RE: [rp-ml] Design for (Rapid) Manufacturing

From: Shane Collins <>
Date: Fri Mar 13 2009 - 06:21:15 EET

Thanks Patrik for the reply whilst I was on the road today. Without going
into a lot of detail on the manufacturing process for acetabular shells (the
hemispherical part that gets attached to the hip), the conventional
manufacturing method machines bar stock, then uses a Ti plasma spray to add
texture for bone in-growth. With EBM® the surface texture, or Engineered
Surface Porosity (ESP™) is created additively as the shell is “grown”. By
combining two processes, manufacturing shells with Arcam machines is less
expensive than conventional machining. The raw Ti shell with ESP costs less
than 100 euro and the product is superior to random plasma spray texture.
There are several sizes, but in all about 10,000 shells have been
manufactured with CE approval. This is a true case where Additive
Fabrication has proven to be a disruptive technology to CNC.


Another medical implant application is the femoral component of the knee.
The conventional manufacturing process is to investment cast (sometimes with
QuickCast®) CoCrMo, and CNC or grind to a finished product. The EBM process
is fast approaching the productivity needed to compete cost wise with
casting. For those companies who want JIT manufacturing, they will be able
to bring in house the foundry process by replacing casting with EBM. Within
a few years, casting knees will become obsolete.


Funny you should mention turbine blades…….




Shane Collins

805 427 0019

-----Original Message-----
From: [] On Behalf
Of Patrik Ohldin
Sent: Thursday, March 12, 2009 12:07 PM
Subject: SV: [rp-ml] Design for (Rapid) Manufacturing




There’s no need to correct you. Ala Ortho and Lima-Lto are both using EBM
for series production of standard products (acetabular shells) in standard


As Shane mentioned in an earlier e-mail these companies take advantage of
the additive technology’s ability to build parts with integrated structures,
and use it to manufacture orthopedic implants with engineered surface
porosity for improved bone ingrowth.


Best regards,




Från: [] För Terry
Skickat: den 12 mars 2009 18:15
Till: RP-ML
Ämne: Re: [rp-ml] Design for (Rapid) Manufacturing


Joe Kerer stated: While you both bring up great uses of RP, it is not really
"manufacturing" as most of these cases are a one of a kind situation. EBM is
not used to make 2000 hip joints that are all virtually identical.


Shane: Correct me if I'm wrong (or Magnus Rene, if you're on this list), but
I'm pretty sure that Ala Ortho of Italy is using EBM for the production of
standard products, not custom. They are using EBM to manufacture hundreds of
the same titanium hip cup.



Terry Wohlers
Wohlers Associates, Inc.
OakRidge Business Park
1511 River Oak Drive
Fort Collins, Colorado 80525 USA
Fax 970-225-2027



----- Original Message -----


To: 'David <> K. Leigh' ;
; Shane Collins <>

Cc: 'Joe Kerer' <>

Sent: Wednesday, March 11, 2009 11:38 PM

Subject: RE: [rp-ml] Design for (Rapid) Manufacturing

Shane, David,

While you both bring up great uses of RP, it is not really "manufacturing"
as most of these cases are a one of a kind situation. EBM is not used to
make 2000 hip joints that are all virtually identical. RP is being used for
hearing aids because each hearing aid shell is unique - again, not really

Lets look at "conventional manufacturing" companies. If you go to them and
tell them you want a 1 off, or even a batch of 100 parts, they would
generally send you to a "prototyper".

How often have you seen someone pay for an RP of something they could have
had machined faster and out of the actual material they needed - and for 10%
of the price of the RP model? We see situations like this all the time.

Some of the RP/RM companies have people believing that injection molds take
months to make and cost millions of dollars. This is just not true for low
production. One of our suppliers can produce mud-based molds in less than 3
days. They utilize RP models as masters. But they are able to injection mold
actual material within 3 days and can Manufacture hundreds to thousands of
parts more quickly, less expensively and with better functionallity than

When I was at GE, we manufactured turbine blades. Manufacturing meant we
made thousands, If only one, or a set of 48, or? that was prototyping, not

It all boils down to terminology. If one comes from a "manufacturing"
background, RP/RM isnt manufacturing. If one looks up the word in the
dictionary without regard to anything else, then maybe it is.


