Publications

29.10.2018

The Impact of Optimizing Tool Path in CNC Punching

The Impact of Optimizing Tool Path in CNC Punching

Sheet metal software can help save time and make sheet metal fabrication more efficient by automating routine jobs and by calculating the best and fastest way to accomplish cutting and punching. The tool path optimization features can reduce time spent punching sheet metal by up to 50 percent or more through a mathematical optimization process based on tool path length. At the same time, the mathematically shortest path may not be appropriate for a particular job and the operator has to be able to set a framework and influence the calculations. The best automation software gives transparent results and allows the operator to tweak the tool path where necessary.

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Choosing the Tool Path

Once the sheet metal program is in place and the parts are positioned and nested, a non-optimized tool path is often long, complicated, and inefficient. The program may jump from part to part and does not sequence the hits in an optimal order. The CAD/CAM software displays the tool path along with the tool path length but the path often looks disorganized and may randomly cross the sheet metal at different angles.

Normal path selection routines work from the coordinates of the hits and base their sequence on the parts to be punched and changes in the x- or y-coordinates. Such a path may jump from side to side on a sheet or jump from one corner of a part to the distant corner of another part. Path optimization software works with the path length and minimizes tool travel. It will look for the next hit closest to the location of the tool but take a jump to a more distant hit if that reduces the overall path length.

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Once the optimization feature is used, the displayed tool path length normally decreases substantially. The optimized tool path is made up of neat rectangles and short jumps as the program takes the shortest route to a hit, but other problems may emerge. Often the starting point of a tool path is important and the sequence of hits between parts, contours and holes may be critical. The operator has to be able to review the proposed path and easily make changes so that the optimized path works for the particular punching sequence. Key to the operator's review is the availability of tools and features in the program allowing the operator to make adjustments easily rather than having to re-program paths manually.

Operator Tool Path Optimization

Even when the optimized path is valid, it may not be appropriate for the particular job. Sometimes first piece inspection is required and at other times sheet rigidity is a concern. Some parts may have to be punched together or it may be best to start at one end of the sheet. The tool path optimization function allows an operator to deal with special requirements easily and transparently.

When first piece inspection of a large number of parts is specified, a first piece can be punched completely and then tool path optimization can be applied to the rest of the sheet. Alternatively, operators can complete the punching of each part in sequence and optimize the tool path that way. The latter does not usually represent the shortest possible path but it may be the best method for a run requiring first piece inspection.

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If the operator decides to start at one end of the sheet and wants to punch sections in sequence, the tool path optimization feature lets him specify zones, the contents of which have to be punched together. For example, it may be appropriate to start in a zone away from the clamps and work back to the clamp positions. Operators can define zones on the sheet and sequence the punching to take clamp position into account.

The software acts as a tool to help operators achieve top quality results in the least amount of time. If sheet rigidity is a concern, zones can be defined to punch some sections before others. Zones can be programmed vertically or horizontally across a sheet of metal and the punching of all the parts in a zone can be completed before starting another zone. Zone definition helps an operator influence the tool path without having to define individual path sections.

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The tool path optimization function can combine operator expertise with an automation of the routine parts of tool path selection. Where punching is routine without special requirements, the tool path optimization feature works to reduce machine time to a minimum without further operator input. When a job has special requirements or when an operator has specific concerns about punching sequences, he can work with the automatic tool path optimization and with zones interactively to quickly achieve the results he wants.

Tool Path Optimization Benefits

Tool path optimization reduces tool travel to a minimum and saves machine and operator time. If the tool path length is reduced by 50 percent and if tool travel time accounts for 40 percent of production time, shops can increase productivity by 20 percent through tool path optimization. When adding time saved in operator programming, the savings could be higher.

Another benefit comes from reduced errors and better quality results. With automatic tool path optimization, operators can rely on the complete execution of the punching program and merely have to apply corrections where necessary. They then have time to ensure that the sheet rigidity required for accurate punching is maintained and that required sequences such as punching holes before contours are observed. The software acts as a tool to help operators achieve top quality results in the least amount of time.

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With sheet metal software and with features such as automatic tool path optimization, sheet metal fabrication shops can become more productive. Turnaround time is reduced, customers receive their orders more quickly and the facility becomes more efficient.

Commentary from Dreambird

One of the main targets of Radan sheet metal software is ensuring the toolpath optimization. The parameters that an operator should consider during managing the toolpath, can be specified and updated in all the modules of the software suite, for all kinds of machines.

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Optimizing the tooling used by a punch machine is paramount to the efficient programming of a punch machine and thus the reduction of the cost to manufacture a part. Simply optimizing conventional tools on a part and their location in the turret or tool rail is no longer sufficient, as tooling suppliers are providing more sophisticated tooling such as close to clamp slitters, wheel tooling, de-burring tools, scribes and flexible part marking tools. Radpunch understands the constraints of tools and the necessary NC codes required to support them.

Radpunch orientation specific tooling permits multiple tooling setups to be applied to a part for different nesting orientations and different machine tools. This enables the downstream nesting process to fully optimize material utilization by part rotation, which may have otherwise been restricted due to tool rotation limitations. The same functionality also optimizes preparation of parts for removal processes on more sophisticated machine tools. Whilst a part may be capable of dropping down a chute or being picked at one orientation, at another orientation it may not be suitable.

Orientation specific tooling enables the appropriate part removal processes to be applied to complement the part orientation during nesting.





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