Rapid Manufacturing Hearing Aids

Precision is one of the many striking aspects in additive manufacturing.  With the importance of precision and customization in mind, In’Tech began manufacturing custom in-the-ear molds and ear shells for the Hearing Aid Industry right here in the Midwest.   All of our products are designed specifically to your needs.

The entire process from start to finish is quite fascinating.

The beginning step in the process is at the Audiologist’s office.  The Audiologist will take an impression of your left and right ears and send them to us.  Our techs will take the mold and create a digital file of your unique ear impression.  This process is done digitally because all ear molds come in different sizes, and the digital copy allows us to customize in terms of comfort, acoustics, fit, etc.  The digital file is spliced into many individual layers, saved as a CAD file, and sent to our SLA machine.

Our iPro 9000 deciphers the CAD file and begins creating your custom hearing aid.  Layer by layer the ultra-violet laser traces and forms the in-ear-mold.  As each layer is created, the previous layers solidify and begin to form your ear piece.  The rapid manufacturing process takes about eight-ten hours, allowing for an extremely speedy turnaround from the time your Audiologist takes your impression to the time you have your new device.

Manufacturing a Prototype

Manufacturing a prototype needs to start with an idea.  Over time, getting that idea from your brain, to the white board, to the prototype, to the final product has taken many forms.  You don’t need all of the fancy bells and whistles to get your idea on paper, but having the prototype manufactured does take a great amount of willpower.

Once you have an idea or concept in mind, get it on paper!  It’s important that you start making a collection of drawings that highlight details of what you want your prototype to look like.  Make sure this collection of drawings is well organized so when it’s time to manufacture that prototype you have your concepts in order.

Now you have your idea on paper!  Is it time to get manufacturing?  Not quite yet.  You are going to want to create a 3D model of your prototype.  This can be done in a few different ways.  You can use a CAD (computer aided design) program which will digitize your prototype, or you can create a physical 3D model of your idea.  There are tons of materials you can use to create a physical model.  You can use wood, metal, foam, cardboard, paper, etc.  Having physical 3D prototype will also give you a good idea of the size and shape your prototype will be.  Having a rough estimate of the size and shape of your prototype will also give you an idea when it comes to manufacturing costs down the road.

The next step in manufacturing your prototype is figuring out how it will function.  Are you going to need an engineer to help with electrical components of your prototype?  What types of materials will your prototype be designed from?  These are questions that you will need to start deciding on; this is also a great point to begin consulting a variety of professionals for quotes on manufacturing your prototype.

Depending on how much time and money you are willing to spend will dictate what type of manufacturing process you might decide on.  Cost is going to be a major factor in the manufacturing process.  If you are creating just one prototype, this may cost a good amount of money.  If turnaround time is important, you might want to look into a process called rapid prototyping.  The rapid prototyping method uses cutting edge technology to manufacture prototypes in a quick and efficient manner.

In the end, it all depends on what type of prototype you are looking to manufacture, but it all starts with an idea.  So getting it on paper or on a computer is the first step!

SLS Additive Manufacturing Process

What is SLS?

Selective Laser Sintering or SLS is another option in additive manufacturing.  SLS utilizes a polymer powder base to create the prototype. The bulk powder material is preheated in the powder vat making it easier to reach the melting point.  Similarly to the SLA process, the prototype is first designed on a computer using a 3D CAD file.  That CAD file is spliced up into layers and then sent to the SLS machine.

Once the device has the layers from the CAD file the first layer is created.  The laser beam comes into contact with the powder base and begins to carve out the layer.  Then, the platform that the layer is being created on drops enough for the next to be started.  As each layer is built, it becomes fused together layer by layer, creating the sturdy and ultra-durable prototype.

What is Rapid Prototyping?

During the late 1980’s a researcher by the name of Carl Deckard came up with an idea.  The idea that the University of Texas researcher had was a process called additive manufacturing, which is now a main component of the rapid prototyping process.  Additive manufacturing is in stark contrast to traditional subtractive machining processes because with additive manufacturing you create an object by using layers, and thousands of layers at that, rather than the traditional process of destroying to create.

So, how do you get thousands of layers melded together to create a precise plastic prototype?

