How to make an iPhone case: Part 2

Before we landed in China, Kaspar and Stefan had been working on creating tooling for our cases.  The tooling includes the mold that is placed into the injection molding machine which is used to make each frame of the Leverage case.

Stefan creating the tooling design files

The tooling consists of extremely hard stainless steel.  A lot of pressure and heat is applied to the tool as molten plastic is pushed through. A strong high quality metal is needed for it to withstand the repeated abuse it endures when thousands of units are produced through the mold.  Since the steel for the mold is so hard, it takes quite a long time to shape. This also means that mistakes in the tool also take a long time to correct.

Minute details like part lines and plastic flows need to be taken into account during the design of the tool.  As molten plastic flows into the mold it begins to cool.  If the plastic cools at different speeds it can leave visible flow lines, so gates have to be placed in the right position.  The color and strength of the plastic is also affected by the rate at which it cools.  Left too long in the injection molding machine, and you can have a case that is no longer the intended color or it becomes extremely brittle.  Daily changes in humidity is also a factor that can affect the consistency of the plastic.  Many of the injection molding machines have mechanisms to regulate the moisture of the plastic pellets before they are melted down.  Luckily for us, the Kaspar and our factory are experts at determining exactly when the pieces need to be pulled out of the machine.

The tooling is the most expensive part of the creation process, not only for the engineering expertise that’s needed, but for the time and labor that is needed to shape a solid piece of hardened steel.  Each undercut and mold cavity also adds to the cost and complexity.  For our Leverage case, it took about 4 weeks to create the initial tooling, and then a couple weeks of refinement after that.  We also had multiple tools for all the separate metal and plastic pieces.

To form the hard steel into the mold, rough shapes are milled out with a computer controlled arm.  The bits seen in the photo below cut the solid steel block and quickly remove metal to start the rough form of the mold.  The CNC machining takes out large amounts of metal when compared to the next step of electrical discharge machining (EDM).

Bits for the CNC machine

The intricate detail work is done with EDM which works by applying an electrical charge to the metal.  This results in a spark that knocks microscopic pieces off the steel surface.  It’s a slow process, but yields the tight tolerances needed to create a properly fitting Leverage iPhone case.

The above video shows EDM in action.  Every time that copper colored piece is lowered, it creates a spark that eats away the steel piece on the bottom.  You can’t see the spark in this case, but if you look closely, you can see the smoke that emerges every time the two metal elements get close. The liquid you see flowing is a nonconductive oil that washes away the small metal particles.

Here you can see the final tooling in the injection molding machine.

One side of the finished mold

Once the tooling is done, the pieces are inspected for fit.  The needed changes are noted and the tooling goes back to EDM where more material is taken away or if necessary, more material is added to the steel. The mold is usually built so that there is a little extra material since it is easier to take away material than to add it.

Leverage case with sprues

When the plastic pieces come out of the machine they are attached to sprues.  These attachments are from the channels that the liquid plastic is flows through.  You might have seen similar pieces if you’ve ever built a scale model kit.  The sprues are removed before assembly.

After the first shots are approved, we do a pilot run that is a small fraction of our order.  This small scale production is used to reveal any issues that might arise in the various stages from injection molding to packaging and resolve them before large scale production occurs.  Once the pipeline is established, scrap rates and quality control guidelines must be established, but that’s probably best left for another post.

Our metal pieces go through a similar process, but instead of getting coated with a soft touch finish, they are hand polished and sent to get plated.  Once all the pieces are properly finished, they are assembled and packaged.

The amount of precision required in just the tooling to build a simple iPhone case is pretty astounding when you really break it down.  It really gives one an even greater appreciation for how spectacular devices such as the iPhone really are.

For those looking on more details on manufacturing techniques, I found Manufacturing Processes for Designers to be a great starting guide.

How to make an iPhone case: Part 1

I stared at a metro map in the Hong Kong airport trying to figure out which ticket to buy. Finding a solution, however, was tough. I was fatigued from a 14 hour flight from Los Angeles and my eyes kept glazing over, losing their way amongst the brightly colored lines. Luckily my traveling companion Peter Szucs, our lead designer at Graft Concepts, had worked in Hong Kong a few years prior and he was quite familiar with the island. Just one Airport Express and Octopus card later, and we were on our way. In a few short days, we’d meet up with fellow co-founder Danny Wen and officially start a month-long stay to oversee the early stages of manufacturing for the Leverage iPhone case.

It had been six months since we had all decided to form this company, with the intention of creating high-end accessories for mobile devices. Naively, I had projected that we’d be at this point three months ago. With this being my first experience in developing a physical product, my expected timeline turned out to not quite measure up to reality. I thought, “don’t we just create a cool design, make it in CAD, and send it off to be made? In a month or two we’ll have a finished product shipped and ready up at our doorstep, right?” Nope.

This is the first product that our team has collaborated on from start to finish. Through the process, I’ve learned a great deal from my partners. I thought I’d share our experience. I hope it will help readers out there who are considering creating their own physical product, but haven’t yet gone through it all themselves.

The Ideation Phase

Our first step was to get as many ideas onto paper as possible.  Having an industrial designer is very helpful in this first step, especially one who can translate their sketches into 3D computer models later in the process.  If you need an industrial designer to help you out, there are many freelancers who post their portfolios on  Pete was able to take our features and vague descriptions of what we were looking for into something visual so that everyone was in agreement on what the product should look like and how it should function.

