5-Axis CAM for Mold and Die

May 2, 2013 By Leave a Comment

5-Axis machining for Mold and Die

More companies are investing in 5-axis technology for milling mold & die components. Part of this is certainly because of the growing numbers of different models of 5-axis machining centers becoming available in the marketplace. As with many other advanced technologies, new entries into the market place have brought innovation providing high functionality for lower costs. One such example is from the camera phone video below. This was from the IMTS 2012 exhibit trade show, and shows a Hurco iSeries mill performing smooth 5-axis movements on a part that had truly a mirror finish.

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Simultaneous vs Positional 5-Axis

When discussing 5-axis, it is usually a good idea to expand on what we mean. 5-Axis simultaneous is when rotations and linear movements can happen at the same time (simultaneously) while milling. This is what you see in the video above.

5-Axis Positional, sometimes referred to as 3+2 machining, is when the mill rotates into an angular position, then mills with linear moves only. It does not rotate while actually milling.

From a practical standpoint, most all 5-axis simultaneous milling machines can also do 3+2 axis machining. However, not all 3+2 axis milling centers can do 5-axis simultaneous.

Why 5-axis for Moldmaking and Diemaking?

3+2 axis machining has been common in mold and die machining for some time. Especially when programming for slides in a mold, where this was the only way to mill that particular area. However, for simultaneous 5-axis milling, there are some real positive reasons why you would choose to invest in this technology, these are:

  • To mill deeper into a part easily, allowing you to use fewer, or no, EDM burning operations.
  • To mill more of the part with short tools, providing better finishes and shorter milling times.

For example, in the sample part below, this lifter pocket has very small radii at the bottom of the pocket. One would need to either mill it in 3-axis with a small diameter tool, which has a long shank, or they would need to mill several electrodes and EDM burn the material away. The problem with milling it in 3-axis is that the length/diameter ratio of the tool is very much out of line, and the tool would vibrate, if one could be found at all.  The problem with burning it is you still need mill time to make several electrodes, then the time to burn it in.

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In the end, the pocket can be milled in 5-axis, all the way to the bottom, quicker, and with a better finish, than other methods. This is one typical reason for utilizing simultaneous 5-axis for milling some parts.

Additionally, 5-axis programming can allow you to use shorter tools, mill more of the part, and provide better finishes and shorter mill times.

For example, the part below can be milled in 3+2 axis to utilize short tools. However, to mill the complete thing, it may take Eight separate 3+2 angled cuts, and you may run into blending issues. All milling machines are accurate when rotating to some tolerance. Blending multiple 3+2 cutterpaths may not provide as good of a surface finish as using one simultaneous cutterpath across the whole part.

3+2 axis machining

3+2 axis machining

Additionally, the 5-axis cutterpath can utilize optimum lead or lag angels for better cutter contact and less variation in finish resulting from milling with the tip of the cutting tool.

5-Axis CAM software for Moldmaking

So what does your CAM software need for 5-axis machining of Molds and Dies?

First it needs traditional 5-axis functions. For example rolling, swarf milling, 5-axis engraving, etc. But then it also needs an easy way to mill an entire part, with a short tool, and be completely collision free of the tool and holder.

This is exactly what the Auto-5 Module in WorkNC does. It takes any 3-axis cutterpath, and allows you to convert it to 5-axis simultaneous cutterpaths, so that the tool and holder automatically avoid collisions. This allows you to mill deeper into pockets, and also allows you to easily finish with shorter tools. The benefits of a module like Auto-5 are:

  • It automatically does tool holder collision avoidance to keep collisions from happening. And automatic avoidance is better than just collision checking.
  • It is easy to program 5-axis. If you can make a 3-axis cutterpath you can make a 5-axis cutterpath just as easy, and almost as quickly.
  • It has intelligence built in to consider the machine kinematics and limits, especially rotational limits.

Amerimold 2013

Visit us at the Amerimold Expo in Rosemont, IL June 12-13. We will be located in booth 428. Preregistration is free and currently ongoing.

During the show, we can demonstrate the benefits of 5-axis machining for mold and die machining, as well as the benefits of the Auto-5 automatic machining module.

