Striving for Faster Changeovers for Multispindles

While extremely productive, one of the pitfalls of traditional cam-driven multispindle machines is that they require an incredible amount of finesse and expertise to dial in and set up.

The latter point — setting up for a new job — is exacerbated these days given the manufacturing skills shortage/lack of experience operating mechanical multispindles, and trend away from low-mix, high-volume jobs to high-mix, lower-volume jobs which require more frequent setups.

This is one of many reasons why Davenport Machine (part of Brinkman International Group Inc.) developed its Hybrid multispindle, which combines the high production speed of a cam-driven machine such as its Model B with the precision and repeatability of computer control as well as simplified tooling concepts to help speed job changeovers.

In fact, the company says its research has shown that the average setup time for its five-spindle Hybrid machine is 50% less than traditional mechanical machines. Often times with Model Bs and other mechanical multispindles, setup times can take a full shift — 8-12 hours. With the Hybrid platform, Davenports says it has many examples with the Hybrid platform in which those setup are 4-5 hours, enabling customers to get back to production much faster than before. On repeat setups within a family of parts, Davenport has performed changeovers in as little as 25 minutes.

One reason is its modular tooling system which starts with form toolholders (available in 13-, 20-, and 24-mm sizes) for the first and second spindle positions using the company’s latest dovetail interface technology. The holders are fully adjustable for center height and taper and can use standard carbide inserts available from any major cutting tool manufacturer. Inserts can be swapped out quickly, the company says, and holders can be adjusted faster than traditional circular form tools or even Davenport’s previous iterations of dovetail holders.

The new dovetail toolholders have hard stops for length control, making holder swaps faster. Taper and center height are locked in at initial set up. Adjusting for size is also far easier for operators now. Instead of turnbuckle adjustments, size is now adjusted digitally on the CNC in 0.0001-inch increments.

In addition, traditional shave tools have a long setup process, which entails adjusting the roller mechanism and cutting the tool itself to a specific size. These tools require quite a bit of finesse and skill to set up properly. The Hybrid has consistently shown the ability to hold forming tolerances in high-temp alloys to 0.0005-inch or better. The ability to profile turn in multiple positions (3rd position, 4th and sub-spindle) provides high levels of precision, the company says.

In addition, CNC cross-slides in the third and fourth spindle positions accept standard, off-the-shelf turning, grooving and threading inserts, and can be adapted to hold boring bars for ID undercuts and grooving as well as round shank toolholders for forming. The setups of these CNC slides allow far more flexibility to move away from specialized tooling and can enable shops to start a new job in a pinch using standard tools.

In fact, the third spindle position features a three-axis cross slide that can use either a two-tool live tooling station for milling-type operations or a dual-stick tool mounting block to provide additional turning flexibility. These compact toolholder configurations enable them to be swapped much faster than bulky bolt-on attachments developed for traditional cam-driven multispindles. Attachment swaps require no major bracket changes like with some of the old Model B attachments. The mounting interfaces always remain in the machines, and all of the attachments use dovetail interfaces and can be removed/changed by taking out two bolts.

Plus, end working spindles on the Hybrid almost exclusively use the company’s Quick Change Toolholder (QCT) technology. Capable of accepting a range of ER collet sizes, QCT holders can be preset/measured outside the machine speeding and simplifying tool changes. Tool offset data is set through a control teach sequence and is then saved in the position specific program page. Plus, the holders can be added/removed with a quarter turn of the toolholder, locking into the taper, and two set screws.

Finally, the Hybrid’s CNC with 15-inch touchscreen runs control software developed (and modified and updated) by Davenport. Each slide axis can be programmed independently. Tool-to-spindle offsetting can be performed to adjust each spindle for part diameter and length. Once set, this offers global offsetting capability for each tool at each spindle to adjust for tool wear, for example. The control system also offers functions such as part counting, stock depletion sensing and spindle load monitoring.

Halving setup times has enabled Hybrid users to consolidate traditional machinery and pursue higher-mix/lower-volume work. The company says this opens up new doors that traditionally weren’t available to multispindle users. But in addition to technology to help speed setups, this multispindle machine platform has been upgraded in other ways since its introduction in 2017. This includes the addition of a three-station backworking axis and servo pickoff spindle as well as design elements to enable the Hybrid to effectively handle stainless steels and other high-temp alloys.