The Impact of Multitasking in Today’s Shops

Continuing advances in multitasking machine tool technology are bringing shops to higher levels of productivity than ever before. The ability to produce parts of the highest complexity in a single setup, limiting human intervention and saving substantial time provides even small shops a cost-effective solution to competing in today’s challenging manufacturing environment.

With a variety of configurations available and builders continuing to offer new designs, shops should be able to find the right combination of components and capabilities to fit their needs. Joe Wilker, product group manager at Mazak Corp., offered us some thoughts on the current state of multitasking technology and how shops can best take advantage of it.

New Features on Multitasking Machines

Among the many features that shops have come to look for in multitasking are twin turning spindles and multiple tool turrets with rotary tool stations and Y-axis off-centerline capability, along with tilt/rotary B-axis milling spindles, rotary/tilt tables and large-capacity tool magazines. According to Mr. Wilker, newer developments include integral-motor roller cam-style turrets, enhanced lower turrets, direct-drive milling spindles and servo-controlled drilling tailstocks. Additional advanced capabilities include simultaneous milling using upper and lower machine turrets and long drilling operations.

Integral-motor turrets that use anti-backlash, roller gear cam drive systems deliver smooth, high-speed, high-accuracy digital indexing as well as expandability. Such versatile turrets typically house 12 tool positions with the ability to expand to as many as 24. Increased tool capacity equals longer uninterrupted run times and the ability to use more common tooling, which helps reduce overall tooling inventory. This turret design eliminates the need for curvic/index couplings, and expandability is possible because the turret indexes digitally to any position without changes to its housing. And once in position, integral hydraulic clamping systems are typically used to ensure maximum rigidity.

As is the case with their upper counterparts, Mr. Wilker states that lower turrets on multitasking machines also continue to evolve and expand in terms of capabilities, along with their tooling capacities. Lower turrets are now more robust and powerful and typically offer as many as nine tool positions with options for live milling spindles.

Some machine builders configure turrets on 45-degree slants. This design maximizes the turret’s machining load capacities and provides ample accessibility to the machine’s spindle and room for part transfers from main to secondary turning spindles.

For increased productivity and part processing versatility, lower turrets can work simultaneously with upper turrets on the same workpiece. Or, lower turrets can work in combination with a machine’s milling spindle that can be applied to either side of the machine’s headstock to further reduce machining cycle times.

Today’s multitasking machine turrets feature rotary tool spindles that implement direct-drive technology that make them faster and more powerful than their predecessors. Direct-drive mill motors deliver spindle rpm that is as much as 24 percent faster, along with torque levels that are as much as 60 percent higher. These capabilities equate to boosts in processing versatility, productivity and tool life along with improved part surface finish quality. Shops can acquire multitasking machines with turret rotary-tool spindles that deliver 10 hp and 6,000 rpm as standard. Or they can opt for those that deliver as much as 10,000 rpm and generate as much as 52 foot-pounds of torque.

The latest NC servo-driven tailstocks enable automated processes. These tailstocks are fully programmable and run on their own AC servomotors and ballscrews. Through part programs, the tailstocks can extend to known positions and with specified approach feed rates and make contact with workpieces at consistent holding pressures. Because of their positive independent drive systems, these tailstocks can also drill holes on shaft centerlines, adding versatility to the jobs a multitasking machine can process.

In most instances, tailstock thrust settings are adjustable in increments of specific foot-pounds of force. This feature allows shops to set thrust levels according to workpiece material and shape to eliminate the risk of part damage while simultaneously providing safe and secure holding and support. Or, shops can adjust thrust settings on the fly while tailstocks are engaged, allowing for drilling, boring and honing operations that would otherwise involve tools in the machine’s tool turret. So, tailstocks with such operational capability, in turn, open up positions in machine tool turrets.

As an increasing number of shops face longer, larger and more complex shaft-type workpieces, multitasking machines can offer extended bed lengths teamed up with innovations such as long drill/tool stockers. These machines significantly boost processing speed and efficiency for those challenging parts.

For deep-hole operations, long-tool stockers allow machines to handle and store multiple tools—typically as many as three, with each about 40 inches in length. Stockers are located above the machine’s second spindle or, depending on machine version, its tailstock to keep tools well out of the way, yet quickly and easily accessible.

Multitasking Machines in Medical Applications

One shop is taking advantage of the benefits of multitasking machining—eliminating manual operations and increasing overall throughput—in the production of its most challenging parts. Lowell Inc. is a medical contract manufacturer in Minneapolis, Minnesota, specializing in implantable devices such as orthopedic implants for the spinal, trauma and extremity markets and cardiovascular parts for mechanical circulatory support and valve repair. These typically very complex multi-component assemblies, such as pedicle screws, cervical plates, cross connectors and left ventricular assist devices (LVAD), are almost all multiple-piece systems in which individual components must function properly when combined with each other. Designs vary from customer to customer, so basically every job at Lowell is a custom one.

