As a very short reply, I would say the one difference is the perspective on the process: Basically, the way the part is generated can be the same, using the same technology and machine in both cases, however, rapid prototyping as an older term is focussed on producing a part that is not meant for service application, but as a prototype. As such, it may or may not (in many cases, like when using stereolothography to create e.g. a design model, the "not" would apply) have all the properties and thus performance characteristics of the final part of which it is a "model". Additive manufacturing on the other hand underlines the use of such methods as actual production processes, i.e. the parts generated are meant for a true product life cycle.

As a second aspect, I believe additive manufacturing is a more general term than rapid prototyping, as it describes any technology that generates parts or merely structures by adding, drop by drop or layer by layer, material. Hence for example in my understanding the classic example of stereolithography again would seem to fit both in the additive manufacturing and the rapid prototyping category. Inkjet printing of strain gauges, on the other hand, is clearly additive manufacturing, but I wouldn't see it as a reapid prototyping process.

As an addition, two colleagues of mine, Juan Isaza and Claus Aumund-Kopp, have recently added a chapter on "Additive Manufacturing Approaches" to a book on "Structural Materials and Processes in Transportation" (Wiley, published April 2013) which I co-edited. You'll find a disambiguation of terms in it, too.

Dear Ng Kei Hoa, dear colleagues, the question is interesting indeed, please let me provide view, hoping it may help:

It is true that rapid prototyping usually uses additive manufacturing technologies (both industrial complex machines, such as stereolithography, selective laser sintering..., and low-cost 3D printers), but not always.

Rapid prototyping refers in fact to the fast manufacture of prototypes for different purposes including ergonomic and visual trials, assessment of functional performance, supporting parts to other processes. In many cases, such rapid prototypes are also obtained by means of high speed computer numerical control machining or using rapid form copying processes, after obtaining initial models.

Additive manufacture makes reference to any manufacturing technology using layer-by-layer or drop-by-drop processes. In many cases, these AMTs are used for obtaining prototypes, as they are not normally oriented towards production of large series. However, in recent years, more and more AMTs are being used for final parts, especially when the geometries are complex or for the incorporation of special functionalities.

Thanks for the reply. I find it very interesting and at the same time, confusing.

I read Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing by I.Gibson, and I ask myself this question. the book refers the AM and what is discussed is in the RP process. And some book just will tell RP processes from simple--> toughest knowledge without explaining/address what is "additive" is all about.

Another question is what if the prototype is able to work as product, it is in the RP or AM?

Regarding your last question, if it is meant as a prototype I would still consider it a prototype based on the fact that serving as such would still have been the purpose it was made for. I mean, a fully functional prototype is still a prototype: Reasons for this classification may well be that production processes employed are not suitable for the final product, or that it was made to be used for product verification of some kind.

Coming back to the initial question of defining additive manufacturing, it may also be helpful to think of the opposite, namely subtractive manufacturing and thus all processes that remove rather than add material. These would be cutting processes like milling, turning etc., but also e.g. etching, if you think of microsystems, or EDM, and naturally many more.

main difference is by their name self.RP means prototype is going to b made and process is rapid. As in case of AP,process may be rapid or moderate or slow with only addition of material as by name.

Hello to everyone,

I know that there were many answers to your question. But in fact this is a very tricky question. I work with Additive Manufacturing (AM) and I consider the answer of Andrez Lantada the most accurate.

I had discuss this subject with Ian Gibson and Paulo Bártolo, both are major references in this area and in short we can consider AM as part of Rapid Prototyping (RP) processes, because it only relates with layer-by-layer/drop-by-drop processes while RP means the fast prototyping of objects disregarding the technology being from AM.

@ Ng Kei Hoa: Also referring to your latest question, yes there are objects made by AM that are used as final parts. I assist to a presentation by Boeing and they are using printed parts in there airplanes and according to the Terry Wohlers report of 2012, this is just the beginning.

Hope that this satisfied your inquiry,

Kind regards,

Dino Freitas

Hi everyone,

I am currently deal with biomaterials that has something to do with the rapid prototyping process. At some point, when I write my literature, I got confused. In fact, most biomaterials are still using RP even they can function as product instead of AM.

About the book that dear colleague, Dirk Lehmhus suggested, I am unable to get this book as it is not available in my library. Hopefully someone able to share.

In my opinion, RP and AM both mean the same. Originally Rapid Prototyping name was coined for the process that used to be called as Layered Manufacturing in mid 1980’s by 3D Systems and other manufacturers. Terry Wohlers because of the nature of the manufacturing process has spearheaded to change the use of Additive Manufacturing for the process so that it will properly reflect the process. It is now an accepted term. See also Wohlers blog who pioneered for changing the word from Rapid Prototyping or Layered Manufacturing to Additive Manufacturing (http://wohlersassociates.com/additive-manufacturing.html).

“Additive manufacturing is the official industry standard term (ASTM F2792) for all applications of the technology”.

