Preparing Drawing Previews Before Making the Final Drawing is Essential

Uncategorized — By Gladys on 7 February 2009 at 10:33 am

Today I will use a new video of the Tec Ease team to tell you about a problem we have to deal with very often when designing and manufacturing checking fixtures: part drawings with design problems. In many cases, we receive from our customers drawings detailing, apparently, the main features of the part for which we have to make a checking fixture; but in practice, the designers have to deal with many practical problems: tolerances or important dimensions are missing, or, in some cases, the design of the part needs to be modified.

What are the consequences? As these problems appear, our customers send us several versions of part drawings.

This complicates the design process of the checking fixture, as the part to be checked keeps evolving; what is more, there is a major risk to make mistakes during the checking fixture production process. Features forgotten, or even works of the customer or of the designer on the project made with on old version of drawing, the risk factors are multiple. This is what is explained in this video of Don Day, for which you will find a written transcription bellow:

Did you ever wonder what really goes on inside an engineering office?

Well, the designers and engineers are working very hard, trying to meet some deadlines to release the drawings.

Then, the drawings go out to the people that are going to use the drawing, for a drawing review. But by then, it is too late: they ask for changes that will help out with the production or inspection of the parts, but engineering is usually off, doing something else, and does not have the time to go back to make those changes.

This is up to creating an adversarial relationship between design and the folks that are using the drawing.

Consequently, production and inspection have to develop their own “tribal” knowledge, with a lot of people call trouble shooting at the start-up, in order to make the purge inspire the drawings. Many people wait until they find the problem, and then fix it. And by then, it is too late.

So, what is the solution? Well, you pull together the multi-functional design team. And I do not mean just designers and engineers – you pull together the people that are going to use the drawing before the drawing ever gets made, before the datums, and the geometric controls have been added.

Design produces the drawing, so they are the supplier of the drawing. And as they produce it, it becomes the design’s customer’s. So nowadays, the designers have to make sure that what they put on the drawing will satisfy the design attempt.

But it has to be produceable, and it must be inspectable. The way you do this is to pull together the team, and discuss how the part should going to be assembled, what the critical features are, what kind of tolerances can actually be hold, what methods of inspection will be, and then the answer to those questions are documented using datums and geometric tolerances.

It is time for drawing previews to be at the model stage, do not wait until the drawing is made and then have a review.

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