2D Detailing Challenge

Q.1) what are the Drawing templates?

Ans:

Drawing templates are the files of frames and title block which convey the design information that are used to generate 2 D drawing from 3 D part.

Neat and detailed Drawing templates convey more information from designer to manufacturer. so we can avoid misunderstanding and make a very effective parts, which saves time and money.

Drawing templates are change as par the company standards,

Drawing templates are provide by the customer at the starting of the project ,if not then we should finalize at starting of project.

Drawing templates has n number of information such as:

1. Company name
2. Project Name
3. Sheet size
4. Sheet number
5. Angle of projection
6. Revision Number/latter(if its revision drawing)
7. Signature or name of drawn by, checked by, responsible engineer and approved by
8. Parts detail
9. Quantity
10. Additional notes(Surface finish,heat treatment, material detail, etc)
11. Scale, date,unit of measurement

* Note : Above points can vary as per company standards

Q.2) What do you understand by angle of projection?

Ans:

1. Technical Drawing usually consist of various two dimensional views to define an object, this is known as orthogonal projection. the two orthogonal projection methods used internationally are first angle projection and third angle projection.
2. If some detailed of view can be inferred from another, then you don't bother to draw that view.
3. The angle at which an observer draw an object to convert it from 3D to 2D plane such as real object image to a plane is known as angel of projection.
4. It's way of showing a 3D object on a 2D piece of paper, and it shows what a part looks like each direction- top, bottom, left And right

According to the rule of orthographic projection. To draw a projection view of a 3D object on 2D Plane. Horizontal plane is rotated in the clockwise direction

Orthographic representation

Orthographic projections are 3D representation of 2D objects. features of 3 d parts are presented on flat plane, as though the outline of part had been projected onto a screen.fig illustrate the principle:

the viewing angles are split into quadrants of first angle, second angle, third angle and fourth angle.

in practically only first angle quadrant and the third angle quadrant are used since these are pure views. the second angle quadrant and fourth angle quadrant are combination of first and third angle projection and cause confusion to the reader.

the principle of first angle projection is shown fig. here the viewer looks at the 3 D shape and projects the image onto a screen behind the component

The Principle of third anglr projection is shwon in fig. here the viewer looks at the 3D shape and projects the image onto a screen in front of the component

Q.3)What is the First angle & Third angle projection? and why can't we use the 2nd and 4th angle of projection

Ans:

First Angle projection:

In the 1st angle projection system, objects are placed in the first quadrant. And it lies in between the observer and the plane of projection.

Symbol-

Below fig shows the view in 1st angle of projection-

Front and top view in first angle of projection-

To draw front and top views, object front and top views are projected on vertical and horizontal planes respectively.

According to the rule of projection, the horizontal plane is rotated in the clockwise direction. Horizontal plane rotation brings top view in the bottom of projected front view.

Right and left hand view in first angle of projection-

To draw Right and left side views. Object right and left side views are projected on vertical left and vertical right plane respectively.

To bring the right side view on 2D plane rule of orthographic projection is Followed. Left plane is unfolded towards the left side. Therefore Right Side View is projected on the left side of the front view.

Whereas the left side view is projected on the right side of the front view

Third Angle of projection:

In the 3rd angle projection, objects are placed in the third quadrant and projection plane lies in between observer and the object

Symbol-

below fig shows the view in 3rd angle of projection-

Front and Top view in 3rd angle of projection-

To draw front and top views in 3rd angle projection. Object front and top views are projected on vertical and horizontal planes respectively.

As per rule of projection, the horizontal plane is rotated in the clockwise direction. This rotation brings top view on top of projected front view.

Right and left side view in 3rd angle of projection-

Object Right and left side views are projected on vertical right and vertical left planes respectively.

To draw the right side view on a 2D plane, Right plane is unfolded towards the right side. As a result, Right side view is projected on the right side of the front view

Similarly, the left side view is projected on the left side of the front view.

Bottom View is projected on the bottom plane and placed on bottom of front view

Why 2nd and 4th angle projection is not use?

Second and fourth angle projection system has some limitations. Therefore only 1st and 3rd angle projection system are used to prepare engineering drawings.

To understand why 2nd and 4th angle projection are not used? Firstly we need to understand the concept behind the orthographic projection system

How projection system works-

Let’s consider a point in A and B in 1st and 3rd quadrant respectively. As per rule of projection, to bring drawing views from three dimensional to two dimensional planes. Horizontal plane (HP) is rotated in the clockwise direction.

As shown, Point A in 1st quadrant lies in between observer and projection plane. Therefore Front view of point A will be in vertical plane (V.P.) and top view will be on horizontal plane.

Similarly Point B in 3rd quadrant can be projected on the horizontal and vertical plane

To understand why the 2nd and 4th angle projection system are not used. We will repeat the above experiment in second and fourth quadrant.