--- On Tue, 3/10/09, Shane Collins <> wrote:

> From: Shane Collins <>
> Subject: RE: [rp-ml] Design for (Rapid) Manufacturing
> To: "'David K. Leigh'" <>,
> Cc: "'Joe Kerer'" <>
> Date: Tuesday, March 10, 2009, 11:57 AM
> In addition to Pat and David's comments, over 2000
> people can now walk
> without pain because they received a total hip replacement
> where the
> titanium acetabular shell was manufactured with Arcam's
> EBMR technology.
> The additive manufacturing technology of EBM allows for
> engineered surface
> porosity to ensure bone in-growth. I would call this a
> serious, series
> RP/RM application as well.
> Shane
> Shane Collins
> 805 427 0019
> -----Original Message-----
> From:
> [] On Behalf
> Of David K. Leigh
> Sent: Monday, March 09, 2009 9:34 PM
> To:
> Cc: Joe Kerer
> Subject: RE: [rp-ml] Design for (Rapid) Manufacturing
> I'd have to agree with Pat.
> There are many reasons you may consider a traditional RP
> method for RM:
> * Unique Design (unmoldable, combined assemblies,
> etc.)
> * Mass Custimization (hearing aids, orthodontics,
> etc.)
> * Batch Size (1 car)
> * Unique material properties
> * Production volume (<1000 per year. . . ag
> products, business jets,
> military, etc.)
> * Rapid Engineering Changes or revisions (amortized
> tooling costs >
> RP part cost)
> * Test market in cases where tooling costs could be
> prohibitive
> (sales samples prior to mass production)
> * Time to market considerations (safety upgrades)
> * Reverse engineering (obsolete or unsupported
> products)
> * etc.
> Many many applications for RM. . . not just
> "neat-O" design competitions.
> -David
> _____
> From: on behalf of Warner, Pat
> Sent: Mon 3/9/2009 8:19 PM
> To:
> Cc: Joe Kerer
> Subject: RE: [rp-ml] Design for (Rapid) Manufacturing
> Whilst I do see where you're coming from I can't
> say that I agree with you.
> RM is cost effective if the batch sizes are small enough. I
> build parts for
> use on our race cars using SLS, and as the batch size
> rarely exceeds 10, RM
> is a perfect fit for us. Tooling for such low volume would
> be ridiculously
> expensive and the lead times involved prohibitive. On the
> odd occasion where
> batch size has been up in the hundreds, I've still
> managed to manufacture
> parts in-house significantly cheaper than outsourcing to
> injection moulding.
> Aerospace companies are putting parts on military aircraft
> every day. I'm
> not sure that I could consider parts used on fighter
> aircraft as joke
> products. They obviously pass all the requirements for the
> product, and if
> it wasn't a cost effective way of producing the parts,
> I'm pretty sure
> they'd be doing it another way.
> Pat
> _____
> From:
> [] On Behalf
> Of Joe Kerer
> Sent: 09 March 2009 22:11
> To:;
> Subject: Re: [rp-ml] Design for (Rapid) Manufacturing
> The best way to design for RM is to put something into your
> design that is
> going to make it extremely difficult to manufacture the
> products using more
> conventional means.
> Lets get real. A good designer designs for manufacturing,
> not RP. RM (RP)
> should only be used in rare occasions, as this is generally
> not a good
> manufacturing method.
> Look at many of the parts that the RP/RM manufacturers are
> showing as RM
> parts. They are mostly a joke, as they can be manufactured
> via other methods
> with better and cheaper results.
> Joe
> --- On Fri, 3/6/09, William Watson
> <> wrote:
> From: William Watson <>
> Subject: [rp-ml] Design for (Rapid) Manufacturing
> To:
> Date: Friday, March 6, 2009, 2:11 PM
> RP-ML:
> I was recently asked by our local IDSA chapter to write a
> short note on
> designing for rapid manufacturing processes. Although
> there is a lot of
> documentation on design constraints for other manufacturing
> processes
> (injection molding, sand casting, et al.), there is little
> help for
> designers in the additive fabrication space.
> I thought I would open this conversation up to the RP
> community with the
> hope of finding more help for the designers looking for
> better prototyping
