New stack mold technology from Mold Hotrunner Solutions now allows plastic cap and closure manufacturers to produce twice as many valve gated parts without having to run additional or larger injection molding machines.
The technology exploits the untapped potential of smaller, more efficient injection molding 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 48+48 mold in a small 200 ton machine can make 96 light weight bottle closures every 3 seconds or almost 3 million parts per day.
In order to lower the production cost of injection molded caps and closures, molders must increase productivity. Without investing in additional equipment, 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.
"This is a technology leap. Buying and running more capital equipment is a major and unnecessary investment. That's why the iVG is the perfect solution." - Harald Schmidt, President MHS
Stack molds that inject parts in both directions using two parting lines are not new and are already being used by many molders to increase production output, so there are no unknown processing factors. What makes Rheo-Pro® iVG™ hot runner systems so unique is that they don't require the same large machines because they are extremely compact. 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.
"Never before was this possible. This is a game changer for the cap and closure industry. This technology provides our customers a real competitive edge." - Evan Goodwin, Engineering Manager MHS
World demand for caps and closures is projected to rise 4.6 percent per year to upward of $40 billion in 2014. Beverages will remain the main consumers of caps and closures, but more rapid gains are expected in other markets such as food and pharmaceuticals.