Looking at buying a 5-axis mill? We created a short pdf slideshow of things to consider when shopping for 5-axis mills. The tips in this paper can save you some headaches later. Simply click the button below:

Download free Tips

Download free Tips

 

 

 

Filed Under: 5 axis cnc software

Switching CAM Software

February 11, 2013 By Leave a Comment

There comes a time in many CNC machine shops where they either upgrade or switch their main CAM software platform. Today’s blog entry will look at some of the reasons why, and some of the opportunities and risks involved.

CAM Software in the Early Days

When CAM software for sculpted 3D parts was in its infancy it was difficult to use, very user interactive, and often took hours to calculate the cutterpaths. Because of this, it was often times sold straight from multiple demonstrations performed by the sales team, or via a benchmark where multiple software products were invited to cut the same parts in competition.

Many things that prospective buyers and customers asked for were going to be provided in “the next release.”  Shops had to make the best decision for them at that time. This decision often used the cost of the software as a main factor, where lower functionality products were chosen based on costs. “High End” CAM Software packages required a premium over a lower end product.

As time went on, the CAD/CAM software industry acted like many other industries; where new innovations start to eclipse older technologies.

Outgrowing Your CAM Software

Sometimes a company would outgrow its CAM Software package. Any cost savings of purchasing and implementing a lower end product were often offset by higher scrap rates of lower performance products, higher machine and labor costs of less efficient CAM software algorithms and higher tooling costs from less than ideal cutterpath strategies.

In this instance, they may then decide to invest in a new CAM package, one that does not have the short comings of their first choices.

Armed with a learning experience from their first purchase, the customer is better educated for their new purchase. They usually will compile a list of functions that are necessary in their new CAM software package, and insist on seeing those items on their own data.

Out Advancing Your CAM Software

Some companies switch their CAM software because they “out-advanced” their current system. What this means is that they customer technologically needs something the CAM software does not provide.

One example of this is when a company buys more advanced technology, such as high speed  mills, or 5-axis mills, yet their existing CAM software does not provide a good solution for their new purchase. They often find that a new CAM software package for their new technology will actually also improve their productivity on their older mills, and make a switch across the board.

Opportunities of Switching CAM Software Solutions

There are several opportunities to be gained from switching to a different solution and some of those are:

  • Higher Productivity – upgrading software can lead to more advanced functions that allow you to be more productive.
  • Flexibility – by also keeping your old software package, you have flexibility to choose more options for exactly what you want to do on any particular part.
  • More Advanced Technology – many people upgrade to take advantage of higher technology, such as 5-axis mills or high speed mills.
  • Employee Retention – Allowing new challenges to employees provides a greater job satisfaction.

Risks of Switching CAM Software Solutions

Of course there are risks to switching CAM software products also:

  • Some employees are resistant to change.
  • Risk of moving to the wrong package, or allowing politics to influence your decision.
  • May need to rewrite custom macros or custom tool libraries.
  • Risk of temporary downtime and lower efficiencies as employees get proficient with the new solution.
  • Risk of needing to upgrade or change hardware.

Tips for Switching CAM Software Products

So you got this far, below we are listing some tips that you may want to consider when switching CAM software. If you have any of your own tips, please leave them in the comments.

  • Try before you buy, do an evaluation of the software on your own parts with your own tooling and mills.
  • Don’t let “rush work” or emergencies get in the way. Commit to giving the evaluation a fair and complete try.
  • Don’t skimp on training, get full training of your people.
  • Test on a variety of parts, on different mills if possible.
  • Make sure your post processors are working to your expectations.
  • Don’t skimp on consulting or customizing. All this work takes time, many companies decide to not pay for consulting, and some of the time savings benefits of what could have been done don’t materialize then.
  • Stay Objective, don’t let emotions get in the way of logical decision making.

Post your own ideas in the comments below.

 

Filed Under: CAM software, CAM tips & tricks

Shop Floor CAM

January 23, 2013 By Leave a Comment

Companies with CNC milling machines and CAM software to program those machines have different ways that they can program their mills.

