New stack mold technology from Mold Hotrunner Solutions® allows plastic closure manufacturers to double production of valve gated parts without having to run additional or larger injection molding machines. This leap technology exploits the untapped potential of smaller, more efficient machines by adding a second parting line to the closure mold. The patented internal valve gate design of the new Rheo-Pro® iVG™ hot runner system is what allows MHS to build back-to-back "short stacks", compact enough to fit into these smaller 180-300 ton machines.
For example, a standard 48+48 iVG™ stack mold running in a small 200 ton machine can produce 96 lightweight bottle closures every 3 seconds or almost 3 million parts per day, making it 30 percent more cost efficient than a conventional 96 cavity single face hot runner system.
In order to lower the production cost of injection molded caps and closures, molders must increase productivity. Without investing in additional equipment, greater production output can only be achieved by reducing cycle times. However, it is impossible to cut cycle times in half on a single face mold, given the high degree of efficiency already in place. Doubling the number of parts produced by implementing a stack mold solution now makes it possible.
The cost of purchasing and operating additional or larger injection molding machines, molds and controllers is substantial. If you are an end user in the packaging business and rely on plastic closures for your product, you are paying that additional cost with each part. As a molder, you are simply less competitive.
Stack molds that inject parts in both directions using two parting lines are used by many molders to increase the production output of their existing molding equipment. There are no new or unknown processing factors. What makes Rheo-Pro® iVG™ hot runner systems so unique is that they don't require larger injection molding machines because of their extremely compact size. They are also maintenance free by doing away with wear items such as seals and lubricants. Molds can run millions of cycles and parts continuously, without interruption. Compared to hot tip or thermal gate systems, valve gating not only significantly increases mold uptime, it also delivers far superior part quality and consistency. This is particularly important when molding high viscosity polyolefins for stronger parts with thinner walls.