal housing. Hydroforming? Tricky welding?

5 Axis CNC Machining of Helmet from Aluminum Billet

Amazing work with this 5-axis CNC. I was impressed with the deep undercuts achievable with long cutters and clever programming and the fact the the finish-pass was done so cleanly in one setup.

Company: Daishin
Material: A7N01-T6 Aluminum
Cycle Time: I’d love to know

Hat tip: C. Sven of ReBang

EDM Tolerances

That’s a trick title. Most of the time design engineers aren’t concerned with the tolerances associated with EDM process directly and I will tell you why.

First some background. EDM, or Electrical Discharge Machining (thanks again Wikipedia), is a material removal process wherein a large amount of electrical energy is delivered to the workpiece, burning material away. Energy is delivered through an electrode, either a block of conductive material (known as sinker, cavity, or volume EDM), or a wire (known as wire EDM). In both types, tools are mounted on machines with CNC controls.

EDM'd Moldbase and Electrode
EDM'd Moldbase (left) and Electrode (right)
Image via Eroda Tools, Ltd.

EDM processes are typically very slow and not suitable for volume production. However, EDM is typically very accurate and very effective on hard materials making it a great process for making plastic, sheetmetal, and other types of tooling. This is why design engineers are not usually concerned with the tolerances introduced by the EDM process; they are usually most interested in the tolerances of the parts coming off the tooling.

In this ongoing discussion of part tolerances (start here) I wanted to bring up EDM before talking about injection molding, metal stamping, metal forming, and other tooling-dependent processes because EDM is where the tooling starts. And you know how I love the fundamentals.

June Issue of Develop3D is Available

I just noticed that the June issue of Develop3D is available. You can download your free copy here.

Inside you’ll find some interesting information on the design process at Marin Bikes and Senz Umbrellas. There are a quite a few nuggets on MCAD software updates and even an article on establishing assembly constraints by yours truly. Have a look and let me know what you think.

Tolerances and Material Removal Processes

If you haven’t already, I recommend reading and understanding my previous post about tolerances before digging in here.

Material removal processes are often used to build tooling for other manufacturing processes such as plastic molds, dies and punches for metal stamping and forming, extrusion dies, EDM electrodes, and many others.  Understanding material-removal process capabilities will be invaluable in understanding capabilities of downstream processes.

Common material-removal processes include lapping and honing, grinding, boring, turning, broaching, reaming, milling, planing and shaping, and drilling.

Engineering Toolbox has a good summary of tolerance limits for different material-removal processes:

Tolerance Grades
4 5 6 7 8 9 10 11 12 13
Lapping and Honing
Cylindrical Grinding
Surface Grinding
Diamond Turning
Diamond Boring
Broaching
Reaming
Turning
Boring
Milling
Planing and Shaping
Drilling

ansi-standard-tolerances

As you can see, lapping and honing give the tightest tolerances while milling, planing and shaping, and drilling have wider tolerances.  Also notice that  the tolerances get bigger as the part size gets bigger, regardless of process.

This is great information, but it doesn’t tell you anything about cost.  In general, as tolerances get smaller the parts gets more expensive regardless of process.  That is, a milled part with a dimension of 1.00 +/-0.05mm will be more expensive than a part spec’d at 1.00 +/-0.20mm.  How much more?  It’s impossible to know for certain because there are so many other factors that affect cost.  The take-home message is simply that better parts are more expensive.

Another key piece of information you do not get from this table and chart is any indication of the applications for these processes.  If lapping gives me the tightest tolerances, why don’t I just make all of my parts by lapping them?  Well, lapping only works on flat surfaces.  I suggest clicking through the links above and checking out what wikipedia has to say about each process.  All of the overviews are pretty good.

We will discuss applications of these process as they relate to mechanical components in later posts.

Tolerances

I’m writing this post to help those in the audience that aren’t familiar with detailed mechanical design. A basic understanding of tolerances is essential to follow subsequent discussions here.

First, a quick definition:

Engineering tolerance is the permissible limit of variation in

  1. a physical dimension,
  2. a measured value or physical property of a material, manufactured object, system, or service,
  3. other measured values (such as temperature, humidity, etc).
  4. in engineering and safety, a physical distance or space (tolerance), as in a truck (lorry), train or boat under a bridge as well as a train in a tunnel (see structure gauge and loading gauge).

Thanks Wikipedia.

Every manufacturing process has some variation on dimensional output and a sound mechanical design needs to account for these variations. If you ask a machinist to make you a block that’s 1″ by 1″ by 1″ you might get a block that’s 1.012″ by 0.923″ by 1.103″. Is that close enough?

Could the machinist have done a better job getting closer to the 1″ target? Probably, but since we didn’t specify a tolerance, technically it’s close enough. If we wanted something closer to 1″ per side we’d need to specify how close. That’s the tolerance. We’d say 1″ plus or minus 0.010″, for example. The 1″ dimension is called the nominal value and the 0.010″ is called the tolerance.

Later I’ll talk about tolerances associated with different manufacturing processes and environmental conditions and how mechanical engineers and product designers account for them in their designs.

IDEO Product UI Design Process Will Be Public

The modular DIY gadget platform, BUG, has teamed with IDEO to redesign the BUG user interface. IDEO has agreed to BUG’s request to do the project in the open, soliciting feedback from the user community along the way. I’m not aware of a design effort of this magnitude, with a firm of this stature, happening in such a public manner.

Here’s what IDEO has to say about the project:

…We’re thrilled to be working with Bug Labs to make this great product even better. We are also prototyping a new, open way of working that we hope will combine the expertise of Bug Labs engineers, IDEO designers, and the BUG community throughout the design process.

This is a quick project with a focused objective: re-envision the interaction with the BUGbase, specifically the display and buttons. We want to hear from you! Share your thoughts about the current BUGbase interface and your ideas for making it better. How are you using your BUGbase interface? How do you wish you could use it? In return for your feedback, we’ll be regularly posting updates on our progress, as well as the end results. We, of course, welcome your thoughts at any point. …

Follow along on the BUG Blogger website and the BUG Community.

The whole point of this exercise is to continue to push the boundaries of how we innovate, not just on the BUGbase UI, but on all things related to BUG. We take pride in thinking our designs are good, but we also know they are exponentially better when the community gets involved.