Comparison of advantages and disadvantages of the

2022-08-08
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Comparison of advantages and disadvantages of common rapid prototyping processes

fused deposition modeling rapid prototyping process is a molding method that does not rely on laser as molding energy, but heats and melts all kinds of silk materials, referred to as FDM for short

In the principle room of selective cladding of filamentous materials, the heating nozzle moves in the X-Y plane under the control of the computer according to the cross-sectional profile information of the product parts. Thermoplastic filamentous materials (such as plastic wires with a diameter of 1.78mm) are sent to the nozzle by the wire feeding mechanism, heated and dissolved into semi liquid in the nozzle, and then extruded, selectively coated on the workbench, and quickly cooled to form a layer of about 0.127mm thick sheet contour. After the section forming of one layer is completed, the workbench drops to a certain height, and then the cladding of the next layer is carried out, as if the section outline is drawn layer by layer, so the cycle finally forms a three-dimensional product part

this process also has a variety of materials, such as ABS plastic, casting wax, artificial rubber, etc. This process is clean, easy to operate and does not produce garbage. The small system can be used in the office environment without the risk of toxic gas and chemical pollution. However, the whole section still needs to be scanned and coated, and the forming time is long. It is suitable for conceptual modeling of product design and shape and function testing of products. Due to the good chemical stability of methacrylic acid ABS (mAbs) material, it can be disinfected by overweight rays, which is especially suitable for medical use. However, the forming accuracy is relatively low, which is not suitable for making parts with too complex structure

fdm rapid prototyping technology has the following advantages:

1. The manufacturing system can be used in office environment, without the danger of toxic gas or chemical substances. 2. The process is clean, simple, easy to work and does not produce garbage. 3. Can quickly build bottle shaped or hollow parts. 4. Raw materials are provided in the form of reels, which are easy to handle and replace quickly. 5. The cost of raw materials is low, and the general parts are less than $20. 6. A variety of materials can be selected, such as dyed ABS and medical ABS, wax for casting and artificial rubber

The disadvantages of FDM rapid prototyping technology are:

1. The accuracy is relatively low, and these brittleness are low that materials try to avoid in use, and it is difficult to build parts with complex structures. 2. The strength in the vertical direction is small. 3. Slow, not suitable for building large parts

sla

selective curing of sensitive resin is a process based on the principle of stereolithography, referred to as SLA. It is also the earliest, most mature and widely used rapid prototyping technology

fill the liquid photosensitive resin in the resin liquid tank, and it will solidify rapidly under the irradiation of UV laser beam. At the beginning of the molding process, the elevatable workbench is at the height of a cross-sectional layer thickness below the liquid surface. Under the control of the computer, the focused laser beam is scanned along the liquid surface according to the requirements of the cross-sectional profile, so that the resin in the scanned area is solidified, so as to obtain the plastic sheet of the cross-sectional profile. Then, the workbench drops the height of a layer of thin sheets, and the cured plastic thin sheets are covered by a layer of new liquid resin for the second layer of laser scanning and curing. The newly cured layer is firmly bonded to the previous layer, and so on, until the whole product is formed. Finally, when the lifting table lifts out the liquid resin surface, the workpiece can be taken out for cleaning and surface finishing

photosensitive resin selective curing rapid prototyping technology is suitable for making small and medium-sized workpieces, and can directly obtain plastic products when the production line is built. It is mainly used for prototype production of conceptual models, or for assembly inspection and process planning. It can also replace wax mold to make casting mold, and as the mother mold of metal spraying mold, epoxy resin mold and other soft molds, making it a relatively mature rapid prototyping process at present

sla rapid prototyping technology has the following advantages:

1. The system works stably. Once the system starts to work, the whole process of building parts will be fully automatic, without special supervision, until the end of the whole process. 2. High dimensional accuracy is the abbreviation of Japanese industrial standard, which can ensure that the dimensional accuracy of the workpiece is within 0.1mm. 3. The surface quality is good. The top surface of the workpiece is very smooth. There may be uneven steps on the side and uneven surfaces between different layers. 4. The system has high resolution, so it can build workpieces with complex structures

sla rapid prototyping technical shortcomings:

1. Over time, the resin will absorb moisture in the air, resulting in bending and curling of the soft and thin parts. 2. The lifetime of helium cadmium laser tube is only 3000 hours, which is expensive. At the same time, the whole section needs to be scanned and cured, and the molding time is long, so the manufacturing cost is relatively high. 3. There are limited kinds of materials to choose from, and they must be photosensitive resins. In most cases, the workpieces made of this kind of resin cannot be tested for durability and thermal performance, and the photosensitive resin pollutes the environment and causes skin allergy. 4. It is necessary to design the supporting structure of the workpiece, so as to ensure the reliable positioning of each structural department made in the molding process

sls

selected laser sintering of powder materials is a rapid prototyping process, referred to as SLS for short

