4 Nesting Strategies to Manage Cut Part Production

Optimation Nested Parts

Optimation Nested Parts

A nesting strategy – to be distinguished from nesting software – that is suitable for a job shop may not work for an OEM.  A made-to-order shop may need different nesting strategies than a shop that uses Kanban.  A nesting strategy perfect for a small shop, may be ill-suited for a multi-facility corporation.  Why?  Because each company has different resources and different production objectives, both factor into the choice of a nesting strategy.

Often, the manufacturing engineering team is challenged to determine which strategy – or strategies – is best suited to achieve their production goals.  When choosing a nesting strategy they must consider productivity, material efficiency, order cohesion, and most of all, the labor resources available.

Similarly, the team is challenged by resource constraints.  There are only so many programmers, a limited number of hours in the day, a material budget, storage space allocations, machine speed, etc.

Making the most of the resources to achieve the right goals through nesting with CNC nesting software is a nesting strategy.

What’s the best strategy to use?  Let’s look at several choices…

Definition of a Nesting Strategy

A nesting strategy is the approach a programmer would take to create a nest.  He considers one or more objectives – material efficiency, throughput, programming time, order cohesion – and determines which is the most important and/or how to balance several objectives simultaneously.  He takes into consideration the available parts, their due dates, the required materials, machine constraints, and he creates the requisite nests.  How those nests are created, in what order, and sensitive to which objectives is, in sum, a nesting strategy.

A nesting strategy may be as simple as maximizing material use.  Every action taken is to achieve the highest material efficiency.  Or it could be a pretty sophisticated strategy to achieve high material efficiency, and order cohesion with minimal programming time.  Finally, a whole different approach may be to keep the orders together at all cost to maintain downstream efficiencies or ease of delivery.

Interactive CNC Nesting Strategy

An interactive nesting can imply interaction on one or two levels, both inferring substantive human involvement in creation of the nest.  First there is manual-interactive nesting where the programmer is literally dragging and dropping parts on a virtual sheet.  The choice, orientation, manipulation, and programming of the parts in the nest is the responsibility of the programmer.  The programmer is making most, if not all, of the decisions going into the nest – which parts, what quantities, what priorities, what material, what sheet size, what part orientation, etc.

The second commonly understood meaning of interactive nesting is less time-consuming.  The user creates one dynamic nest at a time though some level of nesting automation.  The creation of the nest is done automatically, but the instigation of the nesting process and review of the final nest is left to the programmer.

Batch Nesting Strategy

The strategy of batch nesting is all about creating a run or series of dynamic nests over many sheets reflecting many orders and possibly many due dates.  The goal is to optimize material efficiency and do so with a minimal amount of human interaction.

Here’s an example.  Imagine a programmer starts his day by opening up an automatic nesting software package and setting in motion the nesting engine to create 40-50 nests – most are unique with different parts in different orientations and the parts are laid out on 40-50 sheets of metal.  The process takes just a few minutes, and when he’s done he sends the completed file to the machine operator to cut the nests.

What if something changes during the day, and the cue of batched nests isn’t correct now?  Any nests that aren’t already cut can be digitally discarded – erased in seconds, and the orders put back on file.  Then the programmer can make the changes needed – different part, different version, different quantities – and rerun the remaining parts and batch of nests in minutes.

JIT Nesting Strategy

Just-in-Time Nesting is – just as the name would imply – about nesting in real time.  The machine operator calls down one nest at a time just at the time the machine is ready to cut.  The nest will reflect current demand and design requirements.  Any changes to order quantities or due dates, part revisions or additions are all respected in the just in time nest.

This strategy is aware of the ever-changing shop environment, yet optimizes the nests for material efficiency, minimizes programming time with automation, and creates a seamless link between CAD and CAM with integration.

Looking at the JIT Nesting strategy in a multi-machine environment sheds a light on a secondary application.  Because the nests are not created in advance, and assuming the parts are programmed to be routed to like processes among different machines, they can be sent to the first available machine or redirected from a machine that is down.  This gives the machine operators ultimate flexibility in optimizing throughput or increasing productivity when possible.

JIT Kit Nesting Strategy

What happens when you nest a kit or assembly by itself?  All of the parts for that particular assembly are nested together (by material).   However, you’re not introducing any other parts from other assemblies or inventoried items to the nest. What happens is as you near the end of the available parts for the nests, there are fewer and fewer parts to fill a sheet.  And material efficiency goes the way of the scrap pile.

JIT Kit Nesting addresses this by maintaining the cohesion of each kit in the nesting process; however, as one kit is completed, the next kit is introduced co-mingling to some degree the first and second kits on a sheet.  As a result, the high material efficiency at the end of the first kit is preserved.  The shop doesn’t see a tail off of material efficiency at the end of each kit run.

Choosing the Right Strategy

Choosing the right strategy isn’t an all-or-nothing proposition.  Each operation needs to choose the single or multiple strategies that work best for them.  Sometimes that may mean using a different strategy on different product lines, or different shifts, or different materials.  Or a shop may shift from one strategy to another depending on the part mix at the time.  Finally, taking advantage of automation and integration through advanced nesting software can open up new strategies that may not have been an option previously.

What nesting strategy are you using?  Is there a strategy?  How is it working?  What would you like to see improve?  Weigh in on the discussion.

For nesting software capable of handling any of these strategies and more, contact Optimation.


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One comment on “4 Nesting Strategies to Manage Cut Part Production

  1. Pingback: Best Sheet Metal Nesting Process Questions | CAD to CAM | Optimation Nesting Software Blog

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