What is a Boolean operation in the context of CAD What are s

What is a Boolean operation in the context of CAD? What are some applications (at least two) where explicit modeling might be preferable over parametric modeling? What is the advantage of using the \"Hole\" command instead of an extrusion to create holes in Creo Parametric? What is the difference between \"weak\" and \"strong\" dimensions?

Solution

PART A:

1.

The Boolean operations are to create complex solid models out of primitives. The following operations are generally used:

Intersect: Defines a new solid object based on the common volume between selected solids.

Union: Defines a new solid that consists of common and uncommon volume between selected solids.

Subtract: Select two set of solids. A single solid based on the removal of the second set from the first one will be created.

PART A:

2.

Generally parametric modeling is preferred over explicit modeling, but is some cases the explicit modeling is the way to go. For example:

A parametric model captures all its information about the data within its parameters. All you need to know for predicting a future data value from the current state of the model is just its parameters. For example, in case of a linear regression with one variable, you have two parameters (the coefficient and the intercept). Knowing these two parameters will enable you to predict a new value.

On the other hand, an explicit model can capture more subtle aspects of the data. It allows more information to pass from the current set of data that is attached to the model at the current state, to be able to predict any future data. The parameters are usually said to be infinite in dimensions and so can express the characteristics in the data much better than parametric models. It has more degrees of freedom and is more flexible. A Gaussian mixture model for example has more flexibility to express the data in form of multiple gaussian distributions. Having observed more data will help you make an even better prediction about the future data.

PART B:

1.

Extrusion command extrudes the circle of the sketch to create a hole. But, when an extruded object needs to be given a hole afterwards, it is difficult to implement it in the original sketch and then extrude again. A hole command can make a through hole even if the original sketches are different and even if the object is complete (that is, at any stage of the drawing).

PART B:

2.

Weak dimensions and weak constraints are temporary dimensions or constraints that appear in lightblue color. These are automatically applied to the sketch.They may change or completely remove from sketch without any conforrmation from user.So the weak dimensions or weak constraints should be changed to strong dimensions orconstraints, If they seem to be useful for the sketch.Strong Dimensions and strong constraints appear in dark blue color.

These dimensions and constraints are not removed automatically. All Dimensions added manually to a sketch are strong dimensions.You can identify weak dimensions or strong dimensions either by color of dimensions orby placing mouse cursor on dimension.