After a new mold has been manufactured and inspected from cavity to cavity to tolerances within fractions of a millimeter, it is sent to the shop floor. This is where the true test of the mold’s quality can be realized.

Often, this is where the mold-commissioning clock goes into double-time, and days are lost due to sampling issues. This could result in lost profits and lost market opportunities for the product and the processor. This stage in the product life cycle is an expensive and time-consuming necessity, and yet, the industry is hard pressed to find instances when a mold starts up flawlessly and acceptable parts come out of all cavities on the first trial run.
Mold commissioning time can further be complicated when the mold is multicavity; usually the required time will increase with cavitation.

Single-cavity molds are typically the easiest to commission, but as product volume increases it becomes unrealistic to build single-cavity molds due to part cost, production demands and required equipment for multiple molds. These cost factors drove the plastics industry and moldmakers began building multicavity tools. A sixty-fourDcavity mold typically will produce a lower cost part than a single-cavity mold, but the mold commissioning time can often increase from days to weeks or even months.

To help with the mold commissioning process, the five-step process was developed and is now offered as an automated software package. This software is built on the same principles explained in the September, 1999 article. By using the software, the confusing task of flow numbering, performing proper calculations, and graphing all the data is done automatically for the user and printed in a one-page report.

This new technology differs from conventional methods in calculating imbalances. The conventional method simply determines the percent difference from the heaviest cavity versus the lightest cavity in a given shot. This will certainly give the process/technician a percentage value, but it does nothing to help them diagnose the root cause of the variation they are seeing.

By separating out individual flow groups within a mold (typically one cavity per flow group per quadrant, steel imbalances can be separated easily from shear-induced imbalances within a mold. Users will gain additional valuable information as to the cause and required corrective action to the imbalances they are seeing.

The demand for better precision parts at a lower cost continues to grow, challenging injection-molding technology to advance, and ultimately allowing companies to stay competitive in the global marketplace.

A molder must be willing to adopt new technologies in the early stages of the product life cycle and not as a final effort to fix a problem, or the full benefit of the technologies will not be realized. A molder must be able to produce parts in multicavity tools consistently and meet the part-to-production leadtimes by minimizing the mold commissioning stage.

As such, this five-step process gives the molder and toolmaker a better view into the mold by separating out steel imbalances from shear-induced imbalances so that resources can be spent where they will be most effective. With the development of the analysis technology combined with melt rotation technologies, multicavity molds can now be commissioned faster to meet the critical time-to-market timeline, while achieving cost savings and continuous improvement in all aspects of product, process and productivity. These are major competitive tools.

And, last but far from least, the new technologies will enable moldmakers to process invoices and get paid more quickly since the mold debugging operation can be accomplished more readily.