Machines only make money when they are making parts, and two of the biggest losses of production time are setups and tool changes. As shops face more high mix – low volume (HM/LV) part production scenarios, minimizing the amount of time a machine sits idle for these necessary tasks is key to increased overall productivity and profitability, according to Exsys Tool Inc. (San Antonio, FL). Here’s how Exsys describes the challenge and the solution with its Preci-Flex modular quick-change toolholding system from Eppinger, the German manufacturer of high-precision, live and fixed toolholders for CNC turning centers.
For instance, stripping toolholders from a turning machine turret, replacing them to produce a new part and touching tools off to confirm their positions can consume as much as four to six hours. Preci-Flex modular quick-change tooling systems that incorporate a range of adapters engineered to hold a variety of cutting tool types and shank designs can slash those set-up and changeover times from hours down to minutes. They also provide modular adapter systems for quick lathe tooling changeovers and gearbox solutions for a wide range of applications.
The Preci-Flex solution is a tooling system with a single base-holder and multiple tooling adapters that utilizes the ER collet pocket. The adapters have a common connecting feature that locks into standard base units mounted in a turning machine’s turret positions. Preci-Flex was born from Eppinger’s need to reduce set-up and tool change times in its own manufacturing facility. As demand for quality tool holders has grown, the company needed to increase production capacity and efficiency by alleviating the need to remove and re-indicate the toolholders with every tool change. Preci-Flex was the first tooling system of its kind on the market that not only provides the benefits of quick changeovers, but also offline presetting capabilities and better tool reach.
Preci-Flex uses a conical and flat face planar interface with either an adapter or a standard ER collet that enables collets, end-mill holders, expanding collet chucks and shrink-fit tooling to be mounted on a single base-holder in one turret position. The cone face connection guarantees 0.0002″ (mm) runout as far out as an inch from the collet pocket, and every toolholder offers repeatability within five microns. The system also virtually eliminates machine downtime by allowing the adapters to be preset offline. The machine door is only opened briefly to replace them using a T-wrench to install the adapter and tighten four screws while using a hook wrench to keep the spindle from rotating.
The ability to preset offline significantly contributes to increased productivity. Because the machine knows the adapter base position, the process of switching the tool/adapter assemblies in and out of the base units provides extremely accurate tool positioning repeatability. This eliminates the need to re-center, touch off or make test cuts after a tool exchange.
Preci-Flex uses a conical and flat face planar interface with either an adapter or a standard ER collet that enables collets, end-mill holders, expanding collet chucks and shrink-fit tooling to be mounted on a single base-holder in one turret position
Preci-Flex adapters are available for every application. The most common type is an ER standard collet chuck, which is also available in an extended version for use when a job requires the tool to get closer into a workpiece without having to worry about interference. In this situation, a common practice is to use a straight shank extension to extend the collet pocket outside of the spindle, but this application can often cause the end mill to wobble/runout. Preci-Flex allows machine operators to extend the collet pocket reach by 1.870” (mm) without stacking tolerances. And because the spindle supports the adaptor, the result is a much more rigid and stable setup.
Other popular types of the Preci-Flex include an inside nut version, Weldon shank adapters and shell mill holders. The inside nut version features the collet on the inside of the adapter and enables operators to shrink the collet size. This is particularly useful for shops that are vested in ER 32 collets, but need to use an ER 25. With Preci-Flex, they can use ER 25s without having to buy new collet nuts.
Preci-Flex Weldon shank adapters feature a setscrew for a more rigid and highly secure connection. They are ideal for applications where slippage is a problem when using a standard collet during heavy milling and drilling or in high-torque situations. Extended versions of Weldon shank adapters allow longer end mills to be used. This version features more housing space for the end mill to sit into, which, in turn, enables the end mill to extend up to 4.000” (mm) from the face of the collet pocket.
Preci-Flex shell mill holder versions hold an arbor to allow operators to use a CNC lathe to do rough and finish machining. This capability eliminates the need to transfer the workpiece to a milling machine. And the Preci-Flex boring bar version is similar to the Weldon extended version but has more set screws on the outside for increased clamping force.
Use of modular quick-change tooling systems such as Preci-Flex offers real cost-saving opportunities – from less machine downtime to decreased tooling costs. For example, consider a shop with a rate of $250 per hour. A five-hour setup for a single job costs $1,250 in non-cut time. Reducing the set-up time for that same job to 20 minutes, for instance, with a quick-change system equates to savings of $1,000. The system’s versatility allows shops to exchange only adaptors and not entire toolholders, which are more costly and add to a shop’s required tooling inventory.
One of the most important aspects of the machining process is the connection between the machine and tooling. Modular quick-change tooling systems are key to improving efficiency by enabling shops to increase in-cut time. While the initial investment for modular quick-change tooling systems may be higher than that for traditional toolholders, the savings in set-up time alone can have an immediate impact on a shop’s bottom line.