The mold cooling time was reduced from 22 seconds to 10 seconds, a reduction of 55%;
· The temperature of the mold wall is reduced by 40 ° C to 70 ° C;
· The daily output of each injection molding machine increased from 1,496 to 2,101, increasing efficiency by 40%.
If you are the owner of an injection molding factory, would you be excited to see these numbers? Want to make your own factory like this?
Metal 3D printing technology can effectively shorten the cooling time of the mold and improve the production efficiency of the injection molding machine. Now it has been confirmed again.
On August 23, 2018, we learned that the German Alfred Kärcher company (Kacher) used a core with conformal cooling function (made by metal 3D printing) in its injection molding mold to The cooling time was shortened by 55%, which greatly improved the company's injection molding production efficiency. This special mold core was designed by Renishaw and produced using metal additive manufacturing technology.
Injection molding machine is producing plastic casing
The high-pressure cleaners produced by the German company Alfred Kärcher (Kärcher) have not only become a must-have cleaning device for many German households, but are also favored by users in the international market-the distinctive feature of these cleaners is their bright and striking yellow casing. Due to the powerful functions and good reputation of Kärcher high-pressure cleaners, whether indoors or outdoors, more and more people use Kärcher products in daily cleaning of the home.
High pressure washer produced by Alfred Kärcher (Germany)
To meet the growing demands of the global market, Kärcher produces millions of compact washing machines every year. More than two million K2 standard high-pressure cleaners are shipped each year at a plant in Obersontheim alone. However, even with such high volumes, Kärcher is still unable to meet all market demands.
One of the most recognizable features of the Kärcher cleaning machine is its bright yellow casing, but the manufacture of the casing is also one of the main bottlenecks in the production process. For example, the shells of the K2 series washing machines are produced by six injection molding machines, each of which can produce 1,496 shells per day, but this amount is far from enough for Kärcher, because Kärcher has four assembly production lines and workers work in three shifts Uninterrupted production, so the daily assembly volume of K2 high-pressure cleaners can reach 12,000 units.
Obviously, one option is to add more injection molding machines. However, according to coordinator Leopold Hoffer — who heads the injection molding process at Kärcher's Obersontheim plant — he can increase productivity by tapping into the potential of existing equipment. "Our goal is to shorten the molding cycle from the original 52 seconds to between 40 and 42 seconds," he explained. He contacted LBC Engineering, based in Pliezhausen, which was acquired by Renishaw in May 2013, to find ways to reduce the cooling time of the mold.
Original mold design
"The first phase of the project was to obtain data on existing molds to determine if the goals proposed by Kärcher were feasible," recalls Carlo Hüsken, Renishaw project coordinator at Kärcher. Renishaw used the data provided by Kärcher to draw a thermal image of the injection molding process, and then analyzed it with Cadmould® 3D-F simulation software. The results show that the melting temperature of the plastic material is 220 ° C and the demolding temperature is 100 ° C. During the entire molding cycle of 52 seconds, the cooling time accounts for 22 seconds. The mold temperature was controlled with cooling water, and the water flow rate was 10 liters / minute and the temperature was 35 ° C. Next, Renishaw focused on modeling the hotspots detected during the thermal imaging process, as these areas directly lead to the extension of the molding cycle and require further analysis. Using this data, Renishaw completed a data simulation with 20 molding cycles, including analysis of the mold wall temperature.
Improved mold design
According to Mr. Hüsken's suggestion, during the second simulation, Renishaw improved the temperature control method on the nozzle side, that is, by adding two traditional cooling water channels to the mold plate on the nozzle side, Cooling effect of beryllium copper round threaded joints.
