GD&T (Geometric Dimensioning and Tolerancing): A language for communicating

Presentation

Mesh Quality and Aspect Ratio

Aspect Ratio

Element Types

Mesh Quality

Automotive Components Handling Tray FEA Animation

ABCD of Engineering Drawing

It is not possible to build a part that exactly planed but its fitment can match it. The engineering drawing is the controlling document that ensures the manufacturability of part. It creates with GD&T and controlled precisely so that machinists and quality engineers will use, print dimensions, and drawing notes to develop a manufacturing process and inspection methodology. It will construct high-precision components and matching the designer’s original vision.

Drawing is a graphical and GD&T is a symbolic language that communicates ideas and information from one engineer to another.

Levels of Design

Three levels of design are considered in engineering design, which are as follows:

System Design: Design of a system which fulfill the specific function and purpose.

Parameters Design: Mechanical parameters, electrical parameters, thermal parameters, quantity parameters designing... of a system.

Tolerance Design: Design for tolerances for fitment of assembly.

Specification and Tolerance

• 10 ± 0.5: Specification is 10 and tolerance is 1.

• Part to Part variation is control by Size tolerance

• Within Part variation is control by Geometric Tolerance (Shape)

• Size Tolerance > Geometric (Shape) Tolerance e.g. ±1 > ± 1/32 (0.03)

Tolerance: Allowance for specific variation

Size tolerance is independent tolerance while Geometric tolerance controlled by its Feature Control Frame (FCF).

14 GD&T characteristics in 5 categories = 14.5

1. FORM = (4)

1.     Flatness, 

2.     Straightness 

3.     Circularity 

4.     Cylindricity

2. ORIENTATION = (3) 

1.     Perpendicularity 

2.     Parallelism  

3.     Angularity

3. LOCATION = (3) 

1.     Symmetry 

2.     Position

3.     Concentricity

4. RUNOUT = (2) 

1.     Circular run-out 

2.     Total run-out

5. PROFILE = (2) 

1.     Profile of a line

2.     Profile of a surface

8/4/2 Rule for Datums : 8Yes / 4No / 2Yes or No

(Orientation+Location +Runout) / Form / Profile

Symbols except for the Form tolerances (straightness, flatness, circularity and cylindricity) can use datums.

Basic Rules of Drawing

• Dimensions are measured at 68°F (degree fahrenheit) or 20°C in mechanical engineering system design.

               (68°F − 32) × 5/9 = 20°C

• Minimum, Maximum, Basic, Stroke and Reference dimensions never have any tolerances limit. These dimensions are free from tolerances.

• Dimensions shall have only one interpretation in engineering drawing. It never gives you conflict in between the interpretation and understanding of drawing.

• Reference dimensions should be kept as minimum value.

• Centerlines and featurelines are at right angle and angle is not mentioned in drawing.

• No zero allowed before decimal and digits must be equal after decimal in Inch unit system. For example; .12, .25 and .50 . It should not be 0.12, 0.25 and .5 in this case.

• Zero is must before decimal and no extra zero allowed after decimal in MM unit system. For example; 0.12, 0.25 and 0.5 It should not be .12, .25 and .50

• Primary datum control the Orientation of the feature in the drawing.

• All associates dimensions are basic dimensions (tolerance free) in profile tolerance.

Application Engineering

Application Engineering is all about the Planning, designing and implementation of technology.

Application Engineer role on the sales team is to represent the product from a technical standpoint so that sales person can handle the selling and business issues.

Engineering Materials Ductile Vs Brittle

When you select the material for design, you must be very sure about functionality and applications of the product. There are different aspects that can affect the product such as Yielding, Toughness, Hardness, Thermal conductivity etc.

Ductile materials are those which can undergo plastic deformation under the tensile loading and it is the ability to be drawn into wire. Ductile materials are generally used in metal forming processes.

Brittle materials do not undergo any plastic deformation that's why they fracture if load exceed yielding value. Brittle material are harder then ductile materials. Glass, Ceramic, Gray Cast Iron are some of the brittle materials examples. Brittle has less energy absorbing capacity.

In Brittle materials fracture occur before yield point but ductile materials go beyond yield point.