“Every machinist knows that you have to keep your part still,” says Ball, “but this is an aggressive process that involves some very high forces, so it bears emphasizing.” Heavy-duty workholding is needed, as any shifting in the part could be disastrous. Ball recommends shrink-fit holders, high-performance collet chucks or milling chucks with anti-pullout technology.įinally, the workholding has to be robust and rigid. “That means there are a lot of points where the material pulls down on the cutter, so toolholders have to have anti-pullout capabilities.” The slightest offset can create nasty runout, so maintaining a firm grip on the tool is paramount. “The thing to remember about Multi Flute cutters is that there are a lot of points of contact between the tool and the material,” he says. Different machines should be used for roughing and finishing, and an optimized cutting tool should be used for each operation to achieve more precise results. And it is usually performed using a small finishing end mill. ![]() Runout should be less than 0.0004" for this process, according to Ball. It is the process of reducing the amount of material removed in roughing, making way for the finishing operations. Of course, your toolholder has to be as reliable as the cutting tool and machine. End mills with less flutes on the cutting edge will have more chip space, while end mills with more flutes will be able to be used on harder cutting materials. Multi Flute end mills like the Niagara Cutter family of products from Seco Tools are needed to maintain the constant chip load of optimized roughing. “At Seco, we recommend that the toolholder and workholding fixture are both extremely rigid, and we advise using end mills specifically designed to handle this process.” An alternative to face milling cutters for intermittent and light duty use, these cutters allow you to remove and hand-sharpen the tool blank when it becomes worn. As the cutter rotates, the tool blank creates a wide, shallow cut on the face of the workpiece. ![]() “Once you confirm that your machine can handle the process, the next step is ensuring that your tooling and fixturing are also up to the task,” Ball says. Fly cutters clamp onto tool blanks (sold separately) to machine flat surfaces. If you have the necessary machinery and processing power in your CNC, and your parts fit the bill, then it is time to think about how to set up a machine for optimized roughing. “This can cause small areas of workpiece hardening, which is detrimental to both the part and to your tools.” Programming these kinds of tool paths by hand is nearly impossible, which makes the advanced CAM software absolutely necessary. “If the tool does not keep the angle of engagement consistent, you run the risk of scorching high-temperature alloys,” Ball says. This enables the machine to make complex adjustments in tight corners to maintain a consistent angle of engagement. ![]() In addition to a machine tool with high rigidity and a fast spindle, the CNC controller must have sufficient look-ahead capabilities to accurately maintain high feed rates. Most newer machine tools have these capabilities, which evaluate thousands of lines of code ahead of the spindle’s current position.
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