STANDARDIZATION AND PREFFERED NUMBERS

 

 STANDARDIZATION AND PREFFERED NUMBERS

STANDARDIZATION
It is the development and implementation of technical standards. Standardization helps mass production for safety, quality, interchangeability and compatibility. The standards are for size, weight, quality and strength. There are National and International standards. National standards are for almost every item. In India it is BIS (Bureau of Indian Standards). International standards are for many items but not for each item. International uniformity has its own advantages. ISO International Standards touch everyone to improve customer satisfaction. These bring

(i) Quality and reliability

(ii) Consistency in the delivery of services

(iii) Choice and fair competition

(iv) Credibility of standards to support consumer protection laws

(v) Transparency in production information

Following are some of the popular International Standards:

(a) Quality management is ISO 9000

(b)  Environmental management-ISO 14000

(c)  Social responsibility-ISO 26000

(d) Country codes- ISO 3166

(e)  Risk management- ISO 31000

(f)  Energy management-ISO 50001

(g)  Food safety management-ISO 22000

(h) Anti bribery management systems-ISO 37001

(i) Occupational health and safety- ISO 45001

(j) I Information security management- ISO 27001

ADVANTAGES OF STANDARDIZATION
1. Simplify decision making.
2. Helps in improving decisions.
3. Makes mass production possible.
4. Increases efficiency of both machines and men.
5. Reduces time of manufacture.
6. Decreases manpower requirements.
7. Cost of production is reduced.
8. Standard testing methods improve quality of products.
9. Increases durability and life of products.
10. Makes interchangeability possible for worn out and damaged parts.

DISADVANTAGES OF STANDARDIZATION
1. Small scale industry suffers.
2. Loss of motivation
3. Loss of morale

Preferred Numbers
Standardization reduces number of sizes and variety of items to reduce cost and improve quality. These sizes are expressed numerically and are called preferred numbers (also called preferred values or preferred series) . Large number of sizes is reduced to a smaller number of sizes by the use of Renard numbers in FIVE GEOMETRIC SEQUENCES. These are rounded off normally up to two decimal

places. Resulting values are nearly in geometric sequence. Renard series are R5, R10, R20, R40 and R80.
R5 means five standard sizes between 1 and 10 which are given below:

100/5 = 1.00
101/5 = 1.584… ~ 1.60
102/5 = 2.511… ~ 2.50
103/5 = 3.981… ~ 4.00
104/5 = 6.309… ~ 6.30
105/5 = 10 (It is not included in the preferred numbers)

decimal
Thus five standard sizes between 1 and 10 are 1.00,1.60, 2.50, 4.00 and 6.30
R10 means 10 standard sizes between 1 and 10
100/10 = 1.00, 101/10 = 1.25, 102/10 = 1.60, 103/10 = 2.00, 104/10 = 2.50 , 105/10 = 3.15
106/10 = 4.00, 107/10 = 5.00, 108/10 = 6.50, 109/10 = 8.00 and

1010/10 = 10 (it is not included in the preferred numbers)
Ten standard sizes between 1 and 10 are 1.00,1.25, 1.60, 2.00, 2.50, 3.15, 4.00, 5.00, 6.00, 8.00

TABLE: PREFERRED NUMBERS (AS PER RENARD SERIES)
Designation         Preferred Numbers as per Renard Series
R5                        1.00   1.60   2.50   4.00   6.30
R10                      1.00   1.25   1.60   2.00   2.50   3.15   4.00   5.00   6.30   8.00
R20                      1.00   1.25   1.60   2.00   2.50   3.15   4.00   5.00   6.30   8.00

1.12   1.40   1.80   2.24   2.80   3.55   4.50   5.60   7.10   9.00
R40                       1.00   1.25   1.60   2.00   2.50   3.15   4.00   5.00   6.30   8.00
1.06   1.32   1.70   2.12   2.65   3.35   4.25   5.30   6.70   8.50
1.12   1.40   1.80   2.24   2.80   3.55   4.50   5.60   7.10   9.00
1.18   1.50   1.90   2.36   3.00   3.75   4.75   6.00   7.50   9.50
R80                       1.00   1.25   1.60   2.00   2.50   3.15   4.00   5.00   6.30   8.00
1.03   1.28   1.65   2.06   2.58   3.25   4.12   5.15   6.50   8.25
1.06   1.32   1.70   2.12   2.65   3.35   4.25   5.30   6.70   8.50
1.09   1.36   1.75   2.18   2.72   3.45   4.37   5.45   6.90   8.75

It has been found that Renard series R80 is not in much use.

These preferred number series may be converted to sizes in a number of ways. For example, these are multiplied or divided by some multiple of ten (e.g., 100, 160, 250, 400, 630) for R5 series of  1.0, 1.6, 2.5, 4.0, 6.3, 10).

Example: It is required to select preferred numbers between sizes of 28 and 70 mm, then these will be as per R5 series as 40 and 63 mm only.

Example: It is required to select preferred numbers between sizes of  30 and 380 mm, then it will be as per R5 series as 40, 63, 100, 160 and 250 mm respectively.