Multitasking Programming Tips

Complex machine tools mean complex programming

turned and milled part

Creating a turned and milled part in a single setup reduces WIP and cost-per part.

As multiple operations are combined with complicated machine movements, programming becomes more difficult and more important.

The main challenge in the programming of multitasking machines is that more time and energy must be expended in the beginning of the process in order to correctly combine milling and turning techniques in a part’s creation.

These machines require a combination of tasks, and their programmers require the ability to visualize clearly what will happen inside the machining envelope.

According to Delcam’s account manager for central Ontario, Mark Sully, failure to do so can lead to setup issues, programming errors, and, ultimately, underutilization of the equipment.

“Multitasking machines offer a huge degree of flexibility, but they do need extra thought upfront,” said Sully. “A poorly thought out and poorly documented process can lead to major bottlenecks at the machine.”

In addition, unless a complete simulation of the process has been performed, bottlenecks can be created due to the wait/synchronization codes that come with having to deal with multiple turrets and spindles.

Multiple operations done within the same machine can create tremendous cost-per-part savings. In addition, less work-in-progress (WIP) is created because parts are no longer sitting around waiting for the next machine in the process to become free.

Other benefits of the multitasking process include the need for fewer fixtures, which also means less setup time, and fewer geometric errors caused by multiple fixturings.

“However, the price of all of this is a single, more complex process,” said Sully.

Familiar Toolpaths

While the process in general is more complex, the individual toolpaths will be very familiar.

turning and milling single machining envelope

Turning and milling in a single machining envelope create a need for complex programming.

“A turning toolpath on a multitasking machine looks very, very similar to a turning toolpath on a simple two-axis lathe, and the same applies to a milling toolpath,” explained Sully.

Multitasking machines truly shine when they can utilize the full power of both their turning and milling capabilities. It is the combination of both that really gives these machines a large amount of flexibility.

“On occasion there may be the need to use the machine solely as a turning machine or solely as a milling machine, and not being able to is simply a handicap for any manufacturing business. Flexibility is key,” said Sully.

According to Sully, when using only one of the machine’s capabilities, try and finish as much of the part as possible in a single operation. The easiest way to do this is to break the whole process down into more manageable operations.

“As a simple example, in some applications I’ve been involved with, we’ve mounted a small tombstone fixture block between the spindles in a multitasking machine and used it to mount multiple blocks. Then we machined a complete family of parts. No turning whatsoever, but another great use for a multitasking machine,” he said.

Only by examining the type of work and the exact configuration of the machine tool can an effective programming cycle be created.

“We have multiple products capable of being used to program multitasking machines and they each provide critical but slightly different benefits to the user,” said Sully. “Rather than simply offering a single solution and then forcing the user to conform his way of programming to the software, we can offer a solution that is the right choice, without compromising.”

Also of great importance are verification, simulation, and visualization of the program. When multiple turrets and spindles are moving simultaneously, it is vital that the operator is confident no machine collisions will occur and that all toolpaths have been verified as being safe.

Without simulation, setup times can be too long and programmers and operators may have low confidence in the program. The programmer must be confident that the software will produce the correct G-code for the toolpaths and also synchronize the turrets correctly.

Postprocessing

Postprocessing is the single most important element of any programming environment.

“Without a good postprocessor, it doesn’t matter what your toolpaths look like or how good your process is, a user will not make the most of his machine,” said Sully. “The last thing they want to be doing is editing G-code by hand at the machine due to errors.”

Wasted time at this stage can be a costly mistake no matter what the complexity of the part is, or what the shop environment is like.

“CAM software is a tool to generate the code necessary to make a machine tool operate efficiently, and any solution that doesn’t offer a robust postprocessing environment isn’t a solution at all,” said Sully.

Like every other aspect of programming a multitasking machine, training and support can be more complex when compared to traditional machining.

“It really does depend on the experience of the user with multitasking machines,” said Sully. “If they don’t have a lot of experience, then it’s absolutely critical that the correct amount of training is given and then followed up with on-site visits to answer any questions and provide advice where needed.”

Application experts can help to eliminate bottlenecks and underutilization while offering advice on the ultimate goal: lowering the cost of the final part.

For more information, visit www.delcam.com.