When Do You Need a Hot Runner Mold?

Avoid Costly Runners

A hot runner mold is desirable in situations where you would have a large runner that would go to waste, thus raising the cost with excess material.  While the cost of a hot runner tool may be more than a standard cold runner mold, an economic analysis may reveal that the cost savings could pay for itself in a reasonable amount of time.  This would be especially true if the material is a costly specialty raw resin.  

Improve Geometrical Tolerances

In a hot runner mold, the material is injected directly into the cavity through a nozzle, rather than flow through the runner system.  This is done with more pressure than a cold runner tool, and can improve filling and packing into critical dimensional areas.   The pressure utilized in a hot runner tool can improve consistency in the molding process, thus improving the quality of the parts.

Improve Cycle Time

Due to the increased pressure, a hot runner tool may bring an improvement in cycle times.  All plastic processors know the value of an improved cycle time as increased efficiency equates to increased profits.   When applied to a multi-cavity tool on a high-volume project, the savings in cycle time alone could be quite significant, not to mention improving lead times with production parts.   The volume of production required from the tool is a big consideration when weighing the benefits of a hot runner tool versus a cold runner tool.

Flexible Gate Location

A hot runner tool allows for flexibility with the gate location, which can be placed in the most desirable area for consistent filling and packing.  In parts with high visibility, gate location is important to the aesthetics as well as function of the molded product.

There are two different types of gating mechanisms for hot runner tools, a thermal gate or hot-tip gating system, or a valve gate.  With a thermal gate the nozzle hardens at the tip, allowing the parts to disconnect from the nozzle prior to ejecting.

In a valve gating system, a valve slides over the nozzle tip prior to ejecting, assisting with ejection if the material does not solidify completely in the tip.  

Michiana Global Mold has knowledge and experience designing and manufacturing precision hot runner tools for customers demanding a high level of quality.  Contact Michiana Global Mold today for a free cost analysis of your next mold building project.