Waldorf Technik of Germany (U.S. office in Geneva, Ill.) says its newly simplified automation for in-mold labeling (IML) with stack molds overcomes previous limitations of this application. According to Waldorf, label placement has been limited to the outer plates of stack molds, which requires that containers be gated on the inside, which brings a risk of stringing due to unavoidable wear on the tools, and often lower productivity from slower cooling of the tool cores. Alternatively, some systems have used complicated sprue-bar systems to distribute melt to the outer mold plates, but this technique is expensive and susceptible to wear, Waldorf says.
The company says it can now supply IML systems for up to 8 + 8 stack molds with label insertion on the inner plates and allowing for outside gating. Waldorf also says that existing stack molds can be converted to the new IML system with simple adjustment at modest cost, rather than requiring a whole new stack mold as in the past.