selective sintering of powder materials the selective sintering of powder materials (plastic powder, mixed powder of ceramic and binder, mixed powder of metal and binder, etc.) is a process method of integrating three-dimensional entities from discrete points layer by layer. Before starting processing, heat up the chamber filled with nitrogen and keep it below the melting point of the powder. When forming, the feeding cylinder rises and the powder spreading roller moves. First, lay a layer of powder material on the working platform, and then the laser beam sinters the powder where the solid part is located according to the cross-sectional profile under the control of the computer, so that the powder melts and then forms a layer of solid profile. After the sintering of the first layer is completed, the worktable drops to the height of a cross-section layer, and then a layer of powder is laid on it to sinter the next layer. In this way, a three-dimensional prototype part is formed. Finally, after hours of cooling, the parts can be taken out of the powder cylinder. Unsintered powder can support the workpiece being sintered. When the sintering process is completed, take out the parts

the selective sintering process of powder materials is suitable for forming small and medium-sized parts, which can be directly applied to plastic, ceramic or metal parts. The warpage deformation of parts is smaller than that of liquid photosensitive resin selective curing process. However, this process still needs to scan and sinter the whole section, and the studio needs to be heated and cooled, so the molding time is long. In addition, due to the limitation of powder particle size and laser spots, the surface of parts is generally porous. After sintering the mixed powder of ceramic, metal and binder and obtaining the prototype parts, it must be placed in the heating furnace, burning the binder therein, and infiltrating the filler into the pores. The subsequent treatment is complex

the rapid prototyping process of selective sintering of powder materials is suitable for the visual expression of product design and the production of functional test parts. Because it can use various metal powders with different components for sintering, copper infiltration and other post-treatment, the products made of it can have similar mechanical properties with metal parts, so it can be used to make EDM electrodes, directly make metal molds and produce small batch parts

sls rapid prototyping technology has the following advantages:

1. Compared with other processes, it can produce the hardest mold. 2. A variety of raw materials can be used, such as most engineering plastics, waxes, metals, ceramics, etc. 3. The construction time of parts is short, and the height can reach 1in/h. 4. No post correction of parts is required. 5. No design and construction support is required

the biggest advantage of selective sintering is that a variety of materials can be selected, which are suitable for different purposes. The prototype products produced have high hardness and can be used for functional tests

sls rapid prototyping technology has the following disadvantages:

1. Before processing, it takes nearly 2 hours to heat the powder below the melting point. After the parts are built, it takes hours to cool, and then the parts can be taken out of the powder cylinder

2. The surface roughness is limited by the size of powder particles and laser spots

3. The surface of parts is generally porous, and post-treatment must be carried out in order to make the surface smooth

4. The processing room needs to be continuously filled with nitrogen to ensure the safety of the sintering process, and the processing cost is high

5. The process produces toxic gases and pollutes the environment

lom

the rapid prototyping technology of laminated object manufacturing is a sheet material stacking process, which is called LOM for short

the manufacturing of foil laminated entity is to send the command to control the laser cutting system under the control of computer according to the contour line of each section of the three-dimensional CAD model, so that the cutting head can move in the X and Y directions. The feeding mechanism sends the foil materials coated with hot sol on the ground (such as coated paper, coated ceramic foil, metal foil, plastic foil) to the top of the workbench section by section. According to the cross-sectional profile extracted by the computer, the laser cutting system uses a carbon dioxide laser beam to cut the paper on the workbench along the contour line, and cuts the non contour area of the paper into small fragments

then, a layer of paper is pressed tightly and bonded together by the hot pressing mechanism. The price of battery grade lithium carbonate can be raised to about 40000 yuan/ton. The workbench is lowered to support the workpiece being formed, and after each layer is formed, the paper thickness is reduced by one, so that a new layer of paper can be fed, bonded and cut. Finally, a three-dimensional prototype part surrounded by many small waste blocks is formed. Then take it out, remove the surplus waste pieces, and finally obtain the three-dimensional product

the rapid prototyping process of laminated solid manufacturing is suitable for making large and medium-sized prototype parts, with small warpage deformation, high dimensional accuracy, short molding time, long laser service life, and good mechanical properties. It is suitable for conceptual modeling and functional testing parts of product design. And because the made parts have wood properties, it is particularly suitable for directly making sand mold

lom rapid prototyping technology has the following advantages:

1. It is a high-speed rapid prototyping process because it only needs to make the laser beam cut along the contour of the object without scanning the entire section. The larger the part volume, the higher the efficiency. 2. The processed parts can be used directly without post correction. 3. There is no need to design and build support structures. 4. Easy to use, no environmental pollution

The disadvantages of LOM rapid prototyping technology are:

1. There are few kinds of raw materials that can be used in practice. Although several raw materials can be selected, such as paper, plastic, clay and synthetic materials, at present, only paper is commonly used, and other foil manufacturers are in the process of research and development

2. Paper parts are easy to absorb moisture, so post-treatment and painting must be carried out immediately

3. It is difficult to build fine shaped parts, that is, only parts with simple structure

4. Because it is difficult (although not impossible) to remove the waste inside, this process is not suitable for building parts with complex internal structure. When the temperature of the processing room is too high, fires often occur

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