QUALITY ASSURANCE
& RELIABILITY
Name : __________________________
ID :__________________ Class :______
Quiz
DG&T
1.
State two ways conventional tolerances specified in the drawing:i. Plus/minus tolerance
ii. Limit dimension tolerance
2.
Determine the tolerances specified in the figure below:
8.00
10.0
a) The tolerance for dimension10.0 is +- 0.1
b) The tolerance for dimension 8.00 is +- 0.1
3.
Below tolerance note indicated that for dimension in _2 decimal places, the tolerance is +-0.1cm
_and for _3 decimal places_ dimension, the tolerance is_+-0.001cm.
0.01 cm
0.001 cm
3
4.
List two types of assembly tolerance, provide examples and explain (8 marks)
There are several types of assembly tolerances used in engineering and manufacturing to specify
the allowable variation or acceptable limits for the dimensions and fit of assembled components.
Two common types of assembly tolerances are:
1. Type1: Clearance Fit: A clearance fit is a type of assembly tolerance where the dimensions of the
mating parts allow for a gap or clearance between them. This type of fit is used when the parts are
intended to move freely or have clearance between them to allow for proper assembly, disassembly,
or functioning of the assembly. Examples of clearance fits include:


Sliding fit: In this type of fit, one part can slide or move freely relative to another part without
interference. For example, the fit between a piston and a cylinder in an engine.
Free fit: In this type of fit, there is intentional clearance between the mating parts, allowing for
easy assembly and disassembly. For example, the fit between a bolt and a nut.
2. Type2: Interference Fit: An interference fit is a type of assembly tolerance where the dimensions of
the mating parts intentionally result in interference or overlap between them. This type of fit is used
when the parts are intended to be pressed, shrink-fitted, or otherwise joined together with a tight fit.
Examples of interference fits include:


Press fit: In this type of fit, one part is pressed or pressed into another part with interference,
creating a tight, secure fit. For example, the fit between a shaft and a bearing.
Shrink fit: In this type of fit, one part is heated, causing it to expand, and then assembled onto
another part, allowing it to cool and shrink, creating a tight fit. For example, the fit between a
gear and a shaft.
4
5.
Draw the symbols for Geometric Characteristic in the Table below:
(8 marks)
NO
SYMBOL
GEOMETRIC CHARACTERISTIC
1
Profile of a line
2
Profile of a surface
3
Concentricity
4
Position
5
Circularity (Roundness)
6
Total runout
7
Cylindricity
8
Parallelism
5
6.
Draw and Label :i. Equal Bilateral Tolerance
ii. Unilateral Tolerance
6
7.
Draw MMC for External Dimension
8.
Draw MMC for Internal Dimension
9.
Draw LMC for External Dimension
7
10.
Draw LMC for Internal Dimension
11.
Draw Symbol for below geometric characteristics:
-
Profile of a surface
-
Concentricity
-
Cylindricity
-
Parallelism
-
Perpendicularity
8
12.
State four advantages of GDT in the manufacturing industry.
GDT, or Geometric Dimensioning and Tolerancing, is a system of symbols and rules used to specify
the size, shape, and orientation of features on a product. Here are four advantages of using GDT in
the manufacturing industry:

Improved Design and Manufacturing Quality:
GDT enables design engineers and manufacturing people to communicate design intent in a
clear and accurate manner, resulting in higher design and manufacturing quality. The use of
GDT decreases production mistakes and variances, resulting in higher product quality.

Reduced Manufacturing Costs:
GDT enables designers to describe tolerances and dimensional requirements more accurately,
resulting in more efficient production processes. GDT can assist in minimizing production costs
by minimizing the requirement for rework and inspections.

Enhanced Product Functionality:
GDT can be used to describe features and tolerances that improve product functioning.
Designers may guarantee that pieces fit together properly and execute their intended purpose
by establishing exact tolerances, resulting in a superior product.

Improved Global Competitiveness:
GDT is an internationally recognized specification language for product design needs.
Manufacturers may efficiently express design intent across borders and guarantee that items
are made to the same standards regardless of where they are produced by using GDT. This can
help to boost global competitiveness and market share.
9