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How to test and review CADCAM software for your company - The process of evaluating a CADCAM and nesting system

Page 4 of 6: The process of evaluating a CADCAM and nesting system

The process of evaluating a CADCAM and nesting system
The key to an effective evaluation process is being able to demonstrate quantifiable savings in three key areas:

1 Staff time, covering programming, reporting and anything else related to the CAM process
2 Machine cycle time (also referred to as runtime)
3 Material utilisation

All of the above have quantifiable costs. Before you even consider evaluating CAM systems you need to understand what those costs current are. Man-hours are generally simple enough to cost, as are your machine run times and costs, although it is always a worthwhile exercise to follow a few jobs through all processes and note all costs associated with them.  Material efficiency is not much more difficult to calculate if you look at it in terms of waste rather than output. Obviously, the lower the waste, the better off your company is and there are potentially huge savings to be made with the right software. Once you have a clear understanding of all the above, you are ready to move onto the next stage – the benchmark comparison.


Calculating your return on investment
By now you should have a clearer idea of what you need, so it’s time to start investigating the market. Recommendations should carry more weight, especially if they come from users that have the same machines as you. Once you have selected your vendors you need to arrange for a benchmark comparison. Provide each vendor with a series of parts in the form of DXF or IGES files, , along with tooling and nesting parameters and ask them to perform the following:

1 Demonstrate the process of interactively and (if applicable) automatically tooling the parts
2 Demonstrate the process of interactively and (if applicable) automatically nesting the parts
3 Demonstrate how easy it is to move parts or nests between machines (useful in the event of a machine breakdown)
4 Provide the final nests and reports so that you can compare the efficiency against your own nests
5 Demonstrate how information can be extracted from the system for reporting purposes so you can compare it with current methods of creating similar reports. See if additional beneficial information can be retrieved that may be unavailable using your current methods

It is important to check and recheck the figures that you are provided with – do not take them on face value as it has been known for figures or nests to be doctored to make them appear more favourable. Check to ensure that no parts are overlapping on the nest or that they have not been rescaled slightly in order to fit a particularly complex nest. Check gaps between components and components and material edges. Due to each machine generally being uniquely configured it probably will not be possible for them to provide you with resulting CNC programs to check machine run time.

In addition to the savings that you can tally up there may be other benefits which might not be so easy to spot but that will help in providing a quicker return nonetheless. For example, more efficient nesting and the ability to produce complex dynamic nests quickly might allow you to standardise on fewer material sizes. Not only would this make stockholding simpler it can have a knock-on effect on your purchasing power.

Once you have your set of figures it is then a simple process of adding them up and comparing old versus new. Take the difference and divide it by 52 (or your company’s number of working weeks). You now know to the week when your CAM system will have paid for itself!

Various CAM software approaches:
Some CAM systems will simply take component geometries, nest them and then apply tooling or cutting at the nest level. Such practices save a CAM vendor significant development overheads and have certain advantages, but as far as the user is concerned, there is a very significant drawback using this technique. Such system cannot retain any information regarding machining of individual components, which means that any machining information added or modified on a particular component only exists on that particular nest and if one needs to nest that same component sometime in the future again, that same machining information will have to be added/modified manually again. It is impossible to use such systems for reliable automation except for most simple machining technologies where (and if) interactive modifications to the way a particular component is machined are never required.

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On the other hand, some other CAM systems will store component’s machining information in a special component file together with component geometry, but a separate such component file may be required for each machine the user may want the component made on and sometimes even for each different angular position of the component on a nest. This still complicates matters quite a bit, as any revision of component geometry or tooling may force modifications of many similar files, which is obviously time consuming and error prone. However, as the machining information is stored together with a particular component geometry, there is no need for re-entering any of it when a component needs to be nested again.

Paying the price of vastly higher development overheads, producers of the best and most capable CAM systems will utilize a combination of both methods to achieve the most flexible and efficient machine programming system, while storing geometry and machining information in a single component file. In such systems, once programmed (either manually or automatically) a component file will store any important machining information for any angular position that a particular component is desired to be nested at (ie. 0, 90, 180, 270 degrees) and for any number of machines an user may be operating, ready for nesting at any time, at any angle, on any machine, without any human intervention. In this context, it is important to remember that on certain machines (ie. Punch Presses) tooling and unloading information may be very different depending on component’s angular position on the sheet. Depending on the machine tool selected, to finalize a nest, additional machining or modifications (ie. common line cuts, trimming, tool substitution, repositions, lead-in optimization, unloading information, etc.) may be added to the nest by the system automatically.

What this means to users is that if a particular machine breaks down, all unfinished component orders can immediately be redirected to another machine and new nests created in seconds, whether manually or automatically (ie. a component normally produced on a punch press can be redirected to another one or a laser and vice versa). It also means that components can be nested and produced ‘Just-in-Time’ on any machine at any time, based on the current machine loading, ideally keeping all the machines busy all the time.

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