Let’s consider rectangular parts X and Y are placed in 2nd and 4th quadrant respectively.

In the Second quadrant, vertical plane (VP) lies in between object X and observer. Therefore the front view of object x will lie on vertical plane whereas top view will lie on horizontal plane. As per rule of projection when horizontal plane is rotated 90 degree in clockwise direction, top and front view will overlap.

Overlapping projection views create confusion in the drawing. Therefore the 2nd angle projection system is not used.

Similarly when the object is placed in 4th quadrant both top and front view will overlap. Therefore fourth angle projection is also not used

Q.4)What is GD&T? What are the benefits of GD&T?

Ans:

Geometric Dimensioning and Tolerancing (GD&T) is a design approach and manufacturing mechanism that helps engineers and designers communicate how to bring a part design to life. When documented correctly using GD&T, it is possible to build a part that exactly matches its on-paper plans.

The drawing is the controlling document that ensures the vendor is creating precisely what the customer’s design requires. Machinists and quality engineers will use GD&T, print dimensions, and drawing notes to develop a manufacturing process and inspection methodology that will construct high-precision components matching the designer’s original vision. Proper print detailing will also help with measurement correlation to aid in the communication between customer and vendor.

GD&T uses a symbolic language to indicate how significantly part features can deviate from the geometries listed in the design model. This language contains all relevant details involved in fabrication, including dimensions, tolerances, definitions, rules, and symbols that communicate a component’s functional requirements. These all currently follow ASME Y14.5M-2009 (previously ASME Y14.5M-1994).

Engineers and designers look to GD&T to design critical aspects of a part’s features, including a specific feature’s desired location, form, profile and orientation. It is common practice to use the profile designation tied to the datum structure that is related back to the solid CAD model. This allows Manufacturing to use a best fit protocol.

Five major Advantages:

GD&T, a vital part of complex machining, offers a number of major advantages:

• Saving Money — GD&T enhances design accuracy by allowing for appropriate tolerances that maximize production. For many projects, the process provides extra or bonus tolerances, further increasing cost effectiveness.

• Ensuring Dimensional and Tolerance Requirements — By explicitly stating all design requirements, a thorough GD&T process guarantees accurate fulfillment of all dimensional and tolerance specifications.

• Assisting Digital Design Methods — Clear, concise GD&T data is readily adaptable to digital design programs, including nearly universally used 2D and 3D CAD files.

• Offering Uniformity and Convenience — As a single, consistent language, GD&T reduces guesswork and interpretation while ensuring consistent geometries across design and manufacturing.

• Providing Accurate Communication — Today’s intricate designs demand the most accurate and reliable communication. GD&T enables designers, manufacturers, and inspectors to communicate clearly with one other, saving time and making the process more efficient

Q.5)Explain all the symbols used in GD&T

Ans:

There are a total of fourteen GD&T characteristics, and the symbols that represent them are shown in the symbol below

Form tolerances control the “shape” of features and are often used as a refinement of size.

Orientation tolerances control the “tilt” of feature and are always associated with basic angle dimensions, often used as a refinement to location. If applied to surfaces, orientation tolerances also control form.

Location tolerances control location and are always associated with basic linear dimensions. Position locates and orients the median plane or axis of features of size. Profile locates feature surfaces. Profile is the most powerful characteristic of all, and also controls orientation and form.

Runout is how much one given reference feature or features vary with respect to another datum when the part is rotated 360° around the datum axis. It is essentially a control of a circular feature, and how much variation it has with the rotational axis. Runout can be called out on any feature that is rotated about an axis. It is essentially how much “wobble” occurs in the one part feature when referenced to another

some other symboles used in gd&t

Least Material Condition (LMC) - The condition where the feature contains the least material within the stated limits of size. (ex: smallest pin and/or largest hole)

Maximum Material Condition (MMC) - The condition where the feature contains the maximum material with the stated limits of size. (ex: largest pin and/or smallest hole)

Projected Tolerance zone- The projected tolerance zone applies to a feature’s protrusion. In most cases, the zone to which geometric tolerance is applied is limited to the range of the feature specified in the drawing. In contrast to this, indications using the projected tolerance zone can specify a virtual zone for the specified feature’s mating part.

Basic Dimension- Basic dimensions are theoretically exact numerical values used to define form, size, orientation, or location of a part or feature. Basic dimensions are usually shown on a drawing enclosed in a box, but they can also be invoked by referencing a standard or by a note on the drawing.

Free State — Adds the Free State modifier, to indicate that the geometric tolerance applies in the unrestrained condition. This modifier is only applicable for non-rigid parts for which there is a note that indicates that tolerances are specified for the restrained state