Page 27 - MetalForming Magazine August 2022
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  B to nest the rest of the parts.
“Another method makes recommendations,” he continues. “When the software detects turret conflicts that require more tools than available turret space, the software tells the fabricator, ‘If you remove this tool and replace it with this other tool, I can mix these parts together in a nest.’ This method helps promote design to manu- facture.”
At the end of the day, the approaches outlined above allow for comple- tion of all needed jobs, though not necessarily one job at a time.
“This proves useful for
job shops that have little
control over what jobs are
needed, and when,” Car-
nall says. “An OEM fabri-
cator, on the other hand,
may have more control
and can work with its
internal design depart-
ment to optimize productivity and tool usage.”
More Nesting-Improvement Tips
Metamation provides additional tips for improving nesting on CNC punching machines, which Carnall expands on.
Where possible, try for a good mix of parts, but be mindful that pulling orders ahead of time could affect WIP.
“Job shops have less control than OEM operations as to the number and types of parts to be produced. A rule of thumb: The greater amount and types of parts you have to play with, the greater the ability for nesting soft- ware to increase material utilization. A demand list of 50 or 60 parts, as opposed to only four or five, creates a greater opportunity for high material utilization. A nesting engine will work from constraints, with the first con- straint being the variety of parts.”
Try to limit the priorities placed on
machine technology with auto-indexing enables tools to rotate their ori- entation. This provides more options for a nest- ing engine to provide greater material utiliza- tion. Avoid this on some materials such as alu- minum, where bending on the grain will snap a part. But opportunities are there for improved nesting efficiencies on standard steels, for exam- ple.”
It’s better to stick with the largest possible sheet, but other standard sheet sizes, or even dual sheet sizes (large and small), can provide benefits in nesting.
“Some fabricators pre- fer to stick with a single sheet size, but allowing a nesting engine to select from multiple sheet sizes may improve material utilization. Automated sheet handling can help
here, as increased material utilization must be weighed against additional time needed for sheet changeover.”
Review the process required for nest- ing. Some nesting software offers rapid nesting, but then requires the use of additional optimization programs. Oth- ers may be packed with different nest- ing styles and methods where finding the most optimal one may take more time, thus negating time and materi- al-savings gains.
“Some software can nest parts and then require tooling setup afterward, which may not always work. Other soft- ware can provide nesting based on the available tooling. While the first option may offer increased material utilization, it only covers nesting geometry. Some fabricators can fall into a trap of seeing the increased material utilization, then prepare to load a sheet and realize that they can’t punch that nest because they don’t have the available tools.” MF
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Machine management and nesting can bring significant gains in machine performance and OEE in CNC punching applications. Machine manage- ment plays a crucial role, as effective nesting means much more than just the number of parts placed on a sheet. Nesting according to available tools, for example, offers the opportunity for upped productivity.
parts for production, as this allows a nesting engine to be more flexible in part arrangements.
“Excessive priorities handcuff a nest- ing engine. Constraints may be needed due to production schedules and sec- ondary or other operations. Of course, fabricators don’t want to punch next week’s work today because that’s just WIP lying around the shop floor. But job shops may have more control than OEMs to mix in tomorrow’s work as needed.”Try to use adaptable tooling solutions. For example, the cutting process has few constraints other than material grain direction, whereas punching may have tooling constraints that limit the rotation of parts on a sheet.
“If the cropping tools in a turret punching machine only can function at 0- and 90-deg. orientation angles, then 0 and 90 deg. are the only available nesting orientations. But, using
Fabrication: CNC Punching




































































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