Quality Characteristics
QUALITY CHARACTERISTICS
1. Quality of Design
Quality design is a technical term. It can be regarded as a composite of 3 separate terms or steps in a common progression of activities.
(i) Identification of what constitutes fitness for use to the user (Quality of market research).
(ii) Choice of concept of product or service to be responsible to the identified needs of the user (Quality of concept).
(iii) Translation of the chosen product concept into a detailed set of specifications which is faithfully executed, will then meet the user’s need (Quality of specification).
The total progression composed of these three activities is called ‘‘Quality of Design’’ and it may be said to consist of Quality of market research: Quality of concept and Quality of specification.
Example : All automobiles provide the user with the service of transportation. The various models differ as to size, comfort, appearance, performance, economy, status conferred etc. These differences are in turn the results of intended or designed differences in the size, styling, materials, tolerances, test programs etc. Higher quality of design can be attained only at an increase in costs.
2. Quality of Comformance
The design must reflect the needs of fitness for use, and the products must also confirm to the design. The extent to which the product does confirm to the design is called ‘‘Quality of conformance’’. This extent of conformance is determined by variables as :
(i) Choice of process i.e., whether they are able to hold the tolerances.
(ii) Training of the supervision and the work force.
(iii) Degree of adherence to the program of inspect, test, audit etc. motivation for quality.
Higher quality of conformance can be attained with an accompanying reduction in cost.
Example : Two scooters both are produced at the same level of time but one may be 100% according to the drawing and specification of the same design; the second scooter may be 90% according to the drawing and specification and probably a few dimensions may be different from those of drawing. Therefore quality of conformance of 1st scooter is better than the 2nd scooter even though both are of same design.
3. Quality Costs
Quality costs are the incurring in introducting quality and benefits. This is done by identifying and defining the following categories of costs which are associated with making, finding, repairing or avoiding (preventing) defects.
Hierarcy of quality cost or Brakdown of quality cost.
(A) Failure costs
Internal failure costs. These are costs which would disappear if no defects exit in the product prior to shipment to the customer. They include.
Scrap : The net loss in labour and material resulting from defectives which cannot economically be repaired or used.
Rework : The cost of correcting defectives to make them fit for use.
Retest : The cost of inspection and retest of products that have undergone rework or other revision.
Down time : The cost of idle facilities resulting from defects. (Example : Aircraft idle due to unreliability, printing press down due to paper break).
Yield losses : The cost of process yield lower that might be attainable by improved controls. Includes ‘‘overfill’’ of containers (going to customers) due to
variability in filling and measuring equipment.