Rapid prototypes: what is rapid prototyping, what is it for, technologies, examples

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What is rapid prototyping

Rapid prototyping is the set of 3D printing technologies that are used for the quick production of prototypes starting from a 3D model. There are very advanced technologies with which it is possible to produce prototypes with materials and precision very close to mass production pieces. There are also technologies that do not fall into this category like CNC machining. The choice falls on this option when 3D printing fails to meet the user’s needs in terms of material or accuracy. Each case must be evaluated individually.

The steps for creating a prototype can be divided into 5 phases

  • STL file: the starting point of rapid prototyping is always a 3D file which is converted into .STL to be read by the machines. The operator takes care to position the file in the appropriate way to optimize the machine’s working times, the aesthetic areas of the prototype, respect the functionality and resistance that the prototype must have.
  • Feasibility analysis: A free feasibility analysis of the file is performed to check the thickness of the piece and ensure a successful prototype.
  • Machine start-up: production times vary, everything depends on the size of the piece, the total weight, the number of pieces and the production technology. In the preventive phase it is possible to have an estimate of the production times, generally the delivery of prototypes varies between 2 and 3 working days.
  • Prototype cleaning: after the machine job is finished, the piece is cleaned from excess material and processing marks to obtain the finish requested by the customer.
  • Dimensional check: before shipping, a visual and dimensional check is carried out to certify that the production complies with the requirements

What is rapid prototyping for?

Prototyping allows our customers to test a project under development. The reason why these technological processes have had great success lies in the fact that they allow to validate the preliminary phases of the development of a new product before moving on to industrialization. This avoids delays due to engineering errors that negatively affect the project costs and optimizes the product time-to-market because there are no unexpected delays. Rapid prototyping is useful for presenting the product at the fair or to a possible buyer; there are technologies that allow the creation of very aesthetic models or mock-up (also functional) useful for collecting commercial feed-backs before moving on to the production phase. In many cases the rapid prototyping technologies are used to produce definitve parts of the product, this occurs for very customized products where the print runs are very limited and the performance of the materials used are in line with the customer’s requests. This applies to all processes except for the sintering of metal powders (DMLS) where it is possible to produce parts with definitive material.

There are multiple rapid prototyping technologies each of which responds to different needs

  • Functional tests
  • Assembly tests
  • Ergonomics checks
  • Product presentations at the fair or to the customer
  • Small series in ABS-like material
  • Certification test
  • Wind tunnel test
  • Stress test

The main technologies for rapid prototypes. Technologies and materials and comparison

There are different technologies and materials with which it is possible to make prototypes all valid for different reasons. To choose the most suitable technology for our project, it is essential to know what the prototype is and what type of test it will have to undergo. We always say that there is no better rapid prototyping technology, but there is always the best and most suitable technology for your project.

The main rapid prototyping technologies are

  • Stereolithography (SLA) creates prototypes with a high aesthetic impact using resins that simulate plastic materials such as ABS or Polypropylene. Before starting the process, the machine builds supports that are needed to support the piece during construction. The solidification progresses by layers, once the process is completed the details are subjected to a UV treatment to stabilize the resin and make it similar to the final material. We can make monolithic prototypes up to 650X750X550 mm with precision up to +/- 0.05 mm on the smallest machines.
  • Sintering (SLS) is a hot process particularly suitable for the construction of functional prototypes with high mechanical strength. The heat of the laser solidifies the powders layer by layer, which always aggregate in horizontal layers; unlike stereolithography, supports are not necessary because the prototype is self-sustaining on the powder in the tank. At the end of the process it is necessary to wait for the piece to cool down in order to extract it and clean it from excess dust. We can make prototypes in Nylon PA, Nylon PA 30% to increase mechanical resistance or loaded aluminum to increase thermal conductivity.
  • Fused Deposition Modeling (FDM) is used to have prototypes with definitive material but in the face of poor aesthetic and precision performance. The extruder deposits the material in horizontal layers on a surface until the prototype is completely built. The materials that can be used are ABS, PC, PC-ABS, PPSF, Ultem, PC-ISO.
  • HP‘s Multi Jet Fusion is a fairly recent technology for building prototypes similar to sintering. The added value is the waterproofing of the material, the PA12 and the thermal resistance up to 175 ° C.
  • Duraform Flex is a material for SLS technology that allows you to create functional rubber prototypes useful in the case of gaskets. When it is necessary to produce a small series, we always recommend evaluating the production by means of replicas from a silicone mold for greater piece performance.
  • The Direct Metal Laser Sintering (DMLS) uses a principle similar to the sintering technology of nylon powders, in this case the usable materials are stainless steel, titanium, aluminum, cobalt-chromium.

Case History: practical examples

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