Initial Cost is what lures companies to get their plastic injection molds and tools built in China over America. What a lot of companies don’t take into account is Life-Cycle-Cost. From what I’ve seen even with materials spec’d out precisely there is a tendency to not get the material properties you requested. So the cost later becomes How many times do you need to repair it due to poor materials? Down-time? Rework costs? Replacement of custom injection mold built in China with the proper spec’d standard component to meet your customers’ requirements?
One manufacturer that I know of had axles breaking in the field they traced it back to poorly heat treated and improper material being delivered from China. They got cheap axles, but how much did replacing their entire product lines axles out in the field cost them? If a component is critical to injection mold life or human safety put a stringent check process in place and refuse delivery until a 3rd party can verify this process.
Today I am currently quoting a redesign of an offshore injection mold. The plastic mold met the customer standards to the letter, however the plastic injection mold does not function to de-mold the parts as would be expected in a North American Market. A plastic molder in a low-labor rate country may find hand de-mold of a product acceptable. A plastic molder in North America would not want to be hand de-molding parts due to high labor cost. Make sure that if you are a North American customer you spec. out what the de-molding parameters need to be. i.e. Automatic vs. Hand removal. End of arm tooling, vs drop to conveyor, etc.
Cycle time is very important to spec out. The issue with the injection mold tooling I mentioned wasn’t really cycle time for curing. It was a plastic injection mold built that wouldn’t eject the part off of core. Typically in the North American Market an injection mold runs fully automatic, meaning after curing, mold opens, ejector systems pushes part off of core by pins or lifters, part falls to conveyor below, or is removed by a robot. This plastic injection mold was designed such that the part was trapped onto the mechanisms and the press operator had to lean in and peel the part off of the steel. This creates a higher cycle time and poor safety condition for the operator. Specify these requirements in your mold RFQ, ask for a video of the first run rather than just receiving a set of finished plastic parts.
