Prototypes

For ONEOFF the true raw material is a 3D file from which every technology, material and result is possible.

ONEOFF realizes models and prototypes from 3D and 2D files using the best suited technology.

Depending on the requirements we use:


Rapid Prototyping (RP) allows production of objects with a complex geometry, in a short time and without the need for tools, directly from the mathematical model of the object created using a three-dimensional CAD system. 

Traditional technologies such as milling machines or numerical control machines allow us to create objects in all kinds of materials. 

The combination of the various techniques available in house, means we are able to choose the best solution to satisfy the client’s requirements in terms of deadlines, cost and quality.

TECH Conceptual Modelers TECH Laser Sintering (SLS) TECH Rapid Prototyping (RP)
TECH Stereolithography (SLA)

TECH Conceptual Modelers

These are physical representations of a model for evaluating style, ergonomics, costs and design.
The ideal machines for making these models are known as CONCEPT MODELERS.
The fundamental difference in these machines compared to other RP machines is that they can make prototypes in a very short time, so that the designer can verify immediately possible errors.

The special characteristics of these modellers are:

  • High speed construction
  • No problems related to environmental impact
  • Low production cost

Typical Applications:

  • Evaluating style
  • Design verification
  • Ergonomic verifications
  • Cost evaluation
  • Models for silicone moulds
  • Models for investment casting
  • Models for sand casting.

An example of a concept modeller is the 3D printing machine.

The machine was patented by the M.I.T in Boston and is currently considered to be the fastest machine in the world in the field of Rapid Prototyping with a speed of construction of 25 to 50 mm/hour.
The 3D printer is able to automatically construct three dimensional physical models directly from CAD files, allowing designers to have an object in their hands instead of interpreting a 2D drawing on paper or a screen, made in just a few hours.

This technology has shown itself to be able to respond to four important demands in the field of design:

Simplicity and faithfulness:
Direct dialogue with the most advanced design tools exploiting CAD models without changing the shape in any way;

Versatility:
Can be used in many fields such as: architecture, design, fashion, toys, domestic appliances, automobiles, shows, medical, etc.;

Speed:
Prototypes can be made from CAD models in a very short time (24/48 hours);

Economy:
The models created have a low cost compared to those made using other RP techniques.

HOW DOES A 3D PRINTER WORK?

Imagine that your Inkjet printer has instead of a sheet of paper a tank (construction table) 20cm deep and that the head sprays a binder in place of ink.
Now imagine that the CAD model is sliced into horizontal layers and that each resulting section is reproduced by the printer head on layers of plaster as if they were several overlaid sheets.
The machine takes a layer of plaster (plaster or starch based powder) from the supply table and spreads it over the construction table.
At this point the cartridge deposits a binder on the layer of powder, drawing the outline of the object and forming the first section of the model.
Another layer is spread out and a new section is printed. The process is repeated layer after layer until the physical model is completed.
The object is then carefully taken out and the excess powder removed.

Advantages:

  • The powder with which the model is built becomes the support for the model itself which allows for the construction of models with undercuts without the problem of eliminating supports.
  • The materials used are plaster or starch based powders, completely non toxic, biodegradable, solidified with a water based binder.
  • The pieces can be infiltrated with wax, polyurethane, thermoplastic elastomer, epoxy resin, cyanoacrylate based coating or other materials to create specific mechanical properties in order to satisfy a wide range of modelling requirements such as smoothing, waxing, painting, metallization, thermoforming, silicone moulding, investment casting and sand casting.

Appearance of model:

Resined plaster, ivory natural colour with a smooth finish.

TECH Laser Sintering (SLS)

HOW DOES SELECTIVE LASER SINTERING (SLS) WORK?

Laser Sintering is a process that, like 3D Print, uses powdered material.

Maximum size of pieces realized: 380x320x400H mm. When the size of the prototype exceeds these dimensions it is realized in several parts that are then assembled together.