Leverage Ideation Sketches

As you are probably aware, there are many variety of iPhone cases out on the market.  If you were at last year’s CES, you would’ve seen more than 200 vendors selling Apple related accessories.  This year is bound to be just as big (50,000 square feet worth).

We knew we had to differentiate from all the other types of iPhone cases out there. We wanted to aim for a higher-end product and attempted to keep a lot of the iPhone aesthetic intact.  Armed now with at least 50 different sketches of various ideas that we had been throwing around, we narrowed the concepts down to down to 2 different designs.  More sketches were generated based on these final two ideas in order to refine the form and features.

Design Choices

Our intention was to launch with two products.  One that had elements often associated with watches and jewelry.  Elements like small screws, mechanical features,  metal accents, and fine beveled edges.  This design evolved into the Leverage.  Our other design was a bit more architectural and after making numerous prototypes for it, we realized we would have to shelve it.  Our remaining funds did not enable us to produce two concurrent products.  Hopefully we can incorporate the design in future versions of our offerings.  Tradeoffs related to funds, features or feasibility would come up a lot in the product development process.

For instance, some of the team wanted a large port for the headphone jack which would allow more third party headphones to it without having to use an adapter.  The tradeoff was that having a larger hole for the headphone meant that there would be less case material around the in the area around the headphone jack, which would mean a weaker case.  The general rule for plastics is to have 1.5 mm of thickness to ensure it passes a drop test.  With the iPhone 4 being so thin, we didn’t have much room to play with.  We had some seriously passionate debates on the issue, but in the end, it was decided that having people complain about their headphones not fitting was better than having customers complain about their cases breaking.

Now that we had a design, the next step was to create a 3D computer model.  The 3D model is then used to create the prototypes and the basis for the tooling.  Apple actually provides the public with full dimensions of their iPods and iPhones.  From their files, we are able to use those measurements for the Leverage.

Pete using SolidWorks to model the Leverage

Once the 3D computer model looks good, we move into the prototyping phase where physical models are built.  For fast and quick models, we go to our local rapid prototyper/machine shop.  We usually get our first models 3D printed in Polyjet or Stereolithography (SLA).  These methods work great for what we need.  They offer some very tight tolerances and don’t require any extra sanding or other finishing.  The material is also fairly similar properties to the final product.  There are lots of 3D printing options becoming quite accessible to anyone.  There are now many online services that allow you to send them a 3D file and they will mail you back a 3D printed model for a vary fair price.  Some good places to find out more about 3D printing (in no particular order) are:

So after a we have physical prototype printed, we do a test fit on an iPhone.  We make further adjustments to the 3D computer model and then print another unit to test the fit.  This process is repeated until we get satisfactory results.

3D Printed Prototype

Sourcing and Engineering

While doing the prototyping, we were concurrently looking for engineers to help ensure that our design could be manufactured.  We were also requesting quotes from contract manufacturers.  The search for a factory started with going through sites like Alibaba and Global Sources, looking for suppliers with similar products, or ones that worked with both metals and plastics.  Protomold was another very intresesting option, but since we had so many different pieces in our design, and assembly was needed, we had to look elsewhere. We also tried which is a site that lets you upload your CAD file and allow factories to bid on your job.  We didn’t have much luck with either of those options probably because we did not go in with a strategy of how to quickly and properly vet all those factories.  These sites deserve further inspection on the next round of products we produce.

With time constraints looming (we wanted to make sure we got a product out before the next version of the iPhone was announced), we decided to try a sourcing agent.  We had gotten a referral to a sourcing agent who was extremely helpful and familiar with factories in China and worked to get quotes for us. While all this was happening, we were talking to engineering firms here in the US.  Even though our design looked like a finish product, we still needed an engineer to make sure it was manufacturable.

I got some recommendations of some engineering firms from a former college professor (Danny and I went to USC, Pete had gone to Art Center).  These engineering firms were based here in the United States and had had connections to factories, all of which happened to be in Asia.  Using a factory that the engineering firm had experience with was extremely appealing, but the problem was that the US engineering firms was they were too expensive for a new company such as ourselves.  Some wouldn’t even give us a quote because we were so small.  Luckily Pete remembered working with some really good engineers who had started their own firm.  Enter Kaspar and Stefan of 4tec solutions.

Kaspar and Stefan are two Swiss guys who provide engineering services and work as our liaison to the factories.  They’ve been a huge help in not only the engineering of the product (the nice snap you feel when you close the Leverage is attributed to these guys), but whenever the factory runs into a problem, they always have a solution ready to go.  Every product has production issues, but these guys have really made everything go smoother.  Plus, their prices were just within our budget!

Our 3D computer files were sent over to Kaspar, and as soon as they made their modifications.  We had another set of prototypes made, this time the prototypes were made from the actual materials we had planned to use in the final product.

Leverage prototype made with final materials

While 3D printing cost us a few hundred dollars,  and the prototypes made of metal and plastic cost a few thousand, the cost was minor compared to the start of the actual manufacturing.  In the next post we describe the cutting of a tool and getting the first shots.