Difference among Correction, Corrective & Preventive actions

Mostly, all the professionals come across these words specially Quality professionals . But sometimes we confused with the actual meaning of all these three words. I will try to explain all these words one by one with an example;

Correction

Suppose your smart phone touch screen gets damaged by falling on ground. What will you do first, of course you will get replaced your damaged touch screen by new & working touch screen. This is called correction. In short “ Correction is the action to eliminate non-conformity or correcting a occurred problem”.

Corrective Actions 

Now, when you replaced your touch screen of your smart phone what will you do next so that you don’t need to replace your touch screen again. You install a tempered glass on your smart phone touch screen. This is called corrective action as you are safe guarding your smart phone touch screen. In the event of falling of your smart phone, your touchscreen will be safe on the cost of tempered glass. In short “ Corrective action are taken on the root cause of the problem in such a way that it should not occur again”.

Preventive Action 

When you are installing tempered glass on your smart phone touch screen, you also installed tempered glass on your wife smart phone to avoid any future damage to her smart phone touch screen. This is called preventive action. “Preventive action is like failure mode effect analysis (FMEA) or risk management, where the non-conformity or problem have not actually occurred. We need to anticipate the risks that may occur & than think of actions that shall eliminate the cause of non-conformity”.  

I hope this will clears the concept of Correction, Corrective & Preventive actions. If you have any doubt or question please leave a question in comment box.

TYPES OF SOLDER ANOMALIES/ DEFECTS

Following are the list of solder anomalies/ defects which we generally faced in soldering process:

1. Exposed Basis Metal

2. Pin Holes

3. Blow Holes

4. Non - wetting

5. Cold connection

6. Rosin Connection

7. Dewetting

8. Excess Solder

9. Less Solder

10. Solder Balls

11. Bridging

12. Solder Webbing/ Splashes

13. Disturbed Solder

14. Fractured Solder

15. Solder Projection

SMT Process flow chart

Surface-mount technology (SMT) is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface-mount device (SMD).

The flow chart for SMT is as follow:

 

Attenuation of Coaxial Cable

The power loss caused by a coax cable is referred to as attenuation. It is defined in terms of decibels per unit length, and at a given frequency. Obviously the longer the coax cable, the greater the loss, but it is also found that the loss is frequency dependent, broadly rising with frequency, although the actual level of loss is not linearly dependent upon the frequency.

Attenuation of coax-cables is described as the attenuation of the individual parts. Inner conductor, dielectric and outer conductor attenuation form the overall attenuation of the cable according equation [1].

α_tot = α _i+ α _foam+ α_o                                                                               [1]

The individual components are described with equation [2], [3]and [4].

Attenuation of inner conductor

α _{i             =}          36.1*k_i *√f / Z_c*d_e                                             [2]

Attenuation of outer conductor

α _{o          =}          36.1*k_o *√f / Z_c*D_e                                                          [3]

Attenuation of the dielectric layer

α_foam =     9.096 *√ ε_r* tan δ *f                                               [4]

α _i        -           attenuation inner conductor [dB/100m]

α _o        -           attenuation outer conductor [dB/100m]

α_foam     -           attenuation dielectric layer [dB/100m]

Z_c         -           characteristic impedance [ohm]

f           -           frequency [MHz]

ε_r          -           dielectric constant

k_i         -          shape factor inner conductor

k_o         -           shape factor outer conductor

d_e         -          electrical equivalent inner diameter

D_e        -          electrical equivalent outer diameter

The electrical equivalent diameter considers the skin effect, which occurs on high frequency signals where the current tends to flow only in a very thin skin layer. The depth of penetration is given by following formula.

‘δ       =      15.9 / √(σ*f )

δ          -          conducting layer         [mm]

σ          -          conductivity                [m/Ω mm²]

f           -           frequency                    [kHz]

With above relation

de = di _CU  – 2* δ

De = Do _CUinner + 2* δ

8D format example

                                               YOUR COMPANY NAME

                                        NON CONFORMANCE REPPORT

NCR NO.	REF. REPORT NO.				DATE:
PROCESS STAGE		DEPARTMENT/SUPPLIER
NCR RESPONSIBILITY:			REF. ITEM:
NON CONFORMITY OBSERVED
IMMEDIATE ACTION				DATE/DONE BY:
ROOT CAUSE ANALYSIS: ROOT CAUSES: DECISION:				DATE/DONE BY:
PLANNED ACTION				DATE/DONE BY:
IMPLEMENTED CORRECTIVE ACTION				DATE/DONE BY:
ACTION TO PREVENT OCCURRENCE				DATE/DONE BY:
VERIFICATION CLOSURE				DATE/DONE BY:

ADDITIONAL DOCUMENTS ATTACHED:

For information on 8D methodology please click 8D Methodology

Knowledge Guru

REGRESSION ANALYSIS

In scientific research/industrial problem solving often a situation is encountered  where in  a number of variables are involved with possible interactions or relationship among themselves.

Regression analysis is a statistical technique for investigating and modeling relationship among these variables in such situations. As an example, consider the Current and Plating Thickness in electroplating. One may be interested to find out whether they are related and if so, what is the form of relationship. The relationship may be expressed in the form of an equation or model connecting one of the variables, known as the response or the dependant variable (denoted as Y) with one or more other variables known as explanatory or predictor or independent variables (denoted as X or X1, X2,X3 etc.).

The variables can be either quantitative or qualitative.  Examples of quantitative variables are measurable variables like hardness, tensile strength, diameter, width,  etc. Examples of qualitative variables are good/bad, defective/non-defective, religion, sex, region etc  

Applications of regression analysis are numerous and occurs almost every field, including engineering, quality control, physical and life sciences, economics, management, social sciences etc.