Profit through Better Design

CAD should be much more than 2D draughting or 3D modelling. These are some thoughts on how CAD can lead to better design, something which is much more likely to improve profitability than simply saving a few hours in the design department.


Initially CAD stood for Computer Aided Design, but those trying to sell CAD systems in the early days when computer graphics hardware was limited and very expensive, discovered the computer aided design market was highly specialised and fragmented. They soon realised the market for draughting systems was much broader and that sales were easier to achieve. Hence CAD came to stand for Computer Aided Draughting. This was further reinforced by users who were having great difficulty in finding tangible benefits to use to justify the purchase of computer aided design systems. In order to convince the accountants they had to base their cost justifications on exaggerated draughting productivity ratios and draughting time savings.

We now have very powerful CAD systems running on affordable PC hardware. These systems offer sophisticated design programming environments and are capable of very much more than general purpose 2D draughting and 3D modelling. But surveys of companies using CAD continue to show that 2D draughting is still the main focus and performance continues to be assessed on simplistic measures such as draughting productivity gains and time-savings. This is a shameful waste of the potential that current CAD technologies offer for improving design. Even if CAD were able to slash design and draughting times by 95%, in most manufacturing companies this would have a very limited effect on overall costs, little or no effect on sales performance and, therefore, only a very marginal effect on company profitability.

The differentiating factor between successful and unsuccessful companies is far more likely to be good product design than it is to be design productivity. Better design really can result in higher sales. Better design can also provide opportunities for more efficient manufacturing which in turn can lead to lower sales prices and greater market penetration. A sensitivity analysis of the various numbers used to calculate the return on capital employed for manufacturing companies, clearly demonstrates that it is these factors which really have a significant impact upon company profitability.

So instead of worrying whether a CAD system is producing designs more quickly, we should be concentrating on how to harness the potential of the technology to help designers produce better designs. How this can be achieved is very dependent upon the specific circumstances and needs of the individual company. However, some general ideas on how CAD technology can be used to improve design are outlined below.

Analysing Alternative Designs

In most design situations there are alternative solutions available. These need to be judged against such criteria as quality, aesthetics, cost and comparisons with competitive products.

Because finite element (FE) analysis techniques are applicable to a wide range of analysis problems, many tend to home in on the purchase of an FE system as a quick fix solution for improving design analysis. But FE is only one of a rich set of techniques that are available for analysing and comparing designs. For example, take the seemingly trivial case of a design comprising six components, each of which is available in a limited range of different lengths that can be assembled to achieve a given overall length. Even with this small number of components the number of permutations and therefore the number of design solutions that should be compared to ensure that the optimum is found can easily run into thousands.

Rules and measures must be defined so that alternative design solutions can be ranked into order of merit. Some will be absolute measures, for example, manufacturing cost comprising of material and labour costs. Other measures will be of a more comparative nature, such alternative A is better than alternative B because the joint is further away from another design feature.

Solutions for such problems tend to lie with software written specifically for the particular design application. There is nothing new about this type of approach, indeed we were writing FORTRAN programs for such applications in the 1970’s. However, there are now much better development tools available for this type of work. For example, many computer aided design systems now offer high level languages or program interfaces making it easy to customise or enhance these general purpose systems to meet your particular requirements. Also modern rapid application development (RAD) languages, such as Microsoft Visual Basic, now provide a much more productive environment for encoding and testing engineering design programs. There are also a wealth of other development tools and building blocks available such as databases and spreadsheets which, depending upon the application, can be useful for storing and manipulating design and product data.

Better Understanding of Designs

Computer aided design can help designers understand their designs better and, therefore, help in the search for better design solutions. For example, simulation is a powerful but much underused tool. Again it is not a new technique, and it is one we were using in the early 1970's. At that time punched card input and line printer output limited the number of alternative designs that could be analysed in a working day. But even so, relatively simple programs provided some very useful insights which enabled designers to understand the performance of their designs better.

Also 3D modelling techniques are now more affordable and somewhat easier to use. 3D models can provide “virtual prototypes” which reduces the potential for errors. Also alternative design solutions can be compared quickly for fit and function. 3D views are also ideal for quotation drawings, presentations, exhibitions, etc. They have a more immediate impact than 2D drawings, especially for those who are not trained in reading engineering drawings. Click here for some of our thoughts on alternative 3D modelling techniques.

Design Retrieval and Rationalisation

Unfortunately many designers waste a lot of time reinventing the wheel. To consign all previous design work to archives that are never accessed is a criminal waste. Even if a previous design cannot be reused, reviewing other designers attempts to solve similar problems may yield many useful ideas and lateral thoughts. A properly organised engineering data management system can help designers explore previous work in a more fruitful and interesting way. Whereas simply browsing through drawings in the drawing stores can be tedious and unhelpful.

It can be difficult to determine in advance what search criteria will be needed. But in most cases it is not too difficult to design a simple key word system for describing designs in a manner that is sufficiently consistent to provide a suitable search and retrieval function. Also key features and numbers should be stored so that it is possible to retrieve, for example, all six to eight inch valves made in stainless steel.

In some cases an automatic design classification and retrieval system may be possible. For example, in one case we found that geometric properties such as area, perimeter, centroid, etc. provided a very useful means of retrieving similar shaped extrusion sections. Because all the numbers were automatically calculated from the computer aided design geometry it was easy to implement a system where the accuracy was assured.

HarnVis

A 3D view of a wiring harness leg generated by our HarnVis software.

Cable lay design

Cables designed by programs we've developed for two customers that make very different types of cable.

Design check

A yellow warning symbol added to a drawing by HarnWare to indicate a potential design problem.

HarnVis

A 3D view of a wiring harness and lay-up board generated by HarnVis.

Wire selection

The HarnWare program form used to help select the wire most suitable for a given set of design requirements.