Whereas virtual designs are 100% perfect – as designed, with perfect circles, perfect corners and razor-sharp edges – the real world is not.
Any manufactured part which is assembled from pieces and which consists of various materials, comes under the influence of Mr. Thermodynamics and his physical gang members Mr. Temperature and Ms. Pressure. With all those parameters and forces applied during the fabrication process the resulting product is at best close, but never fully identical with the originally designed dimensions.
Important to note: with every percentage we want to minimize these dimensional deviations, represented by gaps and misalignment in assemblies, we increase manufacturing cost due to additional investment in equipment, better materials or just more effort to optimize the machinery.
Depending on the product this will be necessary and justified: if we manufacture a submarine boat we need to take care to have the outer skin absolutely water-tight under all operating conditions and with a safety margin. Here very little deviation is allowed in order to not jeopardize security. No compromises. Building a submarine or alike is complex and expensive.
For less demanding situations the control of dimensions is less critical.
A bicycle for instance needs to meet a set of functional specifications, i.e. it needs to be durable and parts should move without friction. However the physical constraints on the product in operation are less severe than in the submarine case, which means that certain dimensional deviations of assembled parts can be accepted. This results in manufacturing process which is less demanding.
Another view is on aesthetics: we want a car to look good in every aspect. The gap between the hood and the chassis for example needs to be straight, close (but not too close) and overall needs to suite the expert’s eye. Intuitive buying decisions may depend on this feature. I am not joking. So this is important too!
Courtesy of DCS Inc.
I guess I sufficiently hit on this point: when we manufacture a virtual model we have to expect dimensional deviations. We therefore need to understand, control and design for those deviations – preferentially before it is found out from the first product which comes off the assembly line.
This was the introduction to present the domain of competence of DCS Inc. or Dimensional Control Systems Inc., a 125+ employees company headquartered in Troy, Michigan USA, with local representations worldwide. DCS is also a Gold software partner of Dassault Systèmes and they have captured their knowhow of dimensional engineering and process capabilities into a suite of tolerance analysis software applications (3DCS CAA V5 Based) which helps designers and engineers to anticipate real life conditions put on ideal designs. Good news is: 3DCS software is fully integrated in the DS 3D PLM solution and respectively the brands CATIA, DELMIA, ENOVIA and SIMULIA.
What DCS does is clearly heavy duty engineering simulation with a lot of differential equations involved. Don’t try this alone at home. If you are a manufacturer who needs to control dimensional tolerances as a function of production cost, a good advice is to let DCS assist you.
One prominent project where DCS is already part of the competence team is ITER, the nuclear fusion reactor to be built in Cadarache in the South of France. ITER is a highly challenging endeavor with a long list of technical unknowns. With the objective to master fusion technology as an unlimited source of energy for man. DCS’ job is to watch over the design of the reactor vessel built to sustain the physics involved, boost the understanding of dimension tolerancing and gain a certain level of trust for predicting results. (For more general information about ITER, and some 3D virtual fly throughs, go here.)
Ladies and gentlemen, mind the gap.
Soon more from the beautiful world of applied engineering.
P.S. any questions or ideas for future posts in this series – let me know