This document provides an overview of mechanical engineering theory and practical applications. It discusses key topics like mechanical engineering, mechanical drawing, tolerance, and tolerance analysis. The main points are: 1) Mechanical engineering involves applying physics and mathematics principles to product design. It has evolved over hundreds of years alongside other fields like materials science and computer engineering. 2) Mechanical drawings are used to communicate design concepts and functions between designers and manufacturers. They ensure agreements on specifications. 3) Tolerance is a measure of acceptable variation in product dimensions. It is important for quality control and analyzing manufacturing molds, but not a design value. 4) Tolerance analysis estimates failure rates by considering factors like part dimensions,

1. Mechanical Engineering Theory
and Practical Application
- For ME engineer
Charlie

2. Table of content
• Mechanical Engineering
• Mechanical Drawing
• Tolerance
• Tolerance Analysis

3. Mechanical Engineering

4. Engineer: It is not POSSIBLE!
Manager: You are an engineer, You
should make it POSSIBLE!
When getting the bill….
Manager: How come it is POSSIBLE!
Situation

5. 3rd Possible (Bill)
2nd Possible (Manager)
1st Possible (Engineer) Technique
Product
Amount

6. Mathematics
Chemistry
Physics
Astronomy
Mechanical
Electrical
Science Engineering
Computer
Hundreds of years
Today
Hundreds
of years

7. Material Science
Material Property
Mechanical engineering,
Industrial management..etc..
Define Rules of manufacture
Industrial Chain
Mass Production
Optimize
Intuitive and cost efficient way
The birth of a product
requires the cooperation
of hundreds of thousands
people to

8. Technique
Product
Engineer
Manager

9. Conclusion
• The possibility is base on techniques of Mass
production, if you want more than it, usually
you need to pay more
• It doesn’t mean engineers are always right.
Just make sure you guys are on the same page
when driving your engineer

10. Mechanical Drawing

11. Drawing 1

12. Drawing 2
A B
A
B

13. Made by Human
Made by Machine

14. All done by computer
Designer
Manufacturer

15. Drawing 1

16. Conclusion
• Mechanical drawing is more like a contract
between designer and manufacturer
• The purpose of ME drawing is to show the
functions and concept of this design
Designer Manufacturer

17. Tolerance

18. Customer: The standoff doesn’t
align with the mounting hole, the
tolerance is too big. Please control
your tolerance when you
manufacture them.
Situation

20. Difference among things with same characteristics and purposes from the same source
Tolerance

23. Of course we still can do some post-processing to eliminate the tolerance

24. The dimension of Mass production product you think….
~~ 425±0.2mm ~~
-0.2 +0.2
Design Value
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

25. The Truth is…(1st production)
~~ 425±0.2mm ~~
-0.2 +0.2
Design Value
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

26. The Truth is…(10th production)
~~ 425±0.2mm ~~
-0.2 +0.2
Design Value
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

27. Conclusion
• Tolerance is a natural phenomenon
• It can be a filter to control quality, an index to
analyze the situation of mold, but not a design
value

28. Tolerance Analysis

29. Designers should run the tolerance
analysis, otherwise you will design
unreasonable tolerances that
vendors can’t make it.
Situation

30. Tolerance
Or
Analysis ?

31. Name: Ann
Age: 34 (2 children)
Job: Secretary

32. Ann is considering a proper size of pot to
cook the dinner to satisfy her family at once

33. Name: Kevin
Age: 18
Eat more: After baseball training in the school
Eat less: Stomachache or headache or both

34. Name: Mary
Age: 16
Eat more: Dumped by another man again
Eat less: BFF complained she is too fat

36. What factor you think it is the most
critical to affect Ann’ choice?

37. Chassis Base X 1
HDD X 4
Partition X3
Gaps between HDD and partitions (chassis base)
Tolerance

38. Partitions + HDDs + Clearance
Chassis Base

39. Tolerance (Total) – Clearance = Failure rate

41. Tolerance
Or
Analysis

43. Outer dimension ?
Inner dimension ?

44. Only dimensions that shown in the
2D drawing can be used for Analysis
Loop

45. Conclusion
• The purpose of Tolerance Analysis is to
estimate the failure rate
• A designer can understand his design more by
Tolerance Analysis
• If Tolerance Analysis fails, it is design value or
the way of assembling should be changed,
instead of Tolerance

46. Q & A