What is Rapid Prototyping? – Definition, and Types

What is Rapid Prototyping?

Rapid prototyping is the fast fabrication of a physical part, model, or assembly using 3D computer-aided design (CAD). The creation of the part, model, or assembly is usually completed using additive manufacturing, or more commonly known as 3D printing.

Where the design comes very close to the proposed final product, it is referred to as a high-fidelity prototype, as opposed to a low-fidelity prototype, where there is a marked difference between the prototype and the final product.

How Does Rapid Prototyping Work?

Rapid prototyping (RP) encompasses a wide variety of manufacturing technologies, although most use layered additive manufacturing. However, other technologies used for RP include high speed machining, casting, molding, and extruding.

While additive manufacturing is the most common rapid prototyping process, other more conventional methods can be used to create prototypes.

These processes include:

  • Subtractive – Where carving through a block of material to create the desired shape by milling, grinding or turning.
  • Compressive – Being pressed into the desired shape by a semi-solid or liquid material before solidification, for example by casting, compressive sintering or molding.
Rapid prototyping is the fast fabrication of a physical part, model, or assembly using 3D computer-aided design (CAD).

What are the Different Types of Rapid Prototyping?

Types of rapid prototyping techniques:

  • Stereolithography (SLA)
  • Selective laser sintering (SLS)
  • Direct metal laser sintering(DMLS)
  • Fused Deposition Modelling (FDM)
  • Binder jetting
  • Poly jetting

1. Stereolithography (SLA) or Vat Photopolymerization

This fast and inexpensive technique was the first successful method of commercial 3D printing. A bath of photosensitive liquid is used which is solidified layer by layer using computer controlled ultraviolet (UV) light.

2. Selective Laser Sintering (SLS)

Used for both metal and plastic prototyping, SLS uses a powder bed to create a prototype layer by layer with a laser to heat and sinter the powdered material. However, the strength of the parts is not as good as SLA, while the surface of the finished product is usually rough and secondary work may be required to complete it.

3. Fused Deposition Modelling (FDM) or Material Jetting

This inexpensive, easy-to-use process can be found in most non-industrial desktop 3D printers. A spool of thermoplastic filament is used which is melted in a pressure nozzle housing before the resulting liquid plastic is deposited layer by layer according to a computer deposition program.

While the early results generally had poor resolution and were poor, this process improves quickly and is quick and cheap, making it ideal for product development.

4. Selective Laser Melting (SLM) or Powder Bed Fusion

This process, often referred to as powder bed fusion, is preferred for making high strength, complex parts. Selective laser melting is widely used in the aerospace, automotive, defense, and medical industries.

This powder bed-based fusion process uses a fine metal powder that is melted layer by layer to make either prototype or production parts using a high power laser or electron beam. Common SLM materials used in RP include titanium, aluminum, stainless steel, and cobalt chrome alloys.

5. Laminated Object Manufacturing (LOM) or Sheet Lamination

This inexpensive method is less sophisticated than SLM or SLS, but does not require specially controlled conditions. LOM builds a series of thin laminates that have been precisely cut with laser beams or some other cutting device to create the CAD pattern design. Each layer is delivered and glued over the previous one until the part is finished.

6. Digital Light Processing (DLP)

Similar to SLA, this technique also uses the polymerization of resins that are cured with a more conventional light source than SLA. While DLP is faster and cheaper than SLA, it often requires the use of support structures and post-build curing.

An alternative version of this is Continuous Liquid Interface Production (CLIP), in which the part is continuously pulled from a vat without the use of layers. As the part is pulled out of the tub, it crosses a light barrier that changes its configuration to create the desired cross-sectional pattern on the plastic.

7. Binder Jetting

This technique allows one or more parts to be printed at once, although the parts made are not as strong as those made with SLS. Binder jetting uses a powder bed onto which nozzles spray microfine droplets of liquid to bind the powder particles together and form a layer of the part.

Each layer can then be compacted by a roller before the next layer of powder is applied and the process begins again. When the part is complete, it can be cured in an oven to burn off the binder and fuse the powder into an integral part.

Why is rapid prototyping important?

In this fast-paced modern consumer market, companies need to develop and launch new products faster to stay competitive. Since faster product development and technological innovation are the keys to a company’s success, rapid prototyping becomes the most important element in new product development. The following goals are achieved through rapid prototyping.

  • Faster new product development- Prototyping plays a vital role in the process of creating successful products because it speeds up the new product development process
  • Early stage design/concept validation of form, fit, and function of the design
  • Final stage product verification against the technical requirement and business objectives
  • It allows functionality testing to test the objectives of the concept and to finalise the specification
  • Prototype gives the end user, client, customer, user participants hands-on user experience to get feedback

Applications

Product designers use this process to rapid manufacturing of representative prototype parts. This can aid in the visualization, design and development of the manufacturing process before mass production.

Originally, rapid prototyping was used to create parts and scale models for the automotive industry, although it has since been adopted by a wide variety of applications in various industries such as medical and aerospace.

Rapid Tooling is another application of RP where a part like an injection molded plug or an ultrasonic sensor wedge is made and used as a tool in another process.

Advantages and Disadvantages of Rapid Prototyping

Like any manufacturing process or design stage, prototyping and rapid prototyping have their own pros and cons.

Advantages of rapid prototyping:

  • Reduced design & development time
  • Reduced overall product development cost
  • Elimination or reduction of risk
  • Allows functionality testing
  • Improved and increased user involvement
  • Ability to evaluate human factors and ergonomics

Disadvantages of rapid prototyping

  • Lack of accuracy
  • Added initial costs
  • Some rapid prototyping processes are still expensive and not economical
  • Material properties like surface finish and strength cannot be matched
  • Requires skilled labor
  • The range of materials that can be used is limited
  • Overlooking some key features because they cannot be prototyped
  • End-user confusion, customers mistaking it for the finished project/developer misunderstanding of user objectives

FAQs.

What is Rapid Prototyping?

Rapid prototyping is the fast fabrication of a physical part, model, or assembly using 3D computer-aided design (CAD). The creation of the part, model, or assembly is usually completed using additive manufacturing, or more commonly known as 3D printing.

Why rapid prototyping is used?

In manufacturing, rapid prototyping is used to create a three-dimensional model of a part or product. In addition to providing 3-D visualization for digitally rendered items, rapid prototyping can be used to test the efficiency of a part or product design before it is manufactured in larger quantities.

How does rapid prototyping work

Rapid Prototyping, also known as 3D printing, is an additive manufacturing technology. The 3D printing machine reads the data from the CAD drawing and lays down successive layers of liquid, powder, or sheet material building up the physical model from a series of cross sections.

What is the advantage of rapid prototyping?

Rapid prototyping provides engineer, design and development teams with distinct advantage such as: The ability to explore and realize concepts more quickly. This efficiency in time and cost allows teams to move beyond the mere visualization of a product, making it easier to grasp the properties and design of a product.

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