Is GD difficult?
Due to the complex nature of the standard, GD can be incredibly difficult for users to understand and interpret, potentially leading to a disconnect between the design, manufacture, and inspection of parts.
Who is the father of GD?
The origin of GD has been credited to a man named Stanley Parker, who in 1938 developed the concept of position or “true position” as it is referred to today.
What is the latest version of GD?
5 is a standard published by the American Society of Mechanical Engineers (ASME) to establish rules, symbols, definitions, requirements, defaults, and recommended practices for stating and interpreting Geometric Dimensions and Tolerances (GD).
What is the great myth of GD?
This myth stems from the idea that GD prescribes tight tolerances. The tight-tolerance myth is essentially a misunderstanding of GD’s use of basic dimensions, which have no tolerances, and a lack of knowledge of feature-control frames, which do provide tolerances. In fact, GD and its ASME Y14.
How long does it take to learn GD?
The calendar time to learn to read GD properly is about one year when training is followed by mentoring. Combining mentoring with training more than doubles the effectiveness of the training.
What is the best way to learn GD?
I would suggest that you take a basic 2 day course from one of the companies that specialize in the subject where the trainer is a GD Professional. At least any certification would be traceable to ASME. After the initial course, apply it for a while and then look for a more advanced course.
Why was concentricity removed from GD?
Concentricity and Symmetry Symbols Removed Two of these symbols: concentricity and symmetry, have been withdrawn from the toolset. This change is largely due to the hassles related to using these symbols. To start with, it is always possible to define central features using other, more commonly used symbols.
Does GD increase cost?
Due to the complex nature of the geometric dimensioning and tolerancing (GD) standard, a company’s bottom line profitability can be affected as a result of reading and interpreting errors.
What is partially opposed planar surfaces?
Partial Datum Reference Frame – Where only one or two datum planes of the datum reference frame are used. Partially Opposed – Two planar surfaces are partially opposed if some of the rays projected normal from each planar surface intersect the other surface.
How to control the coplanarity of multiple features?
The desired condition is called coplanarity. The correct method to control coplanarity of multiple features, is by using profile as illustrated below.
What is a profile control for a coplanar surface?
There are 3 pages on my attachment, page 3 mentioned the coplanar surface is composed of 64 lead surfaces and the exposed die pad, a profile control will be used to treat them as a single surface, in this type of application, the profile control is a form control and does not use datum references, example is shown below.
What is the difference between profile and flatness control?
Flatness is an individual control. When you want multiple surfaces to lie in the same plane the Y14.5 Standard says to use profile.
How do you use coplanar surfaces as a datum feature?
Coplanar surfaces may be used as a datum feature. If this is the case, it is best to attach the datum feature symbol to the profile feature control frame, as shown in Figure 12-12. This tolerancing arrangement leaves no doubt that datum feature A consists of the two coplanar surfaces.