Información | FabLab MVD

Subtractive technologies

Mariana Silveira — Mon, 26 Jun 2023 19:07:05 +0000

Subtractive technologies

Digital fabrication is made up of design and production processes that harness the potential of combining computer-aided design (CAD) and computer-aided manufacturing (CAM) software, with CNC (computer numeric control) machines. These can be divided into additive and subtractive fabrication technologies.

Subtractive fabrication

Subtractive fabrication is a generic term used to name various fabrication processes based on the use of CNC tools that allow digital designs to be materialized by removing material through cutting, drilling and grinding.

SUBTRACTIVE TECHNOLOGIES

Laser cutting, router CNC, EDM machining and water jet cutting.

LASER CUTTING

A laser cutter is a particular type of CNC machine. There are several types of laser cutters, but all of them cut and engrave various materials from a laser beam. It is one of the most common technologies to find in a digital fabrication lab, and you will find cutters of various sizes and powers.
Operation: Laser beam cutting.
Advantages: Great precision, definition and quality of finish. Relatively low cost.
Disadvantages: Can´t cut metal or glass. You can only process material in the X and Y axes.

ROUTER CNC

A Computer Numerical Control Router is a cutting machine; this equipment works by means of a milling cutter that roughs the material, executing programmed advance movements in three possible axes (X, Y, Z) making it possible to carry out cutting, drilling, engraving and 3D carving in different materials. According to the type and thickness of the material, cutters of different diameters are chosen, and the speed and power values of the cutter are configured.
Operation: Cut by milling machine.
Advantages: Great precision, definition and quality of finish. Relatively low cost. You can process the material in Z, so you can do low and high reliefs in addition to cutting.
Disadvantages: Cannot cut metal or glass.

EDM MACHINING

CNC cutting machine that processes the material from wire EDM, used to manufacture highly hard parts. A metallic wire receives electrical discharges that produce sparks, thus eliminating the material, which is removed with a constantly flowing dielectric fluid.
Operation: Cutting from wire EDM.

WATER JET CUTTING

Uses powerful water jets for hard materials. Combining high-pressure water streams at a precise angle and speed, mixed with an abrasive, the head processes the material into cuts.

Operation: Cutting by water jet.
Advantages: Allows cutting metals and stone.

LASER CUTTING

Specifications, considerations and general aspects

¿How does it work?

The laser beam is generated inside a tube from carbon dioxide with the mixture of other gases. The laser beam leaves the gas tube and is reflected by a mirror system until it reaches the nozzle. The material is located at a certain distance from this, and by means of movements in the X and Y axes the material is processed.

LASER CUTTING PARAMETERS

The focal length of a lens is the distance between the optical center of the lens and the focus. It is important to respect this distance so that the laser cuts the material optimally. This equipment can generate cuts and engravings in different materials. According to the type and thickness of the material, the speed and power values of the laser beam are configured, as well as the distance between the nozzle and the material. The laser cutter has the possibility of cutting, line engraving, folding engraving, kerfing, etc.

DIMENSIONS AND MATERIALS

The maximum cutting dimensions of the cutters available in the FabLab are:

William Gibson: 1118mm in X and 890mm in Y, maximum thickness 6mm
Ursula K Le Guin: 1200mm in X and 2400mm in Y. Maximum thickness 9mm.

The materials that can be manufactured on this equipment are: mdf, multi-laminate, different types of cardboard (grey, Swedish, corrugated, feather, etc.). Various polymers can also be worked (pet, acrylic, eva rubber, etc). This equipment cannot work with PVC.

FABRICATION STRATEGIES

There are many ways to design and manufacture objects from the use of digital manufacturing technologies such as the laser cutter.

One way is to start from three-dimensional virtual models and, based on unfolding or sectioning processes, break them down into pieces that will be cut using the laser cutter.

Another possibility is to design directly in two dimensions, using vector software.

TECHNIQUE BY FACES_ INSERTS

TECHNIQUE BY FACES_ PLICATE

SOLID SECTIONED TECHNIQUE

SECTIONED TECHNIQUE WITH INSERTS

Depending on the geometry of the piece, it is possible to section or divide it into as many parts as necessary to optimize printing, guarantee a good finish of the piece and avoid the excessive use of supports that later affect the surface aesthetics of the piece.

