In recent years, with the development of Industry 4.0, the speed of China's manufacturing industry from "manufacturing" to "intelligent manufacturing" has become increasingly rapid. 3D printing technology has been widely used in China's manufacturing industry, and 3D printers can provide efficient and low-cost support for mold design and manufacturing. Even with the rapid development of 3D printing technology, in some fields, it has gradually begun to overturn mold technology and form a direct competitive relationship with it.
Compared to 3D printing technology, traditional mold manufacturing requires more steps and processes, and the mold production cycle is longer. When mold manufacturers launch a new product, it needs to pass strict international standards and certifications before it is launched, and the certification of many components will take a huge amount of time. This will put the new product in a very unfavorable position in terms of market share time. 3D printing injection molds are an efficient solution. Renowned Manufacturer Yimou does this by using 3D printing technology to manufacture injection molds in their open laboratory. According to Luo Baihui, Secretary General of the International Mold Association, it usually takes several weeks to two months to produce a mold, while 3D printing technology can complete the mold prototype within a few hours, and can immediately modify it based on test results, and then inject the final product sample. These product samples can be directly sent for certification, while traditional mold manufacturing may still be in production, and even 3D printed products have already passed certification before the mold is finalized, greatly shortening the development cycle. Only in the mold production cycle, 3D printing technology has had a certain impact on traditional mold manufacturing.
However, industry experts have stated that although 3D printing technology has many advantages such as short production cycles, convenient raw materials, and uniform product pressure, it cannot completely replace traditional mold manufacturing methods. This is because 3D printing technology still has some problems in the production and manufacturing process. For example, 3D printing technology processes products layer by layer, which may shorten the production cycle of the mold, but at the same time, it can also lead to a step pattern effect on the surface of the mold. Direct printing molds also have similar issues, requiring mechanical processing or sandblasting in the later stage to eliminate these small, serrated edges. In addition, holes smaller than 1mm must be drilled, larger holes need to be enlarged or drilled, and thread features need to be tapped or milled. These secondary treatments greatly weaken the speed advantage of 3D printing molds. At the same time, to ensure good material flow performance, injection molds need to be heated to a very high temperature. Aluminum and steel molds typically experience temperatures of 260 ℃ or even higher, especially when processing high-temperature plastics such as PEEK and PEI materials. It is easy to produce thousands of parts using metal molds, and they can also be used as transition molds before the final mass production mold is produced. The mold materials manufactured using 3D printing technology are generally photosensitive or thermosetting resins, which are cured by ultraviolet light or laser. These plastic molds, although relatively hard, undergo rapid damage under the thermal cycling conditions of injection molding. In fact, 3D printing molds usually fail within 100 uses in mild environments, such as high-temperature plastics such as polyethylene or styrene. For glass filled polycarbonate and high-temperature resistant plastic, only a few parts can be produced.
Another major reason for using 3D printing molds is their low cost. The cost of production level machining mold factories is generally $20000 or even more, which means that printing molds priced at $1000 are comparable in the same category. However, this analogy is not fair. The evaluation of printing mold costs usually only considers material consumption and does not consider labor, assembly and installation, spraying systems, and hardware molds. For example, ProtoLabsd's aluminum mold costs $1500 and can be used for production. If more parts need to be produced, 3D printing molds will be used. For every 50-100 products produced, new molds need to be reprinted and tested by assembly machines. On the other hand, regardless of the plastic used, aluminum molds usually serve well even after producing 10000 parts. Therefore, in terms of production costs, 3D printing is not more cost-effective than traditional mold manufacturing methods.
In addition, in product design, the principles and practices of traditional injection mold manufacturing have a history of over a century, and the industry has conducted thorough research on it. For example, the draft angle must be greater than or equal to 5 degrees to meet most aluminum mold requirements. 3D printing molds for injection molding plastic parts face challenges, requiring extra caution in the number and installation position of plastic mold pins. In terms of increasing the wall thickness of the mold cavity and reducing pressure, 3D printing molds (especially high-temperature injection molding) are to some extent more flexible. The design of the gate is also different, and the use of tunnel and point gates should be avoided. Direct gates, sector gates, and wing gates should be increased to three times the normal scale. The flow direction of the polymer inside the printing mold should be consistent with 3D printing to avoid high filling caused by viscosity and low pressure. The cooling system can improve the lifespan of the mold to some extent, but it will not significantly reduce the number of cycles in the printing mold, as the heat dissipation ability of 3D printing molds is not as good as that of aluminum or steel molds.
In summary, 3D printing technology will not completely replace the position of traditional mold manufacturing industry. Because 3D printing molds still have certain shortcomings compared to traditional mold manufacturing in terms of product quality, product cost, and mold design. Moreover, 3D printing is not suitable for mass production, as the cost per unit for producing one piece is similar to that for producing ten thousand pieces, and the time required for 3D printing is also relatively long. At present, 3D printing technology can only be used for mold production with tight requirements for small-scale production cycles, while large-scale production still relies mainly on traditional mold manufacturing.