To create a plastic prototype using additive manufacturing it starts with an idea.  After engineers and designers brainstorm that idea, it is then taken to a computer and a 3D model of that idea is created as a CAD (computer aided design) file.  The newly created CAD file is then broken into a great deal of very thin layers and sent to a machine that uses SLA (stereo lithography apparatus) or SLS (selective laser sintering) technology to create a solid object from a tub of liquid photopolymer.

Now, once the SLA or SLS machine has the CAD file in place, “the magic” begins, and the rapid prototyping process is put into action.  Remember all of those layers we talked about earlier on?  Now it’s time to use a laser beam to turn those very thin layers into a solid.  The laser is pointed at the liquid photopolymer or ceramic powders and begins to trace one of those layers, then it is coated again with fresh liquid photopolymer and a new layer is added to the previous layer.  The process is called additive, because the machine is regularly adding a new layer to create the prototype.  Once all of the layers have been completed, your prototype is ready.

Before rapid prototyping services were available, the process would have taken several weeks, or even months to create.  A company would put most of their eggs into one basket, a great deal of money, and hope their prototype was produced to the specifications that their engineers had hoped.  Now with rapid prototyping, the process can be done within a few hours (usually overnight), for a fraction of the price, allowing for hiccups in the design process to happen at the beginning of the cycle, rather then millions of dollars into it.

The rapid prototyping process is a really amazing one to witness, one that words don`t do just to.  Here is a brief animated video of the entire start to finish cycle of rapid prototyping.

CAD to Rapid Prototype

Before a prototype can be sent to the SLS or SLA machine a digital file of the prototype needs to be created first.  This digital file is called a 3D CAD file or a 3D Computer-Aided Design file.  A CAD file allows the design team, along with engineers and technicians, to fine tune the 3D image before sending it through the rapid prototyping process.

One example of using a CAD file to customize a 3D image before the manufacturing process is with hearing aids.  After an Audiologist has taken an impression of the ear, it is scanned and a raw CAD file can be rendered.  That file is raw because it has yet to be customized.  It is then file can now be trimmed to the specifications of that individual, to maximize acoustics, fit, and form.  This is extremely important for the fact that just like a fingerprint, ear builds are different and hearing aids need to be built specifically to the individual.

After the CAD file has been tidied up to fit the individuals ear, it is then spliced up into cross sections and sent to an additive manufacturing machine.  That machine then creates layer by layer, a custom mold direct to the Audiologist`s specifications.  The final product is then ready within 24 hours.

Prototyping Equipment

When looking at prototyping equipment it’s important to think about what you are going to be prototyping.  Are you going to need rapid prototyping capabilities?  Are you going to be manufacturing on a commercial scale or at a hobbyists level?  Depending on your budget and location you may be interested in different companies and technologies.

  • 3D Systems– 3D Systems has been one of the industry leaders for a good period of time.  They are a US company based out of Rock Hill, SC.  They are home to several types of additive manufacturing equipment including SLA and SLS machines.  In 2010 3D Systems acquired the UK based company Bit from Bytes.  The acquisition of Bit for Bytes allowed for 3D Systems entrance to a new marketing sector for its prototyping equipment.
  • MakerBot Industries– MakerBot Industries is a New York based open source hardware company that specializes in 3D printers.  They have a reputation of being at a hobbyist level when it comes to prototyping equipment.  Since its inception, MakerBot Industries has showed steady growth and the company has doubled in size.  In 2011 a venture capital firm invested about 10 million dollars into the organization.
  • Ultimaking Ltd. – Ultimaking Ltd. is an open source manufacturer of prototyping equipment that is based out of the Netherlands.  Described as the new kid on the block, Ultimaking has sold over 100 units since its May 2011 start date.  Ultimaking currently employs over 20 individuals, and specialize in personal 3D prototyping equipment.  The Ultimaker uses ABS or PLA plastic during its printing process.
  • LeapFrog– LeapFrog is another Dutch company and has two 3D printers on the market.  As a company, they create easy to use systems that look awesome.  Their prototyping equipment uses additive manufacturing techniques, which aim to reduce the 90% waste that occurs during current manufacturing processes. LeapFrogs Creatr model comes fully assembled, but is very skeletal. Their higher end Xeed model does a good deal more, but will cost you nearly four times the Creatr price.
  • Objet Ltd.– Objet Ltd. is another major player in the 3D printing community.  They are headquartered just south of Tel Aviv, Israel, and have been around since the late 1990’s.  In 2012 Objet merged with Stratasys, similar to the move between 3D Systems and Bit from Bytes.  Objet sells a variety of prototyping equipment ranging from entry-level prototyping machines to fully commercial equipment.

