Friday, January 26, 2007

Advanced Spring Design FAQs

There are four technical questions about our Advanced Spring Design software that come in regularly. I'll take them on one at a time here.

1. Why can't I enter arms angle for torsion springs?
I know, I know... the drawing from the customer/designer specifies an arms angle so that's how you need the spring designed. Unfortunately, knowing the arms angle provides NO valuable information in designing a torsion spring. For example, if you specify an arms angle of 180 degrees, that could mean there are 1.5, 2.5, 3.5, ... coils and the spring will perform very differently for each of those situations. You MUST know how many coils the spring has. That determines the arms angle in the free position. Then you can specify loads or deflections from that point. Knowing an arms angle in a loaded position is no help either. If you know that the arms angle is 90 degrees in the free position and you say that the arms angle changes to 120 degrees when a certain load is applied, you still don't have enough information. The spring may have deflected 30 degrees, 390 degrees, etc. The number of coils and the deflection associated with a given load are unique pieces of information. Arms angles are not. We included arms angle fields in the interface for verification purposes. They're just outputs.

2. Why isn't there a place to add notes to the printed reports?
There is. When the report appears, you have an option to export it as either an RTF or a PDF file. If you export it as an RTF file, you can load it into Word or some other word processing software and add whatever text, graphics, etc. that you want.

3. Where are all the European and Asian material specifications?
Our partner in developing this software is the Spring Manufacturers Institute (SMI). They provided a list of materials and coefficients. We added a feature to the software to allow you to add any other materials you like.

4. Why doesn't ASD report cycle life for more spring types and materials?
When ASD was released, SMI felt that there are too many factors involved and that life estimates would be unreliable for many of the materials and spring types. Some additional R&D has been done in this area and there is a possibility that future versions will provide more results in this area and/or allow users to input more information such as S-N curve data for their particular wire which in turn could be used for life estimation.

In closing, I can tell you that ASD7 is a HUGE step up from ASD6. I've personally learned a lot about spring design in the past five years through my interactions with our customers and the friendly folks at SMI, and I've put considerable effort into making ASD7 a much more functional spring design environment. The new conical spring designer handles nonlinear rates well according to some comparisons with springs already in use. Overall, the number of models has doubled with the addition of compression springs in series and parallel, snap rings, constant force springs, and more. Please be patient a few more months as we fine tune the new interface for an expected release in the second half of 2007.


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