Knowledge sharing by Guangdong Shunde Teamwork Model Technology Co., Ltd, whom with over 20 years rapid prototyping experience.
Email: ken@gdtwmx.com
Website: www.gdtwmx.com
I. Introduction
The development of the times requires packaging design to be innovative and satisfying on the premise of satisfying specific functions, and continuous innovation. Cost-effectiveness is one of the criteria for measuring whether an innovation has vitality. It is the basic requirement for the development of all products, because there is no product without cost-effectiveness. Business success. Packaging products are certainly no exception. We know that in the design behavior, the conceptual design of the initial stage of product molding is a very important stage of product design. It consumes about 60% to 70% of the time and cost. Therefore, how to improve the design quality at this stage will directly affect the product design cycle and cost-effectiveness.
The traditional CAD means not only requires the designer to have expert knowledge, but also to know the details of the product design. The product design tries to enter the detailed product design stage from the very beginning. This detailed product design method is often modified several times before the entire design proposal is issued, and it takes a long time, and the user can only understand the various aspects of the product performance after the product is thoroughly molded. This is obviously not conducive to long product design cycles and high costs. Moreover, the current human-machine interface in the CAD environment mostly uses the graphical user interface, two-dimensional mouse and keyboard, and does not really take into account people's participation. This inhibits people's enthusiasm and creativity from a certain angle and affects innovation. Therefore, people need to constantly seek better ways to improve the existing design and processing processes to ensure the vitality of product innovation and design.
Second, the principle and characteristics of rapid prototyping technology RP (Rapid Prototyping) is a high-tech product developed rapidly in the 1990s. It is based on the principle of layer-by-layer material addition. It is directly driven by CAD data to generate solid models or parts. The essence of RP technology lies in the geometric topology of the objects to be processed. It is described and determined by the CAD model. The numerical control instructions for driving tools and materials are obtained by high-dispersion processing, and the molding and manufacturing are performed by using RP technology equipment. The distinctive features of this technology are: rapid production of models or parts, short cycle times and low cost; almost no restrictions on the complexity of parts; no molds, fixtures, knives, and no machining required in the manufacturing process. The following is an introduction to the principle of RP technology that is relatively mature and can be used in the industrial field.
1. Stere-lithography or stereolithography of photo-curing stereolithography The principle of software is to plane-separate three-dimensional data created by CAD to obtain the cross-sectional shape of each layer, using a certain wavelength of ultraviolet laser beam. The two-dimensional cross-sectional shape of each cut layer scans the liquid photo-curable resin to form a layer of a specific shape of solidified layer. Due to the existence of a certain depth of curing, each layer is cured and adhered to the previous solidified layer (the initial layer is stuck to the upper surface of the lifting platform), and then the lifting platform is submerged in a layer thickness (0.01-0.02mm), and then new One layer forming. In this way, the laser beam irradiates one layer, solidifies one layer, adheres one layer, and sinks one layer. The final solidified material is a three-dimensional model entity designed according to the CAD data. Its molding material is a photocurable resin. If a thermosetting resin is used instead, the liquid surface is scanned with a laser beam, and thermal polymerization is caused by the thermal action of the laser spot, and a three-dimensional model entity designed by CAD can also be obtained. Before the two resins are cured, they are liquid, all of which have the characteristics of flow, plasticity, and easy coating. However, the photocurable resin can be operated at room temperature, stable during storage, short curing time, and good lap bonding performance. Therefore, the light curing technology is bound to be rapid. development of. When the product is used as a practical sample, due to the limited mechanical properties of the existing resin, it cannot be used to manufacture products that have large loads, alternating stresses, and large frictional forces. In order to improve the mechanical properties of the material, a method using a silicone
Rubber Material and a high-performance polyurethane material has been adopted at present.
Molding accuracy is one of the key issues of RP technology in industrial applications. In the SL process, factors such as resin cure shrinkage, depth of cure, coating quality, laser scan linewidth, scan error, and CAD model networking all affect the molding accuracy.
2. Layered object manufacturing LOM (Lominated Object Manufacturing) layered object manufacturing technology is the use of laser beams and thin materials (paper, plastic film or composite materials, etc.) to generate any shape of three-dimensional objects. That is, when the work starts, the feeding drum lays the raw material on the base surface of the workbench, and the hot-pressing roller flattens the material and sticks it to the bottom layer. The laser beam of the two-dimensional numerically controlled
Laser Cutting head is given by the computer data system. The information instructions, cut out the cross-sectional shape of the workpiece, and chopped around the excess material. The workbench then descends to a height of one layer thickness and a new layer is placed on the loading drum. This is repeated layer by layer until the workpiece is manufactured.
3. Fused Deposition Modeling (FDM) Fused Deposition Modeling (FDM) is a method of rapid prototyping using electric heating and thermoplastic materials under the control of a computer. The system consists of a numerical control nozzle, a liftable table, and a feeding device. The semi-fluid or linear melted thermoplastic material is a molding material (eg, ABS plastic, cast wax, rubber, etc.). That is, the work begins, the workbench is in a high position, the raw material is heated and melted by the nozzle, and is continuously extruded and sprayed on the selected area (ie, the cross section of the workpiece) according to the computer's control instructions, followed by cooling and solidification. The workbench descends one layer thick, and then squeezes the second layer. This is repeated until the work piece is fully formed.
