The cycle time of any mold is largely influenced by the cooling cycle—how fast the resin can be sufficiently cooled so that the part can be ejected without permanent deformation. In any given mold, the areas that take longest to cool are those with the thickest wall section.

Since the runner must supply multiple cavities, it is common for the runner to have a thicker wall section than the molded part. By eliminating the runner, the cooling time will be reduced by the difference in cooling time between the molded part and the cold runner.

Injection time is another component that differs between comparable hot and cold runner equipped molds. The injection time difference will be the extra time required to fill the cold runner.

Close and open stroke of the press is extended with cold runner equipped molds. The travel must be increased to accommodate safe ejection of the cold runner.

Parts molded with hot runners better lend themselves to automated part removal. With no runner to interfere with part removal, secondary mold processing times involving manual labor, including part/runner separation, part trimming and packaging, are reduced or eliminated entirely.

Collectively, these individual time reductions reduce the overall molding cycle, contributing to increased output per unit of time. Depending upon the production quotas, you may be able to free up the injection molding machine for another run often days, weeks, or even months earlier than anticipated. and where time savings when using a hot runner tool can be expected.