The demand for customization and adjustability, along with smaller devices for minimally invasive surgery, presents notable machining challenges. Once the shop figures out how to hold these small parts, it must then machine tiny, intricate, highly complex features into them, regularly using cutting tools smaller than 1 mm in diameter.

To handle these challenging parts, Lowell installed three Mazak Integrex i-150 multitasking machines, grouped in a cell configuration. The machines provide complete part processing capability in a single setup to eliminate manual operations and increase overall throughput. They simplify workholding to only collets and chucks; easily handle parts that vary from one customer to the next; and, in many instances, reduce part machining cycle times.

Each Integrex i-150 features a C-axis CNC-controlled turning spindle, vertical B-axis milling spindle and backworking vise/part support center for turning, multi-face, multi-angle and full five-axis contouring. Lowell opted for the high-speed, 20,000-rpm milling spindles and 72-tool-capacity front-loading magazines for its machines as well.

Milling spindles tilt from -10 degrees to +190 degrees, and C-axis chucks feature ample through-holes that accommodate barstock diameters as large as 2.56 inches. For off-centerline operations, the machines deliver Y-axis ranges of ±3.94 inches. Axis travels of 14.57 inches in X, 17.13 inches in Z and 15.75-inch diameter maximum swing allow the machines to process a range of part sizes and shapes, all within a 91.3-inch by 99.6-inch footprint.

With the three machines configured identically and arranged near one another, machinists can easily move from machine to machine without having to learn a completely different machine or programming language.

On the Mazaks, Lowell generates practically all parts from barstock 0.375 inch to 1.250 inches in diameter. LNS Quick Load Servo 65 bar feeders automatically feed 40-inch-long bars into the machines. The shop chose several machine options that further enhance machine performance. These include coolant chillers, scales on all axes and advanced CNC control features for high-speed machining.

The machines have helped to streamline the entire part machining process, including programming and setup. The part processing versatility and improved throughput allow the shop to continue expanding into new applications.

Defense Takes a Turn, Too

Another shop, LCP Machine Inc. of Bunnell, Florida, is a Tier II and III supplier in aerospace and defense as well as Tier I in oil and gas. It currently processes more than 200 different individual jobs per month, with quantities that range from one to 10,000 pieces. Some jobs repeat, but mostly they are unique.

The company has 14 Mazak machines, the most recent ones being a Quick Turn Nexus (QTN) 350-II MSY multitasking machine and some Vertical Center Universal (VCU) 400 5X and 300 5X full five-axis vertical machining centers. The multitasking machine features milling and Y-axis capabilities as well as a second turning spindle to process each of LCP’s parts in a single setup.

Other machines on the floor include multitasking QTNs with milling capabilities, three-axis Vertical Center Nexus (VCN) vertical machining centers and a VCN Compact vertical machining center.

LCP makes most of its parts from aluminum, stainless and nickel alloys, along with brass, copper and several common types of plastics. Parts measure anywhere from 0.030 inch to 18 inches in diameter, and 60 inches long. Tolerances can range from ±0.001 inch to as tight as 0.0002 inch, and machining times vary from 10 seconds to as long as eight hours.

Using technologies such as multitasking and full five-axis machining, the shop often completes parts in single setups. One such part is an enclosure for a military sonar device machined on the QTN, which was acquired specifically for that job and can produce the part for half the cost of the shop’s previous capabilities. The shop runs about 10,000 of these parts per year.

The sonar part requires OD and ID turning and some milling. The real challenge is the ID surface finish, which LCP first thought would require the part to be farmed out for honing. The honing operation would have added extensive time to the job. But knowing the capabilities of the QTN, LCP explained to the customer that acquiring the machine would allow the part to be made in a single operation while maintaining the required surface finish in only the necessary areas, thus staying well within the customer’s price point while leaving LCP a comfortable profit margin. The machine can complete one of these parts in minutes.

As a precision shop in the production of aerospace and defense components, along with those for oil and gas and other industries, LCP knows its customers will continue to demand higher quality and lower prices. It depends on multitasking technology to deliver on these requirements.

Doing More with Less

When machine tool builders refine and improve upon multitasking machine designs, processing versatility increases, and the core benefits of multitasking are further enhanced. Combining operations reduces inaccuracies that can occur when moving parts across multiple workstations and eliminates work-in-process inventory that might otherwise linger between standalone machine tools. As seen in many cases, multitasking machines are allowing shops to accomplish more with less and boost competitiveness.