> guidance as well as developing support for accepted DDM
> constraints.
> The article below was written for the industrial designer
> with little or no
> experience with rapid manufacturing. Obviously there is
> much more detail
> and depth than I covered. Hopefully this is a good place
> to start.
> The original can be found at:
> tml>
> ml Here is the text:
> Design for (Rapid) Manufacturing
> Rapid Prototyping (RP), Additive Fabrication, Direct
> Digital Manufacturing,
> 3D Printing are just four of the many different ways to
> describe the
> twenty-two -year old industry based on technologies that
> build parts up,
> layer by layer. For the designers new to the technology,
> the promise is the
> same:
> Everything drawn in 3D CAD can be sent to a 3D Printer.
> If only product design was that easy. When your design
> process involves
> rapid prototyping, knowing about the materials and process
> can improve the
> outcome of your prototype.
> There are two equally false thoughts about prototyping
> materials:
> . RP parts are super fragile and super expensive -
> . RP materials come from "unobtainium" and are
> a perfect match for all
> designs and assemblies
> Although the first notion was probably true ten years ago,
> things have
> improved dramatically. Materials are stronger and better
> mimic the
> engineering polymers intended for production parts. Also,
> lower cost
> processes have reduced the overhead of many suppliers. For
> many processes,
> ordering a second piece only adds a fraction of the cost of
> the first. Since
> your marketing manager is going to keep the first model,
> might as well order
> two so you have one to use to communicate with engineering
> and
> manufacturing.
> Of course, the thought that RP machines can make everything
> is equally
> false. If your design includes sheet metal, expect to make
> some thickness
> changes before sending the STL file to the model shop. Many
> assemblies
> incorporate multiple materials to optimize the design for
> strength or
> weight. Do not expect one RP material to cover that very
> wide range of
> material properties.
> So, what is a designer to do? First, think about your
> design and product
> development goals. Then pick a prototyping strategy that
> best meets those
> goals.
> General design considerations:
> . When Outsourcing
> - Match your design with the right process
> . Small medical device? SLA
> . Color concept model? Z Corp
> . Over molded plastic/rubber? Objet
> - Be realistic about lead times
> . Start to finish with shipping time, outsourcing
> takes a week
> . Give your supplier a heads up when projects are on
> the way
> - Understand cost and time drivers
> . Material Volume
> . Build Envelope
> . Post Processing
> . In House 3D Printing
> - Know the strengths and limits of your process
> . Modify the design to make post processing easier
> . Know when to use assemblies, and when to manually
> assemble
> components
> . Use hollow or sparse builds to minimize costs
> - Understand support materials and post processing
> - Determine how to make the build more efficient. What
> drives time?
> Just like most other manufacturing processes, RP
> appreciates good design.
> Simple rules like constant or similar wall thicknesses help
> make growing and
> processing the parts much more efficient. Cantilevered
> beams often need
> support, and sheet metal features need to be thickened.
> Most importantly,
> using good design sense and understanding how your parts
> are made will help
> you make better designs in less time with less money
> Bill Watson, IDSA is the managing partner of Anvil
> Prototype & Design (
> <>
>, a Z Corporation
> partner and RP service bureau based in Charlotte, NC.
> Bill Watson
> Anvil Prototype & Design
> <>
> 4101 Stuart Andrew Blvd. Suite F
> Charlotte, NC 28217
> m>
> Voice: 704-527-8171
> -------------------------------------------
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Received on Fri Mar 13 06:18:01 2009

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