Single set-up 5-axis milling and drilling
Falcon Precision Industries specialises in machining complex aerospace components in prototype and low production quantities. To carry out the necessary 5-axis work on these parts required making special devices for holding the workpiece in a fixed position to allow the cutting tool to get at pockets, contours and all sides of the part.
“We have three Mazak Variaxis 630 machining centres with full 5-axis machining capabilities and we are awaiting delivery of our fourth one,” reports John Blankenship, manager of manufacturing engineering for Falcon Precision [see photo right]. “To do the required 5-axis machining of our aerospace parts on these machines, we designed custom clamping devices to hold these complex parts. We didn’t use conventional vices and workholding as the primary holding device because it restricted the machining centre to just three axes.”
That meant setting up the part and running the machine in a three axis mode, stopping to reposition the part and then running the last two axis, defeating the purpose of having 5-axis capability. That was too slow and tedious so Blankenship and his toolmakers came up with special dedicated holding fixtures to allow for the 5-axis work. “This was a more productive way to machine in all five axes,” he said, “until we discovered Kurt’s 5-axis vise. It gave us a more flexible and faster way to set up and clamp parts for our demanding 5-axis work.”
“Scott Lundin, senior manufacturing engineer of Falcon Precision, saw the new Kurt 5-Axis vice at a recent Mazak open house,” reported Blankenship. “The vice was mounted on one of the pallets of a Variaxis machine. While the vice did not have a part in it, Lundin could easily see several benefits of this type of clamping system. Lundin brought back the literature on the vice, which we reviewed together, saw the benefits and immediately ordered one.”
True 5-axis contour machining is a rapidly growing technology embraced by Falcon Precision Industries for its growing list of aerospace customers. With a 20-year history in contract precision parts manufacturing, this ISO 9001:2000 and AS9100 Rev B company recognises the long-term growth opportunities in serving aerospace and other demanding industries with the latest, most cost effective technology available.
Simultaneous 5-axis machining has numerous benefits, as Blankenship observes. “It provides continuous, high speed 5-axis imaging which is ideal for profiling parts. It’s perfect for machining deep cavities and corners, plus it is highly consistent for tighter tolerances while surface finishes are better. And you can accomplish all this in a single machine setup.” [Photos left]
Falcon Precision machines virtually all materials used for aerospace parts, everything from Inconel and Titanium to various grades of aluminum. Clamping rigidity is of concern for both extremes: smaller parts machined from harder materials and larger parts machined from softer material. Using its custom clamping devices held in standard vices and/or mounted directly on the Mazak Variaxis table which rotates 380° (C-axis) and tilts 150° (A-axis), Falcon Precision’s setup technicians devised appropriate rigidity and clamping pressure basically using set screw devices.
Workable as this method was, the addition of the new Kurt 5-axis vice provided a much faster part setup with more consistent and predictable clamping pressures and the rigidity needed for both small and large parts of both hard and soft metals. This versatility was especially helpful with the low part runs and frequent setups Falcon Precision experienced with its aerospace orders. [Photos right]
“Once mounted on the machine worktable, the Kurt 5-axis vice sets up for different jobs in just 10 to 15 minutes compared to as much as 2-1/2 hours using our custom clamps,” reports Blankenship. “We use the two sets of supplied Kurt jaws (round and flat), set the movable and stationary jaw, and we’re ready to run the job. It’s really versatile. Our setup man loves it!"
The Kurt 5-axis vice is adjustable to handle any desired clamping width, so it is limited only by the size of the Mazak’s machine table. With two clamping jaws, one stationary and one movable, the jaws can be positioned at any desired distance from each other.
Actual clamping width for this Kurt system is 0.0787 inch to 9.291 inch (2 mm to 236 mm) that can be extended with optional spindle screws, a clamping depth of 0.315 inch (8 mm), height above the machine table of 6.889 inch (175 mm) with extended height options to 7.874 inch (200 mm) and 8.858 inch (225 mm) - see left.
A typical job using the new vice runs at up to 12,000 rpm and at 130 inches a minute, depending on the tools used, according to Blankenship. Running time varies from prototypes at 15 minutes to production quantities up to five hours.
The system is designed to mount easily on standard T-slot tables, location grid machine tables or custom fixtures. For Falcon Precision, it sets up like a standard vice on the Mazak’s tilting rotary table in about the same amount of time – less than 15 minutes. The 5-axis vice stays mounted on the table with the second pallet used for secondary operations or other projects. Falcon Precision’s application can handle virtually all of its complex aerospace parts without any add-on jaws, spacers or devices with set screws.
Blankenship and his highly skilled machinists Joe Kenyon and Glen Balon say they really like the rigidity of the Kurt 5-axis Schenke clamping system, which was proven on the first project. “We’re getting ±.001 inch angularity tolerances running carbide and other standard tool inserts up to 12,000 rpm with cuts up to 130 inches a minute. We’ve never had a problem with tool chatter or part misalignment at these speeds. The rigidity with this vice has exceeded our expectations, and we’re finishing jobs in half the time or less compared to before. The vice paid for itself the first month we used it,” reported Blankenship.
The reason for this rigidity is that the Kurt 5-axis Schenke clamping system’s design eliminates jaw deflection and/or part misalignment during these high speed operations. By locating the tension spindle directly under the workpiece, the clamping system’s jaws do not flare out under tension and the machine table does not distort like conventional workholding. Also, the system handles a full range of workpiece configurations with equal rigidity including blank, machined, round and irregular shapes with repeatable accuracy. [Images right]
“The Kurt 5-axis Schenke clamping system has been an important upgrade for our overall machining operations,” says Blankenship. “We’ve eliminated the need for all of those special clamping devices and we’ve reduced production time by as much as half with no scrapped parts; and we’re finishing jobs in half the time or less compared to before. The vice paid for itself the first month we used it. We’ve ordered our third Kurt 5-axis vice and are planning to use the two in tandem for holding even larger parts.”
In addition to the 5-axis Schenke clamping system, Kurt provides integrated custom engineered workholding systems and custom gaging systems for automated manufacturing. Both workholding and gaging are designed around a customer’s requirements with systems available for many industries including automotive, medical and aerospace applications.
http://www.kurtworkholding.com
