IMD technology and its application in automobile

01 Discussion on the concept and process flow of IMD plan

1.1 IMD technical concept

The full name of IMD technology is IN MOLD DECORATION, which is a new type of in-mold decoration technology that can realize part injection molding and display decoration at the same time. IMD technology is composed of three technologies: IML, IMF and IMR. The full English name of IML technology is IN MOLD DECORATION, which is often referred to as in-mold insert injection molding technology. To put it simply, the core technology of IML is to complete the film injection molding in the mold, that is, to print the selected film, and then use the molding machine to help shape it, and then cut off the excess edge material, and finally place it in the injection mold. mass production. The film material used in IML technology is significantly different from other technologies. In order to effectively ensure the practicability and aesthetics of the product, the film used in this technology usually has three layers, and the outermost layer is a transparent film with high hardness, which not only can It prevents the film from being scratched and can make the printed pattern appear more clearly; the middle layer is the printed pattern layer, which is made of a film material with high coloring degree, and the last layer is a relatively wear-resistant film with a surface hardness of up to 3H. And the more polished, the brighter, even if it is used for a long time, the printed pattern on the surface of the product will not be easily scratched, and the color can be maintained for a long time. IML technology usually uses injection molding materials such as PC and PMMA. Although it improves the hardness of the product, it is only suitable for flat curved products due to the lack of sufficient elasticity and small curved surface. Therefore, in order to improve this defect, it is also tried to add flannel, leather and other materials with certain elasticity to complete the injection molding of the product. IMR is an in-mold transfer technology, and its full English name is IN MOLDING ROLLER. IMR technology is different from IML technology. IMR rolls the printed film into a roll bag, and then installs it into the injection molding machine to complete the subsequent injection molding process. The significant difference between IMR technology and other technologies is that after the injection molding is completed, the ink will only appear on the surface of the product, and will not splash around, and the film will not come off the web. IMF is an in-mold injection technology suitable for multi-curved surfaces, which is reformed and developed on the basis of IML technology. The full English name is IN MOLDING FILM. The technical process of IMF and IML is basically similar. The only difference is that in order to enhance the elasticity of the product, IMF will stretch the film before injection to make it meet the demand for curved surface production, and then place it into the mold for injection molding. The injection molding materials used in IMF and IML technology are exactly the same. IMF technology improves the lack of elasticity of IML and IMR, can meet the needs of multi-curved products and is widely used in the production of multi-curved products.

The three technologies of IMD complement each other. The technologies of IML and IMF are basically similar. The only difference is that IML technology is mainly used in the production of flat curved products, while IMF is more suitable for multi-curved products. The essence of IMR technology is in-mold transfer printing, which is completely different from IML and IMF in-mold injection molding technology, resulting in different external surface states of the final product. IMR is to place the ink directly on the outer surface, while the ink layer of IML and IMF is on the second layer, and the outer layer is a diaphragm. In the production and application of automotive interiors, suitable IMD production technology can be selected according to the needs of different products.

1.2 The main process of IMD

1.2.1 Processes of ML and IMF

The process steps of IML and IMF technology mainly include the following processes:

①Cut the film: Cut the selected film tape in an orderly manner according to the pre-designed size and shape.

②Ink printing: Print the pattern shape designed in advance on the cut film.

③Fix the printing pattern: In order to prevent the ink from splashing around during the injection molding process, it is necessary to print and fix the ink on the cut film in advance.

④Ink protective film: In order to protect the printed pattern from being damaged before injection molding, it is necessary to cover the ink side of the printed film with a protective film to prevent accidental scratching due to improper operation during the printing process.

⑤Calibrate the positioning hole: The positioning hole is to better facilitate the subsequent process operation, especially in the production process of mass products, to avoid blank or deformed defective products during the injection molding process, which will affect the production quality of the product.

⑥High pressure/thermoforming: After calibrating the positioning holes, the printed film is punched according to the previously agreed design ideas to meet the production requirements of curved products. Generally speaking, this step needs to be completed in a high temperature and high pressure environment.

⑦Cut the shape of the film: After the stamping is completed, calibrate the positioning hole, and cut the excess material on the edge of the film that has been formed.

⑧Material injection molding: complete the product injection molding operation, and integrate the injection molded diaphragm with the product.

⑨ Mold opening: carry out the preparations for the injection molding operation of the subsequent products. The process steps of IML and IMF are very similar, and both contain the above nine processes. The biggest difference is that IMF has one more process of thermoforming and two calibration positioning holes than IML technology. The thermoforming process is to improve the elasticity of the product, and to make the state meet the design requirements of multi-curved surfaces through hot stamping. The alignment of the positioning holes is also to meet the production requirements of multi-curved surfaces and prevent the forming film from leaving defects during the production process.