CONSIDERATIONS

Whatever the manufacturing strategy we have chosen, we must take into account the following considerations:

MATERIAL THICKNESS

Although the cutter only makes cuts in the X and Y axes, that is, in two dimensions, we are going to work with different materials that have different thicknesses. This must be considered when designing joints and inserts.

CUTTING LINE THICKNESS

Although it is considered that the thickness of the cutting line is negligible, in relation to other technologies, if we are working with models that require great precision, we must consider that the cutting line is actually approximately 0.2mm.

JOINTS TYPES

Flat edge joint

Finger joint

T-slot joint

INSERTS

ASSEMBLIES

KERFING AND ELASTIC INSERTS

MACHINING PROCESS

Subtractive technologies

The setting procedure for engraving/cutting is called “machining” and is done in the laboratory. To achieve a good result, the file that is taken to the laboratory must be carefully prepared, with the considerations detailed below:

The files must be vector since the machining process does not recognize images. In other words, once your cutting file has been designed, you must export it as .dxf preferably or in .pdf, .svg or .cdr (Corel X4 version). Other types of files will not be accepted.
In digital fabrication we always work on a 1:1 scale, and the units must be mm. When exporting the files, it is your responsibility to ensure that they are at the exact scale of the model.
The format of the sheet configured in the program must match the size of the material to be used (A0, A1, etc.).
Always dimension a part.

To indicate the different types of cutting, they must be differentiated by color and the entire file must be worked exclusively with the CMYK color palette.
Color reference: Engraving: magenta; Cut: cyan. In the case of needing more colors to prioritize the order of the cuts, or the different types of operations, any color from the CMYK palette can be taken and then indicated to the person in charge of the FabLab.
Layout: leave a 10 mm edge margin around its entire perimeter.
Avoid waste.
The minimum distance between cutting lines must be equal to the thickness of the material to be worked.
Verify that there are no overlapping lines (overkill or SelDup command)
Verify that all lines are coplanar
Do not work with hatches

DIE CUTTING SYSTEM

To prevent pieces smaller than 80x80mm from falling between the ribs of the laser cutter bed, it is necessary to implement a die-cutting system. This is accomplished by leaving the polylines open. The opening must be at least 1mm.

MACHINING SOFTWARES

COMMON MISTAKES

POINTS

NON-COPLANAR LINES

SUPERPOSITIONS

PROCEDURE FOR PROTOTYPING

Digital Fabrication Laboratory Operation – FabLab MVD

All people who want to make use of the laboratory in any of its modalities must schedule a day and time at least 72 hours in advance through the email labfab@fadu.edu.uy. The students will be able to use the laboratory for a maximum of 2 hours per month. The laboratory service for students will be subject to the availability of the FabLab, so it is advisable to coordinate this date as far in advance as possible.

The number of hours necessary to carry out the work must be taken into account, including the machining of the files and the cutting and engraving time.

To schedule the students must send the cut file by mail as soon as posible, and then they must present themselves personally with a copy of the Authorization Form signed by a teacher responsible for the subject or project on which they are going to work, and bring the material for the cut. The form is available at http://www.fadu.edu.uy/labfab. During the cutting, the student must remain in the laboratory.

In return for the use of the Laboratory, in the case of students, we request that the same amount of material to be used be left as a donation; so they must bring double the necessary material. In the case of teachers, the donation of supplies is requested to be previously agreed. It is convenient to bring a box or bag to remove the cut/engraved material.

DIGITAL INTEGRATION CENTRE PROJECTS

Fabricated in subtractive technologies

Uthopia, the unbuilt

Digital fabrication of unbuilt architectures

View project

Studer

Exhibition: Obsesion; MPR+TTG

View project

Dieste Ex Machina

Cristo Obrero church

View project

Architecture models

Laser cutting in acrilic material, Vilamajó house.

