Additive manufacturing technology began to attract the attention of the mold industry around 2005, when some foreign enterprises began to use the so-called "rapid prototyping" technology to manufacture samples, and even some media claimed that once this technology was popularized, product manufacturing would no longer rely on molds. This information to the mold industry has brought a greater impact. But soon, as the understanding deepened, mold companies began to realize that additive manufacturing will not "destroy" the industry, but the manufacturing process technology that can be used for it.
By about 2012, some hand-run enterprises in China began to transform to use 3D printing of resin or nylon materials to replace the traditional open-mold trial production method, and the process of using 3D printing to manufacture casting sand molds or wax molds began to spread. Since 2015,Metal materials 3D printingIn the field of injection molding or die casting, more and more enterprises are trying to use selective laser melting technology to manufacture all kinds of inserts in the mold, especially cooling inserts. Today, the advantages of using additive manufacturing to make molds mainly include:
Responding to frequent changes in the product design phase
In recent years, the overall manufacturing industry overcapacity and increased competition, the use of multi-species small-volume product strategy has become the consensus of research and development enterprises, the use of iterative agile development model began to spread, this model means a large number of design changes and the need for rapid response to change. Additive manufacturing processes-although of a wide variety-are formed by stacking materials layer by layer, and the freedom of processing is easy to deal with this market demand.
Additive Manufacturing Brings Mold Function Improvement
and reduce the total cost of manufacturing
When using such processes as injection molding or die casting, functional requirements such as temperature control and exhaust must be considered to improve the processing yield. For this reason, various functional inserts for cooling or exhaust must be added in the mold design. In the past, due to the limitation of traditional processing technology, the design of this kind of insert has been greatly restricted, and its function has been greatly limited. Using additive manufacturing, the design of this type of insert can break through many constraints, such as the injection mold cooling water circuit (Figure 1), the use of additive manufacturing processing, its temperature control function is fully released, so that this deep cavity and multi-rib products injection molding pass rate greatly improved.
In addition, additive manufacturing also brings a competitive advantage in terms of cost. When using this type of additive manufacturing functional inserts, although the mold manufacturing cost has increased, but due to the improvement of product yield, as well as the savings on capacity investment, the total manufacturing cost of the total manufacturing cost can be reduced. For example, taking an air-conditioning component as an example, assuming its injection molding cycle is 90 s, 100 injection molding machines and matching molds were originally required to be deployed to meet market demand. However, after the use of additive manufacturing functional inserts, the injection molding cycle is assumed to be shortened by 30%, and the theoretical capacity demand is reduced to 70 injection molding machines and supporting molds. With the saving of space and manpower, the total manufacturing cost will be greatly reduced.
Figure 1 Cooling inserts processed by FADO in Italy using additive manufacturing
Additive manufacturing technology to achieve mold repair
Thereby reducing the cost of re-opening the mold.
Some high-end molds have been used for millions of times, and the surface is seriously worn. However, due to changes in the supply chain or other reasons, the cost of reopening the mold is extremely high or even infeasible. The use of additive manufacturing technology can give full play to its advantages in material mixing, and the durability of the repaired mold can be greatly improved by adding the modified material to the mold matrix after peeling off the worn surface.
Tianjin Radium Laser Technology Co., Ltd. (hereinafter referred to as "Radium Laser") has specially developed two kinds of additive manufacturing equipment for the mold industry. One is a LiM-X260M mold industry customization machine based on selective laser melting technology (Figure 2), which is specially used for mold steel or stainless steel materials commonly used in the mold industry. With the special printing process and post-processing process, the density and hardness of the material can be improved, which can meet the requirements of high-end molds for surface quality and durability. We are also working with material manufacturers to develop high thermal conductivity materials and processes to help mold companies get rid of the dependence on traditional high thermal conductivity materials (such as beryllium copper).
Figure 2 LiM-X260M Equipment
Specially developed for the mold industry, for the direct manufacture of mold functional inserts
The other device is based on arc additive technology and is used for surface repair of some high-end molds (Figure 3). The repair technology has been used in the nuclear power, mining and metallurgical industries in the past 10 years, and a large number of practices have proved that the durability of the repaired mold can be significantly improved through appropriate material modification and appropriate process.
Radium laser arc additive WT1400 equipment, dedicated to high-end mold repair
After years of practice, the mold industry has accumulated some experience in the application of additive manufacturing technology. However, technical difficulties remain, and they include:
The mold design specification based on additive manufacturing still needs to be improved.
In recent years, through practical application, the mold industry has initially mastered the mold design principles based on additive materials, such as the flow channel cross-sectional area, flow channel curvature and wall thickness and other important parameters, the industry has reached a general consensus. However, there is still a lack of uniform standards for some special problems, such as internal flow channel surface treatment, how to balance the conflicting needs of flow rate, heat exchange efficiency and rust prevention.
At present, the material grades suitable for additive manufacturing process are still limited, which greatly limits the further mining of the value of additive manufacturing. Additive manufacturing of copper alloys, for example, is still difficult, forcing us to work hard to find alternative materials.
Grafting positioning technology still has room for improvement
Since additive manufacturing is still mainly used for the processing of inserts, how to accurately graft these inserts that are independently processed and need post-processing operations with the mold matrix is a problem that must be considered. Especially for some small batch manufacturing mold, how to ensure the consistency of grafting is a difficult problem. At present, the mainstream solution is to develop special fixtures to achieve, but the available fixtures on the market are still scarce.
Standardization of Post-maintenance of Additive Manufacturing Mold
In recent years, the industry has found that some inserts processed by additive manufacturing have shown quite good performance advantages in the early stage, but with long-term use, these advantages gradually weaken or even disappear. To solve this problem, it is necessary for mold users to follow strict lean standards in the daily maintenance of molds, especially the quality control of cooling water and the regular cleaning of waterways. Only by implementing this idea of full production and maintenance can we continue to have the value brought by additive manufacturing.
At present, the main resistance to the large-scale application of additive manufacturing technology in the mold industry is the lack of design experience and high manufacturing cost. To better reap the value of additive manufacturing, all stakeholders in the industry need to work together.
On the one hand, product designers of OEM enterprises should communicate closely with mold enterprises, try to take advantage of the freedom created by additive manufacturing from the product design end, and give full play to its functional advantages in mold design. This reduces the total cost of product manufacturing.
On the other hand, additive manufacturing service providers, material manufacturers and equipment manufacturers should work together to continue to reduce the cost of manufacturing services. In recent years, with the improvement of the maturity of the manufacturing process, the time and material waste in the process have decreased significantly. At the same time, with the maturity of domestic equipment and domestic materials, machine time and material costs have also been on a downward trend. For example, the cost of the additive manufacturing process for die steel has dropped significantly from 9-10 yuan/g in 2017 to 2-3 yuan/g in 2020. As demand rises, manufacturing service providers will have more opportunities to make orders, which will further contribute to a benign decline in manufacturing costs.
It needs to be emphasized that these efforts need to be coordinated, and it is difficult to promote them only by relying on spontaneous cooperation among enterprises. Therefore, in this process, the participation of the media, industry associations and schools is also essential. Radium Laser is willing to participate in this collaboration, share knowledge and experience, and contribute to the healthy development of the industry.