One way is to not program their mill, but rather just run programs provided by customers and other third parties. While this method can save the cost of purchasing CAM software, it can also be the most risky method when you consider the safety of the mill and its tools. Without the CAM system, or some other software, to view the CNC files and possibly make simple edits, you are trusting the programming of someone that is not even there, for the safe operation of your milling machine.

Additionally, machine down time can be considerable if you have the part to be machined mounted on he mill, yet are waiting for the third party to finish programming the part, or worse, the down time involved if waiting to get some changes to the programmed files made.

For companies that invest in CAM Software, typically either they can program off of the shop floor, in a separate design or programming room. The alternative is to program the CNC CAM software packages right on the Shop Floor. It is this route we will focus on for today’s blog entry.

Typically in shop floor CAM programming, the mill operator has a seat of the CAM software next to his mill, and can create the necessary CNC cutterpaths to machine his part right there.

Shop Floor CAM Benefits

Shop Floor CAM programming has many benefits, some listed below:

  • The mill operator can program the part exactly how he wants, without complaining about how someone else programmed the part. This in turn eliminates a lot of interruptions and downtime of the CAD/CAM programming room personnel to answer questions or make changes.
  • Shop Floor CAM allows for closer timing between the part and the milling operation. Many parts, especially with custom manufacturing, go through many design and engineering changes. Shop floor programmers typically simultaneously program their next part, while the current part is being milled. If the cutterpaths were made well ahead of time, in a programming room, a higher percentage of them will need to be re calculated due to engineering changes.
  • The shop floor programmer knows which cutting tools are available and which ones are in short supply or are out. There are few things worse than programming several cutterpaths on a part, only to find out you are out of that particular sized tool. Especially if later cutterpaths are dependent on the earlier ones.

Machine operators can multitask, and do important tasks, like programming, whilst running their mills.

Shop Floor Programming can make sense for some companies

Chop Floor CAM

Tricks to do Shop Floor CAM

Some tricks to help make shop floor programming successful are:

  • Provide adequate training to your programmers, and compensate them accordingly. If they are doing more, and handling more responsibility, than that is a win/win for them and the company. To help them program most efficiently, do not skimp on their training!
  • Strategically place the computer they are working on by the controller for the mill, so if they hear anything abnormal in their mill, they can react quickly.
  • Invest in a quality shop floor management ERP and scheduling system, such as the sister product WorkPLAN, so the machine operator will know what to expect for future jobs. This way, they can think about tooling and fixturing ahead of time.
  • Allow the machine operators / shop floor CAM programmers, to share with each other what has worked and not worked. This sharing of tips can often have a large positive impact on efficiency.
  • Let the programmers experiment and try new things once in a while, it can lead to new ways ideas and ways of cutting parts that were not thought of before.

Best of all, depending on the parts you cut, Shop Floor CAM programming does not have to be a once CAM system to one mill proposition. With advanced CAM software like WorkNC, we have seen one shop floor programmer run four 5-axis milling machines all at the same time.

Filed Under: CADCAM, CAM software

Spiral Movements in High Speed Machining

January 10, 2013 By 2 Comments

High speed milling machines have been around for several years now. Generally, it has been found that if you can keep the mill moving in a continuous motion, without breaks, retracts or sharp corners, then you can generally get the best performance out of your high speed CNC mill.

One way to maximize efficiency and have continuous cuts is by milling with a spiral strategy. This allows the tool to keep moving in a continuous motion, especially useful on pockets and holes, as shown in the figure below.

Spiral cut on pocket and wall

With the part above, the tool cuts the wall of the pocket, as well as the wall of the hole with a spiral strategy. There is one approach lead in and one lead out retract, otherwise the tool moves in one continuous, fluid motion, without sharp corners, retracts or unnecessary lead in/ lead out movements. Movements like this benefit high speed mills and the high speed milling operations by keeping the tool engaged and eliminating sharp corners forcing the machine to decelerate more often than necessary.

While spiral milling is not new technology, not everyone is doing it, and it’s worth mentioning it as a tip. What is slightly newer, are spiral movements while performing 3D high speed machining. Some CAM software packages have this functionality and some do not.