Renishaw then performed two more simulations to evaluate potential improvements that could be achieved when conformal cooling was applied. The traditional mold cooling method is to drill holes in the mold to form a network of coolant channels. The geometry of the channel formed by the drilling method will be limited. For simpler molds, this cooling method can achieve the desired effect, but for more complex molds, the cooling effect will be greatly reduced. The mold core adopting the conformal cooling method uses a metal additive manufacturing method, that is, this type of mold core is processed layer by layer using the additive method. Additive manufacturing is very flexible, which means that the complexity of the coolant channels in the mold is almost unlimited. In general, the conformal cooling channels in the mold can maintain an equal distance from the mold wall, so the cooling effect is more uniform; or in areas where hot spots are concentrated in the mold, the density of conformal cooling channels can be increased, and these are the The area provides faster cooling.
The simulation process shows that after conformal cooling, the cooling efficiency of virtually all hot spots can be effectively improved, and the temperature of the mold wall is reduced by up to 70 ° C.
Finally, in an area where there is not enough space for the conformal cooling channels in the mold, Kärcher cleverly improved the product design to alleviate the problem of mold cooling.
Based on the simulation results, Renishaw proposed a comprehensive improvement plan for Kärcher, pointing out that conformal cooling can be used to improve the temperature control of hot spots in the mold, thereby making the cooling rate of each part more uniform and reducing the overall cooling time. The revised mold design incorporates two metal 3D printed mold cores to provide conformal cooling to identified hot spots.
Renishaw checked the effect of the modified mold design using thermal imaging technology and confirmed that the temperature of the mold wall can be reduced by 40 ° C to 70 ° C, and the cooling time can be shortened from 22 seconds to 10 seconds, a 55% reduction. Volker Neu, the head of the Kärcher injection technology team, also proved through actual production that the new mold design and readjustment of some peripheral processes (filling system, processing system, etc.) can shorten the molding cycle from 52 seconds to 37 seconds. Today, the daily production of housings for each injection molding machine can be increased from 1,496 to 2,101.
Subsequently, Kärcher also improved the design of other molds. Renishaw produced these conformal cooling cores using additive manufacturing technology. Mr. Hüsken actively supported Renishaw during the manufacturing process.
Mr Hoffer was initially skeptical of the project, and now he said: "The results were better than expected. Renishaw sold us a complete set of improvements. They thoroughly investigated and analyzed the molds we used to help us. For optimal productivity. "
Renishaw always provides customers with exclusive solutions based on the comprehensive use of various technical means. "In our case, it involves both traditional cooling technology and conformal cooling technology. It includes both the coolant channel processed in the traditional way and the mold core processed in the additive manufacturing method. "Vacuum brazing technology," he added, "with all these technologies, we can work out the most suitable production plan."
Through this project, Mr. Hoffer gained important knowledge and experience. "In the future, we will pay more attention to mold cooling efficiency during the design phase," he said. "In Kärcher, the calculation of cooling efficiency will become a key part of mold design. Using this information, we can decide whether to use the traditional cooling scheme or Cooling solution. "
"Renishaw provided us with perfect support. In this project, Renishaw was the right choice for us; in the future, when we need to design a closed contour temperature control solution, we believe that it will also be our most suitable Partner, "Mr Hoffer concluded.
Renishaw metal 3D printer introduction:
Renishaw is one of the world's leading engineering technology companies, leading the world in the field of additive manufacturing (also known as 3D printing). It is the only UK to design and manufacture industrial additive manufacturing equipment ("printing" parts through metal powder )s company. The metal conformal cooling injection mold core described in this article was printed using a Renishaw metal 3D printer.
Renishaw's additive manufacturing system uses metal powder bed melting technology to make complex parts directly from digital CAD files. There are currently four models of Renishaw's metal 3D printers. The latest RenAM 500Q is the Renishaw multi-laser AM system. It is equipped with four 500 W high-power lasers, each of which can cover the entire powder bed surface at the same time. RenAM 500Q significantly improves processing efficiency, which in turn greatly increases the production efficiency of each part and significantly reduces costs. RenAM 500Q with an automated powder and waste disposal system helps to achieve consistent process quality, reduce human-machine interaction time and ensure high standards of system security.