November 20th, 2017

The production engineering process is about more than just writing a CNC program.  It includes, creating stage models and drawings, designing fixtures and generating setup sheet information for the shop floor.  All these processes involve design tools, yet it amazes me that while the design department gets state of the art CAD software, many production engineering departments are still using 2D geometry creation.  Either as a cheap CAD solution or the design tools provided within their CAM software.

When I was a subcontract programmer, I was surprised at how much of my time was spent in design relate production engineering activities.  To become more productive, I had to get the percentage of this time down to a minimum.  Within the CAM world we constantly talk about associativity between the design part and the CAM toolpaths, yet we spend little time looking at the associativity within the production engineering design process.

The question people ask is:  Why spend time create solid models for fixtures etc…

The answer is simple, the benefits in downstream time saving and quality of information outweighs any extra time spent.  In fact, using the latest CAD technology, designing in 3D solids and then creating 2 drafting views shouldn’t take any longer than using an old 2D system.  Another good reason is that today all the top CAM solutions have automatic clamp avoidance; if you create a full solid model manufacturing assembly, the toolpaths will know to miss the fixture.  Setup sheets are another area that can take time to create, once the manufacturing assembly is created setup sheets can be generated within a matter of minutes, providing clear and accurate information every time.

For many, the idea of creating a solid model is to sketch a 2D profile and extrude into a 3D form. Technology within CAD has changed significantly over the years, two of these changes that benefit production engineering are inter part associativity and direct synchronous modelling.

Interparty associativity enables you to create a linked copy of the original geometry as a new part that can be worked on or modified as required – for example to create a stage model. The benefit of this technology is that if the original model is changed, the stage model will also update while maintaining its own modifications.  Linked geometry can also be used to design associative fixtures and fixture assemblies.  How many times have you designed a fixture and positioned the clamps; identifying during programming that a clamp must be moved to give a required clearance.  With associative design, all you need do is move the clamp to the new position, the associated parts and any design features within these parts will move automatically.

The use of direct or synchronous design enables features to be easily manipulated, modified or deleted even from imported geometry.  Creating a stage model from a design part can be a complicate process if using the traditional sketch / extrude method or using surfaces.  The lasted direct synchronous modelling technology has revolutionised the way parts can be manipulated making the creation of stage models far simpler.

In most cases the final output from the production engineering design process will be 2D drawings for the creation of fixtures or setup sheets to relay manufacturing information to the shop floor.  In both cases, the drafting views are fully associative back to the original models, so if there are design changes to the solid models, these will automatically be reflected in the 2D draft drawings.

For more information on how CAD can help your production engineering process contact OnePLM.