With a traditional 3D stepover movement, the milling machine may perform an arc lead in and lead out on every pass, as shown in the image below.

3D Clean out without spirals

Traditional lead in / lead out movements

However, by utilizing a Spiral Linked Movement, then the 3D steps on this geometry can be machined in a high speed motion, allowing for more continuous finishing and faster yet smoother movements by the high speed mill. This spiral movement is shown in the image below.

Spiral 3D Stepovers

Spiral 3D Stepovers

In conclusion, if you have spiral machining options in your CAM software, make sure to take advantage of them, especially if using High Speed Milling Machines. Does your CAM software allow you to finish with a spiral motion? Do you use it? Leave a comment about our blog post.

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Want to learn about the Benefits of Ease of Use in CAM Software? Download our free Whitepaper.

Download our whitepaper on Ease of USe Benefits for CAM Software

 

 

Filed Under: CAM software, CAM tips & tricks

Automatic CAD CAM Part 2

December 13, 2012 By Leave a Comment

Automatic CAD CAM

In our previous blog article, we discussed how to automate the CAM software programming task, often with the use of standard sequences. This could allow you to easily program completely different parts either easily. The parts would be programmed either completely, or mostly, from past knowledge, minimizing the user interaction required.

This process only works if the CAM software also has automated cutting routines for milling the part. For instance, if the individual CAM software algorithms require a lot of user interaction, then it may not be possible to efficiently utilize a custom sequence and apply it to a variety of parts.

Thus, it’s not just the ability to quickly program the parts via the sequences, but it is also the ability to have multiple cutterpath styles defined with a minimal amount of user interaction.

Sometimes these cutterpaths are given the moniker of “automatic” cutterpaths, and a few of these are listed below:

 Automatic Holder Collision Avoidance and Automatic Roughing

When machining, taking care of the tool holders and spindle becomes important for safety and reliability. When Roughing, it is usually best to rough with the largest and shortest tools to get the majority of the material out, and utilize automatic Re-Roughing to machine the leftover areas.

This is shown in the two pictures below. It is possible to rough the majority of the part with a relatively short tool, as shown in the first picture. Next, one automatically removes the leftover material utilizing  different tools, holders or angles, as depicted in the second picture.

CAM Roughing with Short Tools

Short Tool Roughing

Automatic ReRoughing in CAM programming

Automatic ReRoughing

This automatic Roughing and Re Roughing must look at the tool and holder with regards to the actual in process stock material so that all of the cutterpaths can be created collision free to not only the part, but the material.

 Automatic Remachining

Automatic remachining is sometimes referred to as rest material machining. What it refers to is the rest of the material, or the leftover material. For example, if you have a part with concave fillet radii of say 1mm, and you finish the part with a 5mm tool, then the corners would have residual material, and need to be remachined.

An example of remachining is shown in the picture below. Again, the CAM Software finds the “rest material” areas automatically and machines them.

Rest Material Cutterpath for automatically milling the est of the material

Rest Material Cutterpath

What is important with rest material machining is that it be able to work with all tool types, from ball mills to flat end mills, and also to be able to work in any axis.

Automatic 5-Axis

Although many people believe 5-Axis programming is difficult and time consuming, in many instances it does not need to be. One particular goal for 5-Axis machining is to utilize short cutters to mill deeper into parts. Reducing the areas needed to manufacture via an EDM process.

Automatic 5-Axis in this case means to use the short tool, in 5-axis to automatically avoid collisions, all while providing smooth output that does not rotate outside of the machine limits.

Below is a picture of an Automatic 5-Axis cutterpath, which was just as easy to program as a 3-Axis cutterpath.

Auto 5-Axis easiest way to use short tools and finish the whole part.

Auto 5-Axis CAM programming

In this instance, the 5-axis cutterpath is just as easy to program as a 3-axis cutterpath, and the toolpath automatically rotates the tool vector so that the entire part can be milled with a short tool, and no electrode.

Can you think of any other automatic functions a CAM software product can do or that you would like them to do in the future? Leave your comments on the subject.

