Magic Trackpad | Mac Book Pro 2018 Force Touch Trackpad

Taptic Engine

In older days tiny joysticks are used in Laptop’s which are replaced by touch pad’s. Later touch pad’s with the function of separate mouse buttons feel immense. Already the latest gadgets have multiple fingers at once, Pinch to zoom and scrolling with two fingers.

Latest technology adapted to the Apple’s watch, Macbook Pro and Iphone 7 are Apple’s Force Touch Taptic Engine enabling smooth operations. Now this feature enables how hard you press, which creates new oscillating signals for the new interface.

Why the name created as Taptic?

The word is the combination of “Tap” and “Haptic”. A technology which generates vibration from the forces developed while pressing by the user to convey the information. Think of a game controller when the character fears when shot produce a vibration to the user. This signal is called as “haptic feedback”.

Parts of the Tactic Engine

The whole assembly is made up of a force sensor and a lateral vibrator. Underneath the force touch pad have a force sensor which detects how hard you press. Strain gauges and Thin Piezo electric force sensors are placed at each corners of the track pad. When the user presses the track pad strain gauges creates resistance and it is recorded by micro controller which translated into force values. Simultaneously a piezo electric sensor when it’s deformed generates a voltage and the micro controller converts as a force. So both devices create the output signal in a matter of microseconds. The whole experience is much like using a two stage camera shutter button that clicks once to focus and depresses further to capture the shot.

History of Tactic Engine

The type of haptic effect can vary in complexity from simple vibrations to versatile effects driven by complex mathematical models. Simple rumble vibrations have been used in mobile phones for several years, but they are evolving to more intricate effects. High fidelity force feedback has been shown to produce a more authentic response and engaging user experience. The new gesture rich user interfaces that are beginning to appear in Macbook pro, Iphone 7 will undoubtedly require high fidelity feedback.

BIS Indian standards for Designation of steels | Designation of steel alloys

Bureau of Indian Standard shortly BIS uses the following designation. Symbolic Letters and Numbers to designate the steel grade (e.g. Mechanical, Physical, and Chemical). The standard IS No. is 7598:1990.

Classification of Steel names

For the purpose of designation, steels are classified into two types. They are:

  • Group 1
  • Group 2

Group 1 – According to their application and Mechanical or Physical properties

Group 2 – According to their Chemical composition

Principal symbols:

G – Steel casting

P – Steel for pressure purposes

D – Flat products for cold forming

R – Rails

nnn – specified minimum yield strength for the smallest thickness range

Cnn – Cold rolled

Dnn – Hot rolled for direct cold forming

Xnn – Product where rolled conditions are not specified

Additional Symbols:

B – Gas bottles

M – Thermo-mechanically rolled

N – Normalized rolled

Q – Quenched / Tempered

S – Simple pressure vessels

T – Tubes

G – Other

H – High Temperature

L – Low Temperature

R – Room Temperature

X – High and Low temperature

Designation of Plain carbon steels

These are denoted like x, C, y


x – Number 100 times the average percent of carbon

y – Number 100 times the average percent of Manganese




30 = 100 times average % of Manganese

8 = 100 times average % of Carbon

Average % of Carbon = 30/100 = 0.3%

Average % of Manganese = 8/100 = 0.08%

Actual means, the actual carbon % is not 0.3, but varies between 0.2 – 0.4%, so that the average becomes (0.2 + 0.4)/2 = 0.3%, and

Manganese from say 0.07 – 0.09%, so that the average (0.07+0.09)/2 = 0.08%

Designation of Alloy Steels

Alloy steels are denoted by arranging the alloying elements in the descending order of their proportion, and the average % of each element is shown with its chemical symbol before that number. The letter C is omitted here, and just the number is written to denote carbon percentage. When an alloying element is less than 1% that element is denoted by an underline, after written up to two decimal places.


An alloy steel of the following composition is to be designated

Carbon = 0.13 to 0.17%; Silicon = 0.1 to 0.4%; Chromium = 0.5 – 0.8%; Manganese = 0.4 – 0.5%


Carbon varies from 0.13 to 0.17

Therefore average % of C = (0.13 + 0.17)/ 2  = 0.15

Among the other alloying elements, Chromium is largest in composition with average % being 0.5 to 0.8%

Therefore average % of Cr = (0.5 + 0.8) / 2 = 0.65

Therefore the above example’s designation will be 15 Cr 65

Note: since it is less than 1% it is shown by an underline

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