Sorry Guys, Rotomolding Is Not Dead

I thought this was interesting when it was posted in early April, but decided not to pile on to the responses. Every once in a while, the folks at Core77 do step in it and their faithful readers are only too glad to point it out.

When frequent contributor hipstomp posted about some nifty watering cans, quizzing readers to see who could figure out how these hollow products were produced, his reveal was somewhat anti-climatic:

Rotational molding! I’d practically forgotten this technique even existed; we see it so rarely, probably because you could accurately describe it as being “expensive, and takes freaking forever.”

For those of us who design products utilizing a wide range of materials and processes, it wasn’t that rotomolding was the chosen process that was notable in his post, it was hipstomp’s apparent surprise that rotomolders weren’t extinct. As many respondents reminded our dear poster, rotational molding is still very much alive and kicking. I have personally worked on several rotomolded products in the last year and know that most molders and mold builders are quite busy indeed.

One of the reasons why you don’t see rotomolding as often as other processes might have something to do with the poor job the rotomolding industry has done promoting its process to the design community. True, rotomolding isn’t appropriate for high-volume applications, but for specific situations requiring the kind of rugged parts this process can produce, there are few other processes that can do the same as cost-effectively. Perhaps watering cans aren’t the best example of that as some observed–perhaps blow molding might have been a better choice (depending on the production volumes), but there would still be a fair amount of scrap generated by that design.

Hipstomp goes on to suggest that RP processes might be more appropriate for the creation of hollow parts. I’m not saying that these products can’t be produced using rapid prototyping methods like Polyjet, but I guess I still question why. As commenter Dave observed:

RP materials and processes are improving, but this is a question that should be posed to people with knowledge of roto-molding and other processes, as well. RP is not a silver bullet, despite what seems like an ID fascination with having a one-size-fits-all answer to manufacturing. As for surface finish, there are RP machines (polyjet) that do pretty high resolution (.0006″ layer thickness). With texture built into the build file, maybe surface finish will eventually not be an issue of “can we make it this way?” “Should we make it this way?” will remain though.

A more fundamental limitation comes into play. RP methods require high precision movements of the RP machine for every part. Roto-molding, like injection molding, blow molding, etc. requires high precision to build the tool, then much lower precision to build the parts.

To be clear, I’m not beating up on hipstomp; I myself am a moderator of the Materials and Processes discussion forum on Core and I’ve re-posted many of his articles on this blog. But it does say something about how we as a design community looks at M&P as the foundation of what we do as industrial designers. True, not all ID’s engage in the development of artifacts, but many of us still do and not all of them are mass-produced to justify infection molding or so custom as to warrant using RP processes regardless of how novel that might be. I think it’s worth taking the time to properly educate our students and continually educate ourselves and our community on the materials and manufacturing technologies (old and new) that are being (still) used today and where each fits in the broad spectrum.

Take a look at the post as well as the comments and let me know what you think.

[Core77 post]

Materials and Processes Behind the HTC EVO 4G LTE

If you can get beyond the marketing hype, there’s some pretty interesting bits about new materials and manufactiong tricks incorporated into HTC’s EVO 4G LTE. They’re using aircraft-grade aluminum in the kickstand and multiple finishing processes for the case. Worth a watch.

[via Product by Process]

Persol Sunglasses: Art and Craftsmanship in Plastic

For those who think plastic is just some material used in throw-away mass-produced trinkets, take a look at this lovely film produced by Persol showing ‘The Magnificent Obsession of Hand Making’ their signature sunglasses. Beginning with the hand-mixing and coloring of the acetate, the insertion of the ‘Victor Flex’ nose bridge, the meticulous bending, forming and polishing of every surface and ending with the precision installation of the hardware, this is clearly a labor of love and thoughtful design. These are not the sunglasses you carelessly leave on the beach.