 

Filed Under: CADCAM, CAM software, CAM tips & tricks

Automatic CAD CAM

November 28, 2012 By Leave a Comment

Automatic CAD/CAM

The adjective “Automatic” gets used a lot when referring to CAM software. What makes something automatic? How automatic can you make CAM software? When do you not want something to be automatic?

From our web page for WorkNC we describe part of the “automatic” question this way:

The automatic features of WorkNC allow novice CAM operators to automatically set up toolpaths in just a few minutes. Experienced users of other CAM software quickly appreciate the profitable and unique benefits WorkNC provides. Used either directly on the shop floor or in your CAD room, the reliability and quality of WorkNC’s CNC programming are unsurpassed!

So what does it mean to Automatically set up Toolpaths?

There are different ways that you can automatically set up NC toolpaths and their corresponding parameters. One way is to have the parameters set up in your tool library, when you pick a particular tool, then all the parameters come with the tool.

Utilizing tool libraries are a good way of quickly entering the parameters for any particular toolpath. Parameters such as step over, step down, tolerance, speed, feed and what not can all be in the tool library and brought in to the CAM software when the tool is selected.

When the same tool is used for different materials or strategies, then often one makes duplicate entries into their tool library.

Templates and Sequences

Here I will use the term template and sequence interchangeably. Toolpath sequences can often have a whole set of cutterpaths and their corresponding parameters set up for automating the task of programming NC toolpaths.

For example, I may cut a lot of different parts that are similarly sized, and of the same material. Often this relates to the regular jobs associated with any particular mill in your shop. Even though the parts are dissimilar in shape, I can still use templates for a bulk of the programming.

Below we loaded and created cutterpaths to mill this crankshaft part. We utilized standard tools that were in the tool crib at the time.

Template to machine crankshaft

CNC Cutterpaths to Finish Part

If I really like how the cutterpaths turned out, I can turn everything I did into a NC machining sequence. I can then apply this template to other parts, even though they are shaped very differently.

For example, I can load the clutch housing below, apply the same template I liked from the crankshaft, and be done with the programming for this part in about 10 seconds.

Automatically program this in 10 seconds

Programmed in 10 seconds

With this strategy, parts of similar sizes and material can be programmed in very short order. With multi-core CPU’s, batch processing, parallel processing, one can literally program dozens of parts before their first coffee break.

The best part is that even if the template is not perfect for 100% of the machining, I can easily modify one parameter, or add a few more cutterpaths to complete the machining process.

Potential Pitfall of CNC Templates:

One potential pitfall of using templates is that you become too dependent on them, and do not experiment or keep up with advances in the CAM Software.

For example, one company made multiple templates for about any situation. These templates included Roughing templates, Semi Finishing templates, Finishing templates and 2D machining. New employees became so accustomed to using the templates, they did not know how to run the regular software.

As time went by, new CAM Software cutting algorithms were developed, but they were still using old templates. The new functions provided higher reliability, more efficient milling patterns and extended tool life.

Eventually this particular company asked for some software enhancements, not realizing the enhancements were already in the newer versions, and they just had to be implemented into their templates.

So the moral is to definitely use templates and sequences to save time, but don’t forget to update them for new advances in your CAM software.

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Want a free whitepaper that discusses the cost benefits of Automatic CAM? Download it from the link below.

Cost Benefits of Automatic CAM

Filed Under: CADCAM, CAM software, NC software

What is Brep you ask?

November 21, 2012 By Leave a Comment

Brep or boundary representation is a way of defining geometric forms using edges, faces and vertices.  The advantage is that these edges are stitched together, so with the addition of surface data, this too can be stitched into a complex solid model.

Entities such as cone, plane, torus, cylinder and sphere can be easily represented by Brep technology as their intersections and edges can be exactly calculated. The result is a solid model defined by its edges. With Nurb surfaces, the edges are not so exact, as different CAD systems will have small calculation inconsistencies which can result in microscopic gaps between surfaces. Additionally, surfaces have direction, so this may be pointing in the wrong direction. With Brep, these edge gaps can be stitched together and surface direction modified to form a solid entity.

