Methods used to assure quality


Quality inspection has undergone a lot of changes in terminology, methods, stages with more and more sophisticated equipments and gauges / tools available for the purpose. The significant changes in a nut shell are,

1. The term ‘Inspection’ was replaced by ‘Quality control’ which thereafter was renamed as ‘Quality Assurance’. Today the concept is TQM or Total Quality Management which calls for quality management of not only production processes but also all other supporting services until the time the product reaches the customer.

2. “Final product inspection� is replaced by inspection from design stage through components to sub-assembly to finished product and finally even at the delivery stage to the customers.

Quality of a product can be assured or controlled by:

Inspection Method can be100% inspection or a sample inspection.

Statistical Quality Control Method:

Various types of control charts
Pareto analysis
Automated Control

Different Inspection methods are adopted to assure the quality of materials, parts, components, equipment, finished products, process or methods of production etc. Inspection and testing is done by competent and technically qualified personnel called inspectors. It is a type of first action in the chain leading to ‘customer satisfaction’. This inspection sorts out given lot or batch into two categories—good or bad, low quality or high quality, acceptable or non-acceptable etc. It is essentially a sorting process. It is not a preventive process.

The responsibility of inspection and testing lies with the ‘Inspection’ or ‘Quality Assurance’ department. This department is responsible for checking the following aspects,

1. The purchase department has procured material, parts, components etc as per the specifications or standards.

2. The production department has produced standard quality products and standard processes, methods of production and tools and equipment are used in that department.

3. The repair and maintenance department has worked properly to repair and maintain the tools and equipment used in the factory.

4. The stores department has taken proper care in storing material until they are used and finished products until they are sold.

On the basis of information given and suggestions made by this department, after the inspection and / or testing is over, the concerned department takes corrective steps to improve the defects or arrange to supply fresh acceptable lot so that production process is not disrupted.

Technological development has made the work of inspection and testing more precise. Inspectors are now equipped with better means to judge and take proper decision on quality.. Absolutely correct decision is possible, but the decision should be design, specification and need of the product oriented. Therefore, the inspectors have to be very conversant with the gadgetry they use while performing their duties.

In no case, should the inspection department accept substandard goods etc or reject the goods etc on simple grounds. No doubt, it may be very difficult to decide whether the goods procured or manufactured in house conform to the specification or not, but the problem can be solved by proper justification of the facts. Sometimes in borderline cases the components are tried out in the assembly and accepted or rejected. Trying out on the assembly is advisable when large machinery is getting assembled on the shop floor. The efficiency of a manufacturing firm depends on the decisions of this department.

Consequences of accepting defective goods:

1. Spoils the quality of products.
2. Increases customers’ dissatisfaction due to inferior quality.
3. Results in loss of trade or markets
4. Increases cost of production in the form of higher rate of spoilage and defective, rework on defective etc.
5. Result in production stoppage due to poor quality of material, parts etc.
6. Increases servicing, repairing and replacement costs, etc

On the other hand the acceptance of materials, parts on the basis of strict specification also increases the cost of production. It may also result in stoppage of work for want of material etc as per the strict specifications. It is very difficult and moreover costly to procure material etc on the basis of strict specifications. The solution for this we have already outlined in the aforesaid paragraphs.

As mentioned earlier in this article sub-assemblies or semi finished products during process are inspected which is called ‘stage inspection’. It saves the cost of further work in defectives. 100% inspection of the finished goods does not serve the purpose fully, because there may be trouble during the production processes. Nowadays for quick and reliable inspection special automatic devices are built into the machines which reduce the work of inspection to a great extent. Due to something going wrong in the process, the defective products may come out, defective products may have been received from the preceding process etc. in most of the cases it becomes possible for the workers connected with that process to find out the fault and to determine the responsibility for that fault. The workers may themselves be at fault. A worker is the best judge of his own work but it is not advisable to allow him or to expect him to serve at his own judge. It may create unnecessary conflict and may give rise to cpnflict. Therefore, for impartial and effective inspection to assure the quality at this stage, inspection department should be entrusted with the responsibility of inspecting the products during the process.

Finished products should be tested to know the performance or chemical properties. Sometimes, testing may destroy the whole product e.g. a gun shot or a missile or a rocket. In such circumstances only samples are tested.

Products should also be inspected or tested while delivering the same to customers. They must be delivered to customers with ‘zero defect’ because the product is the ultimate image of the company.