For any plastics process, there are short and long runs. This has an impact on the wear placed on molds.
With proper care, molds can have a long lifespan. This can vary depending on how many shots they have, but molds can do 300,000 to 400,000 shots a year without issue, with some extending past those marks.
There are many reasons to change molds, and shops today have plans in place to ensure down time is kept to a minimum when a change is required.
Significant reductions in changeover times have been achieved using transfer systems, in some applications reduced by more than 70 percent.
For shops, there are several effective solutions that can help shorten several operations, including energy connections, mold clamping, mold loading and maintenance as well as automated processes.
Shops should define their priorities as well as detailing and timing the mold changing processes to identify time-saving opportunities.
Ultimately, reducing changeover times will eliminate waste.
The ideal setup change is no setup at all or within minutes, depending on the size of the press. For an efficient changeover, shops should ensure that all tools are always ready and in perfect condition. Changeovers also can vary depending upon the size of the molds being utilized.
A larger tonnage injection molding machine could require 30 to 60 minutes for a mold change, but some companies can even do this in minutes.
Goals can be set to reduce changeover times. The times can be recorded and displayed near the machine. On the shop floor, distinguish between internal and external setup activities and try to convert internal to external setup.
One option to streamline is the use of a transfer fable to provide safe and efficient side-changing of molds. This can be effective in shops where the floor design doesn’t accommodate the use of cranes. Heavy molds can be moved into position using a forklift. The mold is secured on the table to reduce the chance of damage to the mold or its connectors. This process can be adapted for each application, incorporating push/pull systems for smaller molds as well as powered transfer units for larger molds.
A transfer table can prove to be cost effective, providing shops a quick return on investment.
On shop floors utilizing more automated systems, one transfer system can be placed between two machines. The two-directional loading table can serve both machines and provide maximum flexibility and efficiency for each production cell, incorporating if required a preheating station.
Other processors may require automatic mold changing. In these instances, a transfer system can be set on each side of a machine for the fastest method of mold changing. On one side, the mold from the previous production run is unloaded, while simultaneously on the opposite side the new mold is loaded.
Taking another step toward complete automation is the use of rail carts. A loading/unloading table is mounted on a rail and transfers molds from a storage location directly to the molding machine.