Why Do We Need Quality Inspection In Manufacturing Industries ?

In order to determine the fitness of anything made, man has always used inspection. But industrial inspection is of recent origin and has scientific approach behind it. It came into being because of mass production which involved interchangeability of parts. In old craft, same craftsman used to be producer as well as assembler. Separate inspections were not required. If any component part did not fit properly at the time of assembly, the craftsman would make the necessary adjustments in either of the mating parts so that each assembly functioned properly. So actually speaking, no two parts will be alike/and there was practically no reason why they should be.

Now new production techniques have been developed and parts are being manufactured in large scale due to low-cost methods of mass production. So hand-fit methods cannot serve the purpose any more. When large number of components of same part are being produced, then any part would be required to fit properly into any other mating component part. This required specialisation of men and machines for the performance of certain operations. It has, therefore, been considered necessary to divorce the worker from all round crafts work and to supplant hand-fit methods with interchangeable manufacture.

The modern production techniques require that production of complete article be broken up into various component parts so that the production of each component part becomes an independent process. The various parts to be assembled together in assembly shop come from various shops. Rather some parts are manufactured in other factories also and then assembled at one place. So it is very essential that parts must be so fabricated that the satisfactory mating of any pair chosen at random is possible. In order that this may be possible, the dimensions of the component part must be confined within the prescribed limits which are such as to permit the assembly with a predetermined fit. Thus industrial inspection assumed its importance due to necessity of suitable mating of various components manufactured separately. It may be appreciated that when large quantities of work-pieces are manufactured on the basis of interchangeability, it is not necessary to actually measure the important features and much time could be saved by using gauges which determine whether or not a particular feature is within the prescribed limits. The methods of gauging, therefore, determine the dimensional accuracy of a feature, without reference to its actual size.

The purpose of dimensional control is however not to strive for the exact size as it is impossible to produce all the parts of exactly same size due to so many inherent and random sources of errors in machines and men. The principal aim is to control and restrict the variations within the prescribed limits. Since we are interested in producing the parts such that assembly meets the prescribed work standard, we must not aim at accuracy beyond the set limits which, otherwise is likely to lead to wastage of time and uneconomical results.

Lastly, inspection led to development of precision inspection instruments which caused the transition from crude machines to better designed and precision machines. It had also led to improvements in metallurgy and raw material manufacturing due to demands of high accuracy and precision. Inspection has also introduced a spirit of competition and led to production of quality products in volume by eliminating tooling bottle-necks and better processing techniques.

Types Of Quality Inspections :-

Four types of quality inspection services are usually distinguished. Each one corresponds to a particular step in the production process. They are all part of the toolbox of every importer, when it comes to buying in China and other low-cost Asian countries.

The four types of quality inspection services:-

Pre-Production Inspection :-
A pre-production inspection tells the buyer which kind of raw materials (or components) will be used. Factories are often suspected of lowering their costs by purchasing substandard materials, and this can be disastrous for the buyer (e.g. the wrong kind of chip in an electronic device).
The pre-production inspection can also focus on the processes followed as production starts. Sometimes this can also be critical, as Chinese factories very often cut corners and do not respect the buyer’s blueprints (e.g. patterns for cutting fabric are received from the buyer, and they are modified to make the process easier and faster).

During Production Inspection :-
A during production inspection (often called “DUPRO” in the industry) allows the buyer to have an idea of average product quality, early in the production cycle. It is the most useful and the most under-rated tool at the disposal of importers, who often only rely on final inspections.

It usually takes place once some finished products have come out of the lines. If quality issues are found, what is already produced might be re-workable, and corrective actions can be taken for the rest of the job. It gives buyers the time to plan ahead, and even to avoid delays (repairs and re-inspections take much more time when problems are noticed after all production is finished).

Final Random Inspection :-

The final random inspection (also called “pre-shipment inspection”) is by far the most common type of QC check. It takes place once 100% of shipment quantity is finished and at least 80% is packed, so it can be a real random inspection (this is not exactly the case if quality is checked earlier earlier) and suppliers cannot play games.

It puts pressure on suppliers and gives power to buyers. Its objective is really to confirm a shipment’s quality, rather than catching issues early. Therefore I usually advise my clients to complement final inspections with a DUPRO, to avoid finding disasters at the last minute.

Container Loading Inspection :-

The container loading inspection, like the pre-production inspection, it is seldom used. But it can be a worthwhile option in some specific cases.

It can be useful if the buyer has a precise loading plan and needs it to be respected very precisely (e.g. some cartons are too fragile to be placed at the bottom), or if the packaging is not conventional (e.g. some garments hung on bars, with no carton protection). It can also ensure that the right kind of products are shipped out in the right quantity, when the importer places no trust in his supplier or when several suppliers bring their products for consolidation.

Only the most sensitive projects require all four types of inspection. Generally, only one or two of these tools are used, depending on the risks identified by the buyer.

These quality inspection services are used mostly for consumer goods involving little customization. Different approaches are often chosen for ensuring that industrial products are up to specs (much more attention is spent during development and early production).