For those materials geeks out there (you know who you are), the frames are made from a natural material: cellulose acetate (sometimes just called ‘acetate’), which is derived from cotton and tree pulp. In the eyeglass industry, the material is referred to as ‘zyl,’ short for zylonite, the trademark name for cellulose acetate. One of the most versatile of all plastic frame materials and the most commonly used, the frames are milled from blocks of zyl, which come in an enormous variety of colors and patterns. In the video, you can see them combining different colors to create the ‘tortoise shell’ effect in the material.

As opposed to injection molding, cellulose acetate is formed into thick blocks from which the glasses are machined, formed with heat and hand polished. Heat is also applied so it can be stretched for lens insertion. The resulting product maintains many of cotton’s natural properties – hypoallergenic (allergy free), warm to the touch and pleasant on the skin. Other than it’s more expensive than injection molded plastic, the only downside is that it doesn’t do well in high heat (don’t leave them in the car on a hot day) and that it tends to oxidize with a milky white film over time. Regardless, cellulose acetate is the most commonly used material for high-end plastic eyeglass and sunglass frames.

You’ll have to watch this a few times to catch all of it (I suggest watching on Vimeo).

[via Product by Process]

How a Bicycle is Made from 1945

“They don’t make them like they used to.” Well, maybe they still do…

Enjoy the British Council Film from 1945 on how a Raleigh bicycle is made. Despite it’s almost 70-year age, this film is still a very comprehensive review of many of the metal manufacturing methods I just finished teaching at NC State College of Design. From tube bending and roll forming to forging and stamping, this covers many of the same processes used to today on bike manufacturing. Sure, there’s no carbon fiber or CAD models and not as many gears on that bike, but there’s a lot to be learned by young designers today.

[via Adafruit]

Micro Arc Oxidation on HTC One S Phone

Originally designed for use on satellites and race cars, the Micro Arc Oxidation process starts with aircraft-grade 6000-series aluminum. 10,000 volts of electricity hit the metal, almost like lighting strikes, causing a microscopic transformation which creates a super-strong ceramic case that is five times stronger than aerospace aluminum.

Wicked cool.

[via product by Process]

Co.Design: Plywood Revolution

In her article, “How Plywood Revolutionized Design And Changed The World (No, Really!)”, Co.Design senior editor Suzanne Labarre reflects on a mid-20th century “modern” material after her visit to Plywood: Material, Process, Form, an ongoing exhibit at New York MoMA:

That plain little sandwich of lumber and glue–with its origins in ancient Egypt and its reinvention under the auspices of 20th-century military research–gave designers from Alvar Aalto to Charles and Ray Eames the raw material with which to shape some of the most iconic furniture of the past 100 years.

Those products represent a time when designers were experimenting and innovating with materials. The role plywood has played in the history of product design is significant and underscored by how expensive Eames and Aalto’s furniture are today. Labarre notes the irony that while they might have been developed the common man in mind, few of us can afford them.

EcoDesigner: LCA Plugin for Solid Edge

I’ve posted on similar tools from Sustainable Minds and Sustainability Xpress for SolidWorks, and now entering the Lifecycle Assessment (LCA) arena is EcoDesigner. EcoDesigner is a plugin for Solid Edge and was developed by Trayak, a consulting and software solutions company that focuses on product sustainability. The folks over at SolidSmack spoke to Prashant Jagtap of Trayak to get the deets on EcoDesigner and what makes it unique among other competing products.

Very few designers are aware of the environmental impact of their product designs. If designers are able to understand the baseline environmental footprints of their products and can analyze what can be done to reduce these it would drastically improve the overall sustainable aspects of design. 

I’ve been asking for more case studies to demonstrate the real-world applicability and viability of these tools and Prashant agrees that there is no easy way to “optimize” material choice using multiple properties. We need to use many more parameters that are relevant and important besides the existing LCA indicators. This is a huge problem requiring us to simultaneously solve for multiple parameters to be successful. But with software like EcoDesigner and those like it, we’re moving (albeit slowly) towards smarter product design.

[Read the entire SolidSmack interview here]


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