The working process is divided into the following steps:

  • The chamber where the sintering takes place (the fusion of the powder) is kept in an inert atmosphere, both to minimize the energy required by the laser and to minimize the change in volume due to the transformation taking place, and at a temperature close to that of the fusion of the material (185°C);
  • A layer of powder is deposited by a roller and pressed onto the elevator;
  • The radiation laser sinters (fuses) the powder creating the section profile (the laser used is the CO2, with a power greatly superior to that used in stereolithography);
  • The elevator lowers a distance equal to the thickness of the section and the process is repeated until the model is completed;

Thanks to the method of construction, supports are not necessary in the working model that is held together by the non sintered powder.
The finished model (red part) does not usually need post-treatment, has to be extracted and cleaned from the non sintered powder.
The making of prototypes is however longer than other RP techniques as the machine has to reach 185°C before beginning the construction process and once ended complete cooling of the chamber has to take place (this takes 4-5 days).

Maximum size of pieces realised: 380x320x400H mm. When the size of the prototype exceeds these dimensions it is realised in several parts that are then assembled together.

Typical applications:

  • Complex, thin-wall ductwork: Motorsports, Aerospace
  • Housings and enclosures
  • Impellers and connectors
  • Consumer sporting goods
  • Vehicle dashboards and grilles
  • Snap-fit designs
  • Functional prototypes that approach end-use performance properties
  • Appropriate for low- to mid-volume rapid manufacturing
  • Medical applications requiring USP Class VI compliance, or biocompatibility
  • Parts requiring machining or joining with adhesives
  • Complex production and prototype plastic parts
  • Form, fit, or functional prototypes

Features:

  • Excellent surface resolution and feature detail
  • Easy-to-process
  • Compliant with USP Class VI testing
  • Compatible with autoclave sterilization
  • Good chemical resistance and low moisture absorption

Benefits:

  • Nicely balanced mechanical properties and processability
  • Build prototypes that withstand functional testing
  • Produce durable end-use parts without tooling
  • Create accurate and repeatable parts as demanded by manufacturers
  • Machinable and paintable for demonstration parts

Available materials:

DURAFORM PA

  • Appearance of model: White polyamide (Nylon) with a smooth finish
  • Layer thickness: 0,1 mm
  • Minimum wall thickness of the model: ≥ 0,8 mm
  • Build Envelope Capacity XYZ: 380x320x400H mm
  • When the size of the prototype exceeds these dimensions it is realised in several parts that are then assembled together

TECH Rapid Prototyping (RP)

Want to save time and money during the design stage?
Want to reduce the number of prototypes needed?
Want to reduce costs due to errors at the design stage?

Rapid Prototyping (RP) is an innovative technology that allows the production of objects of complex geometry in just a few hours without using tools, directly from the mathematical model of the object made using a three dimensional CAD system.

It is useful for making:

  • Styled objects to check the design
  • Physical prototypes, to check that the parts fit together
  • A master for creating moulds

During the development phase of a product the following types of prototypes are made:

  • Conceptual models
  • Prototype for validation
  • Technical prototype
  • Final pieces

Various techniques exist for making prototypes (3D Printing, Selective Laser Sintering, Stereolithography). All these techniques work on the notion of layers, they differ from each other mainly in terms of the materials used, the physical principles exploited and the purpose of the prototype.

And the human touch?

When working with Rapid Prototyping techniques, the professional know-how and support is applied in two distinct phases: pre-production and post-production.
During pre-production the CAD file is evaluated, and the geometry of the mathematical model checked. The time required for this process is difficult to quantify beforehand as it depends totally on the software and the precision with which the mathematical model has been generated. The model is translated into an STL, which describes it as a mesh of perfectly closed triangles (a kind of skin that covers the entire volume of the object). The mesh must not have holes, overlaid triangles or be made of triangles that are too big, making curved surfaces come out faceted. It is necessary that the files are checked by experts in the use of a wide range of 3D modellers and skilled in identifying any anomalies.
Fundamental in this operation is the scaling of the piece to obtain a prototype with the desired tolerances.
Not to be underestimated is the nesting (positioning in the machine) in order to create an object with the best possible shape and structure.
In the postproduction phase the model undergoes operations of drying, resin treatment, smoothing and other surface treatments that may be needed. In this phase the more traditional model making experience of the skilled artisan is required.

TECH Stereolithography (SLA)

HOW DOES STEREOLITHOGRAPHIC PRECISION PROCESS WORK (SLA)?

Stereolithography is one of the most widespread methods used in RP.
The model is made by superimposing planes.

The material used is an epoxy resin in liquid state, solidified layer by layer by means of a laser beam.

