Collision Avoidance or Detection? (Part 2)

May 16, 2012 By jjaje Leave a Comment

Automatic Avoidance is always better than detection.

In the last Blog Post, there was discussion about collision avoidance and detection, especially as automatic avoidance relates to 5-axis machining.

Today we will look at collision avoidance earlier in the process, during roughing.

Difference between Collision Detection and Avoidance.

Collision detection is when your CNC CAM software calculates a cutterpath, which often only takes the tool shape into account, but not the holder or the physical milling machine, then afterwards recheck it for and collisions. If there are any, then manual editing, or some other changes are required to remove the collisions yet still mill the entire part.

Collision Avoidance is when the collisions can be avoided in the first place, during the calculation of the CNC cutterpaths. When roughing, this may include the Tool and Tool Holder, and possibly the spindle.

Mill With the Shortest Tool Possible

You will that mantra from tool vendors all the time, when speaking about performance. Do as much milling with eh shortest tool as possible, and only use a longer tool where necessary, or utilize the short tool at different cutting angles if possible, to maximize performance.

Look at the picture below, in this case we can actually mill out 90% of the material with a very short cutter. We are using the strategy of roughing with a large cutter to take advantage of good material removal rates, and we will use a cutter with a Length/Diameter ratio of 0.9.

Part with tool and holder

Part with tool and holder

In this case, the holder is quite large, so although we can remove the majority of material with this short and sturdy cutter, there will be areas of additional stock to remove.

When you look at the cutterpath from the +Z direction, you can readily see that the CNC CAM  Software automatically limited the cutterpath, taking the tool and holder into consideration, to avoid all collisions, versus just finding collisions after the fact.

Stock Condition after +Z cutterpath

Stock Condition after +Z cutterpath

How the remaining material is removed can be done in multiple ways. Perhaps a different tool or holder from the +Z direction, or if you have the capability to rotate the part, either by a multi axis machine, or simply unbolting it and flipping it on the side, then you can continue to use the same short, sturdy tool to machine the part from other angles, as shown in the picture below.

Roughing with short tool in alternate directions

Roughing with short tool in alternate directions

Other Necessary CAM software Technology

To accomplish multi axis roughing, your CAM software must include the ability to work on a 3D stock model.

To accomplish automatic collision avoidance during roughing, as we did here, then your CAM software must also include the Dynamic Stock Model. Which is a topic for another blog :)

 

 

Filed Under: 5 axis cnc software, CADCAM, CAM software, CAM tips & tricks, NC machining, NC software

CNC – Collision avoidance or collision detection?

April 30, 2012 By cjordan Leave a Comment

For 5-axis applications not only does the CADCAM software have to consider actual collisions with the tool and the tool holder, but also the kinematics of the machine tool itself. For 3-axis machining the concern is mainly the tool length and holder ensuring that it can get into each part of the job without a collision.

For systems with just collision detection, the software tells the user that there is a problem and where the problem is, but the user then has to work out what needs to be done to get over the problem for himself. In some cases this can be very complex and requires detailed investigation of the surface topology of the part.

With CNC software such as WorkNC, users can generate the collided and uncollided toolpaths and get information about the minimum tool length required to finish the job. With this information engineers can cut as much of the part as possible with short rigid cutters and restrict to a minimum, machining with long tools. Best of all, the software does all the calculation for you, so that you can be sure of a reliable, safe and optimized result.

One of the benefits of 5-axis machining is being able to cut much more of the job in one setting with the shortest possible tools, minimizing resetting and secondary operations. If the CAM software just pinpoints where there is a problem, which it will do with collision detection, it is likely that the whole toolpath will need to be recalculated after the problem has been resolved. Producing a useable toolpath this way could take several attempts so at the very least it will be time consuming and tedious. With collision avoidance, the software goes a stage further as it anticipates potential problems as you are programming. Again giving the uncollided toolpath and inserting flip and unwind movements where the axis limits of the machine have been reached.

Having intelligence within the CAM software that provides a solution to potential problems as they occur has got to be a lot better than just letting the user know that a problem exists.

