Week 9:- 2D Detailing Challenge

1) What are Drawing templates?

Ans) a) Drawing templates are basically the drawing standards as per customers' specifications. They are formats that are used for detailing of different parts or units of the fixtures. There is ‘n’ number of details that are already available on the template and are useful for various manufacturing processes, such as machining finish, tolerances, surface treatments, material, name of the parts, name of the assemblies etc., Preparing drawing templates at the start of the project can help us save time, as these templates can be used as a model for detailing different parts. Drawing templates also give information about the angles of projection to be used, views to be considered, scaling of drawing as per the part or unit.

Templates are mainly used for engineering drawings and templates are also called frames. These are providing information about engineering drawing. Templates are used as standard sizes and custom sizes in the drafting. In a few cases templates are designed according to the engineering drawings. Designing of drawing templates is followed by engineering standards. These frame is designed as blocks type by horizontal lines and vertical lines end to end with standard distance. These empty blocks are filled with alphabets and numerical words. The light thickness of lines are appearing in the frame border only in the drawing area lines are disappearing.

2) What do you understand by Angle of projection?

Ans) Engineers are mainly involved in the design and development of machines and structures. To design and communicate every detail of a machine/structure, engineers must prepare a drawing that shows the true size and shape of the entire structure. It is difficult to represent a three-dimensional object exactly on a sheet of paper by showing a single view.

Hence a set of views from different positions are prepared to define the object completely. Though different methods of projections are available to obtain the views of objects, Orthographic projection (sometimes referred to as multi-view projection), is a geometric procedure used in the engineering disciplines to project multiple graphic images of three-dimensional objects, onto a single two-dimensional plane. The procedure is called engineering drawing or drafting and is the primary means of communication used by designers and engineers in the design process.

Multi-view drawings consist of orthographic projections, which show a structure’s height, width, and depth. For example, the top view, one kind of orthographic projection, shows an object’s length and width. The left orthographic view shows the length and height, and the front view shows height and width.

Importance of angle projection:

1. a) Angle of projection are basically the view formats for orthogonal views of assemblies or part.
2. b) First and third angles of projection are mainly used in automotive standards.
3. c) Understanding the angles of projection help us to derive the actual image of 2D drawing.
4. d) It is also very important for various manufacturing processes for machine shop operators.

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

First angle projection:

a) The object lies in the 1^st

b) The object lies between the observer and the plane of projection and the plane of projection is always behind the object.

c) The plane of projection is assumed to be non-transparent.

d) The top view or plan view is always below the front view or elevation, the view of the object as observed from the left-side is drawn to the right of elevation.

It is represented by the symbol:

Note: BIS has recommended the use of First angle projection in line with the specifications of ISO adopted by all countries in the world.

Third angle projection:

a) The object lies in the 3^rd

b) The plane of projection lies between the observer and the object and the plane of projection is always in front of the object.

c) The plane of projection is assumed to be transparent.

d) The top view or plan view is always above the front view or elevation, the view of the object as observed from the left-side is drawn to the left of elevation.

It is represented by the symbol:

Second and fourth angles projections:

1. In the second angle projection, the object is considered to lie in the second quadrant, i.e., behind the vertical plane and above the horizontal plane.
2. In the fourth angle projection, the object is considered to lie in the fourth quadrant, i.e., in front the vertical plane and below the horizontal plane.
3. In both cases, there is the possibility of overlapping of the front and top views after rotation of the horizontal plane in the clockwise direction.

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

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 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.

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.

When to Use GD&T

While many applications benefit from GD&T, there are certain situations in which the process provides fundamental assistance, including scenarios in which critical or interchangeable parts fit into a larger assembly, tolerance analysis needs simplification, or the project requires functional gauging techniques.

GD&T replaces complex description notes with a single symbol or set of symbols, allowing for effortless reference and fast, precise communication. The process provides additional clarity when clients are working without a standard interpretation or tolerance, making even the most in-depth and complicated projects easier to complete.

5) Explain all the symbols used in GD&T?

GEOMETRIC CHARACTERISTICS SYMBOLS

Name	Symbol	Description
Straightness		The standard form of straightness is a 2-Dimensional tolerance that is used to ensure that a part is uniform across a surface or feature. Straightness can apply to either a flat feature such as the surface of a block, or it can apply to the surface of a cylinder along the axial direction.
Flatness		Flatness is very straight forward. It is a common symbol that references how flat a surface is regardless of any other datums or features. The flatness tolerance references two parallel planes (parallel to the surface that it is called out on) that define a zone where the entire reference surface must lie.
Circularity		Circularity describes how close an object should be to a true circle. It is also sometimes called Roundness. Examples of features that might have Circularity controls would be cylinders, spheres, and cones. For moving parts, circularity is often used to help ensure the parts move smoothly and wear evenly.
Cylindricity		Cylindricity is a 3-Dimensional tolerance that controls the overall form of a cylindrical feature to ensure that it is round enough and straight enough along its axis. Cylindricity is independent of any datum feature the tolerance needs to be less than the diameter dimensional tolerance of the part.
Profile of a Line		Profile of a line describes a tolerance zone around any line in any feature, usually of a curved shape. Profile of a line is a 2-Dimensional tolerance range that can be applied to any linear tolerance.
Profile of a Surface		Profile of a surface describes a 3-Dimensional tolerance zone around a surface, usually which is an advanced curve or shape. If it is called out on a curved surface, like a fillet on a welded part, the entire surface where the radius is has to fall within the tolerance zone.
Perpendicularity		Perpendicularity can reference a 2D line, but more commonly it describes the orientation of one surface plane perpendicular to another datum plane. The tolerance of the perpendicularity callout indirectly controls the 90° angle between the parts by controlling the location where the surfaces have to lie.
Angularity		Angularity is the symbol that describes the specific orientation of one feature to another at a referenced angle. It can reference a 2D line referenced to another 2D element, but more commonly it relates the orientation of one surface plane relative to another datum plane in a 3-Dimensional tolerance zone.
Parallelism		Parallelism can refer to either Surface Parallelism or Axis Parallelism. Surface Parallelism is a tolerance that controls Parallelism between two surfaces or other features. The feature is controlled by two parallel planes acting as the tolerance zone, similar to Flatness.
Circular Runout		Circular Runout defines a circular tolerance zone associated with a datum axis. It controls how much a feature or surface can vary with respect to a datum if the part is rotated 360 degrees around the datum axis.
Total Runout		Total Runout is how much one entire feature or surface varies with respect to a datum when the part is rotated 360° around the datum axis. Total runout controls both the amount of variation in the surface as the part is rotated, but the amount of variation in the axial dimension.
Position		position is a versatile tolerance that can be used to control location, coaxiality, orientation or axis offset of a part feature or axis. Position tolerance is generally applied to features important to assembly like holes or slots, and it is often included when performing a tolerance stack.
Concentricity		Concentricity is a 3-Dimensional cylindrical tolerance zone that is defined by a datum axis where all the derived median points of a referenced circular feature must fall into. the median points of the reference surface cross sections form the theoretical axis that must be in this tolerance zone.
Symmetry		Symmetry is a 3D tolerance that is used to ensure that two features on a part are symmetrical across a datum plane. Put another way, Symmetry establishes a tolerance zone for the median points of non-cylindrical part features.