View project

3D Printing

Mariana Silveira — Tue, 20 Jun 2023 21:03:14 +0000

3D Printing

Digital farbication are design and production processes that combine the use of computer-aided design (CAD) programs and software, computer-aided manufacturing (CAM) with CNC numerical control (computer numeric control) machines. These can be divided into additive and subtractive fabrication technologies.

Additive fabrication

Additive manufacturing technologies are those used to convert digital models into three-dimensional objects, basing their construction on the deposition -that is, adding- material in successive layers.

Mechanization in 3D printing

FORMAT FILE

We can use any 3D modeling software to generate the models, as long as there is the possibility of exporting it as an .STL (Stereo Lithography) file.

STL is the standard format used for 3D printing. Polygon mesh that must be closed in order to print correctly.

When exporting the .stl file it must be in 1:1 scale. In digital fabrication, the units we work with are millimeters.

MACHINING PROCESS

Slicers or machining programs are responsible for converting digital models into trajectory and traversal information for the printer (gcode files).

In these programs we can configure the different printing parameters and values, such as layer thickness, supports (if necessary) and gives us an approximation of the amount of material needed and printing time.

PRINTING PARAMETERS

The printing parameters (extruder temperature, speed, type of support, filling, etc.) must be adjusted according to each material, piece, filament diameter and even the 3D printer model used by the user.

Some of the parameters to configure when printing and their consequences are explained below.

FILLING DENSITY

Defines the amount of material used inside the object. A higher infill density means there is more material inside the print, leading to a stronger object. A density of around 20% is used for models for a visual purpose, higher densities can be used for end-use parts. The filling pattern is another variable to define depending on the material and type of piece that we want to achieve.

2. LAYER HEIGHT

The layer height has a direct effect on the surface of the final piece, as well as it will determine a longer or shorter printing time, the higher the height, the lower the total printing time. Depending on the objective with which we manufacture the piece, we can prioritize the aesthetic factor or the printing time.

3. USE OF SUPPORTS

If the part has overhangs, it is important to place supports. Within these parameters it is possible to select if you want the supports to be placed everywhere or only to the printing base.

On the other hand, depending on the distance and angle of the overhang, if it is necessary to place supports. In pieces whose angles are less than 45° (figure 2) it does not require support structures.

PRINTING STRATEGIES

POSITIONING

The orientation of the object on the printing bed can influence several aspects:

The surface finish of the piece: the surface against the printing bed is smoother and brighter than the rest.
The “resolution” of the part, or its level of detail.
The resistance.
The amount of material needed as well as the printing time, depending on the number of support structures that are necessary.

2. DIVISION AND SECTIONED

Softwares used

Parametric Design

Mariana Silveira — Tue, 13 Dec 2022 20:44:16 +0000

Parametric Design

Design process based on an algorithmic scheme of rules that are established through dynamic parameters that join the design components, and establish direct and indirect relationships between them.

Another way of understanding design

Parametric design is a different way of understanding design thanks to technology and, specifically, advanced digital design techniques. Ideas are projected from computational thinking, imposing other types of dynamics and forms that are the consequence of a more complex but versatile result when it comes to modifying, adding or eliminating aspects of the design.

Parametric design features

Design FLEXIBILITY
ADAPTABILITY
UNIQUE DESIGNS
REDUCES THE TIME devoted to manual revisions and adaptations of plans, etc.
Parameters can control weight, dimensions, volumes, repetition, modulation, but simulations can also be incorporated for structural, climate and thermal analysis. As a result, an EFFICIENT final product is obtained with a BETTER PERFORMANCE.

Parametric design procedure

Generally, the process presents four activities. Frequently, these activities and data are combined and define conditions while preparing or executing the procedure, or adjust it according to the results or new possibilities that are envisioned. However, differentiating them contributes to their development and generalization.

Definition of initial conditions.

Preparation of the parametric procedure.

(or selection of a specific utility).

Execution of the procedure.

Selection and interpretation of results.

In addition to the set of parameters considered.

Parameters

The parameters have the function of expressing specific ranges, limits and configurations. From the same parameterized model it is possible to visualize different results that meet the established conditions.

The use of parameters (technical and formal) in early phases of the design allows to achieve a better constructive performance and new expressive possibilities.