Antonius Köster, who uses WorkNC Auto 5 in Germany, gave this example of one of the problems resolved with collision avoidance. “For an aerospace supplier from the Black Forest, we machined a component which required the tool holder to move inside the part through a drilled hole so that we could mill a pocket at the bottom. Not only was the cutter moving inside the part, but the whole tool holder. This was a really challenging task.”

Filed Under: 5 axis cnc software, Aerospace, CADCAM, CAM software, CAM tips & tricks, NC machining, NC software Tagged With: , , , , , , , ,

Are apps relevant to CADCAM?

April 19, 2012 By cjordan Leave a Comment

Mark Zuckerberg of Facebook has just paid $1 billion for Instagram a small app company that has yet to turn a profit. Facebook is known for its anticipation of web trends and one wonders what this could mean to CADCAM users and if we could learn anything from it.

As the engineering demographic gets younger, the use of smartphones, tablets and social media is bound to increase. Apps let users go directly to the applications they use most and allow them to carry out dedicated tasks without having to search the Web.

Because they are designed to be light and efficient, the speed of operation is much quicker so that you can complete a dedicated task in a much shorter space of time and without the distraction of all the other irrelevant information on the Web. Perhaps Mark Zuckerberg’s vision is that each of us will narrow down our use of the Internet to the topics which interest us and that random surfing from one site to another will become a thing of the past.

Using a bit of imagination about how this might benefit CADCAM users could be very productive. Certainly applications like view mark-up and analysis of CAD data would benefit from this type of approach, and maybe some CAM functionality could be split off into small apps. One possibility might be tool library and tool reordering. You could maintain your tool library in the app, which could be linked to your CAM and ERP system. When you find that a new tool is required, either through a new job or low stock levels, the app could order it from your supplier – just an idea!

Perhaps this type of approach could be a halfway house to cloud computing, which requires very fast broadband speeds to manage the large data files common in CADCAM and without some huge investment in infrastructure is unlikely to be a reality for some time.

 

Filed Under: CADCAM, CAM software, NC software, Other productivity software Tagged With: , , , , , , ,

Software Maintenance – reasons to stay current

January 18, 2012 By jjaje 2 Comments

Today we are having some fun with our blog. We are actually going to have two firsts in it.One is commenting on the topic of software maintenance, and the other is to actually reference one of our competitors. The topic of software maintenance often bring up a lot of discussion on various forums, and we welcome your comments also.

What is CAD CAM Software Maintenance & Subscriptions?

Software maintenance is simply paying a set fee, yearly, to receive updates, upgrades and usually technical support for the software product. Software subscriptions, on the other hand, are a form of renting the software product for a set period of time, and then the product “times out” and is no longer available for use, without re-renting the product.

If one does not pay their maintenance, they are stuck with the version of software they had when maintenance ceased, but can still us that version. If one does not pay a subscription, the software stops working after a period of time.

Three Reasons to Maintain your CAD CAM System (from MasterCAM)

MasterCAM software may be a competitor to WorkNC, however, a previous article, published in Moldmaking Technology magazine and on their web page in November of 2010, was written by Steve Bertrand from CNC Software. This article, linked here Three Reasons to Maintain your CAD/CAM System makes some good points. Rather than quote the whole article, I will list his three main points below:

  • Take Advantage of the latest technology – This is absolutely true, as new version of software introduce new features, often geared at increasing productivity and efficiency.
  • Make budget planning smoother – because software maintenance is a known yearly cost, it can be budgeted easier than budgeting for purchased upgrades
  • Help improve the software – People on maintenance often provide the best feedback on new features and functions they would like to see in the software.

To Steve’s listed reasons I would like to add a few of my own.

Support – WorkNC users on maintenance in the U.S. receive phone and digital technical support. We strive to to have live persons available during regular business hours instead of  utilizing voice mail purgatory. Email, file uploads and other digital forms of technical support are also available.

We have found this is the quickest way for customers to get an answer to something, and continue their job. Need a quick configuration change, or a modification to a post processor, it is a simple process.

Increased Productivity – When comparing current versions of CAM software to past versions, users can be more productive now than ever before. New functions like WorkNC’s Multi-Threading and Parallel Processing have cut calculation times dramatically.

New functions can increase productivity, for example, Feature Recognition cut the time to drill holes for some people from an hour or more to two minutes. Other functions, like rib machining or electrode machining can reduce programming time by 90% or more from traditional methods.

