Inspection[1]

Product Quality Inspection By: Erik Martin Penn Sate University

What will be covered This presentation deals with the question of describing and evaluating product quality inspection processes.

What is to be discussed • Classification of characteristics proposed for describing the effects of industrial processes. • Formulation of definitions of the effectiveness and efficiency coefficients of quality inspection processes.

• Practical examples of effectiveness and efficiency analysis, using numerical data.

Designating the effects of the process • Ontological designations

• Axiological

-describe the effect of the process in respect of quantity, quality, or financial value.

-the determination of the relative worth of the process results.

Organizational usefulness • Using some simple mathematical equations and some data from earlier productions, one can use those particular figures to demonstrate the practical usefulness of the characteristics of the effectiveness of the quality inspection process.

How it works • Taking concepts and data; inspection processes are very important in many companies.

Notation for the main characteristics of the quality inspection process. • Of(0), If(0) - are, respectively, the rejection losses and the total outlay for the inspection and preventive actions in the previous calculation period. • OFA, IFA outlay in

- are the expected losses and planned the present period.

• OFP, IFP present

-

are the actual losses and costs in the period.

Selection of the most effective or the most efficient system of inspection and preventive action. Designations of the process

Type of designatio n assessment

ontological Ex-ante ontological Ex-post axiological Ex-post

effectivenes s

Efficiency

EOA= Of(0) - OFA

SOA = OF(O) – OFA/

EOB= OF(0) OFP

IFA SOB=OF(O) – OFP/

EAB = OF(O)-

IFP SAB = (SOB)(SOA)

The mathematical model for the optimization of the effectiveness of a quality inspection process takes 2 forms.

• Minimize the total expected loss OFA • Maximize the expected efficiency SOA

Examples of 2 quality inspection processes process A Number of the production phase

Process fraction defective

Actual inspection operation

Actual rejection probability

Actual outlay

1

.2

None

0

0

2

.2

None

0

0

3

.3

Type 3

8

300

Second example Process B Number of the production phase

Process fraction defective

Actual inspection operation

Actual rejection probability

Actual outlay

1

0

none

0

0

2

.077

Type 2

.95

166,490

3

.087

Type 2

.932

224,130

4

.073

Type 2

.947

427,200

Actual values of the outlay and the rejection losses in the previous period were

• Process A : IFP = 300; OFP = 4790 • Process B : IFP = 817,820 OFP= 5,282,180

Results of investigations

Production process

Expected

Obtained

effectiveness Efficiency

effectiveness Efficiency

EOA

SOA

EOB / EAB SOB / SAB

A

345.6

1.15

170 / .49

.57 / .49

B

25,481,000

31.16

25,528,820

31.22 / 1.00

Conclusion of process A • The actual system of inspection operations for the production process A is both ineffective, since the real effect is half as high as the expected result, and inefficient, since the decrease in the rejection losses is lower than the outlay for the inspection performance; the real efficiency is half as high as the expected result.

Conclusion of process B • The actual organization of the quality inspection is much better: the real effect is nearly equal to the expectations (EAB = 1); the efficiency of quality inspection is both near to the expected efficiency (SAB = 1) and also high in absolute numbers (SOB = 31.22, I.e. one unit of the outlay produces 31 units of the effect, which means a reduction in losses.

summary • • • •

Quality inspection is useful Quality inspection is effective Quality inspection is efficient Quality inspection is necessary

references • Hall, M. and Winsten, C., 1965. A dictionary of the Social Sciences. New York. • Lubicz, M., 1983. On the problem of optimization of a quality inspection process structure.. Int. J. Prod. Res., 21(3): 369. • Lubicz, M., 1979. Investigations of decision premises for product quality formation. Ph. Thesis, Techn. Univ. Wroclaw. • Milward, G.E., 1960. Organization and Methods. MacMillan, London.