4. Selective laser sintering SLS (Selective Laser Sintering) Selective laser sintering technology is similar to SL technology. It also uses a laser beam to scan each layer of material, but uses powder (plastic powder, metal powder, ceramic powder) instead of liquid polymer. The powder is preheated to a temperature slightly below its melting point, and then the laser is used to scan and heat the powder to its sintering temperature so that it is bonded to the matrix material and the non-lasered powder remains in place. After a layer of sinter is fired, the workbench is lowered by a layer of height, and the long two layers are sintered until the entire part is manufactured. Since the unsintered powder surrounds the unsintered part, it has a supporting effect on it, so no complicated support system is required in the production.
In the selective laser sintering system, laser types, laser scanning patterns, computer slice thickness, computer control of the laser scanner, and powder material selection all affect the forming accuracy and performance of the workpiece. Most powders shrink when they are sintered. The result is internal residual stress and strain deformation that affects accuracy. The thickness of the powder particles also affects the surface quality of the part. After the ceramic powder is laser sintered, in order to improve its mechanical properties and heat resistance, it must be post-processed, ie the sintered ceramic body is put into a temperature-controlled furnace and fired at a higher temperature.
Third, RP technology for innovative packaging design and processing Packaging design includes structural design, modeling design and decorating design. The structural design mainly solves the problems of scientificity and technology, embodies the containment, protection and convenience; the design is the use of aesthetic rules (point, line, surface, body and other forms of elements of the law) on the three-dimensional packaging The artistic design of the appearance mainly solves the problems of artistry and psychology, reflecting display and display. The two are complementary but independent. Packaging structure design is the basis of packaging design. Different structural designs have a direct impact on the appearance of the packaging. Each innovative structure design also requires an innovative shape to match. The same structural design can be used with different designs, but it is not possible to change the structural design based on the design. The sculptural expression techniques are flexible and can promote moderate structural adjustments. In particular, the shaped cosmetic bottle and shaped condiment bottle in the packaging product may be various shapes of polyhedrons, elliptic cylinders, combinations of various rotating bodies, and other art shapes other than ordinary round bottles. These containers have different appearances and are updated rapidly. In design, they must pay more attention to the innovation of structure and styling. At the same time, it should take into account its complex structure, poor force, bottle thickness, special mold design and manufacturing, low production efficiency, is not suitable for automated production, production and transportation costs are higher issues. Traditional packaging CAD three-dimensional model can not provide sufficient space and convenience for this kind of design and processing. RP technology has obvious advantages in this respect with its distinctive features. Now we use RP technology for the model of innovative packaging design and manufacturing. Explore as follows.
1. Innovative packaging design
In the stage of new product development, designers use drawings or computer simulation to express and display the structure and shape of packaged products. This is not intuitive, and it is not conducive to making correct judgments and modifications, which hinders timely access to market feedback information. . If RP technology and equipment are used, the molding machine does not need a lot of installation cost and profound manufacturing process knowledge. It can quickly and inexpensively provide 3D solid model and sample in the design room for designers to directly measure and accept the user's direct Evaluation, at the same time can quickly make repeated changes in the structural model, the cost is not high. Even if the design meets the expected structure, shape, and functional requirements, the new product design cycle and market evaluation cycle are greatly shortened, so that the product can be quickly and easily put into production and occupy the market in advance. According to statistics, 43% of rapid prototyping products are used to confirm the design.
2. Packaging product processing
Since the RP technology is not limited by the complexity of the container structure and the processing speed is high, it can directly realize the production of single pieces of plastic and ceramic packaging containers. It can also be used to make molds for plastic and ceramic containers. Mold manufacturing can be divided into two methods: indirect molding and direct molding. Indirect mold making is to use RP technology to make the product master mold, and then according to the master mold to produce plastic or metal molds. Such as: according to the mother model replica silicon rubber mold production of metal parts, plastic parts or injection mold, or according to the mother model replica hard epoxy resin mold, manufacturing injection mold. It is also possible to use a master mold instead of a wood mold to make a sand mold and produce injection molds or metal parts. Or use RP die for investment casting. In direct molding, selective laser sintering (SLS) is mainly used to directly make metal molds. The metal powder is coated with an easily-disappearing polymer, a metal bonded body is obtained by selective laser sintering, the resin is decomposed and disappeared at a certain temperature, and the shaped metal powder is sintered at a high temperature to obtain a metal sintered part. This sintering is often a low-density porous structure that can penetrate the metal with a lower melting point of the second phase and form the metal mold directly. The steel copper alloy injection mold produced by this method can have a life of more than 50,000 pieces.
Fourth, the conclusion Packaging design is a dynamic design activity whose vitality lies in continuous innovation. Especially in the fierce competition of goods, the time-related problem of packaging design is particularly prominent. RP technology is precisely because of its distinctive features and advantages to meet the rapidly changing market needs and become an effective means to achieve innovative design. Its prospects are very broad. Of course, as RP technology is still in the development stage, the molding accuracy and mechanical properties of the products need to be further improved. At present, the United States uses the most RP technology and equipment in the world, followed by the European Community and Japan. China's statistics in 1996 have imported 12 sets of various types of molding machines. In 1997, at the China International Machine Tool Exhibition, domestic AFS-300 SL molding machines and F-260 FDM molding machines were exhibited. This indicates that China's RP technology and equipment have entered the practical stage and will form an industry. Therefore, it is of great practical significance to study the use of rapid prototyping technology for innovative packaging design and manufacturing.
September 04, 2020
