On the surface, adaptive control (AC) technology seems to be a viable alternative to software optimization. After all, AC senses cutting conditions and adjusts feed rates in real time. It can be directly connected to a CNC machine tool.
But there are a number of issues to consider if you’re thinking of investing in AC technology. The first is set-up and maintenance expense. Each CNC machine must be outfitted with its own AC – which can cost thousands of dollars per machine. Each must then be individually installed and configured, and ACs behave differently on different machines and controls. Once the AC is setup and finally operating correctly, as with any electro-mechanical system, there are also adjustment, reliability, and maintenance considerations.
Next, AC technology is a ‘reactive’ system. ACs adjust feed rates based on feedback they receive from the spindle drive motor – that is they adjust feed rates to maintain a constant load on the spindle drive. This type of optimization is appropriate for certain types of very rigid cutters that can take a heavy load, such as face mills or large end mills.
But, spindle load optimization cannot always provide the best feed rates for diverse cutting conditions. For example, a ramp cut does not always significantly increase spindle load. It increases the load on the axis motors as it becomes harder to push the cutter through material, but it doesn’t become equally difficult to turn the spindle (Figure 1). By the time it becomes difficult to turn the spindle, you better be hiding behind a scatter shield!
Figure 1: Tangential force (spindle load) is not greatly affected by end cutting. Because AC uses spindle load to control feed rates, it doesn’t detect the poor cutting conditions and slow the feed rate accordingly.
Another example is machining with today’s high-tech carbide insert milling cutters. They are designed to cut very freely (don’t require much horsepower for high volume removal rates). The goal for these cutters is to cut at an optimum chip thickness. But there is a point where the chip thickness becomes too great, causing the cutting edge to breakdown pre-maturely. This ultimately leads to early tool failure. Spindle load is a poor indicator for the maximum feed rate to use, since the increased load on the spindle is negligible – even if the feed rate is too high. By the time the AC adjusts the feed rate, it’s too late.
The bottom line is that AC technology is limited to adjustments based on when the spindle load crosses a pre-set threshold. It has no ‘knowledge’ of what the actual cutting conditions really are during the machining process, so it cannot accurately determine the ideal feed rate for every cut (Figure 2).
Figure 2: AC technology attempts to choose the ideal feed rates based on pre-determined spindle load tolerances.
OptiPath, on the other hand, automatically adjusts feed rates based on the specific cutting conditions for each segment of the tool path. It is the only product available that optimizes feed rates based on solids verification technology. Rather than react to feedback from the spindle drive motor, OptiPath assigns the best feed rate based on the current cutting conditions (volume of material being removed, depth, width, and angle of cut).
Instead of striving for constant spindle load, OptiPath maintains a constant cutter load. In the ramping example, maintaining a constant cutter load produces safer feed rates. For high-tech milling cutters, maintaining a constant cutter load prolongs tool life. Sometimes it is desirable to maintain a constant chip thickness while cutting – a simple task for OptiPath, but something AC cannot do.
OptiPath is also a more cost effective method of feed rate optimization. A small number of software licenses can provide optimization capability for dozens of CNC machines - of all types, driven by all kinds of controls. An AC is limited to a single machine.
Airbus is selling so well that the demand to increase build rate has never been higher. BAE Systems (Filton, UK) needed a simple way to improve throughput - it found the answer in VERICUT.
With VERICUT, engineers at Stellex Monitor modeled the Sidewinder and Spar Mill machines.
Tell Tool of Westfield, Mass., has integrated VERICUT CNC simulation software into its numerical control program prove-out process.
VERICUT enabled us to start ordinary production after a minimum of time. Since this product is new for Volvo Aero Norge and our company had never before had parts with similar machining complexity, it is difficult to estimate the amount of cost saving.
Before implementing VERICUT, the company experienced the usual time-consuming and expensive manufacturing problems related to NC program prove-outs such as scrap loss, broken tooling, and a danger of occasional machine crash.
Over the last two years, GE Aviation (formerly Aerostructures Hamble) has used Machine Simulation to speed the implementation of several new 5-axis machine tools.
VERICUT showed the NC programmers leftover or heavy stock." And the software detected a couple of places where the depth of cut was too large and tools were shanking out," said Collings. They then went back and corrected the errors in the tool path before
Dassault, Seclin initially purchased VERICUT in order to reduce the number of manual prove-outs using polystyrene material, which represented a significant expense in terms of time and money.
VERICUT enabled the designers and programmers see exactly what they were building as and in-process model in different stages of the machining cycle.
We utilized VERICUT to verify the CNC programs for cutting the tooling before they were sent to the machine control,
To protect their investment, they have been using VERICUT since 1996. They have two people to verify the accuracy of their G-code files.
"When we first started using OptiPath we concentrated on the feed rate option; now we use the constant chip thickness capability. With jobs up to 200 hours long, 50% saving is significant – like having another machine tool."
The entire process took less than two hours and no manpower was required, whereas, creating the same pattern manually (the old way), would have taken one of our designers several days.
The verification process stays ahead of the actual machine position in the NC code being verified. Opera-tors can see errors before they occur.
The bottom line? Using VERICUT has made Supreme's existing machine tools more productive. Enthusiasm is up, delivery times have been reduced, and pricing is more competitive.delivery times have been reduced, and pricing is more competitive.
Using VERICUT to compare the electrode burn with the mold cavity ensures that we have all the correct clearances in the electrodes and that we have 100% clean-up." says Allen.
If I was using VERICUT at the time I would've caught the problem, and had a chance to fix it before it damaged the part.
Now I rarely see the potential crashes because the students find and correct them before I review the work. Catching those costly problems is a non-event now!
VERICUT can change speeds and feeds according to cutting conditions including difference in material and tooling. It is done automatically; the programmer does not have to make even one manual insert into the code."
Flying shrapnel from shattered cutting tools and components is avoided by using VERICUT to test student programs before they are run on NC machines.
The NC programmers at Ingersoll also rely on the simulation software to prevent mistakes when programming complex, five-axis parts.
After creating the NC programs in Mastercam, they began simulating the machining process in VERICUT by simulating the G-code data. There often can be a difference between the motion as programmed and the code after it's run through the post processor
After selecting VERICUT for third-party verification, each NC programmer attended two days of basic training where they experienced first-hand the type of results they could expect to achieve.
The program simulates milling, drilling, turning, wire EDM, and mill/turn machining operations using both G-codes and CAM output.
VERICUT provides simulation capabilities for the all the 3-5 axis and wire EDM parts, with focused control over the orientation of our 5-axis machine tool including the cutters used on that machine.
The inspection probe is created as a tool in VERICUT so the complete in- cycle gauging sequence is checked for collisions.
The bottom was machined first. This effort took about 24 hours from start to finish. By using VERICUT software from CGTech, Elliot was able to test the NC program for any problems before it was ever cut on the machine.
Cosworth Racing Integrates Walter TDM Tool Management into Manufacturing Systems
With data exported from NX, Vericut simulates the cutting process on the shop floor utilizing the machine G-code to detect any issues prior to NC Program release.
VERICUT software removes this potentially hazardous stage by allowing ReedHycalog to do all of their prove-outs on a computer.
VERICUT verification detects errors such as: inaccurate programming, incorrect tool path motions, rapid motion contact, collisions with fixtures and clamps, tool shank and holder collisions, & CAD/CAM and post processor bugs.
VERICUT Machine Simulation supports G-codes and Multi-axis (5-axis or more) support for milling, drilling, turning, grinding & EDM machines
