axis machining is an interesting sub-section of CNC milling, and is an integral part of the precision engineering world. To understand why a fourth axis is used on CNC mills, and to understand what this fourth axis does, read on below. You may be mistaken into thinking that a 4th axis is used in the same way a rotary table is used in manual machining. This may be the case in some projects, but it is not generally true to manual machining. Manual 4 axis machining usually involved cutting along an arc, this being something that is difficult to achieve manually. Cutting along an arc is however easy with CNC, and this is just one use for the 4th axis in CNC milling used by CNC experts you find at http://www.cam-machine.com/cnc-milling/.
4 Axis Machining Indexing
A 4th axis is typically used for indexing or in a continuous mode. When used for indexing, not cutting will take place until the 4th axis is stopped and locked with some kind of brake. Some 4th axes are known as indexers, and these are used to index in fixed degree increments. When the 4th axis is used continuously however, the 4th axis will be rotating as cutting takes place. An example of a part produced in such a way is the CAM lobe.
Index machining is more useful than you may first think, and continuous machining is not always the best solution to CNC needs. There are advantages of 4 axis indexing, and one of these is that the CAM software required for indexing is not as complex as for continuous machining. Indexing will also allow better access to the part in question, and this can be very useful when manufacturing something complex like a gear. The 4th axis machining of a gear will index the part, stop, allow for cutting of one tooth of the gear, and then index the next position where the next tooth in the gear is to be cut.
4th axis indexing in horizontal machining centres is far more productive than vertical machining. Horizontal machining is aided by gravity, and also due to the fact that almost all horizontal mills have a 4th axis tombstone arrangement. This tombstone arrangement is powerful and improves the productivity of the CNC machine shop. A tombstone can also be fitted to a vertical milling machine, although there is less clearance and it can only be used for parts that are relatively flat.
4 axis machining can also be continuous, and in this case it is often known as 4 axis contouring. Continuous 4 axis machining allows for the production of extremely complex parts that would be virtually impossible to produce with indexing. Indexing in multiple positions can provide a similar effect to continuous machining, but the process is not as powerful as true continuous machining on 4 axes.
4 Axes Wrapping
A special case of 4 axes machining that should be mentioned is the 4 axis wrap machining that is commonly known in CNC as wrapping. This special procedure can be used for engraving text on the side of a cylinder, this being a fine example of wrapping in CNC. Try to wrap text around a cylinder without a 4th axes to work with would be impossible, and the text would not wrap correctly around the cylinder. Here, the fourth axis allows the machine to believe that it is actually engraving on a flat surface, when in fact it is engraving on a cylinder that is being turned, providing excellent results and a finish that would be painstakingly difficult with only 3 axes or indeed with a manual engraving machining.
4 axes machining is commonplace in all modern CNC workshops, and in some of the most modern workshops you will even find machines that work on 5 axes. A 4 axis machine is a powerful machining, and it facilitates existing jobs as well as making new and improved techniques possible. 4 axis machining require less setup than 3 axis machines, and allows for CNC machine shops to work faster and more efficiently than ever before.
Advances in CNC technology, and CNC milling mean that CNC machine shops can work quicker and more efficiently than ever before. CNC milled and turned parts are available to the consumer at affordable prices that were not available some decades ago. With machines becoming more efficient and more powerful, and advanced technology allowing for more complex parts to be machined, CNC will continue to grow from strength to strength, CNC machine shops around the country being the backbone for many hundreds and thousands of industries.
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