The manufacturing sector is moving toward greater automation is inexorable, as unmanned machines offer increase productivity while reducing waste. Before 2015, about one in 10 five-axis universal milling machining centers sold by GROB Systems Inc. featured automation, but now nearly half do. Under pressure to reduce scrap and increase throughput, smaller job shops often lack the budget for higher-end five-axis machines. Now, new five-axis machine technology is available to help them evolve in this Industry 4.0 era of machine monitoring and connected machines.
High-productivity machining — GROB Systems’ new Access Series five-axis machining center is an example of entry-level five-axis machine technology being developed for job shops: it offers many of the features of high-end machines but at a price that results in a short payback time.
With the new technology, job shop owners and operators can maximize spindle utilization, including keeping machines running when no one is there. For example, if they are changing a part at first shift, they can keep the machine running without an operator for several shifts, resulting in less cost to the customer. In addition to automated production runs, the flexible machine can be operated in manual mode for part set-ups, prototyping, or small-batch runs.
Three linear and two rotary axes permit five-sided machining, as well as five-axis simultaneous interpolation. The axis arrangement provides a large swivel range, larger than most other options for positive angle of solutions. For negative angles, two options give good access to the part without having to make different fixtures and compensate in other ways. This means the largest possible part in the work area can be machined with maximum tool length.
The compact machine concept provides smaller job shops with a small footprint, but with features often found only in larger machines. One feature is a rigid spindle axis, designed so the machine is most rigid at the part, thanks to an optimally positioned bearing close to the operating point. This rigidity at the part means the machine can remove material faster, with less vibration and a more constant process. The rigidity also reduces tooling costs, enabling operators to be more productive, and increasing the profit from the machine.
Another design feature is a long Z-travel path, which enables tool change to happen outside of the work area. Many other designs require tool change to occur in the work area, which provides a smaller available area for the part. The new machines provide 1,020 millimeters of Z-axis travel – the longest in this machine class – while competing machine models range from 400 to 650 mm.
Active cooling of heat-absorbing components and assemblies makes for efficient machine cooling, and a unique overhead machining function offers excellent chip fall and reduced thermal load in the component. Operators may choose between Siemens and Heidenhain machine control systems.
The reference axis’ linear guidance system can be equipped with a temperature-controlled cooling function, and a wide-opening work area door ensures safe and ergonomic access. The machining process is viewed through a laminated safety glass.
Most flexible job shops need tool storage capacity, and the new technology offers a variety of options for storing tools inside the machine. The single disk option enables job shops to hold approximately 50 tools around the outside of the disk; the double disk option increases tool capacity without making the machine bigger.
The machine uses GROB’s Swivel Axis Calibration (GSC) technology to locate and compensate for volumetric errors. Unlike technology that can compensate for four positions/compensation points using the controls, GSC is freely definable and can compensate for 40-50 positions/compensation points.
The entry-level five-axis technology can run on the same platform as other machines, which can all be connected to the same automation. Since operation across the range of machines is identical, operators and maintenance staff already have familiarity, making transition easier.
Low-investment linear pallet storage — The entry-level five-axis machine technology is available with a linear pallet storage system (PSS-L) that can be used for a wide variety of part types. Flexibly configurable according to user requirements, the PSS-L provides a complete solution from a single source, in a standardized design and an interface optimally matched to the machine.
The PSS-L is a modular system for individual machines or for interlinking the same machining systems. It can be used with different machine types, numbers of machines, and numbers of set-up stations. Users can customize the mechanical layout to make it fit plant or part requirements and can customize the software. For example, if the user has a database for tracking fixtures or tooling offsets, the machines can communicate with the database and control that data. Up to five machine tools can be connected to pallet-storage racking with a maximum of 87 pallet positions. The PSS-L also can operate as an independent machine.
The PSS-L provides a longer and unmanned production period and allows optimal access to the machine’s work area during automation, for example, for manual loading or set-up work.
Customers can connect a mix of machine types on one line, keeping all operations in the same system, performing them all in the same cell. For example, they may perform part-turning first, then move to a milling-only second operation. If they want to segregate operations between machines they can do so. The key is that they do not have to remove the part from a lathe for turning and then move the part over to the linear system.
The PSS-L features a linear traveling pallet changer system with a pallet gripper to transport the materials between setting stations, workpiece deposits and machines. It does not use any cable track and the pallets are staged close to the machine to prevent long exchange times. An easily accessible set-up station features crane loading capability.
The system also comes with production control software, so users have a simple, intuitive organization of pallets and parts with associated process steps. Customers can have autonomous part and pallet control while considering resources, along with monitoring and verification of tool resources for all scheduled orders.
Proven in the field — The new technology was launched in September 2019 and already is being used in Europe and Asia. One example is an aerospace repair center in Poland, which did not have the budget for a larger machine and is using the new unit for engine repairs and overhaul.
A U.K. aerospace manufacturer purchased a unit because it liked the idea of getting all its machines from one supplier. They had several large GROB machines and will use the smaller units to automate all the existing machines, which are used for manufacturing aerostructure parts.
A mechanical engineering firm in Germany looking for a lower cost solution opted for the Access unit to manufacture parts for their own automation products.
A final example is a die-and-mold shop in Germany, which purchased a unit as a lower-cost alternative to the machines already on its production floor. The unit is being used to manufacture injection molds.
The new Access Series five-axis machining center and PSS-L automation technology will be available in North America by summer 2020 — being built in the Bluffton, Ohio, manufacturing plant.
Automation often involves many issues that may be difficult to navigate. Many job shops are looking for one supplier that can furnish all required equipment, rather than one supplier for automation and one machine tool builder for the machine. GROB Systems new Access Series machining center and linear pallet storage system fit the bill, with one supplier supporting an entire system that is ideal for increasing unmanned operation and reducing scrap and waste.
Derek Schroeder is the Universal Machines Sales Supervisor – Proposals & Applications, for GROB Systems Inc.