Eight Common Rapid Prototyping Mistakes

The good folks at Malco Design created this fantastic white paper about the common pitfalls people experience when making rapid prototypes. The eight examples are really important to understand so that expectations and decision making can result in an optimal prototype tailored to the customer's needs. They are:

1. Poor communication/coordination between designer and prototyper - There are many variables that effect the final part strength, features and dimensions, like overall part size, process used or build orientation. It is very important that the prototyper make clear where uncertainty can occur and how to minimize it and just as important that the customer make clear the critical requirements of the prototype.

2. Overestimating users' knowledge of rapid prototyping - Many services bureaus are receptacles for uploading files and producing them in order to cut down on labor. In those instances it is incumbent upon the customer to know all the rules of rapid prototyping, may of which change over the course of months as new technologies and materials are developed. Prototypers need to keep designers informed and designers need to be vigilant to fill in their own gaps in knowledge.

3. Belief that anything can be built as a rapid prototype - There is a lot of hype in the industry that rapid prototyping can build anything and solve any design issue. Vary large parts are often not suited for the process and unless doing rapid machining, same goes for tight tolerances. Sometimes when experiences don't line up with expectations, customers are wary to use the technologies again.

4. Expecting prototypes to be perfect the first time - My favorite by far! If prototypes were always perfect, you wouldn't need them and you would instantly cut your $50,000 mold. Never forget that prototyping is an iterative process and some design flaws cannot be discovered until one tests the physical prototype in front of them.

5. Using wrong materials or processes - SLA or Polyjet photopolymers degrade in UV light over time, making them not great for production parts, SLS can have rough surface texture and feature definition, Z Prints are brittle and FDM has great variance in strength between its layers. Each of these processes has innate benefits as well. Selecting the correct material and technology is essential to getting the prototype right the first time.

6. Selecting a vendor whose capabilities don't match your needs - Some vendors are fast. Some are knowledgable. Some focus on good customer service while others focus on bargain basement pricing. Research the company with whom you plan to do business. All prototypers are differentiated to work with a specific customer niche and you should make sure you are the customer that fits their capabilities and strengths.

7. Ignoring the value of prototyping - Time is money and many companies are willing to put the extra cash down to get the product right the first time and as fast as possible. Tooling up a factory for mass production is a lengthy and expensive process. The later an error is discovered, the more costly it is and the longer it takes to solve. This could be devastating for companies trying to maintain their margins or release products when consumers actually buy them (think electronics at Christmas or pool toys in the summer.)

8. Building more than is necessary - Many times designers try to make an entire assembly without being sure that each individual component works correctly first. It can save a great deal of cost and time if the components are individually created, and then, once proven, used to build a larger, more complete device.

3D Printed Casts

The technique is antiquated and could use a little something of a shake up thanks to new technology.

Setting castings in plaster is centuries old and has a variety of uncomfortable problems. Scanning and imaging of the body are common place in the medical field in order to diagnose injuries and illnesses, but the ability to create prosthesis and custom fixtures directly from those scans is brand spanking new, from printed bones and teeth implants to entire artificial limbs. The parts either fit to the contours of your body or are exact replicas of the body part which they replace. 

This technique now produces a superior cast taken directly from a 3D scan of the broken body part and 3D prints a cast from the digital negative. The cast is designed with snap fits which enclose the arm, keeping it from moving, but making it accessible to air and hands. Much more comfortble.

Just another simple example where the medical field can benefit from applying new technologies (additive manufacturing/3D printing) to ones that are already pervasive in the medical field (3D scanning and imaging.)

Additive Manufacturing in Aerospace

A stainless steel bracket optimized for weight reduction (front) and the traditional cast bracket in the back.

Additive manufacturing (AM) has long been the holy grail of Aerospace OEMs like Boeing and Airbus. Where typically the costs of metal laser sintering can be prohibitive to mass producing parts, in the aerospace industry volumes are low enough and the design optimizations can easily pay for themselves in fuel and material savings. 

EADS Innovation Works recently released a study that says implementing additive manufacturing into planes and other aircraft could reduce material use up to 75% and fuel consumption up to 40%. 

Let's set aside the obvious environmental benefits for a moment. In an industry that is a slave to fuel costs and customers who always buy the lowest sticker price ticket off aggregator websites, airlines tend to get squeezed when it comes to making their margins.

Cutting just one pound of weight out of an aircraft can save over $10,000 in fuel costs every year. Not only do AM parts cut out that 75% of the material by only using structure where it is absolutely necessary, but light weight, high cost metals like titanium are now available where they were traditionally cost prohibitive, further lightening the load.

Machining titanium parts from billet generally causes up to 90% material waste versus virtually no waste from making the parts additively. Couple that with needing less material in the part design as a whole and scores of components that used to be made from stainless steel or aluminum can now be made from the valuable metal.

This is why we now hear engineers and executives dreaming about the development of printers that are large enough to manufacture entire wings. They see the value in a future where aircraft are created entirely from printed components. 

Maybe the additional payload provided by these technologies will eventually even eliminate the need for bag fees. Unlikely, but one can dream!