These are just a few of the companies that are involved in prototyping equipment.  Some are focused on the larger commercial machines, while others cater to the hobbyist niche.  Depending on what you and your company need will help decide what type of machine you will need.

SLA Machines We Use In The Rapid Prototyping Process

In 2001 In’Tech purchased its first SLA rapid prototyping system which provided us the ability to manufacture custom ear molds and ear shells for the Hearing Aid Industry. In 2005 we began applying our internal SLA rapid manufacturing expertise within the Dental field.

We have built our Minneapolis based business on quality products and customer service. We know how to provide you with the exact component you need when you need it. Our engineering and production staff is obsessed with quality assurance and customer satisfaction. We grow our business by helping you grow yours.

We currently use several stereolithography systems in our rapid prototype manufacturing process.

The machines we use for the rapid prototyping process are from 3D Systems.  Our largest machine is the 3D Systems iPro 9000.  It is a large size production printer that uses a side-by-side platform setup.  It has a manufacturing build of 650 x 750 x 550 mm (25.6 x 29.5 x 21.65 in).

Another 3D Systems machine we use in the rapid prototyping process is the 3D Systems iPro 8000.  This is a mid-size rapid prototyping machine that features exceptional edge definition and creates brilliant smoothness.


We also use the 3D Systems Viper SI.  The Viper si allows for products to be created with very fine and precise details because of its high resolution.  It is a very user friendly system, which means your prototype will be completed quickly and efficiently by our hard working engineers.


SLA Machines in Rapid Prototyping

What is Stereolithography or SLA?

Stereolithography or SLA is an additive manufacturing technique that uses an ultraviolet laser to build a plastic 3D model or prototype by building hundreds of layers right on top of each other to manufacture a prototype. The laser beam is focused on the surface of a tank filled with photopolymer resin and traces a single layer right into that resin. Once the layer is traced, a new coat of resin is applied, and a new layer is traced. There is a platform underneath the resin that drops after each layer is complete. Each time the platform drops a new completed layer is build. This process is repeated until the model is finished.

So, how does the 3D printer know what to trace?

The SLA printer receives a file from an engineer called a CAD file or Computer Aided Design file. That file is a computer rendered 3D image that is then spliced up into thin layers allowing the stereolithography printer to create the prototype.

How long does the SLA process take?

This is the impressive part! The stereolithography process is amazingly fast. Once the printer receives the CAD file, your prototype can be created in just a few hours. This is where the term rapid prototype comes from.

Nylon Materials in Additive Manufacturing

3D Systems

When manufacturing a prototype using an additive manufacturing process such as selective laser sintering (SLS) there are an assortment of materials manufactures can use.  One of the most popular materials is nylon and glass-filled nylon.  Nylon materials are used in the rapid prototyping process because they are extremely durable, can withstand real-word testing, and are an actual plastic form.   Not only are nylon materials durable and practical, but they are environmentally kind.  Nylon materials are safe for use with food products and are harmless to the environment.  Another positive aspect of nylon materials are their high resistance to chemicals such as solvents, alkalines, and hydrocarbonates.  So, by creating your prototype using nylon, you get a durable and chemical resistant product while doing your part in taking care of the environment.  Some practical applications of nylon materials are:

  • Complex production or prototype plastic parts
  • Form, fit or functional prototypes
  • Applications where stiffness is required
  • Heat and chemical resistance testing
  • Snap-fit assemblies
  • Durable patterns for sandcasting & silicone tooling
  • USP Level VI certified for brief in-vivo exposure
  • Parts requiring machining, welding, or joining with glue


3D Systems

An even sturdier type of nylon is the glass-filled nylon.  The glass-filled nylon material is a hybrid type of nylon that has been blended with glass beads.  This highly durable blend of materials is great for products that will undergo functionality testing.  Some examples of practical applications come from glass-filled nylon materials are:

  • Durable prototypes that require elevated stiffness and heat resistance
  • Low to mid volume direct manufacturing of end-use parts
  • Enclosures and housings that require more stiffness
  • Aircraft and motorsports parts
  • Sporting goods