Monthly Archives: August 2013

Tabbing for Punch Nesting

Tabbing – the processing of creating a material “bridge” between a part and its parent sheet of material – is important in both contour and punch nesting processes.  However, it takes on a special dimension in the punch process because of the means by which the tabs are created.

Punch tabs are often created as the result of space left between two punch hits.  Imagine two rectangular tool hits adjoining each other would create a continuous punched entity on the side of a fabricated part.  If two tool hits were spaced 0.012” to 0.030” apart, they would create a metal tab holding the part to the sheet.

Because tabs hold the parts in place while the remainder of the sheet is being punched, the turret can proceed without interruption from tip ups or loose parts.     By tabbing parts, the entire sheet can be removed at the end of the nest which avoids stopping the machine as each part is separated.

In some nesting software packages, the programmer needs to manually insert the tabs.  With hundreds of parts and possibly thousands of tabs, this can become a very time-consuming and error prone process.  One missed tab and you have the possibility of a loose part and a tip up (floating scrap).

By automating the tabbing process each part can be automatically tabbed and placed in a part library.   Complex tabbing rules make sure that there are not too many or too few tabs on each part.   These rules can also identify small parts that are dropped down a trap door and avoid all tabs on those parts   This process saves valuable programming time and effort and ensures that the quality of each part is consistent each time it is produced.

Special Circumstances

Sometimes parts require tabs in very specific locations.  There are often parts which have an edge that cannot have any burrs or indications of a remaining tab edge. A common reason not to tab on a particular side of a part is so residual burrs do not end up against a brake press backstop.  This could cock the part at a slight angle, putting the bend in the wrong place.  In these special circumstances, tabs can be assigned in a specific area on the part and locked in during programming.  In this case, a dynamically assigned tab would not be placed based on the shape of the part and its location on the nest.  The pre-assigned tab would override the automatic tabbing logic.

Tabbing of all parts also allow the sheet to be automatically unloaded using an edge grabber of suction cups to remove the sheet as a single piece from the machine.

For more information, contact Optimation.

Contact Optimation

Contact Optimation

Automatic Tool Management for Turret or Punch Fabrication

Nesting for the punch processes takes on a whole new level of sophistication above and beyond the contour processes because of tool management.  Either the human or the software needs to nest with so many more variables in mind.

Here are just a few tool management variables.

  1. Available tools in inventory
  2. Tools in the turret
  3. Tool classification in the turret
  4. Auto-Index stations available in the turret
  5. The tools location in the turret.
  6. The distance the turret must travel to reach the hit destination
  7. Tool wear.
  8. Hit sequence of the tools.
  9. Tabbing and tabbing tools
  10. Tool station reach
  11. Sheet Rigidity
  12. Forming Tools
  13. Special Tool Shapes
  14. Tonnage and Die Clearances
  15. Extrusion Interference with other tool hits

So, given the number of variables to consider, it may be surprising to realize that the process can be automated by intelligent nesting software using advanced strategies.  A time-consuming process typically fraught with stress and the potential for error can be done to your specifications automatically and in seconds.

Letting the Software Manage Tools

Consider the complex issue of making dynamic nests and sending them to the shop floor.   A static nest that is run over and over is common in the industry.   This is because of the difficulty to create a punch nest and account for all of the dynamics.   The problem with these static nests is that they have no knowledge of what we ran before and therefore no knowledge of the state of the current turret setup.    Because the nest is static, each time it is run the tools must be set up to match the static nest requirements; this causes a setup every time the nest is run.

Software that creates dynamic nests not only creates nests that match the quantity requirements from moment to moment, but also allow for tool setup to be shared from nest to nest.   Because each nest is dynamically produced as it is needed, the current setup on the machine is known.   Knowing the current setup allows the nesting software to automatically map the tool stations requirement to the current location of the previous setup.   This means that if a ¼ inch punch is in station 103, the new nest will use the ¼ punch in that station and not require the operator to move the tool.   Most manufactures try to keep there tools in a standard location.   This works well for very common tools or when there are so few tools use that they all fit in the turret.   However, most manufactures have hundreds of tools and tens of tool stations.   When this condition occurs the sequence of how parts are nested, (common tooled parts together), and the sequence of how new tool requirements are entered into the turret can greatly reduce the setup on the shop floor.



Automatic Part Programming

When parts are programmed, the programmer has no knowledge as to when the part will be run relative to all other parts that may be ordered.   This lack of knowledge has led to the concept of a standard turret.   Using a standard turret, new parts are programmed with the same tools and station setup.   This works well in simple environments where only a few tools are needed.   Unfortunately, this simple environment is not common.   In more complex environments, it is important to use a many common tools as possible so that parts can be nested together on the same sheet and setup is minimized.   The method of a standard turret can be expanded to a preferred tool set.   This is a set of tools that are most frequently needed to produce the part mix.   Often these are not the most optimal tool for any one part.   This is because it takes much more time to change a tool that to make additional hits with a more commonly used tool.   A high speed machine can make many hits per minute so a ten minute setup represents a lot of hits.   The optimal tool is often not the optimal production solution.

What does a preferred tool set do?

Using a preferred tool set allows the manufacture to optimize tool inventory, tool changes, turret tool arrangement, tool selection, and setup, by analyzing the current and upcoming nests to determine the optimal tools.    By mapping the tool requirements to best use the tools in the turret.   Dynamic nesting with dynamic tool management can automatically provide optimal solutions that are impossibly hard for an individual programmer.   The machine operator is freed from excessive setup and the duty cycle and throughput of the turret improves.

By leveraging automation using nesting software with a dynamic tool management, the nesting, tooling, and machine time are cut dramatically.

For more information, contact Optimation.