Another reason also that Rapid Prototyping has been adopted in other areas such as “Rapid Tooling”, and “Rapid Manufacturing”. That way Rapid Prototyping is essentially reserved when you use Additive Manufacturing for Prototyping applications. Hope it clarifies the matter.

Interesting discussion:

If part is produced by RP by material addition (any means) and the part produced can be used in actual application, then the both processes/terminologies (AM and RP) suits the manufacturing process.....

in other way... "RP can be AM and AM can't be RP"

Here is the ASTM std link addressing the terminology used in AM process

http://enterprise.astm.org/filtrexx40.cgi?+REDLINE_PAGES/F2792.htm

Thanks for providing the answer,I found that this books explains clearly what is AM and RP is all about

http://books.google.com.my/books?hl=en&lr=&id=9mjbAgAAQBAJ&oi=fnd&pg=PA1&dq=Introduction+to+rapid+prototyping+of+biomaterials&ots=yEOs9E3Pr0&sig=WW67tpy-JssI3so5d9XgKKWkUO8&redir_esc=y#v=onepage&q=Introduction%20to%20rapid%20prototyping%20of%20biomaterials&f=false

Additive manufacturing means making the product by adding material and Rapid prototyping means making the prototype quickly by using any manufaceturing process

Rapid prototyping is sort of legacy name....now sice RP does not justify "rapid" terms.... So at present ,3D printing or additive Manufacturing are more popular name...

Additive Manufacturing is a technology that is used in building 3D objects by adding materials layer by layer. The term “additive” refers to the method of adding and building the product repeatedly while Rapid Prototyping is an application used in additive manufacturing to create a model to be faster.

Ng Kei Hoa When the rapid prototyping techniques are used for manufacturing, it becomes additive manufacturing.

for more details, you should follow this link-

https://www.ge.com/additive/additive-manufacturing/information/rapid-prototyping

Narendra Kumar Vishal Francis

Rapid prototyping is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design (CAD) data. Construction of the part or assembly is usually done using 3D printing or "additive layer manufacturing" technology.

RP refers to Rapid Prototyping or 3D printing and it comprises as a group of processes used to rapidly fabricate a scaled prototype of a part or machine element with input a 3D CAD Data. The 3D printers enable designer to quickly generate tangible scaled model of their design in comparison of its 2D pictures.

It can be three types:

1. Additive Manufacturing

2. Subtractive Manufacturing (Desktop Milling)

3. Combined

Hope you can understand now.

Rapid prototyping and additive manufacturing are closely related but different. Rapid prototyping means producing a prototype rapidly. Additive manufacturing refers to any manufacturing process which makes products by gradually adding materials. Rapid prototyping is usually achieved by additive manufacturing process. In earlier years, the additive manufacturing processes developed for rapid prototyping were expensive, so they were used for making prototypes only. When the technologies advances, they become economic enough for manufacturing parts in large quantities, so they have evolved from a technology for making prototypes only to a technology suitable for mass production, which is usually referred to as additive manufacturing.

It is not right to say that "additive manufacturing is 3D printing". It is a very common mistake. Any manufacturing process which leads to increase in weight is called additive manufacturing, in contrast to subtractive manufacturing (which leads to decrease in weight) and formative manufacturing (which leads to neither increase nor decrease in weight). Welding, adhesive bonding, and thermal spray coating all lead to increase in weight, so they are all additive manufacturing processes, but they cannot be called 3D printing. Only when the additive manufacturing is carried out using a printing head technology (e.g., powder bed selective laser melting), it can be called 3D printing. It is correct to say that 3D printing is additive manufacturing, but it is incorrect to say the other way round.

Wei Zhou thank you for your interesting answer. However it is self explaining and seems satisfactory.

Dear Ng Kei Hoa ,

Rapid Prototyping is a process of building a prototype that allows testing in a short time of manufacture.

Additive Manufacturing is one of forms of manufacture with composition of raw material in the shape of piece you need, that is, differently from Subtractive Manufacturing, in which pieces are modeled by removing raw material, or even from Formative Manufacturing, which piece is manufactured by injecting raw material in a pasty or liquid form. In Additive Manufacturing, raw material is placed in the proportion and density chosen in process.

Rapid Prototyping via Additive Manufacturing is widely performed on machines called 3D printers.

As you saw, they are different things, but they can work together. In fact, Additive Manufacturing has helped in Rapid Prototyping, as it is cheaper and faster and in any type of material and density.

I wish everyone a lot of health!

Compliments,

Prof. Wiltgen

Rapid Prototyping is the name of making prototypes through any available method weather it could be additive,subtractive or formative manufacturing,however, additive manufacturing is the process of making desired components (prototype or application oriented finished product) through the addition of materials either layer by layer or drop by drop.

@Saeed Nawaz answered very well. Rapid prototyping is to create prototypes for initial testing. 3D printing or additive manufacturing or rapid prototyping is a slow manufacturing process and cannot be replaced with traditional machining. But still rapid? What does the term rapid mean? It means if you have to change the design for some reason, it is very easy, just to change the CAD model, reprint and test. Let's say you create the same prototype by moulding, first you have to create a moul which is time and cost-consuming.