Real-Time Mold Production
An automated five-axis machining/EDM cell offers a cost-effective alternative to series and batch mold manufacturing.
Today’s mold builders must focus on quality, cost and delivery in order to improve productivity and remain competitive in the marketplace, but how is this best accomplished? In the past, moldmaking revolved around the individual skills of master moldmakers, but today that pool of craftsmen has grown ever smaller, and fewer or no replacements are entering the market. Shops end up having highly skilled tradesmen operating an EDM for 10 hours a day instead of running unattended 24 hours a day, or they add a second or third shift and are challenged with ensuring the same part quality across all shifts. Let’s face it, one highly skilled craftsman operating one or two machines for an entire shift is not very cost-effective.
Then there is the matter of time and delivery to market. Still today, mold construction is completed in series. This means parts are rough-machined on various pieces of equipment (knee mills and CNC VMCs) then heat-treated. This is followed by finish-machining on surface grinders, machining centers, and wire and sinker EDMs, and then mold polishing. This series manufacturing also includes electrode design and manufacture, after the number required for each detail is determined. This might include, for example, one roughing electrode for each part and two electrodes (or more) to finish the detail. Better yet, three finishing electrodes per part plus a few spares is a smart way to go, just in case. You don’t want to be caught short in the middle of a run and have to make more electrodes.
The series approach can also be combined with batch manufacturing. This entails setting up a part at a certain orientation and machining a feature on all of the parts, then breaking down the setup and repeating, machining another feature at a differ-
ent orientation. When the batch of parts is complete, the process is repeated again for another feature or orientation. The mold is not complete until the last part in the batch is machined in the final setup. The manual setup and tear-down of the operations for this approach increases both time and costs.
An Automated Alternative
Take, for example, a 32-cavity mold for which the operator sets up the first operation and machines all 32 parts before moving on to the next operation. Each part goes through four machining operations, in series. Each setup for the operation takes 15 minutes, and each operation takes five minutes: