The main aims of part-nesting programs remain the same--to maximize material utilization, improve process flow, and enhance flexibility. But as it's improved, nesting software is becoming more process-specific and integrated. Rather than standing alone as a separate application, more nesting programming is being built into software that can handle multiple aspects of a fabrication process, whether for laser, waterjet, or plasma cutting; punch machine processing; or even press blanking.

"Expert" Laser Nesting

For example, Cincinnati Inc.'s (Cincinnati) version 3.6 of its Laser Programming and Nesting Software features more than 30 improvements for nesting and process optimization. It reportedly incorporates "expert system" programming, which follows a rules-based process customized with user-defined variables to simulate the behavior of a human expert.

Along with building nests of individual parts, the software can nest structured group files composed of multiple parts, allowing a user to specify entire sets of parts at one time. The software also determines the best sheet size for a nest, particularly useful for systems with automated material handling. And it allows a nest file to be used by more than one model laser without rebuilding the nest, a feature that's said to be useful for multi-laser operations or laser upgrades.

But the software targets improving process efficiency in other ways for the company's laser cutting systems. For example, it automatically provides output for laser sequencing and feature avoidance--programming that typically would require manual input by a skilled operator. It also optimizes part programs and codes for each machine's speed and cutting capabilities.

Low-Volume Nesting

Software upgrades like the foregoing particularly benefit high-volume operations, but the production situations in which shops are using nesting tools are changing. In these lean economic times, Shawn Thompson, CAD/CAM business manager for Strippit/ LVD (Akron, NY), has noticed a tendency in manufacturers' uses of nesting software. "With the economy changing, we're seeing a lot more small-volume production runs." Moreover, to keep busy, shops are diversifying their orders and each day's requirements.

As a result, more shops are using the nesting functions of Strippit's CADMAN package software on a daily basis for very low-volume production, he says. Each day, a company creates a work order for nesting that day's part requirements, treating listed parts almost as if they were part of the same part family.

Strippit/LVD's CADMAN

This wasn't exactly the software's target application, he adds. Typically, the software's work-order component was meant to combine parts of the same assembly, such as all the parts needed for a home appliance. "We were leaning this software more toward larger manufacturers, but we're finding a lot of customers have some really clever uses for optimizing their material utilization, and basically mixing together multiple jobs of low-volume runs."

The approach works for day-to-day needs in which a "small shop treats each day as one product." Users simply "drag and drop" part data onto the work order, whether from a parts database or a parametric library of shapes, such as a library of HVAC ductwork components the company released this year.

Punched-Part Databases

Any parts database used for nesting, however, has to be a bit more packed with information for punch-press operations than for laser or torch cutting, notes Thompson. In a punched-part database, part entries have to define what punches and tool sizes are needed to make each feature, and indicate whether to nibble or punch an entire hole, for example. "Laser-cut parts are much less ambiguous. You don't have to make all those decisions ahead of time."

Tooling complications in punch-press nesting can be simplified by data-sharing programs like the one from Striker Systems (White House, TN). The company's Mike Boggs says the PARTshare application is being released to handle part data for both SolidWorks and Autodesk Inventor platforms.

"Basically, the PARTshare library allows engineers to save parts directly in the same library that is used for nesting," says Boggs. For punch-press fab, a programmer retrieves the current part data, enters tooling information needed for manufacturing, and saves this tooled version of the data back into the library. This helps coordinate a shop's engineering and manufacturing, letting each department view current part data simultaneously.

The software addresses issues that interfere with getting the proper nests, schedules, and NC programs to the shop floor automatically. With CNC laser or plasma cutting, with only a single tool path, it's easier to operate in an automatic, "hands-off" mode, he says. But "a hands-off scenario such as this is much more difficult with a turret punch press because of numerous tooling issues."

Nesting Accommodated for Punching

Training instructor Dave Lowrie of Merry Mechanization Inc. (MMI) (Englewood, FL) agrees that parts nesting for punching machines can be a real challenge. "The total number of tool stations and the availability of auto-index stations are just two considerations that will have an effect on the nesting process.

