Mold Failure to Prematurely Permanent
Mold failure is the most common and costly manufacturing defects in the injection molding industry. The cost associated with the failure of a tool to meet design intent, process control requirements, and production output is significant. The primary causes of premature and permanent tool failure fall into three main categories: design, material and process control.
Design failures are often the most obvious and most easily corrected. Poorly designed molds can lead to undercut locations, sharp edges, and incorrect draft angles that lead to part scrap and tool damage. A poorly balanced tool can lead to corrosion and warpage of the tool as well as poor part quality. Importantly, a poorly designed tool is repeatable, meaning that the same issues can continually arise with each new build lot affecting production output and quality.
Material selection is perhaps the most important consideration for a long-life tool. The plastic material used in the injection molding process can cause premature failure of the tool. Plastics that are too soft and flexible can cause sticking and deformation of the cavities and moving components of the tool, resulting in failure. Furthermore, the molds exposed to aggressive chemicals are more prone to degradation. The chemical components of plastic resins can corrode specific material strains such as hot-work steels, stainless steels and aluminum, if the alloy is not correctly selected and/or hardened, machined, and surface treated.
Process control issues are equally important but may not be obvious. Factors such as cycle times and pressures, the functioning of the ejection system, and the accumulating heat of components may all contribute to premature component failure if not addressed. Further, incorrect mold positioning, molding parameter setting, and material contamination may cause uncontrolled changes in part-to-part variability.
Each area of potential failure must be thoroughly examined to ensure a well-functioning injection mold. Poor design decisions, incorrect material selection, and/or lack of process control should be eliminated in order to adorn or prevent premature wear or breakage of the tool. Whenever an injection molding tool fails, the root cause must be determined. Identifying the primary cause or causes of failure will help the toolmaker make adjustments so that the same failures are not repeated in the future.
In conclusion, injection molding tools can fail prematurely and permanently due to poor design, incorrect material selection, and lack of process control. It is important to identify the root causes of the failure and take steps to prevent the same errors from happening again. Furthermore, regular maintenance and monitoring of the injection molding tool are essential to help increase its life and maintain superior quality. By addressing each issue individually, manufacturers can have confidence that their injection mold engineering efforts have achieved quality that not only meets but exceeds its customers’ expectations.