¿What software are used?

In general, the software implemented for this advanced 3D type modeling and generative design are Rhinoceros (3D modeling) and Grasshopper (generative algorithm editor), and architecture-focused Revit (3D modeling) and Dynamo (generative algorithm editor).

Projects

Computing applied to architecture (postgrade course project)

The course propose to create a generative algorithm and its materialization.

3D Textiles

Development of textiles in 3d printing, from patterns with algorithmic design.

Computing applied to architecture (postgrade course project)

The course propose to create a generative algorithm and its materialization.

Digital hybridization (grade course project)

Design and fabrication of a cube from a given pattern, and with the use of parametric design, using Dynamo software.

Aditive and sustractive fabrication

Mariana Silveira — Fri, 09 Dec 2022 17:34:46 +0000

Digital Fabrication

Additive vs Sustractive fabrication

Digital fabrication consist of an integrated and computer-asisted system composed by simulation tools, 3D visualization, analysis and collaboration to create product and fabrication process definitions simultaneously.

This type of manufacturing allows the processes to be repeatable as many times as necessary. In turn, the complexity of the object does not have a significant impact on the cost of production. The possibilities within digital fabrication are not linked to the human scale.

Digital fabrication technologies can be divided into two large groups. On the one hand the additive fabrication and on the other the subtractive, each one of them presents certain limitations, advantages and disadvantages to the other.

Aditive fabrication

Aditive fabrication is the type of digital manufacturing, which allows the construction of objects in three dimensions in a sequential way, during a process of adding material by layers. In many cases it uses heat to provide fluidity to the material used.

Advantages

It does not generate waste of material in the process.
It is possible to change the physical properties of the object.
The interior is also designed.
Wide range of machinable materials and it is expanding: polymers, ceramics, cement, metals, sand, chocolate….

Disadvantages

Expensive processes.
Very slow processes compared to massive processes technics, like injection.
In the case of 3D printing, they are limited to the dimensions of the printing bed.
Parts made from 3D printing often require some type of cleaning and finishing to achieve their final properties and appearance. On many occasions, the model requires the use of support structures, which are removed once printing is finished. These can be made of the same material as the impression or made of materials that dissolve in water, which allows for easier removal and a better finish on the final piece.

Technologies

3D printing:

Polymers: Fused Deposition Modeling (FDM), Stereolithography Sintering (SLA), Digital Light Processing (DLP), Selective Laser Sintering (SLS).

Metals: Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM), Binder Jetting, and Selective Laser Melting (SML).

Sustractive fabrication

Sustractive fabrication gathers all those forming operations in which the excess material is removed from an initial work piece. The most important processes in this category are machining operations such as turning, drilling, milling, and grinding. Non-traditional processes are used because they use lasers, electron beams, chemical erosion, electrical discharges, or electrochemical energy to remove material.

Advantages

In general, it uses the same materials as traditional techniques.
Higher precision parts are obtained than additive manufacturing methods.
Repeatable process.
Efficient use of material (nesting). The optimization of the cuts saves material.

Disadvantages

Generate waste material.

Technologies

Laser cutting
CNC (drilling machine, lathe, panel saw, router)
Water jet cutting
Plasma cutting
Electrical discharge machining (EDM)

Basic terminology

To carry out the fabrication of any object through any of the technologies mentioned above, it is essential to understand and manage the different languages so that the machines, operators and software correctly interpret the projects.

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CAD

Computer Aided Design

The file containing the design to be manufactured. It is important that the design does not contain double lines, curves without closing or elements that do not touch each other.

Software: Autocad, Illustrator, Corel, etc.



CAM

Computer Aided Manufacturing

Translates the CAD file into a set of instructions that the machine can interpret: CAM= translator. This file must contain the specific elements/parameters that the machine will need for manufacturing: speeds, intensity, times, etc. For this reason, the plans must express not only what is necessary for the machine but also what is necessary for the operator who will configure the machine.

Software: Cura, Fusion 360, etc.

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CNC

Computer Numerical Control

It is used to create programming instructions for a computer to control a certain machine/tool. CNC is related to the manufacturing process and improves automation as well as flexibility.