Selective laser melting is an additive manufacturing technique that can be used to produce mold inserts with conformal cooling runners. ABB OY's power transmission and control department uses additive manufacturing technology to redesign mold inserts, which greatly shortens the cycle required to produce a cable sleeve and also reduces the scrap rate in production.
ABB OY produces millions of cable sleeves every year. The cable sleeve in this case is made of thermoplastic elastomer (TPE). Previously, the mold used for injection molding was not equipped with any cooling inserts in the original design. The production cycle of a single product is about 60 seconds, of which the cooling time accounts for about 30 seconds.
Cable sleeve products made of TPE
Selection laser melting technology to achieve innovation
In order to achieve the best optimization effect, the mold insert has designed six different conformal cooling schemes. One group uses the traditional design as a reference, and the other solutions are designed based on the advantages and requirements of SLM technology, taking into consideration factors such as unsupported angle, minimum wall thickness, flow channel size, and flow channel shape. The plan has been optimized accordingly. Before the actual cooling experiment, the testers simulated each mold insert according to the water flow rate and thermal conductivity. The results showed that different part designs will exhibit different cooling performance.
The Finnish company VTT used stainless steel 316L to print these six mold inserts on the SLM125 equipment, and heat-treated them according to the product requirements, after the inserts reached the target hardness of 54HRC, they were machined accordingly. . At this point, the preparatory work for the cooling performance test has been completed.
Performance Testing
In order to test the cooling effect, the insert needs to be heated to 70 ℃ for tempering and cooling to 20 ℃, and this process is similar to the cooling process of TPE in the injection molding process. By using infrared temperature measurement to collect the data of each insert cooling, and make a unified comparison.
Among them, the fountain type, thin U-shaped and thick spiral design have the best cooling performance, can complete the cooling process within 10 seconds. Because the cooling speed of the tip area of the insert is relatively slow, the turbulent flow rate can be accelerated by reducing the cross-sectional area of the flow channel, and the cooling efficiency can be improved. By placing the flow channel as close to the insert surface as possible, the cooling efficiency can be maximized. Considering the forming difficulty, the forming effect of fountain type and thin U-shaped insert is the best.
Inserts with conformal cooling can be used in injection molding molds, and it appears that the use of these inserts does not cause cavities in the molded parts. The production cycle of TPE is shortened to 14.7 seconds, and the cooling time is shortened to 6 seconds.
Conformal cooling facilitates the production of high-volume injection molded parts
The use of SLM technology brings a significant reduction in production cycle and production costs. By using conformal cooling inserts in injection molding molds, the cooling time can be reduced from about 30 seconds to about 6 seconds, and the production cycle from 60.5 seconds to 14.7 seconds.
3D printing case-mold insert with conformal cooling
• Incorporate conformal cooling channels directly in the mold insert • In the case of conformal cooling inserts, TPE cooling time is reduced by 80% • Total production cycle time is shortened by more than 75% • Conformal cooling enables injection molded parts Even cooling reduces the occurrence of defective products