Increased Safety – As processing power in computers increases, CAM software developers are able to do more advanced calculations. WorkNC has had tool holder collision checking for a long time now, providing additional safety from early CAM systems. Now, it’s not just collision checking, but automatic collision avoidance with the tool holder and spindle that allows for confident lights out machining.

Remaining on maintenance allows you to receive the latest software versions, to receive the increased efficiency and the increased safety from newer versions.

What are your feelings on Software Maintenance? Is your preference for paid upgrades, yearly maintenance or yearly subscriptions? Leave your comments below.

 

Filed Under: CAM software, NC software

Optimizing the post-processed NC code can yield big benefits

January 11, 2012 By cjordan 2 Comments

nc speed toolpath optimization with worknc cadcam I am sure that every CNC machinist would like to chop a further 20% off their cycle times. Well with toolpath optimization you can!

Toolpath optimization programs which sit inside the CAM system and work on the actual post-processed code, which is the ultimate way of making sure that the machine is running at maximum efficiency, can achieve this sort of productivity boost.   The technology uses volumetric analysis to dynamically calculate the amount of material being removed at any instant. That way it knows the load on the cutter throughout the machining cycle and adjusts the feeds and speeds to keep it steady and within the limitations of the cutter. 

Not only does this speed up machining where cutting conditions are good, but for small tools it greatly reduces the chance of a tool shattering when subjected to a sudden shock load. For the engineer, going faster where possible can produce a big reduction in cycle times, while going slower where machining conditions are challenging, increases tool life and eliminates the possibility of tool chatter which will, in turn, make the tooling itself last even longer. 

As well as saving on the cost of excessively worn or broken tooling, toolpath optimization can reduce the chances of producing scrap and also greatly improve the quality of the surface finish. Vibration from toolpath chatter will damage the machine tool itself, and will also adversely affect the finished component through ripples on the surface. 

The optimization process does not stop when the tool is out of the job. By looking at rapid movements and their physical relationship to the job, the system can ensure rapid moves are used whenever the tool is above the workpiece reducing cycle times even more. 

A further advantage of keeping cutter loads constant is that tool deflection is kept to a minimum. The resulting increase in accuracy will make it much easier to produce very high precision parts.

Filed Under: CADCAM, CAM software, NC machining, NC software, Other productivity software Tagged With: , , , , , , , , , ,

CAM software – cheap is not cheerful

December 29, 2011 By cjordan Leave a Comment

In pretty much any walk of life if you buy something cheap, you expect it to have significant limitations or not last very long. I think it is safe to say that this is certainly true in engineered products. Materials are poorer, design is less elaborate and functionality is reduced. A BMW has the same number of wheels as a Lada, both will get you from A to B, so why do people want a BMW? With apologies to Lada drivers, most people can come up with a whole host of reasons.

For CAM software the same principles apply. If you buy a cheap CAM system it may do the immediate job you bought it for, but usually there is no upgrade path so if a job comes along which is too complex, you have to throw the software away and start again with a better system. Not only does that waste money, but you have all the installation costs and the associated disruption of a new learning curve to go through.

Another consideration is the level of support you are going to get with a cheap system. Realistically if there is little or no profit for the CAM system vendor he can’t afford to give proper support. You only have to look at low cost and free software on the net to see that you have to work out any problems you have for yourself. This is fine if you are just typing a document, but if your machine is stopped and the customer is on the phone, all because you can’t get the software going, it can have some very serious consequences.

The same applies to software development. If there is reduced profit for the vendor, development is bound to be slow, software releases risk being inadequately tested, and the system may be full of bugs. The user is certainly not going to be happy if the CAM system causes a machine collision, which can cost more to repair than the cost difference between a reputable CAM system and a cheap one.

Some companies are on a tight budget, so the price of a product is very important. However, if instead of just looking at the purchase price, consider what the lifetime cost of the CAM system might be. This is more difficult to quantify, but elements such as the ability to do more complex and profitable work, less danger of machine damage, more uptime on the machine tool and faster machining cycles will easily outweigh the cost difference several times over.

