Rapid prototyping service

With the formation of the global market integration, the competition in the manufacturing industry is very fierce, and the speed of product development has increasingly become the main contradiction of the competition. In this case, the ability of independent rapid product development (rapid design and rapid tooling) has become the basis for the strength of global competition in the manufacturing industry. At the same time, in order to meet the ever-changing needs of users, the manufacturing industry requires strong flexibility in manufacturing technology, which can be produced in small batches or even single pieces without increasing the cost of products. Therefore, the speed of product development and the flexibility of manufacturing technology become critical.

1. The principle of rapid prototyping technology.

Rapid prototyping manufacturing technology is a comprehensive technology integrating material forming, CAD, numerical control, laser and other technologies.

The basic principle of rapid prototyping manufacturing technology is: in the absence of any molds, tools and tooling, according to the layered data of the three-dimensional CAD model, materials are stacked (or superimposed) to quickly manufacture product prototypes of any complexity or a digital forming technology of parts.

See image 2-65. Rapid prototyping manufacturing mainly includes the following four sections:

(1) Construction of part CAD data model. There are two ways to construct a 3D CAD data model: ① 3D modeling based on ideas. Designers use various 3D CAD modeling systems, such as Pro/E, UG, Solidworks, etc., to perform 3D solid modeling of parts, that is, to convert the conceptual model of parts conceived by designers into 3D CAD data models. ②Three-dimensional modeling based on entity data. Designers use three-dimensional measuring machines, laser scanners, nuclear magnetic resonance images, solid images and other methods to reverse, calculate and build a three-dimensional model of the three-dimensional entity.

(2) Generation of data transformation files. The three-dimensional modeling system converts the part CAD data model into a data file that can be accepted by the rapid prototyping system, such as STL, IGES and other format files. STL file is a file formed by discretizing the inner and outer surfaces of a 3D solid. STL file is easy to perform layered slicing processing of the model, so it has become the file format accepted by most of the current rapid prototyping systems. At present, all CAD modeling systems also have the function of outputting STL files for 3D entities.

Image 2-65

(3) Generation of data conversion files. The three-dimensional modeling system converts the part CAD data model into a data file that can be accepted by the rapid prototyping system, such as STL, IGES and other format files. STL file is a file formed by discretizing the inner and outer surfaces of a 3D solid. STL file is easy to perform layered slicing processing of the model, so it has become the file format accepted by most of the current rapid prototyping systems. At present, all CAD modeling systems also have the function of outputting STL files for 3D entities.

(4) Hierarchical slices of the model. The three-dimensional solid model is cut into two-dimensional slices one by one along a given direction (generally along the z-axis), that is, discretization. The thickness of the sheet can be selected according to the forming accuracy of the rapid prototyping system, such as 0.05-0.5mm.

(5) Rapid accumulation molding. Orderly and continuously superimpose in a plane processing method to obtain a three-dimensional entity. With the development of RPM technology and people's in-depth understanding of this technology, its connotation is gradually expanding. At present, rapid prototyping technology includes all the forming processes directly driven by CAD, and the main technical feature is the rapidity of forming. The transfer form for the material can be free addition, removal, or a combination of addition and removal.

There are more than 30 specific processes of PRM technology, among which Laminated Object Manufacturing (LOM), Selective Laser Sintering (SLS), Fused Deposition Modeling (FDM), and Stereolithography (SAL) are the most mature in technology and have been widely used,and has been well commercialized methods

The following takes Fused Deposition Modeling (FDM) as an example to introduce its process method

2.Process method of fused deposition modeling

Fused Deposition Modeling (FDM) is based on the geometric information determined by the CAD model. The filamentary material is fed into the nozzle by the wire feeding mechanism, and a heater is used in the nozzle to heat the filamentary material into a semi-fluid state. Under the control of the computer, the nozzle moves along the section profile and filling trajectory of the part according to the sheet parameters, and squeezes and controls the flow at the same time, so that the viscous fluid is evenly spread on the section layer and stacked layer by layer, so as to manufacture the prototype of the part. Its working principle is shown in Figure 2-66, Figure 2-67 is the outline of the 3D printer using the principle diagram of fused deposition modeling, and image 2-68 is the work of fused deposition modeling. The materials used in the fused deposition modeling are ABS engineering plastics, Wax, polyethylene, polypropylene, ceramic and nylon, etc.

Image 2-66 Fused Deposition Modeling Schematic

Image 2-67 Outline of 3D printer

Image 2-68 see final product