Indexable inserts give considerable efficiency boost

Automakers typically manufacture over a third of their stamping dies in-house. Making these tools is time-consuming and, with some 750 of them required to build a car, a major production bottleneck. Today, shorter lead times, more models and tight budgets have made this process even more critical.

Kenneth Rooth, an auto industry veteran, has seen auto industry tooling go from wooden models and plaster molds to CAD manufacturing and efficient 21st century production. He knew that much of this cutting and milling work was done by individual operators, with much manual finishing, something that requires great skill and a good deal of time. The result was not only higher costs, but also lower standardisation. The quality and fit of a right door could vary from a left door if two different operators were programming the machines.

Sandvik Coromant was given the assignment of finding a way to bring costs and lead times down and quality up. A new process was developed with new tools and machining processes. The results: machining times were cut by over 30%, manual tool polishing was totally eliminated and other manual machining was reduced considerably.

Perhaps the largest savings in machining stamping dies can be found in new methods for material removal. Here are a few examples of measures that helped make Kenneth Rooth a hero in cost cutting.

Round insert milling cutter

A common rough machining method on 3D surfaces is to use a ball nose cutter in a copy milling operation at varying depths of cut. In combination with long overhangs from the spindle nose, this puts excessive stress on the cutting tool and machine spindle.

By switching to a contouring tool path using a round insert cutter, a higher metal removal rate can be achieved by taking advantage of the larger number of effective teeth. A constant axial depth of cut gives a more even and constant load on the spindle, allow process optimisations to be made.

Faster hole making on die shoes

Holes are traditionally drilled with high speed drills in cast iron die shoes. Since die shoes often contain lots of bolt holes and eye-ley holes etc, the total drilling time is usually long. By replacing these drills with an indexable drill such as CoroDrill 880, huge productivity improvements can be achieved, even in dry machining.

Plunge drilling in a trimming steel

Traditionally, these oval hole features are made with a high-speed steel drill, and then widened with a milling cutter. CoroDrill 880 replaces this combination by using an intermittent plunge drilling operation to widen the hole. This method removes 85% of the material, in much shorter time, leaving the rest for a traditional round milling cutter.

Lifter feature

The standard method is to make the hole with a high-speed steel drill, followed up by a solid milling cutter to open up the feature. Instead, we chose to drill straight down with an indexable insert drill (CoroDrill 880) and then widen the slot with an indexable plunge cutter (CoroMill 210).  A highly efficient trochoidal milling method was then used to remove as much material quickly, at large cutting depths and at the more narrow part of the slot.

Taking advantage of the CoroDrill and CoroMill system with its excellent stability and modularity makes it possible to optimise your tool assembly.