This component refers to the programmers and their available options. Clearly, the software (CAD/CAM) available to the user dictates many of the programming variables from which they can choose. While an excellent software package will create various avenues to machining a part, poor software can limit machining options drastically and prevent the programmers from getting the most out of their machine and tooling. Material entry methods, toolpath generation and surface tolerance all are fundamental concepts involved in this component of HSM. The power of the software dictates how each of these fundamentals can be applied to the machining process. For example, many CAM packages allow the user to program helical engagement as a method of material entry. However, while some systems create a helical path using true arcs and radii, others simply follow straight-line moves that do not maintain consistent arcs as the tool cycles down into the part. This results in diminished tool life.
Other nonsoftware programming issues that often exist have everything to do with the programmers. In an industry in which trends and concepts often come and go, it is extremely easy to get lost in the seemingly endless pool of machining techniques used to enhance production. The following is a brief list of a few programming tips recommended to ensure the best machining results. They illustrate how just a few oversights could lead to poor productivity, even with the most advanced machine tool.
Using air blow when machining die steels such as D-2, H-13, P-20 etc., helps prevent thermal cycling by allowing the heat generated from the cut to leave with the chip. Introducing flood coolant to the machining process will result in the heat being induced back into the part and the tool. The heat causes the carbide tool to crack and thus, decreases tool life and tool performance. Using air blow also allows the operator to predict tool failure before a crash ever occurs. Prior to tool failure, changes in the color of the chip and tool can be noted, and tools can be replaced prior to any failure. As a result, tool life is predictable and the operator essentially can leave the machine unattended until it is time to change the tool again. Flood liquid coolant makes identifying what is referred to as the halo glow impossible. As a result, tool failure cannot be predicted using this coolant method. Lastly, most carbide tools for HSM should be coated with titanium-aluminum-nitride (TiAlN). This coating excels at higher temperatures due to the formation of aluminum oxide on the outside of the tool. The aluminum oxide, which is more prevalent in applications with consistent temperatures, provides added hardness and lubricity to the cutting edge.
Use mist coolant for all applications with small-diameter tools, approximately 1/8-inch diameters and smaller. Mist coolant will extend tool life and improve surface finish quality. It also provides added lubricity to small diameter tools, while still allowing the heat to evacuate with the chip.
To achieve better surfaces for finishing operations, adjust the finishing radial step-over so that it is equal to the chip load per tooth of the given end mill. By maintaining this equal relationship, the finish is the same in both directions.
Use helical engagement as the material entry method in materials above 40 HRC. Helical engagement does not leave behind a slot like the linear ramping method. By eliminating the slot, the tool is no longer subjected to an interrupted cut and can maintain more consistent tool deflection, which is critical for tool life in harder die steels.
When applicable, use trochoidal milling for roughing applications. This method of machining dramatically improves tool life. Heat is reduced as the cutting edge is only engaged for 5 percent of the tool's rotation versus 50 percent with conventional milling toolpaths. This method also improves metal removal rates because higher feedrates are maintained more consistently.
Use the tools with the shortest overall lengths and flutes possible. For hard milling, shorter means more rigidity and longer tool life.
Always plan for the next tool. Finish stock plus the added cusps from the previous tool, must both be considered to ensure that the next tool is able to run fast without exceeding its maximum depth of cut and ensuring the best possible surface finish.
Take the guesswork out of programming speeds and feeds by getting the necessary information from the cutting tool manufacturer.                     

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