For STL data, the representation is mainly through triangles and quadrilaterals which approximate to the surface. Smoothing techniques in Brep, which work on the boundaries of these elements, can help to improve the surface topology by reducing the number of triangles required to define a component.

The majority of CAD systems use Brep technology so translation between different systems using the same technology is considerably easier. Other advantages include the ability to carry out sophisticated analysis of the geometry to determine volumes or surface areas, for example. Sescoi’s WorkXPlore 3D mark-up and analysis software uses Brep technology, enabling it to import CAD models from a wide range of systems and, because it can find edges very easily, it can give accurate dimensions and volumes. For imported STL files, it can also smooth and simplify the result to give a better representation of the scanned part making it much easier to interrogate and use.  Good stuff this Brep technology….

 

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

CNC Machine Simulation & Collision Detection

October 17, 2012 By 8 Comments

During the course of programming your CNC mill, you may find it necessary to perform a Milling Machine simulation which includes some form of batch collision checking, as part of your routine. This can become especially important when programming in a 5-Axis CNC machining environment.

CNC Milling Machine Collision Checking:

Some, not all, CAM software packages have the ability to perform a machine collision check of the calculated cutterpaths. Having the ability to find any potential problems before running on the actual milling machine can save you the expense of replacing a block of material, or worse, repairing a machine, and the associated downtime.

Basically, what this functionality does is utilize a CAD model of the milling machine and move it through point of the CNC output file, and check for any collisions between the part, tool, tool holder or any portion of the mill, such as the spindle, rotation axes, etc.

Tight areas really need collision checking

Full Machine Collision Checking

Why Do Machine Collision Checking?

The first thing people often say is that they thought this was done by the CAM program all the time, automatically. Most CAM programs calculate their cutterpaths considering just the tool, or sometimes the tool and tool holder. They are usually not calculating whether the spindle or some other portion of the part collide or not. Full CNC milling machine kinematics collision checking is usually an extra step in the CAM software programming process. Some reasons to do the milling machine collision checking are:

3+2 or 5-Axis machining: Not only are these machines more expensive then their 3-axis counterparts, but the chances for collisions increases every time the part, or the spindle and head rotate. Full simulation and collision checking can verify that the cutterpath is safe, before actually running it on the mill.

Lights Out Machining: If it is one of your goals to run unattended machining, you need to be very confident that your cutterpaths are completely safe. Running a batch collision check can give you that confidence to run lights out.

High Performance Machining: Watching the simulation of the milling machine can show you if there are areas of unnecessary machine movements, or unnecessary retracts & rapid moves, that you can possibly edit out before running. Because time on the mill is more expensive than time on the computer.

Does you CAM software have Machine Collision Checking?

There really is no standard way that CAM software companies handle machine simulation and collision checking. Some CAM products do not offer it at all. Some include a 3rd party product to handle this. Some CAM software companies develop it for themselves, but charge extra for it, while very few include it as standard functionality.

Some CAD companies do not develop their own CAM software, but rather use third party solution partners for their CAM solutions. Usually the API of the CAD package does not allow the CAM developer to provide an integrated machine simulation and collision checking function. In these cases, you usually end up running it in separate windows, with separate interfaces and learning curves.

CNC Machine Collision Checking in 5-Axis

Collision Checking is only as god as the CAD model of your mill

Tips for Machine Collision Checking:

Maybe you are convinced that doing some collision checking is beneficial to your business, here are some tips:

  • The simulation is only as good as your CAD model of the milling machine. Make sure your CAD model is as accurate as possible. In some cases, the CAD model does not include extra added on later like some coolant lines, or tool setting lasers. Make sure your CAD model is accurate.
  • Place the part in the simulation in the same location you place it on the mill. This seems like a no-brainer, especially if your simulation software is also checking whether you approach any linear or rotational limits of the machine. If you simulate with the part in one location, but actually put it in a different location, then your limit calculations could be wrong.
  • Utilize the actual correct tool lengths, otherwise your calculations will not be accurate.
  • Run your simulation in a batch mode if available in your software. Computers are really good at repetitive calculations, so let them do something they are really good at.
  • The first few times you use it, test the results very carefully, to build confidence in your product and your process.

