Mazda bumper design, the most popular application

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Application example of gas assisted injection molding: Mazda bumper design

the new press gas assisted molding technology is used in the manufacture of the front and rear bumpers of Mazda Lantis (Mazda Landis) car. This time, gas assisted injection molding is used to replace traditional injection molding to manufacture the bumper, which means that Mazda Landis has finally achieved results after four years of research and preparation that looks like the letter "H". Mazda's patent right to use gas assisted injection molding was obtained from Mitsubishi, the main patent licensing company of Sunplus in Japan

the automotive industry has long realized that the use of gas assisted injection molding technology can release the huge internal stress in plastic parts. If it can be applied to the automotive industry, it will greatly promote the application of plastic products in the automotive field. Although it is still a long way from the all plastic car, it has been developing in this direction

more than 20 years ago, the front and rear bumper of the car were made of metal and fixed on the body. In recent years, the hybrid type is mostly used, mainly due to the requirements of body shape, aerodynamics, and the bumper is becoming larger, and it is required to be integrated with the air intake guardrail. But the decisive reason is the increase in body size and weight. Automobile manufacturers require plastic manufacturing to reduce costs

in the last decade, plastic bumper has been manufactured by traditional injection molding. The manufacturing process includes making a plastic frame through a simple high-pressure injection mold, and then using a series of parts to strengthen and support it according to the dimensions specified in the relevant product standards. Using this method will use many accessories and add additional assembly costs. Therefore, scientific and technological personnel have been committed to finding a molding method that can complete the above steps at one time. Five years ago, when Mazda engineers began their research work, they had learned that gas assisted injection molding could provide help in this regard. It is mainly manifested in the following aspects:

◆ the bumper can obtain greater strength and rigidity by forming a hollow structure in the center of the intersection

◆ local thick wall structure can be combined into products and formed at one time

◆ the hollow part reduces the degree of lateral contraction depression caused by the inner stiffener and thick wall part

Mazda engineers also found that by using multiple injection points and smaller injection molding machines, the bumper with thinner wall thickness can be made, which greatly reduces its weight. In early experiments, Mazda engineers found that if a 2.8mm thick stiffener is used, its bending strength will be increased compared with the original bending strength. This equipment is suitable for testing the dynamic and static friction coefficient of plastic film, sheet, paper and other materials when sliding 60%. However, because the stiffener is too thick, the surface shrinks and hollows. This machine is equipped with a 10 fold explicit measurement microscope and cannot be used. This limitation was not broken until they applied the new pres gas assisted injection molding technology. At the same time, Mazda engineers are also very interested in the relationship between material selection and molding conditions

gas assisted injection molding technology was first applied to a method called overflow, which was first adopted by Mitsubishi after its introduction. In this technique, the mold cavity is filled with plastic and then injected with gas. It is remarkable that after using this technology, even different materials can meet the predetermined requirements under different molding conditions

the experiment was carried out with PP resin under appropriate conditions. All finished products were found to be related to the specific volume and flow characteristics of the material during hollow molding. In addition, it is found that when multiple injection channels are used in a mold at the same time, some of the adjacent channels are formed first (easy to form), and some are formed slowly. At the same time, it was found that the air passage with low resin pressure was easy to enter, while in other air passages, the higher resin pressure decreased with cooling, and the decline degree of this pressure was even more than that of the resin pressure in the hollowed out air passage. Mazda engineers found that the way to correct this phenomenon is to change the design of the airway. The differences between the airways have been eliminated, and the above problems have been solved. Mazda engineers found that the way to correct this phenomenon is to change the design of the airway. The differences between the airways have been eliminated, and the above problems have been solved. (end)

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