Dynamic machining, automation, software help match machine choice to applications
Shop owners are pretty careful when it comes to spending their dollars on the latest machine tool technology. In the past that has often meant filling their shop floors with machines requiring the least initial investment and overpowering their demand requirement with numbers of individual machines. A lot of machines, typically vertical machining centers, handled a wide variety of jobs on dedicated machines.
Today, advances in horizontal machining center technology have changed the numbers game. Examples of new HMC technology include high-torque and high-speed spindles, automation with integral twin pallets, pallet pools, FMS stockers, robots, and gantry loaders and unloaders. Shops can also add in software that can optimize scheduling for cellular automation, capture data for self-diagnosing maintenance, and monitor machine conditions. And when you complete that package with dynamic fixturing like rotary tables on trunnions for five-axis simultaneous profiling and five-sided machining, you have all the ingredients for mixing and matching machines to your specific applications.
New HMC Series for Five-Axis Production
There’s a sweet spot in machining automotive parts that applies equally to general engineering applications. To meet the requirements of five-axis machining of complex prismatic parts, Heller Machine Tools (Troy, MI) has introduced two new models in its HF Series five-axis horizontal machining center line. “HF-Series machines are designed for machining automotive parts including axle parts, steering column housings, and angular machining for holes,” said Markus Schlipphak, Heller vice president-engineering.
The two models, the HF 5500 and HF 3500, are aimed at the popular work envelope sizes of 900 × 950 × 900 mm (HF5500) and 710 × 750 × 710 mm (HF3500), respectively. Workpieces range from lighter and smaller to heavier, up to 800-kg table load. The fifth axis of the two machines is provided by the workpiece on a swiveling trunnion with a rotary table or a pallet changer for higher volume production. Users can choose from a range of four spindle packages based on the material they are processing. Spindle speeds up to 18,000 rpm and torque up to 354 N•m are available.
“With three linear axes in X, Y and Z and two rotary axes in A and B integrated into a rotary table on a trunnion, the HF machines are designed for five-sided machining and simultaneous five-axis machining. The HF machines may alternatively be equipped with a lift-and-rotate pallet changer for series five-sided production. Standardized pallet automation solutions may be supplied by Fastems or Schuler,” said Schlipphak.
Unlike conventional five-axis machining centers, Heller’s HF Series is not only based on single-part clamping but also provides the possibility of multiple clamping or the clamping of very large components, such as transmission cases using “window-type” fixtures.
Boring Mill Replacement with HMC Bona Fides
According to Joe Kraemer, manager of national accounts, the new HCN 16000Q from Mazak Corp. (Florence, KY) is a true boring mill replacement with all the symmetrical design elements and fast and accurate performance characteristics of a horizontal machining center. “The HCN 16000Q features a 130-mm diameter quill with 550-mm of W-axis travel for machining deep inside workpieces with shorter tools. For stability, reliability, and accuracy, the HCN 16000Q’s double-column design centers the quill head to eliminate potential problems resulting from overhang or imbalance, problems which are typically associated with traditional boring machines,” said Kraemer.
“The quill provides a lot of production advantages for large, long workpieces like those typically found in the oil patch for fracking pumps, as well as meeting the parts machining requirements of the major mining, construction and farm equipment builders. The quill provides the reach that enables machining with heavy, shorter tools without exceeding the machine’s ability to handle them,” said Kraemer. Machine workload capacity is 8000 or 10,000 kg depending on the pallet model chosen, either single or twin-pallet.
“The 16000Q is equipped with an automatic attachment changer that increases part processing flexibility through the use of various special operation attachments such as U-axis boring tools and facing heads, U-axis OD turning heads, including Davis and D’andrea heads,” said Kraemer. “The speed of our new Smooth CNC controls and spindles with their own servodrives enable us to synchronize the rotation of a boring bar with the insert on the outside of the bar with the X–Y axes for OD turning or even machining tapers,” said Kraemer.
The HCN-16000Q can be added to existing manufacturing cells, including those with dissimilar machines such as the Mazak e-Vertical and Integrex series of machines. And when the HCN-16000Q is part of an automated Mazak Palletech cell, the machine further increases the cell’s overall versatility with the addition of deep boring and U-axis machining capabilities.
