Optimization software saves time: General Industry Coverage

Every CAM developer, machine tool builder and cutting tool manufacturer promotes the importance of cutting optimization. But what does “optimization” really mean? To stay competitive, manufacturing professionals must create NC programs that run as efficiently as possible and operate CNC machines to their full capabilities.

Achieving the shortest cutting time is related to feed rates, but that is only one of many factors. High-efficiency machining—cutting a part in the least amount of time—is the real goal. But as NC programmers and machinists know, there are many challenges to achieving optimal metal removal.

The known challenges to optimal machining include heat, vibration, deflection, chip buildup, material hardness and a machine tool’s horsepower, torque, rigidity, spindle speed, maximum feed rate and accuracy. End users must also select the appropriate cutting tools and machining parameters. Good optimization software must take all these factors into account.

During optimization, the user can visually graph lots of information for analysis. In this example, the top of the graph shows the reduction in cutting time, per tool. In the lower “cutting conditions” area, the graph displays the volume-removal rate and chip thickness created with the original feeds and speeds. Image courtesy of CGTech.

Cutting at a greater depth often enhances efficiency, but the cutter may become overloaded and break or exceed the available horsepower on the machine. The most important parameter for achieving optimal machining is maximum chip thickness. Optimal cutting will only be achieved when the chip thickness is correctly controlled, based on the material’s chip formation properties and the design of the applied cutter.

Thin chips are the most common cause of low productivity that results from poor tool performance. Thin chips can also cause premature tool wear due to friction and heat and breakdown of the cutting edge. On the other hand, chips that are too thick will overload the cutting edge, which can lead to breakage.

The key to achieving high-efficiency machining is to control chip thickness by varying the feed rate to achieve the desired result for each cutting condition. Effective optimization software knows the chip thickness throughout all cuts and takes advantage of thin-chip conditions by increasing the feed rate when it is beneficial to do so. Without rapid verification and optimization tools, this would be an overwhelming task—one that most CAM systems cannot perform.

Advanced CNC simulation software is a true knowledge-based system for high-performance machining. Through the simulation process, the software learns the exact depth, width and direction of each cut, and knows exactly how much material is removed by each cut segment. With this knowledge, motion is subdivided into smaller segments and optimal feed rates are assigned for each cutting condition. The software then outputs a new optimized toolpath, which has an identical motion path to the original but with an improved feed rate for the specific cutting condition.