Filed Under: 5 axis cnc software, CADCAM, CAM software, NC machining, NC software Tagged With: , , , , , , , , , , , ,

Plunge Roughing – Part 2

December 14, 2011 By jjaje Leave a Comment

Previously, we discussed the use of Plunge roughing as an alternative roughing strategy, especially to utilize older or under-used milling machines. What I wanted to do with this entry is provide a few pointers on plunge roughing.

Plunge Roughing – not for all parts.

First, as with all cutterpath styles, you need to match the best cutterpath strategies with the part geometry. Some parts are better suited to a plunge roughing strategy than other parts.

First, consider the amount of material removal. Plunge Roughing works better if removing a larger percentage of material from the original stock, as opposed to a small amount of material. If you only need to remove a small amount of stock from a part, plunge roughing, on a global level, may not be the best choice.

Second, consider the part geometry. Plunge roughing in an automated fashion work best when removing a larger amount of material from larger areas. That is, if you have a whole lot of small pockets, then plunge roughing may not be the best choice. However when you have larger, open, areas for which to rough, it can work much better.

One particular example where Plunge Roughing can be ideal is in hydroform tooling. See the image below of an example of a good part for plunge roughing. There is a high percentage of material removal, compared to the original block of material, and it has larger open areas.

Plunge Roughing example

Plunge Roughing example

Utilizing Finer Control with Plunge Roughing

We saw in the previous post that sometimes the stock condition after roughing is “rougher” with a plunge roughing approach. While a global automatic approach may work in most instances, sometimes a person wants finer control. This may be around certain features in the design, or more often, to mill a larger channel into a part.

In this case, you may make drive curves to follow around particular features, or in a channel. This is shown in the picture below, where we utilize a curve to follow the feature more closely.

Plunge Rough around Feature

Plunge Rough around Feature

Dynamic Stock Model and Plunge Roughing

When Roughing it is important for the CAM software algorithm to know where the tool has been, and where there is stock remaining. This is done via a Dynamic Stock Model, allowing the CAM software to know the condition of the stock at every point in the cut.

This is critically important with Plunge Roughing, because after the plunge cutting motion, the tool steps away from the wall, and off the floor a little before retracting. This keeps the cutter inserts from rubbing along the wall on the way back up. If the CAM software does not know the stock at all times, then that step away can not be calculated safely, and if it were to step awaay into material, it could mean disastrous results for the cutter and spindle.

Plunge Rough Step Away

Plunge Rough Step Away

So in conclusion, plunge roughing works better on some parts than other parts. As always match the CAM milling strategy to the CAD design. Utilizing a Dynamic Stock Model is the only way to ensure the safest Plunge Roughing.

Filed Under: CAM software, CAM tips & tricks, NC machining, NC software

dramatic toolpath calculation time savings using task threading and parallel processes on multi-core processors

December 2, 2011 By cjordan Leave a Comment

In this post I want to share some of benefits of CADCAM software that enables “task threading” and “parallel processes” on multi-core processors , but first a quick explanation of those two terms:

* Task Threading: certain cutterpaths run multiple threads. That means individual portions of the cutterpath will be calculated at the same time. Computers with multi-core processors will run those threads individually, on separate cores, decreasing calculation times. It is not just cutterpaths that can be multi threaded, but other calculations as well.
* Parallel Processes: multiple cutterpaths in the workzone can be run simultaneously, as long as one is not dependant on another. For example, Planar Finishing in the WorkNC CADCAM system can run at the same time as a Z-Level Finish, since one is not dependant on the other. However, a Global ReRough may need to wait on a stock model update before calculations start. Parallel processing will allow you to calculate more cutterpaths faster than ever before, taking advantage of multi-core processors.

We tested the new version of WorkNC CADCAM software with task threading and parallel processes (Version 21) on some typical customer parts.
The same toolpaths were calculated in WorkNC Version 20 and then in WorkNC Version 21 with one CPU, followed by WorkNC Version 21 with 2 CPUs.

