Tool paths

The use of HSM strategies normally requires the material to be removed with very shallow cuts and with small stepover. The smoothness of the machined surface is determined in large part by the height of the scallop between adjacent passes.

Thus, lighter depth of cuts contribute to reduced hand polishing. At the same time, HSM offers an efficient way to use very small tools. This can make it practical for high-speed CNC machines to generate fine details that might otherwise require inserts or EDM.

Reducing or eliminating EDM can lead to substantial time-savings—not only because EDM is a slow process, but also because it requires the additional step of producing the electrode. In other words, high speed machining lets the machining center do more.

When will this system arrive? About the author: Dan Marinac is strategic marketing manager for Cimatron Ltd. Livonia, Michigan. Different machines offer different approaches to rotary travel, and each design has its own strengths. Here's how they compare. Torque, not power, is the most important characteristic for determining the cutting performance of a spindle. Increasing spindle torque for a high speed machining center ultimately affects not only the choice of spindle but also the design of the machine.

Milling complex forms in hardened tool steel involves more than just fast, light cuts, says this maker of medical-related injection molds. Here are some of the ingredients of an effective hard milling process. Dan Marinac. Here is Advice On Starting Small. What's Your Shop Worth? Increasing Torque For A High Speed Spindle Torque, not power, is the most important characteristic for determining the cutting performance of a spindle.

Find a Manufacturing Supplier or Service. Subscribe to Modern Machine Shop Magazine. The process for creating toolpath is as follows:. Create outline vectors around any 3D data using the drawing tools or the 'Create vector boundary from selected components' icon. Make sure you have the right combination of 3D Components displayed. Everything you see in the 3D View - the result of all the visible Components will be machined.

Check the depth of the combined 3D model to make sure it fits into the material you plan to use, edit this using the Scale Model Height function if necessary.

Check the overall material size Job Setup to ensure it matches or exceeds the size of the finished product. But, cutting movement, with the exception of holes, happens mostly in X and Y, with a constant Z value. The walls of Prismatic Parts are vertical unless tapered cutters were used. And curves are strictly in X and Y, so no convex or concave curves happen on the face of the part. Here is a typical Prismatic part:. Parts are shaped this way because they go together in mechanical assemblies.

Having square faces and walls makes it easier to fit them together. By contrast, here is a part that has curved surfaces and is therefore not a Prismatic part:.

The 3D part is more organic. This one is perhaps an exaggeration to make to point, but you get the idea how different these two kinds of parts are. One thing to keep in mind about these Toolpaths and Operations is they generally fall into two categories:.

One of the difficulties with simple Prismatic or even full 3D machining is the spindle can only approach one side of the work.

What if the part has Features that can be reached by the spindle while it is held down in one position. Our example Prismatic Part has some holes like that:. This diagram gives an idea how many degrees of freedom are available on a 5 Axis machine:.

There are many CAM software packages and they have MANY different detail features designed to optimize the work and give each package its own competitive advantage. Getting the Big Picture and then drilling down for detail will make it easier to get your arms around how all this works.

We all know a hole when we see one. Most parts have a number of holes in them. Well, they can be specialized and more accurate as well when it comes to holes. The title of this section has a link that allows you to drilldown on our Complete Guide to Hole Making.

A deep hole is anything over 5 diameters deep. They have all sorts of special challenges that require special tooling or strategies to deal with. If not, you may have to do a little hand programming. The chart above summarizes various techniques to use depending on the hole depth, and we have an entire Deep Hole Drilling Guide to take you through all of it:.

There are several potential additional operations you may need before the hole is finished:. Since holes are so common, being able to automatically identify them and do some or all of the CAM programming for a hole can really save a lot of time. As you can see, there are a lot of techniques there. The path may be intended to cut a part out by following its outline. It may be intended to finish a wall on the part. Not a lot special about 2D Profiling as it is very common and sort of the lowest common denominator toolpath.

There are even programs that do nothing but follow a line from a DXF file, which gives ultimate flexibility at the cost of least usability. A word about Slots, as they can require some special technique. Instead, use a slightly smaller endmill, take it right down the center, and then give each wall its own finish pass. A Trochoidal Path cutting a slot looks like this:.

Pockets are part features that are bounded on all sides by the part. Pockets are very common features, and they present some of the hardest problems for CAM software to solve, so we often see a fair amount of sophistication where pockets are concerned. BTW, you generally want to convert the whole interior of the pocket to chips. Just machining the outline and hoping the middle falls out the bottom can lead to a broken tool if the middle starts flopping around and jams the tool.

They produce a toolpath that looks like this:. The pointer doesn't turn to the expected - and remains a hand. Click to delete the handle. Move mode allows to move one or all components of a path. Simply click on the path and drag it. If you have several components, only the selected one is moved. If you click and drag outside the path, all components are moved. Pressing Shift key toggles to move all components also. With this option, segments are linear only. Handles are not available and segments are not bent when moving them.

This button allows creation of a selection that is based on the path in its present state. This selection is marked with the usual "marching ants". Note that the path is still present: current tool is still path tool and you can modify this path without modifying the selection that has become independent.

If you change tool, the path becomes invisible, but it persists in Path Dialog and you can re-activate it. As the help pop-up tells, pressing Shift when clicking on the button will add the new selection to an eventually pre-existent. In previous versions, you could access to this command only by the Edit sub-menu in the Image Menu. Now you can access to it also via this button. See Section 3. Paths 5. Paths tool. Activating the Tool. Key modifiers Defaults.