StackTeck Systems Limited started building In-Mold Labeling (IML) molds in the 1990s, typically with just 2 or 4 cavities in a single face mold. As the market for IML products developed, many applications required higher productivity. This led to the adoption of stack molds to run IML parts, using specialized mold and robotics innovations. In the past, non-IML systems typically utilized higher cavitations with greater productivity than In-mold Labeling molding systems. However, this productivity gap is narrowing over time. Today, IML systems are running with as many as 32 cavities and 2 level stack molds are becoming commonplace.
Growing IML System Productivity
For many In-Mold Labeling applications, there is an ongoing drive to increase the number of cavities per system, in order to drive down part costs and to keep up with the capacity requirements of ever-larger IML projects. Advances in IML molds and robots have paved the way to enable higher productivity systems:
- equipment cost per part reduced by approx. 50%
- over 300 IML molds built by StackTeck, with over 1500 cavities total
- systems have been proven to run well with 32 cavities in the system
- over 25 StackTeck molds are running with 16 or more labels per cycle
Developments in Hot Runner Technology for Stack Molds
Hot runner technology has made it possible to configure stack molds to suit In-Mold Labeling robot requirements (label insertion away from the center section) while keeping part design options open, i.e. both inside and outside gating configurations can be achieved.
Stack Mold Advantages
In many applications, the use of a stack mold layout enables the simplification of an IML robot, for example a 2×16 IML robot may be simpler than the comparable 1×32 version, while machine tonnage required is typically cut in half.
Stack molds can also be configured with “Quick Product Change” (QPC) modules for flexible changeovers, as well as incorporating family mold capability to mold dissimilar parts in each face of the stack mold.
StackTeck has concepted and quoted In-Mold Labeling systems based on 4 level stack molds, which is expected to be a future milestone as the productivity of IML systems catches up with non-IML cavitations.
Conventional 2×16 StackCup Mold (outside gating)
IML 2×16 Stack Cup Mold (outside gating)