The results are as follows:

WorkNC CADCAM customer part 1 Part 1 with 4 roughing and 4 finishing toolpaths 

Calculation times:
2h 09 min  V20
0h 37 min  V21 one CPU
0h 29 min V21 two CPUs
WorkNC CADCAM customer part 2 Part 2 

with 4 roughing and 4 finishing toolpaths

Calculation times:
1h 30 min  V20
0h 33 min  V21 one CPU
0h 27 min  V21 two CPUs
WorkNC CADCAM customer part 3 Part 3 with 2 roughing and 5 finishing toolpaths 

Calculation times:

0h 49 min  V20
0h 24 min  V21 one CPU
0h 13 min   V21 two CPUs
WorkNC CADCAM customer part 4 Part 4 with 8 roughing and 9 finishing toolpaths 

Calculation times:
2h 11 min  V20
1h 13 min  V21 one CPU
0h 39 min V21 two CPUs
WorkNC CADCAM customer part 5 Part 5 with 4 roughing and 11 finishing toolpaths 

Calculation times:
1h 41 min  V20
0h 44 min  V21 one CPU
0h 22 min  V21 two CPUs

Using 2 or more CPUs leads to a significant savings in CNC toolpath calculation times.

Dramatic reductions, but as the examples show, the toolpath calculation time savings for parts having a high proportion of roughing toolpaths is, due to the interdependent toolpaths, less important than for parts with a greater number of finishing toolpaths.  Interesting stuff.   If you are using CAM software that supports parallel processing, what are the most dramatic toolpath calculation time savings you have seen?

Filed Under: 5 axis cnc software, CADCAM, CAM software, NC software, Parallel processing Tagged With: , , , , , , , , , , ,

Working with lots of different CAD systems

November 18, 2011 By cjordan 1 Comment

Working with lots of different CAD systems – for subcontractors and suppliers this can be a real headache and especially if you are working with automotive or aerospace customers that use some of the high-end CAD packages.

In some cases there is no alternative to actually installing one of these CAD systems and employing a very expensive design engineer to run it, which can be justified if the majority your work is in the one market sector and you have to actively participate in the customer’s design process.

Thankfully for most people, CAD translation has moved on enough to make this unnecessary. For CAM systems neutral formats such as IGES and STEP or direct translators for products like CATIA, SolidWorks and Inventor are very reliable, enabling manufacturers to accept data from many different sources without a problem.

Once you have accepted that translators are OK, you can then choose the best CAM system for your application. Even if you have had to install the high-end CAD, transfer of model data is generally one way into the CAM system, so even for these applications a specialist, best of breed, CAM package will provide the best solution, reducing cycle times, improving quality and reducing tool breakage – real tangible savings.

Filed Under: Aerospace, Automotive, CADCAM, CAM software, CAM tips & tricks, NC machining, NC software, Other productivity software Tagged With: , , , , , , , , , , , , , , , , , , , ,

Are CAM systems really all the same?

November 15, 2011 By cjordan 2 Comments

The answer has got to be an emphatic no!

If you just look at a CAM system’s graphics, it is true that the toolpaths can look similar, but the big difference is what happens when you actually try to cut metal and use the system as part of your daily routine.

Stories abound of companies continually editing programs, suffering from tool breakage, producing poor surface finishes, putting up with long cycle times and extended programming times, and having difficulty programming certain types of component. A good CAM system overcomes all these problems, changing CNC programming from a drama into a safe and fool-proof process.

The other factors to look at, when trying to distinguish one CAM system from another, is what the systems will actually do and how easy they are to use. The system needs to be able to cope with all the types of work your company does, so CAD data translation might be the first hurdle, then it could be 5-axis or 3+2 axis machining, feature recognition when there are a lot of holes or pockets, high-speed machining of molds, or even specialist applications such as dental prosthesis manufacture.

“Ease of use” is a major factor for any CAM system, because if it is difficult to program, not only will it take a lot longer to produce CNC code, but it will reduce the number of people able to handle it. The ability to have more people producing CNC code makes better use of available skills and minimizes the possibility of a programming bottleneck. Are all CAM systems the same in terms of reliability? Certainly not….

So overall, don’t be fooled by fancy graphics and promises, try the system out on your work and machine tools to see what really happens when you press the start button. So, do you believe that there is little difference from one CAM system to the next? Let us have your comments or share your experiences!

Filed Under: 5 axis cnc software, CADCAM, CAM software, CAM tips & tricks, NC machining, NC software Tagged With: , , , , , , , , , ,
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