Sunday, 28 July 2013

Pro/ENGINEER - making edges more visible
If you are a Pro/ENGINEER user who finds the fact that the model's edges are not easily distinguished and causing features hard to find, then you may try this option to make the edges more prominent.

A sample 3D model in the original settings (above), with the circled area zoomed in (below).

Monday, 22 July 2013

Bimetallic Coin – The Making
Singapore has just launched its third series of coins last month, with the $1 coin stealing the limelight with its bimetallic composition. A golden brown outer ring encased a chrome inner core, which in fact are respectively brass plated and nickel plated metal. Much as a coin calls to mind the buying and selling process, there are also engineering involved in the metallic item – the manufacturing of it.

The array of new Singaporean coins launched in June 2013, with the $1 bimetallic coin taking center stage in this article's discussion (images taken from Monetary Authority of Singapore website).

Sunday, 28 April 2013

Indentation Hardness
Among the three hardness types shared in the previous article, indentation hardness is the one which most engineers are familiar with. In fact, I bet that the general reply to the definition of hardness matches that of indentation hardness so much so that they are interchangeable in most discussions. Even engineering textbooks seldom mention indentation hardness as a separate topic – it is instead discussed as a hardness topic without an in-depth subtopic on other hardness types. 

Ball indenter used for Rockwell hardness testing. Different macroindentation test methods uses different indenter geometry and measures different dimensions of the indentation geometry (image taken from Instron).

Indentation hardness quantifies the resistance of a sample to material deformation, plastic deformation to be specific, due to the effect of a constant compressive load of a sharp object, hence the term “indentation”. In this test, a specific indenter is exerted onto the test material until an indentation is formed, of which dimension is measured and determines the hardness in accordance to a certain scale. 

For engineers personally involved in testing materials, it would be important to understand that most indentation tests have specific load rate and specific dwell time (the period in which the indenter load is held without moving), but not all of them are so. 

Thursday, 18 April 2013

Hardness - How Hard Is Hard?
It is quite easy to say that a piece of metal is harder than a block of rubber, but how hard is hard? And is a cast iron harder than a stainless steel sheet? How would one find out information about hardness when you are reading the material properties from a specification sheet? 

In fact, when I read more into this property, it is not as simple as we usually would have thought, seeing that we use the descriptive term daily in our conversation. It could be said that: 
Hardness is a measure of how resistant solid matter is to various kinds of permanent shape change when a force is applied.

Diamond - not only were they a fascination with the ladies, they were also a fascination of engineers. With its reputation of being the hardest substrate ever known, it could cut through almost everything else. So how would you define the hardness of a diamond? (image taken from Jonathan's Fine Jewelers)

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