Industry 4.0 Technologies Inform All Machining Platforms
Industry 4.0 (i4.0) software is the latest technology that DMG Mori is leveraging on all of its machining platforms, not just HMCs, according to Jeff Wallace, general manager, DMG Mori USA National Engineering (Hoffman Estates, IL). “With our latest control platform, CELOS, we are able to collect and analyze real-time data from the HMCs,” he said. “Not only are we collecting the basic machine telemetry (i.e. spindle uptime, machine in cycle, machine in alarm, etc.), but we also have sensors embedded in almost all of the components of the machining centers so that we are now monitoring the condition of ancillary equipment such as coolant pumps, lubrication systems, column and bed.”
What the future holds for HMC technology is very much dependent on requirements of manufacturers and their changing strategies. “We are seeing benefits across almost all industries, from low part number count/high volume, to high part number count/low volume. With sophisticated cell controllers and the ability to schedule any job in any quantity, dedicated cells are no longer required,” said Wallace. “The ability of the machine to ‘self-diagnose’ any maintenance that is required and the real-time monitoring of the machine condition and its production status gives the customer the ability to not only schedule production based on current capacity, but also to optimize unused capacity and schedule maintenance on [their] schedule and not have to react to a critical failure after it occurs.”
DMG Mori’s latest solutions are not just software related. “New advancements in spindle design and spindle production have allowed us to reduce the size and power consumption of our spindles and, in most of our designs, we have actually increased the performance with no increase in operating costs,” said Wallace.
HMCs, by design, are very productive as most have pallet changing systems as standard, according to Wallace. However, integrating HMCs into LPP (Linear Pallet Pool) systems increases productivity and pushes spindle utilization as high as 95% is some cases. Automation solutions range from simple two-pallet systems to complex hives of dozens of pallets and machines in the same system.
Matching Machines to the Work at Hand
Errol Burrell, HMC product specialist, Okuma America Corp. (Charlotte, NC), describes Okuma’s two types of HMCs: “The MA Series of horizontal machining centers are very stiff and rigid for heavy-duty cutting. The MB Series is designed for dynamic machining and high-speed cutting. The latest addition to the MA Series is the MA-600II, which incorporates powerful high-torque spindle options for high-volume material removal rates. It’s available with an HSK-A100 20,000-rpm spindle that boasts 50/55-kW power for everything from heavy-duty cutting to fine precision work on aluminum alloys, cast irons, and difficult-to-machine materials.” The MA-600II allows for steady milling, boring, drilling, and tapping for applications from mass production of parts to long, continuous cycles for die/mold.
Burrell foresees a future in which automation between machines of different types will be readily integrated into cells using a universal pallet system, mixing horizontals with verticals or five-axis machining centers. “Interest in automation on all of the horizontal machines is coming from across the board, from the smallest to the largest shops,” he said. “Automation isn’t out of reach for even the smallest shops.”
Okuma HMCs feature rotary pallets, pallet pool systems, Fastems systems, and robots for machining large mold and die work as well as high-volume production. Flexible manufacturing can be achieved via 6–12 multipallet APC units and multiple matrix magazines that hold up to 400 tools.
“We’re not a one-size-fits-all machine tool builder. It’s important to ask the customer what kind of work is coming through the shop and matching the right spindle and machine to that workload,” said Burrell. “We offer a 6000-rpm, high-torque spindle for machining Inconels, titaniums, and high-temp alloys, for example. For aluminum and a wider breadth of materials we offer a 15,000-rpm spindle for high-speed machining.”
HMCs Designed to Adapt Easily to Automation
“What I see for Makino’s horizontal machining centers is the need to maintain the ability to adapt stock machines to fit into a changing marketplace,” said John Einberger, horizontal machining center product line manager, Makino Inc. (Mason, OH). “For example, we often see a need to adapt standalone machines to operate in an automated environment. It’s the loudest call for change from our customers. To accomplish this, we pay a lot of attention in HMC design to make them easy to retrofit automation support options such as auto doors, fixture hydraulics, and coolant wash systems both quickly and cost effectively. As another example, we make it easy to integrate machines initially installed as standalone units into our MMC2 pallet handling system or the MMCR robot loading cell. We also offer a retrofittable robot interface that allows our machines to be integrated into an automated system managed by a master cell controller,” said Einberger.
“Our design choices are intended to maintain and increase performance levels while becoming more reliable from a total cost of ownership point of view. Our customers expect it, and we’ve been able to achieve good results with something as simple as designing our HMCs to use single-piece way covers wherever possible to significantly increase the reliability of this often problematic machine element in a high-volume environment,” said Einberger. “Moving forward, there is an increased focus on collecting data about machine performance for maintenance predictability, again with focus on reducing the total cost of ownership for our customers.”
