by Mary Scianna
Drive to cut costs spurring interest in multi-tasking machines
Multi-tasking machines make a compelling argument for job shops and OEMs in low volume production environments: one machine for multiple machining functions means you can reduce or eliminate stand-alone lathes and mills, reduce setup errors and costs of fixturing, and improve productivity.
“What gets you paid is when parts ship and manufacturers with the right small lot sizes have to consider this if they’re running conventional machines instead of multi-tasking machines,” says David Fischer, product specialist with Okuma, Charlotte, NC.
While it is true that a multi-task machining cycle will take longer than a typical machining cycle on a CNC mill or lathe, you make up for that with the elimination of multiple part set-ups on different machines.
“The challenge today is for shops of all sizes to machine as many part features as possible in a single setup on a single machine,” says David Barber, director of marketing for Hyundai-WIA America Corp., Carlstadt, NJ.
Multi-tasking machines are typically equipped with automated quick tool change systems that can hold up to 200 or more tools in a magazine, allowing for multiple machining processes in one machine.
For many, investing in a multi-tasking machine can save floor space and cut fixturing and tooling costs.
“With one machine you can do different operations, so you may not need other machines and it saves floor space,” says Roberto Colombo, product manager with DMG Canada Inc., Mississauga, ON. “You’re able to do different operations with the same tools, but in a different B axis position as compared to a standard machine that might require two or three tools for those different operations.”
Multi-tasking may make sense if you’re a machine shop, but remember that not all machines are created equal, says Nitin Chaphalkar, manager, advanced solution development at DMG Mori Seiki USA, Hoffman Estates, IL. “There are different levels of multi-tasking. We offer what I would describe as a “mill-turn light” that is essentially a lathe with milling capabilities; so it’s an 80/20 turning/milling combination. An example would be a three axis lathe with live tooling. But then we offer full mill-turn, 50/50 in terms of full milling and turning capabilities with a B axis head.”
Like any machining technology you might want to purchase, you need to consider your application, the parts you make, and the machining processes you use, because they will determine the type of multi-tasking that’s right for your shop.
More capability, more complexity
Machine tool builders have expanded functions in today’s multi-tasking machines. “It is not just milling, turning and drilling, which are standard processes. We now offer machines with some specific options, such as laser or ultrasonic combined with milling, which is a good solution for very hard metals and provides more flexibility for manufacturers,” says Colombo.
Indeed, Mazak Corp. (Mazak Corp. Canada, Cambridge, ON) has developed 101 machine configurations that fall under the multi-tasking machine category, says Joe Wilker, product group manager with the Florence, KY, based company. “Today, a five axis machining centre with turning capabilities can be considered a multi-tasking machine, but we’ve extended the concept of multi-tasking to â€˜ultra-tasking’ and â€˜multi-tasking automation’. Ultra-task machines perform all the functions of a multi-tasking machine with other specific tasks, such as gear cutting, grinding and deburring.”
Mazak’s “multi-tasking automation” concept is a “single machine cell capable of completing a part from raw material without operator interruption with the added requirement of material handling devices such as bar feeders, gantry loaders or robots,” says Wilker.
Chaphalkar adds, “these machine don’t offer just a combination of machining processes, but they also offer the capability of nine axis motion [some up to 12 axis motion], and when you get to this level of machining it is more complex.”
This complexity means you need a highly skilled machinist who can grasp the technology.
“What adds the complexity is the number of turrets, not the spindles or the B axis,” explains Fischer. “It is the turrets that will get you into trouble with collisions. A lot of machines have two spindles and operators want to have the turrets moving all at the same time. That’s fine if you can handle it, but programming two turrets takes longer because you have to program in collision avoidance. A one-turret, multi-function, multi-tasking machine is the easiest.”
Machines should be equipped with controls designed for multi-tasking and machining simulation software, advise machine tool builders contacted for this story. “The more complex the machine, the more difficult it is to check interference between the component and the machine, or the component and the spindle, so the machine needs to be set up with good software, good machining solution, very good CAD/CAM systems, and post processing,” adds Colombo. SMT