3D printed metal conformal cooling molds have been verified in the mold industry. B & J Specialty uses 3D Systems metal 3D printers to manufacture conformal cooled injection molding inserts for customers. The new mold inserts cool the temperature during the cooling process. The change was reduced to 18˚C, and the mold shrink cycle time was reduced from 1 minute to 40 seconds, and the overall production efficiency was improved by 30%.
3D Systems' metal additive manufacturing process and Cimatron mold design software have significantly reduced the cooling cycles of mold inserts.
If the temperature change during the injection cooling cycle is large, the risk of parts warping will increase greatly. When testing traditionally designed and manufactured injection-molded automotive pipes, a temperature fluctuation of 132˚C will be generated during the entire test process. B & J Specialty recommends conformal cooling injection-molded inserts to its customers in order to achieve more balanced cooling. . To achieve this, B & J Specialty's engineers used 3D Systems' Cimatron® software for mold design, and the internal cooling water path was designed to conform to the surface of the component. In order to produce complex and precise internal cooling water channels, they used 3D Systems metal additive manufacturing equipment ProX® DMP 300 for printing. The new conformal cooling mold insert reduces the temperature change to 18˚C during the cooling process, and reduces the mold shrink cycle time from 1 minute to 40 seconds, which improves the overall production efficiency by 30%
Suboptimal cooling water paths cause large temperature changes
Conformal cooling molds use modern technology to solve long-standing problems. Many injection-molded parts are curved, but the holes used to create the cooling water channels can only be drilled in a straight line. In most cases, this means that the cooling water circuit cannot match the geometry of the component. The cooling line manufactured in the traditional way must bypass the outermost layer of the part to avoid interference with the mold cavity, which means that the part closer to the center of the part is usually farther from the nearest cooling water path. As a result, significant temperature changes often occur at the beginning of the cooling process.
B & J Specialty has redesigned automotive pipes to increase cooling efficiency and is characterized by multiple irregular surfaces. In the original mold design process, a cooling line was drilled through a center and stator block in order to adjust the geometric characteristics of the mold and allow a certain degree of warpage. For irregularly shaped pipes, several important characteristics of the pipes are not related to the cooling water channel, because there are restrictions on straight channels. The resulting temperature changes can cause residual stress, which can cause parts to bend when they cool. In the past, component manufacturers used to extend the cooling cycle to solve this problem, to ensure that the component was fully cured before removing the component from the mold, and the insert was adjusted to allow a certain degree of warpage. The problem with this method is that prolonging the cooling cycle will reduce production efficiency and increase parts manufacturing costs.
Compared with the traditional linear cooling water circuit, the metal 3D printing conformal cooling water circuit reduces the temperature change by 86%
Improve mold with conformal cooling water
According to Jarod Rauch (Information Technology and 3D Printing Manager at B & J Specialty), automotive piping is a good example of an improved conformal cooling design that can improve part quality, reduce scrap rates, and shorten cooling cycles . B & J Specialty proposed the solution to a customer (automotive supplier) who promised to test the new method. After obtaining the CAD file of the original geometric data, B & J Specialty engineers started the design work using 3D Systems' Cimatron mold design software.
Rauch said B & J Specialty was Cimatron software that came into contact while studying the application of conformal cooling to metal 3D printers. "We saw that 3D Systems provided a complete end-to-end solution, including mold design software, 3D printing modeling preparation software, and 3D printers, and that was what made me very happy with this solution," Rauch said. "3D Systems focuses not only on equipment, but also on the additive design process for engineers."
After cooperating with Cimatron, B & J Specialty engineers abandoned the original linear cooling water channel and replaced it with a conformal cooling water channel. The distance between the water channel and the surface of the component remained constant. The use of metal 3D printing technology for final mold production allows engineers to design complex cooling water channels, while improving the quality of cross sections and interface surfaces. Such features ensure turbulence, which further increases the amount of heat transferred from the mold to the coolant, making cooling more efficient. When the mold can be cooled more efficiently, the defect rate of parts (such as warpage and sink marks) is reduced, and the quality of parts is ensured. This method reduces the correction, trial and error rate and sampling rate, produces higher quality parts, and saves a lot of time and money for mold makers and operators.
Setting expectations through accurate simulations
B & J Specialty engineers then imported the mold files from Cimatron software into Moldex3D (injection simulation software) for overall cooling simulation. "Cimatron is fully compatible with Moldex3D, which makes it easy for us to simulate the entire injection molding process, draw a graph of temperature changes of molds and components, find hot spots and cooling points, and simulate the effects of different cooling times. "Rauch said. The simulation process also points out some areas that can be improved, and the cooling strategy of such areas can be redesigned before actual production. The simulation comparison between the original mold design and the new conformal cooling water circuit design shows that the temperature distribution of the new parts has been greatly improved, and the temperature change has been reduced by 86%.
Cimatron is fully compatible with Moldex3D, which enables us to easily simulate the injection molding process in order to use digital means to evaluate the design.
3D printed mold insert with conformal cooling water circuit
B & J Specialty engineers then used 3D Systems 3DXpert ™ metal additive manufacturing software to design mold inserts in preparation for production. They import the data of parts, optimize the geometric feature data, calculate the scan path, lay out the 3D printing construction platform, and send the data directly from the 3DXpert software to the 3D Systems ProX DMP 300 metal 3D printer.
The ProX DMP 300 uses a high-precision laser head, and uses 3D Systems LaserForm® materials to selectively build metal powder particles in horizontal thin layers, layer by layer. For automotive pipe molds, B & J Specialty uses maraging steel. "The ProX DMP 300 excels in manufacturing conformal cooling waterways because its accuracy is very high," Rauch said. "We can tolerate one-thousandth to four-thousandth of a tolerance." 3D Systems' patented direct metal printing (DMP) technology allows us to create the finest details and thinnest walls with smaller material particles thick. Finally, the surface roughness of parts can be 5μm (200Ra micro inches), and does not require much post-processing.
Greatly improved production efficiency
After printing, B & J Specialty used a Blu-ray 3D scanner to scan the inserts into 3D Systems Geomagic® Control X ™ inspection metrology software, overlay the mesh on the designed geometry, and verify the metal 3D printed mold inserts. The insert is then sent to the automotive supplier, who then installs the insert on the molder. "The benchmark results show that the conformal water path makes the cooling process more balanced, thereby reducing the cooling cycle time and increasing production efficiency by 30%," Rauch said. "Because conformal cooling shortens the cooling cycle time, which reduces the injection pressure, which leads to a significant increase in the life of the mold, which in turn reduces the wear on the parting line and reduces the complexity of the mold."