Plastic rapid prototyping: what it is, what it is for, advantages, why choose Coesum services

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Plastic rapid prototyping

Rapid prototyping of plastic parts is the set of 3D printing technologies suitable for the production of prototypes in plastic materials.

In reality, vacuum casting and conventional CNC machining are also used for the same purpose.

What is plastic rapid prototyping

In the field of additive manufacturing, plastic prototypes are made using various technologies such as stereolithography, selective laser sintering, Multi Jet Fusion, silicone mold replicas and CNC machining.

Each machining has differences on the process, materials used and precision of the prototypes that are obtained.

In stereolithography, the laser of the machine solidifies the photosensitive resin contained in the tank.

There are several transparent materials for this process; the main use is for aesthetic models, mockups and first assembly tests.

In selective laser sintering, the heat from the laser melts the Nylon powders and solidifies them layer by layer.

The prototypes made are characterized by having high mechanical performance also for food use.

The finishing of the models is porous but workable in post-production with primer and painting.

The Multi Jet Fusion process is the evolution of sintering, with lower costs it makes parts that are more compact, precise and with a more defined surface, as well as waterproof and resistant to high temperatures.

Beyond rapid prototyping there is vacuum casting

Silicone mold replicas, better defined vacuum casting, excellently replace rapid prototyping technologies, especially when it is necessary to create pre-series or models with very high performance.

The process begins with the creation of a stereolithography prototype which is used to build a silicone mold.

After the construction of the mold, vacuum casting with polyurethane resins are carried out for the production of prototypes in rigid, semi-rigid and rubber materials.

It is possible to co-mould several materials and insert metal inserts inside the mould.

The process of silicone mold replicas does not belong to additive rapid prototyping technologies, nevertheless it is the best solution especially in these cases:

  • to produce more than 4 or 5 prototypes: in this condition it is recommended to evaluate this process in order to have an economic benefit. In fact, for the same number of other rapid prototyping processes could be more expensive. Added to this is the advantage of having prototypes with better performance and a mold that produces 25 pieces on average.

  • if the performance of the 3D printing processes are not adequate for the tests to be carried out on the prototypes: the materials that can be used in vacuum casting have very high performances of various kinds. All specifications are available through the materials technical data sheet.

  • when the product I have to produce has a very limited run that does not exceed tens of units per year: the mechanical resistance of the prototypes is very close to the performance of injection molded parts. This allows the prototypes made with this process to be used even on final machines.


Finally, CNC machining which, unlike other processes, is a subtractive technology suitable for the production of low-volume parts, even with plastic materials.

The artifacts made with conventional technologies are characterized by a precision not yet achievable by rapid plastic prototyping.

The processing and management of individual parts have on average longer costs and production times than 3D printing.

Advantages in the production of plastic prototypes

The benefits associated with the realization of plastic prototypes are mainly attributable to time, quality and cost factors, in particular:

  • Possibility to test a project before moving on to the industrialization phases

  • Substantial reduction of errors with relative validation of the design phases

  • Ability to produce high quality parts quickly

  • Advance commercial management: prototype models are often used for the creation of photographic books, for fair exhibitions, for pre-sales commercial activities.

  • Minimum initial costs for creating the necessary molds and tools.

  • For certain products, 3D printing or rather the replicas from silicone molds are the definitive production process.

  • Cost and time optimization

Possible applications

The fields of application of prototypes made of plastic can vary considerably also according to the material used.

The applications are transversal and concern all industrial sectors.

Continuous research into improving process and material performance allows for ever wider applications and this trend is set to grow in the future.

If until a few years ago these technologies were widespread only in the main sectors of the manufacturing industry, today the involvement is global and increasingly growing. In fact, there are more and more requests on niche sectors or from SMEs, PMMIs and even startups.

Why choose Coesum for the realization of your plastic prototypes

Our added value is the experience with very advanced technological processes.

With our twenty years of experience, we are able to guide you towards the most suitable technological solutions.

After the first years dedicated to 3D printing processes, we have evolved by inserting a development department within our company to follow our customers also in product design and related engineering activities.

This choice has amplified our value in terms of development time reduction, project quality and cost optimization.

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