Using an appropriate CAD programme, supports are added to the 3D files and it is divided into a series of 2D sections.
The actual process takes place inside a tank of liquid resin that is hit by an ultraviolet laser beam.
Each section is drawn individually on the surface of the photosensitive liquid resin.
The resin solidifies by being exposed to UV light (polymerization process).
With each successive layer, the platform of the machine lowers into the tank.
To prevent the model from collapsing inside, supports are constructed using the same process and movement used to made the model.
Because of the time needed for polymerization, the laser cannot solidify entirely the section but is limited to the profile and a certain number of lines that join the internal perimeter to the external.

At the end of this phase, the detail (green part) is solidified outside but not completely inside (red part).
The post treatment allows the polymerization process to be completed.
This consists of exposing the model to a UV lamp.
The length of this process depends on the size of the detail.
When post treatment is completed the supports are then removed and the piece is finished.
The end result is a solid model in translucent resin, with a tolerance of 0,1mm with respect to the CAD model.
The pieces can be used to check the shape and functionality of a design and as a sample for secondary processes for small productions of plastic or metal parts.

Available materials:

WATERSHADE XC 11122

  • Low viscosity liquid photopolymer that produces strong, tough, water-resistant, ABS-like parts.
  • Appearance of model: Optically clear, near Colorless
  • Layer thickness: 0,125 mm [Min. - 0,05 mm (0.002 in); Max - 0,15 mm (0.006 in)]
  • Minimum wall thickness of the model: ≥ 0,5 mm
  • Build Envelope Capacity XYZ: 500x500x450H mm
  • When the size of the prototype exceeds these dimensions it is realized in several parts that are then assembled together.


This material is ideal for many applications in the automotive, medical and consumer electronics markets and include:

  • Lenses
  • Packaging
  • Water flow analysis
  • Aerodynamic tests
  • RTV patterns
  • Durable concept models
  • Quickcast patterns
  • Details with high level of precision
  • Styling
  • Checking assembly

 

Features:

  • ABS-like
  • water-resistant
  • Excellent surface resolution and feature detail

 

Benefits:

  • Semi transparent material that allows to see inside the object

ACCURA 25

  • Simulate the properties and aesthetics of polypropylene with this accurate and flexible material.
  • Appearance of model: White
  • Layer thickness: 0,125 mm [Min. - 0,05 mm (0.002 in); Max - 0,15 mm (0.006 in)]
  • Minimum wall thickness of the model: ≥ 0,5 mm
  • Build Envelope Capacity XYZ: 350x350x320H mm
  • When the size of the prototype exceeds these dimensions it is realized in several parts that are then assembled together.


Typical applications:

  • Functional components for assemblies and mock-ups for: Automotive styling parts (trim, fascia, and other components), Consumer electronic components, Toys, Snap fit assemblies
  • Master patterns for RTV/silicone molding
  • Replace CNC machining of polypropylene to produce short-run plastic parts
  • Simulate injection molded parts
  • Concept and marketing models
  • Details with high level of precision
  • Checking assembly

 

Features:

  • Look and feel of molded polypropylene
  • High flexibility with excellent shape retention
  • Outstanding feature resolution and accuracy
  • High production speed
  • Fully developed and tested build styles

 

Benefits:

  • Increased market opportunities for models
  • Reliable and robust functional prototypes
  • Suitable for master patterns

NANOTOOL

  • NanoTool produces strong, stiff, high temperature resistant composite parts. This third generation material is heavily filled with non-crystalline nanoparticles allowing for faster processing. It exhibits superior sidewall quality, along with excellent detail resolution as compared to other composite stereolithography materials.
  • Appearance of model: Off White with smooth surface
  • Layer thickness: 0,125 mm [Min. - 0,05 mm (0.002 in); Max - 0,15 mm (0.006 in)]
  • Minimum wall thickness of the model: ≥ 0,5 mm
  • Build Envelope Capacity XYZ: 250x250x260H mm
  • When the size of the prototype exceeds these dimensions it is realized in several parts that are then assembled together.


Typical applications:

  • excellent for metal plating
  • strong, stiff parts that resist high temperatures
  • wind tunnel models for aerospace and automotive applications.
  • rapid tooling for injection molding
  • Concept and marketing models
  • Details with high level of precision
  • Checking assembly

 

Features:

  • strong and stiff
  • resists high temperatures
  • fast processing
  • superior sidewall quality
  • excellent surface resolution and feature detail