Green means go: Turning Performance

When manufacturers look for ways to improve machining productivity, they usually start with metal cutting efficiency. But machine utilization has an equally, if not more, important impact on productivity. A stopped machine directly affects production output, and the only time that a machine makes money is when the green light is on.

So what are the typical time killers that keep machining time and profitability low? Setting up machines for a new batch of components, measuring and touching off tools, adjusting coolant lines to get coolant to the cutting area and not having backup tools when a crash happens all contribute to lengthy downtime. Also, machining operations can be interrupted for changing out worn cutting tools, removing chips or changing components.

How cutting tools are loaded and measured has a major influence on machine utilization. Relying on traditional toolholders requires much longer stoppages, more often, to change out tools and set up a machine — anywhere from five to 30 minutes depending on the tools and application. That time lost can add up quickly to a lot of unproductive, unprofitable hours that could be avoided.

Quick-change tooling solutions can increase machine utilization in industries that use complex assemblies and longer tools, such as aerospace engine component production, by reducing the time that it takes to measure, set up and change tools. Image courtesy of Sandvik Coromant

For this reason, quick-change toolholders are becoming an increasingly powerful way to reduce downtime and improve productivity. Today’s solutions do more than reduce time spent on measuring, setting up and tool changing — they also can offer a range of features that improve metal cutting efficiency, tool life and maintenance.

Speed Up Setup Times

CNC lathes and sliding head machines have fast tool indexing, but they often have lower utilization than machining centers because of the time that it takes for setup and tool changes. Here, quick-change solutions can make a big impact on utilization by dramatically reducing changeout times. Swapping turning tools may go from 10 minutes to 30 seconds, and driven tools might go from 20 minutes to 30 seconds. There are even more advantages for boring bars, which can be more time-consuming because of center height setting and coolant plumbing. With a quick-change solution, they could be changed in less than a minute, with better accuracy.

But how do you achieve these advantages? There are a number of features to look for in a quick-change solution that will ensure faster tool changes and setup times. The stability and sophistication of the coupling design play an important role. Designs that use loose parts like pins can mean more fumbling with changes and less accuracy. And couplings that rely on moving parts like ball bearings may wear out more quickly.

The coupling design in Sandvik Coromant’s Capto system, for example, uses a triangular polygon shape with a tapered contact surface for quick, accurate positioning within 2 µ. The coupling locks into place and centers itself by locating off of the three polygon lobes. The large contact area of the coupling also improves rigidity and maximizes even torque transmission. With this patented design, clamping the cutting unit in a static or driven toolholder can be achieved manually with a quarter turn of a hexagon key or with an automated solution in a machine tool spindle.

Improve Flexibility

Other critical features that manufacturers should look for in a quick-change solution are range and modularity. Some toolholders may offer a quick-change solution for one machine or a specific tool size, but a piecemeal approach will greatly limit your time-saving opportunities to improve utilization.

With advances in quick-change design, toolholders can use high-pressure jets to deliver coolant, which not only cools the cutting tip but helps break chips and improve chip evacuation. Image courtesy of Sandvik Coromant

Systems like Coromant Capto, for example, offer a full range of quick-change options, extensions and reductions for all types of turning and rotating tools. The system also provides a universal coupling design to enable the use of quick-change solutions interchangeably on any machine. This added flexibility considerably increases the area of opportunity for faster tool changes and setup times, especially for industries that use complex assemblies and longer tools, such as aerospace.