Lastly:

Machine simulation and collision checking can help you run your mill with more confidence, a larger factor of safety and possibly unattended. In many cases, it is only a few mouse clicks to activate this functionality, so there is no real reason not to use it.

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

CAM systems must keep tool loads constant

September 26, 2012 By Leave a Comment

To maximize tool life and avoid tool breakage, CAM systems need to be able to maintain a constant tool load. Tools are most in danger when entering the material, when taking a full diameter cut, when rubbing in corners and when coming across unexpectedly thick material. In all these cases shock loads are applied to the tool either due to vibration or through sudden heavy cuts. This leads to tool flexing which not only introduces inaccuracy and a poor finish but also a shorter tool life and in extreme cases tool breakage.

To avoid this type of problem, CAM systems use a number of strategies which work together to provide a solution. These include -

Keeping the tool in the job -

By producing a continuous spiral toolpath with ideally only one start and finish point, the software reduces the chance of damage when the tool enters the material. Climb milling where possible will also produce the best cutting conditions. Any cutting strategy that reduces the number of lead in and lead out movements will help to reduce risk.

Helicoidal lead in moves –

When the tool enters the job or feeds down from one level to the next the creation of helical moves ensures that the tool is not cutting on its full diameter as it goes into the material.

Knowledge of where excess material is located –

An accurate stock model and rest model is probably the most important feature for avoiding shock loading. With this capability, the CAM system knows exactly where material needs to be removed. Not only does this avoid running into thick pieces of material, but it minimizes air cutting and reduces unnecessary retract movements.

Trochoidal toolpath –

In some instances there is no way of avoiding taking a full width cut with the tool. With a trochoidal toolpath the system knows that it is about to take a full width cut, and introduces a spiral movement in the forward direction which only cuts with part of the tool diameter. This is useful for hard materials and where a large depth of cut is being taken.

Smooth changes in direction –

These are many and varied and include spiral movements in corners to stop the tool rubbing with its full diameter, smooth transitions at corners to eliminate sudden direction changes and extensions of cutter paths to produce a smooth exit and finish between passes. For Z-Level machining smooth circular entry paths at each level minimize shock loading and, as in all the methods for achieving a constant tool load, help to improve the surface finish.

How is your CAM system performing?

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

Tricks to achieving high metal removal rates

August 9, 2012 By 2 Comments

For many mold tools and aerospace parts, it is not unusual to machine away more than 50% of the material you started with. Obviously this needs to be done as quickly and efficiently as possible to keep costs down and speed up manufacture.

Global Roughing and Re-roughing toolpaths can achieve very high step overs of around 95% combined with large Z depths of cut. To do this requires an accurate and dynamic stock model which updates as each toolpath does its work. With corner smoothing and HSM techniques the software can reduce the number of retracts necessary and create efficient toolpaths with a constant tool load. Other features include trochoidal moves where the tool has to cut into solid material which again enables the tool to operate at large depths of cut and at high speed.

Identifying and machining flat surfaces separately, further increases metal removal rates. Automatically finding these makes it possible to process these areas with a large flat cutter and, where it is possible to use 3+2 techniques, identify flat areas which can be made normal to the cutter by tipping the job or machine head and machine these too with the same strategy.

Plunge roughing is another technique which can yield very high metal removal rates. With this strategy the software drills into the job stepping over and using the dynamic stock model to pick where the machining should take place while avoiding leaving any small upstands and also considering the evacuation of swarf. Re-roughing with this method makes it possible to get to the near net shape very quickly indeed.

For some parts, especially in aerospace applications where there is a thin wall which may be deformed by conventional roughing and finishing, special methods are needed. Thin wall strategies rough each side of thin walls in turn by level so that there are no excessive sideways cutting forces imposed on the wall. This stops it bending as cutting continues and maximizes metal removal.

..Easy when you know how or with the right CADCAM system.

 

Filed Under: Aerospace, CADCAM, CAM software, CAM tips & tricks, Mold, die and tool, NC machining, NC software Tagged With: , , , , ,
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