VERICUT is a true knowledge-based machining system: through the simulation process, it learns the exact depth, width, and angle of each cut. And it knows exactly how much material is removed by each cut segment. With that knowledge, OptiPath divides the motion into smaller segments. Where necessary, based on the amount of material removed in each segment, it assigns the best feed rate for each cutting condition encountered. It then outputs a new tool path, identical to the original but with improved feed rates. It does not alter the trajectory.
4½ hours of programmer time spent on optimization saved us $75,000!
Aerospace Dynamics, International
Simple Setup and Use
A setup wizard prompts you for cutter settings as you machine the part. Essentially, you add intelligence to the cutter. All the settings for that cutter are stored in an optimization library. You define the settings once. Every time you use that cutter the results can be instantly optimized! OptiPath also features a “learn mode” for creating the optimization library with no setup required. For each tool, OptiPath finds the maximum volume removal rate and chip thickness and uses them to determine the optimization settings for the tool.
How it Works…
As the cutting tool encounters more material, feed rates decrease; as less material is removed, the feed rates speed up accordingly. Based on the amount of material removed by each cut segment, OptiPath automatically calculates and inserts improved feed rates where necessary. Without changing the trajectory, OptiPath writes the updated feed rates to a new NC program.
Could You Benefit from OptiPath?
Do any of the following sound familiar? If so, OptiPath can help!
Removing a lot of material
Long machining times
Large NC programs
Interrupted cuts (multiple entry/exit)
Cutting at variable depths/widths
High speed machining
Thin wall machining
Delicate tooling and materials
Expensive tooling and materials
Hard materials, soft materials
Premature cutter wear/failure
Optimizing programs “by ear”
Reworking programs for feeds/speeds… or no time to do so
CAM system and/or programmers don’t have necessary knowledge
“Resident expert” retiring/leaving
Poor surface finish
Excessive bench time
Chip thinning problems
Cutter deflection problems
Chatter in corners
Air cuts or light cuts at slow or programmed feed rates
OptiPath® reads the NC tool path file and divides motion into a number of smaller segments. Where necessary, based on the amount of material removed in each segment, it assigns the best feed rate for each cutting condition encountered. It then outputs a new tool path, identical to the original but with improved feed rates. It does not alter the trajectory.
You input ideal feed rates for a number of predetermined machining conditions. OptiPath automatically combines them with factors such as machine tool capacity (horsepower, spindle type, rapid traverse speed, coolant, etc.); fixture and clamp rigidity; and cutting tool type (material, design, number of teeth, length, etc.), to determine optimum feed rate for each segment of each cut. OptiPath also considers factors dependent on the nature of the tool path such as:
Volume removal rate
Entry feed rate
This solution is automatic and determines the best feed rates before the program is loaded on the machine. It also uses the expertise of the NC programmer and machinist to determine the best feed rates for specific cutting conditions.
HIGH SPEED MACHINING VS. HIGH EFFICIENCY MACHINING
High speed machining is a hot topic. But, what is ‘high speed” machining really? Is it simply running at maximum feed rates and taking multiple shallow passes? This strategy is often less efficient than taking few passes at slightly greater depths! Achieving the shortest cutting time is related to feed rate, but the relationship is not necessarily ‘fastest feed rates = most efficient.” High-efficiency machining, cutting a part in the least amount of time, is the real goal. The key to achieving high-efficiency machining is to vary the feed rates to achieve the result each cutting condition encountered.
“Typically, high-speed machining is accomplished with very small axial cut depths in order to achieve good surface finish and avoid damage to the cutter, workpiece or spindle. Feedrate optimization software can be employed to achieve better cutting efficiency with greater axial depths at the high feed rates of HSM and protect the cutter, etc., in those few places where the chip load momentarily increases. Constant chip load tool paths allow optimum use of the cutter’s strength and the machine’s speed and power. The software detects conditions where the chip load is too great and adjusts the feedrate to a more reasonable level. It then returns the machine to the higher feedrate when the chip load permits.”
Alan Christman, CIMdata
Software Trends Enhance Moldmaking Industry MoldMaking Technology, November 2002
Cutting at maximum feed rate, with very light cuts, small step-down and step-over can actually require many, often inefficient, passes and can defeat the goal of reducing time. Cutting at a greater depth (in this example .500″vs.100″) is more efficient. But the cutter may encounter an overloaded condition causing breakage or exceeding the horsepower on the machine.
This is where automatic optimization software shines. VERICUT knows exactly how much material will be removed in each segment of the cut and slows the feed rates down where the load is too great. This prevents breaking cutters and keeps the machine from exceeding horsepower limitations. The same high feed rates are maintained where possible, but with greater cutting efficiency and less time than when stepping down only .100″ for each pass.
OPTIMIZATION VS. ADAPTIVE CONTROLS
Proactive vs. Reactive Machining
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!
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).
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.