"For example, what happens if a nest contains parts with a greater variety of hole sizes than there are punch stations to accommodate them?" As a solution, MMI's approach allows complete tool loads to be saved. The user can then search a sheetmetal database for all parts that use the same tool load before creating the nest. This ensures adequate tooling for all the nested parts.

And what about the limitations of auto-index stations on typical punching machines? True-shape nesters can turn parts through any angle, which is essential for cutting machines, but a lower-cost, rectangular-shape nester can be used to rotate parts in 90-degree increments for punching. Non-rectangular parts can be put into material-optimized "sub-nests," which can be added to the larger nest with the company's programming, says Lowrie.

Suppliers of packaged software are also upgrading products to streamline production flow by speeding up nesting and punch programming. The new release of SigmaNEST software from SigmaTEK Corp. (Cincinnati) features Auto Dynamic Nesting, which reportedly allows a punching machine to "tool on the fly," enabling faster programming and increased throughput.

This upgrade has been "pre-released" to a general fabrication shop in Georgia for just-in-time production, says the company's Glenn Binder. The fabricator uses the program to nest parts at the last possible moment before production, allowing substantially reduced inventories and freeing up cash.

Likewise, dedicated machine software is being upgraded for more flexible fabrication. For its punching and shearing machines, Salvagnini America (Hamilton, OH) is releasing Metalnest, an application that's replacing its current Autonest program.

Forming Technologies' BlankNest optimizes nesting for blanking, based on raw coil width and pitch.

Besides being easier to use, the new software accommodates parametric part programs. "This means we can have on the machine a small number of master programs that can produce a very wide set of parts," says application manager Ricky Hansson. By assigning numbers to specific parameter values, the software allows the user to preview processing results (see lead photo).

The software also allows the user to choose from algorithms for a specific "format optimization"--that is, to nest parts for improved process attributes other than material utilization. For example, "the user can decide that the best format is one with minimum scrap, minimum time, or the one that guarantees a predefined sequence of parts," says Hansson. And for machines with integrated shears, the software can also manage the lengths of blanks cut from coil, calculating the ideal lengths for various part nests.

Blank Nesting

As with processes that cut or punch out small parts, large-scale press-blanking operations can also benefit from nesting software, says Dan Marinac, director of business development for Forming Technologies Inc. (FTI) (Oakville, ON, Canada).

Stampers have similar concerns about sheet utilization as fabricators. But the differences in their processes are significant: blanks are cut with press dies from a continuously fed steel coil rather than from a sheet of fixed size. Thus, FTI specifically designed its BlankNest program for transfer-press stampers who are producing high-volume developed blank shapes.

This software addresses nesting issues unique to blanking, explains Marinac. Each stroke of a blanking press cuts one or two blanks from the coil, requiring "one-up" or "two-up" nests. "In the case of a one-up nest, all blanks are in exactly the same orientation. Because these stampers can custom-order coils of steel in any width, the software must perform a double optimization: it must optimize for both blank orientation and coil width.

"A two-up nest layout typically will improve material utilization by nesting the blanks more efficiently. This is done by producing two blanks in different orientations for each press stroke. To produce blanks in this manner, a more complex blanking die is required. Therefore, material savings due to improved material utilization must justify the increased tool cost." Material efficiency is also improved in situations where left- and right-handed parts of an assembly can be nested together.

Mazak's nesting software, for use with its 3-D rotary lasers, nests individual parts cut from tubes and pipes up to a foot in diameter.

BlankNest reportedly saves time and improves accuracy over makeshift approaches to blank nesting, he adds. "Typically, most people involved in nesting calculations today use a simple 2-D CAD system and a trial-and-error process to guess at the optimum layout, or they use cardboard cutouts to try different scenarios." Using software is a step forward from this approach.

Nesting in 3-D

The need for nesting is not limited to flat materials. Nesting software can add efficiency to the 3-D world of tube and pipe cutting--target of a new application from Mazak Nissho Iwai Corp. (Schaumberg, IL).

Mazak's "FG CAM" was developed for nesting parts within tubes, pipes, and related "stick" shapes up to 40' (12 m) long. The company developed the software for new users of its 3-D rotary lasers. FG CAM creates nests for all sizes of raw material the lasers can process--up to 11.8" (300 mm) in diameter and 0.875" (22.2 mm) in wall thickness.