by Nick Bergmann
Live tool adaptor systems reduce the 7+1 wastes of Lean
High quality tool adaptor systems offer a viable solution to manufacturers looking to remove waste from their processes and improve profits. When using them, machine tool operators load cutting tools into removable cartridges that are then loaded into a live tool station chuck as opposed to loading the cutting tool directly into the chuck. Incorporating the use of these adaptor systems into the manufacturing process makes tooling changeovers quick, accurate and provides increased flexibility that can have far-reaching effects in each of the 7+1 wastes of Lean Manufacturing.
Transporting cutting tools and toolholders between machine tool work stations and tool rooms can be a noticeable drain of resources. Typical preset live tool holders can range in weight from 4.5 to 27 kg (10 to 60 lb), and many of today’s machines have multiple stations and turrets. Tooling 36 stations on a turning centre that has three turrets with 6.8 kg (15 lb) toolholders, for instance, requires transporting a total of 245 kg (540 lb) to set up a production run.
Using an adaptor system eliminates unnecessary trips to and from the tool crib and reduces the amount of weight needing to be transported. Each adaptor weighs about .5 kg (1 lb) and can be transported on a small hand cart. In the example of the three-turret machine, the operator now transports only 16 kg (36 lb) instead of 245 kg (540 lb), a 93 per cent reduction.
Inventory, including work in progress (WIP), adds costs for manufacturers. Quicker tooling changeover times made possible through the use of adaptor cartridges can be an effective method for improving work flow and reducing excess WIP by producing smaller lots sizes.
Quick changeover times offered by adaptor systems enable flexibility to use machines intermittently, work parts through the production process more efficiently and reduce work-in-progress inventory. Here, instead of making all pieces of the part with the largest lot size, the manufacturer can make just 250, then changeover to another part while those first 250 pieces continue to work through the process to maximize machine use and reduce WIP inventory.
Machine operators spend countless hours setting up workholding fixtures, aligning tool holders and probing offsets. A reliable adaptor system can reduce machine downtime by eliminating, combining and modifying steps.
When using a traditional ER collet system, the first step for setting up a live tool is to clamp the cutting tool either with or without a presetter.
Not presetting the cutting tool’s length requires probing the offset and changing it in the parameters. Each time a machine operator removes the toolholder and puts it back in the same station, it must be realigned to ensure it is repositioned within microns. Loading the cutting tool and aligning the tool holder requires several hours for one 12-station turret, even longer on a multi-turret machine.
Machine operators can eliminate efforts by presetting adaptors offline for the next job while the current job is running and leaving the live tools in the turret where they are already aligned. Presetting adaptors is easier, faster and just as accurate as presetting the entire live tool.
Live tooling emergencies can result in significant downtime and lost production while manufacturers wait for replacements or repairs. Purchasing a spare unit is often a good investment that enables continued production while the original unit is being repaired.
Another way to eliminate unplanned downtime and waiting for repairs is by adhering to regular preventive maintenance. Sometimes, however, when live tools get switched from machine to machine, it is easy to lose track of how many parts were produced with the holder and how long it has been in service. Keeping the holders in the machine while changing adaptors makes tracking of the live tool usage per machine easier.
Live toolholder adaptor systems can support Just-In-Time (JIT) manufacturing by reducing lot size, balancing workstation capacity and reducing set up times. Adaptor systems enhance tooling flexibility and maximize the usage of live tooling. Many manufacturers use an assortment of adaptors to create a buffer for incorporating new jobs intermittently between an already established production schedule, which can help reduce the build-up of WIP inventory and create flexibility to meet customer demands.
Some parts are complex and require a variety of machines to render a finished product. Using an adaptor system with live tools can help manufacturers avoid over processing by eliminating or combining operations. Today’s mill-turn machines easily manage the turning and drilling processes, but require extra effort to complete the milling operations. End mills usually have a Weldon Shank or a Whistle Notch style shank, but use an ER collet for clamping. The Weldon and Whistle Notch are designed to be secured using a set screw for greater clamping force and to avoid pulling or slipping of the end mill while cutting. Using a collet negates the purpose of the set screw. An adaptor system can make a mill-turn machine more flexible by enabling convenient switching from ER collet to Weldon to Whistle. Securing the end mill with a set screw not only eliminates pulling and slipping, it also allows for deeper cuts and faster feeds.
In JIT manufacturing where smaller lot sizes are produced, the quality of each piece becomes more important. Systems must provide adequate torque transfer, the right amount of overhang, and be well-machined to provide the desired level of performance and quality. Systems without adequate torque transfer can loosen or fall out of the live tool as a result of vibration. The adaptor will attempt to absorb all the vibration during the cut instead of transferring it back to the turret/machine, which can destroy the adaptor system and lead to defective parts.
Systems with too much overhang can cause the cutting tool to flex during operation and leave chatter marks on the workpiece. Too much overhang also creates excessive vibration that can transfer back to the machine with negative consequences to the drive system. This could lead to a much costlier repair than the live tool and adaptor. High quality adaptors will provide excellent repeatability and low runout.
The underutilization of talented people is the unofficial eighth waste in Lean Manufacturing. Use of a high-end adaptor system makes the production process smarter and more efficient and enables manufacturers to reallocate human resources.
Using a high quality adaptor system will result in higher productivity and greater ability to satisfy customer demands for faster delivery of high quality parts. SMT
Nick Bergmann is general manager at EXSYS Tool Inc.