Normally an Aluminum Tooling Mold’s life expectancy can be several thousand to 1 million + plastic parts if using an unfilled resin and simple part geometry. Difficult shutoffs, and undercuts developed by using mechanical slides, lifters, or hand loads does affect wear and tear on an Aluminum Mold.

With the right knowledge, Aluminum Mold can be groomed and enhanced in worn areas cheaper than a soft tool. A soft tool is a mold not made from hardened or heat-treated steel alloys. Even P-20, pre-tempered steel is considered a soft tool. This can be surprising to people, especially when we are all led to believe that Aluminum is “soft” and “inferior”. Nothing could be further from the truth. Aluminum Tooling Myth 1 clearly shows that the hardness levels of Aluminum are comparable to P20.

Phoenix Proto inherited a customer’s problem P20 molding tool that was never able to run correctly, much less efficiently enough to justify the exorbitant cost of $125,000. This Mold was completed with 4 cavities, a hot runner system, and cavity detail that was “Cut in Solid”. “Cut in Solid” means that you basically “get what you get” with no adjustments, and as is. On top of that issue, the P20 Mold was a very large one as was 4 feet high. A large tool like that would require a 400-ton press. The actual component was the size of a bottle cap, about 1 ½ inches in circumference. That is an enormous amount of wasted material; a guesstimate would be ½ ton worth of unused P 20.

The size of the injection molding press needed was also overkill in the best-known injection molding practices. Generally, for cost savings, the smallest-sized injection molding press is used, especially for small parts that, even as a family tool, could be built to run in a much smaller injection molding press.

Generally, you would expect that a four cavity Injection Mold would have a better piece price than a two cavity Injection Mold. This problem Mold experienced such a great amount of scrap that any output gains were essentially lost. To make matters worse, a hot runner system’s costs are generally justified through reduced scrap from runner waste and potential increased cycle times from not waiting for the part to cool.

Once again, this Mold defied common Mold-making 101 logic. The tool ran so inefficiently at a 40-second cycle with such large amounts of scrap the cost of the hot runner system was insult upon injury. Add in that the resin selected was Polypropylene. Unfilled resins generally run smoother in the process than more complex filled resins. This tool seriously jeopardized our customer’s project from every angle.

We normally will take a worn, problem, etc tool and fix it up. We then maintain it till the end of life to help our customer’s bottom line while they are working with us to create an Aluminum Tool that will better suit their needs. In this case, Phoenix Proto recommended that we build a new Aluminum Mold in 7075 materials. We suggested an Ampco core and “case hardened” the cavity detail with a process called Nituff, which took the Aluminum from an initial soft state,
to a 58 Rockwell hardness. The hardness process penetrated the aluminum just .0003, which treated it as a case of hardness and protected wear surfaces and life expectancy. We also used a cold runner system (Tri-Plate with a single gate drop) to further reduce costs for our customers.

The new Aluminum Mold reduced the original cycle time from 40 seconds to 24 seconds. Scrap was also reduced as the process ran smoother allowing for even fills on every part shot. Aluminum’s natural thermal conductivity reduces “hot spots” and “cool spots” in a Mold. Aluminum heats and cools evenly, which is why it is a favorite in the Cookware Industry. The reduction in cycle time and scrap took the piece price from $0.15, down to $0.12. That might not seem like much, but when multiplied by several hundred thousand it adds up.

We initially guaranteed the mold to run 250,000 parts since the resin to be used was Polypropylene. The customer eventually was able to get 800,000 parts with regular maintenance and grooming. This new Aluminum tool saved our customers thousands of dollars, not just in part costs, but thousands of dollars in future mold repairs from the original steel mold.