Greater Efficiency, Stability Sought in HMC Technology
According to Bernie Otto, KIWA products manager, Methods Machine Tools Inc. (Sudbury, MA), today’s manufacturers are striving to achieve the highest levels of efficiency while increasing their productivity. There are many ways to approach these goals, including choosing reliable machines with greater capabilities, increasing automation and even adding technologically advanced accessories.
To achieve a reliable machine, builders consider machine stability in their design. One example would be the KH4500-PC6 HMC, equipped with coolant-through ballscrews. Chilled ballscrews allow a machine to be more thermally stable over longer periods of time and thus more accurate.
With reliable machines in place, large and small job shops are always looking for additional ways to be more efficient, thereby utilizing fewer people and resources. Automation is one way to increase efficiency and can come in many forms. “The efficient use of compact pallet pools allows the staging of additional pallets outside the work area. This allows the machine to run untended for longer periods of time and reduces the changeover time between jobs,” said Otto. “Also, adding more tools, either up front or in the field, allows the machine to run more jobs unattended, even with multiple programs staged to run on a mix of pallets.” He went on to say, “adding an additional rotary table to an HMC provides for 4+1 programming capabilities, coupled with the benefits of cutting efficiently on a horizontal.”
Harnessing technology can also allow manufacturers to do more with less. Implementing wireless technology accessories, like a KME CNC wireless tombstone with multiple indexing heads, can greatly decrease changeover time while increasing machine capability. With no wires or cables to bring into the work area, getting the tombstone—equipped with its additional axis—in and out is quick and efficient.
Hybrid Technology Leads to High MRR
Mitsui Seiki USA Inc. (Franklin Lakes, NJ) has adopted hybrid machining for its HMC platform in the form of GE’s Blue Arc electro-erosion metal removal technology. “The beauty of Blue Arc is that manufacturers will be able to realize higher metal-removal rates compared with conventional milling of difficult-to-machine materials,” said Robb Hudson, CEO of Mitsui Seiki USA. “Machining goes back and forth between Blue Arc and conventional milling with the heavy-duty roughing being done by the Blue Arc process. The result is that there are significantly lower perishable tooling costs when machining more difficult-to-machine materials like nickel alloys, tool steels, stainless steels, titanium, and other hard metals.” Applications that could benefit from the Blue Arc hybrid technology for roughing very large workpieces include aerospace (airframes and engines), industrial gas turbines, oil and gas, and die/mold.
Also, automation systems and software for HMCs have become more sophisticated. “Automation systems from Fastems and Liebherr, for example, link multiple HMCs into FMS lines so customers have maximum flexibility. They can run large families of parts, increasing spindle utilization from 80% to more than 90%,” said Hudson. “For scheduling, the larger automation companies have created their own sophisticated software. For example, a Fastems system can load weekly and monthly production across a family of parts and automatically optimize spindle utilization.” If production requirements change for a week or a month and a shop needs to accommodate a component with higher demand, the software will recalculate and maximize spindle utilization to the new production requirement.
Shops Beginning to See Impact of HMC ROI
The days of contract manufacturers packing their floors with vertical machining centers because of a lower initial cost and their ready availability are coming to an end, according to Don Langley, Midwest regional manager, Doosan Machine Tools America (Pine Brook, NJ). “A lot of owners are beginning to see the value of the horizontal machining center in terms of ROI and the ability to fit into crowded floor space,” he said. Doosan recently introduced its NHP4000 and NHP5000 40-taper HMCs with 400 and 500-mm pallet configurations and targeted for high-precision automotive applications with automation.
“Demands from our customers, whether in medical, aerospace, or automotive, are essentially the same. They want quicker ROI, increased production capacity, more spindle time with fourth and fifth-axis machines, and automation with pallet changers,” said Langley.
Like other machine builders, Doosan sees the trend of manufacturing coming back to the US. Automation is a critical part of the process. “Horizontals today are being set up to accommodate modular linear pallet systems, matrix-style tool changers with multiple tool magazines, as well as robotic interfaces for loading and unloading machines,” said Langley. “More and more multiple HMC platforms can accommodate fourth and fifth axes on the table or in the actual head. Our goal is to meet customer needs for best performance, lowest cost of ownership, and increased reliability through the use of industry standard FANUC drives, servos, and thermal compensation.”