High-quality 3D CAD geometry: saves time in design, lowers costs in engineering.

Problems in the design phase

  • CAD designers can’t easily see the difference between a good geometry and bad geometry
  • Bad geometry and general geometry errors and faults are well hidden, just because you don't see them, you need to proactively look especially before exporting to suppliers
  • The CAD system is showing a ‘solid model' icon therefore the geometry must be OK? Not always. Just because it’s a solid doesn’t mean it’s OK
  • No-one is taught properly which tools to use to check geometry, it’s not mentioned in detail in the standard courses
  • Users sometimes blame the software and feel that changing the software to another will fix the problem. This is incorrect because the mathematics core the software uses represents the geometry, not the software company
  • The CAD model becomes slow when the user chooses to use the wrong feature and adds bad geometry on top of bad geometry
  • The features operations themselves become slow when applied to bad geometry, e.g. fillets and offsets are slow to apply and make the models even slower
  • Large assemblies also become very slow and cumbersome especially with 2D drawings where you must work in the ‘top’ assembly all the time
  • The centre of gravity feature is often inaccurate when assemblies use badly imported models (imported as surfaces and not solids)
  • There are frequent random crashes causing hours of lost work and therefore hours of re-work and frustration, this adds pressure on the design time and causes mistakes to be made which appear in engineering/production costing thousands of euros/pounds/dollars
  • When the models are slow and don’t update properly, modelling shortcuts and workarounds are then done which actually make the problems worse as you approach the deadline
  • Inflexible models slow down design decisions, at design crossroads, quick decisions can’t be made if design variations take hours to do instead of minutes
  • Bad supplier models (because of logos etc.) get imported into assemblies as parts and are not cleaned up. These cause very slow large assemblies and make section views fail
  • User frustration and anger because of waiting, therefore high coffee costs!
  • Frequent missed deadlines
  • Slower time to market
  • Missed supplier production windows
  • Bad geometry causes missing bodies and faces and/or incorrect colours to be applied to faces in rendering software such as Visualize
  • If a CAD designer is forced to wait 20 minutes a day whilst working on slow models, this adds up to 14 days per year or €5600 per year of lost design time! If you have a design team, don’t multiply this figure for every member of your design team until you are sitting down!

Problems in the engineering or production phase

The geometry problems from the design phase also can appear in downstream processes i.e. CAM, FEA, CFD, mould tools and production runs causing slow analysis, introduces inaccuracies in the manufactured part.

Models which are changed by the suppliers due to having to fix bad geometry cause a mismatch between the design team’s CAD model and manufactured part. This change is never recorded by the design team, this change is typically only noticed if there is a fault with the product. In this case who is to blame? Who is liable? Ultimately, trust between the client and supplier is lost and valuable investment time and money is wasted.

Fixing problems in the engineering or production phase costs nine to ten times more than in the design phase. If the 3D model needs to be changed due to geometry imperfections or because the design needs to be modified at this stage (due to insufficient design time from having to struggle with a slow performing CAD model) then the mould tools often need to be scrapped and made again. This is typically a large investment cost which needs to be written off. There could also have been a small production run of product which would also need to be scrapped.

Future problems which would make it worse

With the increasing 'drawingless' environment, high-quality 3D geometry will become more relevant and important as dimensions and annotations are applied to faces and if these faces are unstable then the dimensions may not update properly when the model is changed.

Detailed views of 3D geometry also highlight any poor geometry and may even cause the symbols to show a different face or may disappear altogether. For example, dimensions may be placed on fillets which can be split into many faces when applied to bad underlying geometry. These fillet faces often change a lot when the radius changes and the dimensions or PMI dimensions may not change or disappear.