body diameter. Also important to note, heavy-wall shrink fit holders have higher gripping force, while slim-wall holders have reduced gripping force. While shrink-fit is best suited for moderate to rough milling, the superior vibration control of hydraulic chucks makes them a good choice for finish milling, reaming and drilling work. Hydraulic chucks aren’t reliant on as many variables, while their production is imminently consistent. Once a master bore is established during manufacturing and assembly, it’s a repeatable process over thousands of cycles. This translates to consistent clamping tolerances and forces over the life of the holder. The second advantage is the natural damping characteristics hydraulics provide. That’s not to say shrink-fit holders are ineffective in terms of vibration management, their runout is five times better than side-lock holders. There is also a cost that needs to be accounted for both on the holders themselves and the support systems. Hydraulic holders are slightly more expensive upfront but only require a standard hex wrench to operate, allowing anyone with some training to change a cutting tool. Shrink-fit holders are slightly cheaper, however, require a shrink-fit machine to heat and cool the holder correctly, along with an understanding of how to avoid overheating and reduce the risk of burn injuries. Coolant Strategy Coolant delivery that is as direct as possible is the key to providing proper heat dissipation, increased tool life and surface finish. Flooding the part doesn’t always work best. The first option, which should be standard on all machines, is through- spindle coolant. This gets the fluids right at the cutting tip of a drill and helps force chips back up the flutes to evacuate the cut. Coolant right at the cutting edge of a mill helps for the same reason, however, as machine spindles get faster, the coolant will fan out from its intended target. The next option to consider is to use directed jets of coolant on the holder. We offer holders, or in some cases collet nuts, that specifically angle the coolant delivery holes to maintain the direction of the coolant flow. Cutter Dimensions Five-axis control opens up new opportunities to better utilize cutting tools. On the other hand, new cutter geometries are emerging that are better equipped for 5-axis work. When machining the
workpiece at different angles with different portions of the tool, these applications require symmetrical cutters. Very few cutters are immune to blend lines or poor finish.
Five-axis control opens up new opportunities to use cutting tools better.
Ball Nose End Mills
Ball nose end mills have zero cutting action at their tip, causing the material to “smear” rather than be cut to be lifted away by the flute. This is where the concept of tipping the cutter comes from. Tilting the tool axis allows the flutes to grab the material, pulling it away from the part, rather than pushing, which causes it to build up on itself, the cutter and
the surface of the part. Circle Segment Cutters
Designed specifically for five-axis machining, circle segment cutters have contoured profiles that enable wider cutting contact with a contoured workpiece surface, almost like a super-large ball nose end mill. They fall into a few basic types: taper, lens, oval and barrel. The biggest advantage of this tool is that it provides an equivalent or better surface finish with larger stepovers, resulting in fewer passes required to machine a 3D surface. Then, with the small radius tip of the tool, you can get into tight corners. Not only can you do more with a single tool, it results in continuous machined surfaces with significant reductions in
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