1.2.2 Process of IMR

The process of flat printing and ink drying in the early stage of IMR technology is the same as that of IML and IMF technology. The obvious difference lies in the different injection molding methods. IMR is through in-mold transfer, while IML and IMF are through in-mold direct injection. The in-mold transfer process of IMR mainly includes the following processes:

①Calibrate the positioning holes: Roll the film into a roller shape, and then mark the positioning holes according to the design requirements. The injection molding machine is equipped with a surveying instrument, which can accurately calibrate the positioning hole and complete the film positioning with the aid of the positioning mark.

②Material injection molding: Install the film on the front mold surface of the mold. During the product injection molding process, the ink will be directly separated from the film and then covered on the injection molded parts to complete the transfer of the printing pattern. Since the film on the front mold surface will not be released from the mold with the transfer of ink, the outer film is still connected to the film roll.

③Mold opening: After the transfer in the film is completed, the injection molding is completed, and the product is formed. At this time, the film roller is rotated to the next positioning hole. Then calibrate the positioning holes to start the injection preparation of the next product.

02 Comparison of product features of various IMD technologies

In terms of product output, IMR is suitable for the production of super large-scale products, and the minimum order output is usually set at more than 100,000, while the production quantity and batch of IML and IMF are relatively flexible, and are suitable for general-scale or large-scale quantities and batches of products. production. In short, the three technologies of IMR, IML and MF included in IMD are all suitable for mass production of a certain scale, and there is a certain demand for the quantity and batch of products.

From the analysis of product surface shape, IMR technology is mainly aimed at flat surface products. The pattern surface of injection molding needs to be as flat as possible, and the surface fluctuation changes are not large. The surface pattern height that this technology can withstand is up to 1.5mm. The IML and IMF technologies make up for the deficiencies of IMR, and improve the elasticity by stretching the film to meet the production needs of multi-curved 3D products.

From the perspective of product surface wear resistance, IMR technology is an in-mold transfer technology. The ink layer is the outermost layer of the product. During the production and use process, the printed ink pattern is often scratched accidentally. However, IML and IMF place the ink layer on the second layer of the film, which better maintains the integrity of the ink pattern, and the more polished the outer layer of the film selected, not only improves the wear resistance of the product, but also promotes the outer surface of the product. More clean and beautiful.

From the analysis of the feedback results of the printing effect, the IMR process has a simple process flow, and the printing technology is relatively limited. It is basically only suitable for the production of the transfer effect. It is troublesome to change the color of the product during the production injection molding process. However, the ink effect produced by IML and IMR technology can use a variety of colors to meet the needs of diversified production, and can change the color randomly during the printing process.

In summary, due to the poor wear resistance of IMR, the pattern color on the surface of the product is easily scratched during use, so IMR is not suitable for the production of buttons and other products that require strong wear resistance, while IML and IMF can be used. In the production of buttons and other products.

03 Application of IMD technology in the automotive industry

IMD technology was initially applied to flat surface products such as instrument panels, button buttons, and center control panels in automotive interiors. However, with the continuous development and improvement of IMD technology, IMD technology has also been widely used in multi-curved products, such as the entire instrument panel, the top of the car and even the engine cover, etc., which makes the manufacturing process of automotive interiors more comprehensive and diversified. The research and development of IMD technology breaks the limitations of traditional interior craftsmanship, and creates a manufacturing process for interior products with small space, large curved surface, beautiful appearance and clear pattern, which is favored by consumers and gradually makes IMD automobile interior manufacturing technology into sales. A major selling point in the market.

IMD is a relatively mature new injection molding technology in the domestic automotive interior manufacturing market. Compared with other traditional processes, the process flow is simpler, which weakens some unnecessary production and assembly links, optimizes the product production structure, and improves production efficiency. , to ensure the production quality. At the same time, under the large-scale, large-scale production mode of big data, the production cost of a single IMD product is extremely low. IMD technology not only effectively guarantees the production quality of the product, but also enhances the practicability and aesthetics of the product, and prolongs the service life. At present, the IMD technology is gradually perfected, and it can be fully applied to the fields with special requirements such as multi-surface, imitation metal, special texture, etc. Compared with other technologies, it has significant advantages and has a broad space for development. It is the mainstream of the future automotive interior manufacturing process. trend.