What is Quality Control

Quality control is the verification of the conformity of the quantitative or qualitative characteristics of a product or a process on which the quality of the product depends on the established technical requirements.

QC Main Tasks

The main task of quality control is to prevent the appearance of defects and other non-conformities of products with established requirements. Therefore, in the course of control, a constant analysis of deviations of product parameters from the established requirements is carried out. As a result of the control, deviations from the requirements are revealed – inconsistencies and defects.

If the parameters of the products do not meet the requirements, the quality control system allows you to quickly identify the most likely causes of non-conformities and eliminate them.

Control is an integral part of the process of managing any object, including the quality of food and non-food products.

Control, including sensory testing and measurement of certain characteristics of the product, originated in the XX century and was carried out by technical controllers working in enterprises. They controlled all products, dividing them into quality and defective.

Effectiveness of QC in the world

In the conditions of modern mass production, the effectiveness of such control is low, since after the completion of the production process, the control actions can only have a corrective nature. Corrective measures for inconsistencies that have occurred are highly ineffective and do not guarantee the absence of repeated deviations. Moreover, they can be expensive.

To ensure the required quality of goods, efforts should be focused not on combating identified defects and inconsistencies, but on preventing their occurrence, that is, on managing production processes. It is on the management of processes that modern quality and safety management systems are built.

However, to this day, traditional quality control is widely used by many industrial enterprises. It is based on technical control – checking the compliance of the controlled object with technical requirements.

The essence of control consists in obtaining information about the state of the controlled object and comparing the results obtained with the requirements contained in regulatory and technical documents, supply contracts.

The object of control is products (goods), the processes of their production, transportation, storage, operation, maintenance and repair, as well as technical and accompanying documentation.

Who performs the quality assurance

The need for a software quality assurance team grows with the size of the organization and the level of its quality policy. Where such a team is required, it is essential that the QA function remains independent of the project and operational teams. Their line of communication, however, must provide them with powerful support in exactly the form in which it is required.

Some organizations have a QA function built into their enterprises by a separate link – the Project Management Office. This meets the criteria for independence, however, organizations that follow this model need to ensure that this team is composed of trained and / or specialized quality assurance analysts.

While you take responsibility for ensuring the quality of your software, you can experience a variety of problems. Some of these problems are outlined below.

Features of the 3D scanning process

Volumetric scanning is a contactless reading of data on the physical configuration of a real object and the translation of this information into digital format. The result is a file with a volumetric image of the object. The usual format of such a file is STL, but converting to other formats is acceptable – WRML, PLY and others. The file can be opened by any program for three-dimensional modeling, edited in a graphical editor and printed. Any suitable material is used for printing.

The 3D scanning service has a wide range of applications:

• quality control of objects. Scanning makes it possible to examine the manufactured item in digital format and compare it with the drawings;
• design of structures and their components in the absence of technical documentation for the original product;
• digitization of objects of complex configuration;
• creation of models for the subsequent production of a particular object;
• copying, duplicating items;
• selection of orthopedic means (“digitization” of a part of the body or completely of a person makes it possible to most accurately select orthopedic or devices).

In a broad sense, quality control (QC) is the process by which a manufacturer maintains or improves product quality. Control is carried out by setting quality control indicators and testing products for deviations from them. Product testing and comparison of the obtained data with the specifications determine the need for any corrective actions in the production process. An important aspect of 3d scanning quality control is the use of metrological measuring instruments to standardize production processes.

Geometry control is a special case of quality control, where technical means are used to measure the tested object, its size and shape. The use of metrological 3D scanners allows you to obtain a cloud of points of the surface under investigation, on the basis of which the most accurate 3D model of the part is created, which is then used for comparison with the reference or CAD model.

The need for quality control in production

Automated methods of geometry control can significantly reduce the cost of quality control, compared to traditional methods of checking products. If with the help of manual measurement it is possible, without slowing down production, to control the quality of parts manufacture only selectively, then with the help of modern methods it is possible to check every part on the conveyor.

Certain types of quality control are generally not possible with conventional methods. Evaluation of the wear of aircraft parts, turbines or some other geometrically complex equipment operating under high load is possible only by comparison with the design models available to the manufacturer and constituting a trade secret. Only 3D scanning allows you to quickly take the required measurements and send the results for comparison or evaluation anywhere in the world, manufacturer or expert.

Methods for controlling the geometry of products

Various methods and types of equipment can be used to control the geometry:

• Manual measurement;
• Optical 3D scanners;
• Laser 3D scanners;
• Ground 3D scanners;
• Control and measuring machines (CMM);
• Manipulators with sensors;
• Photogrammetric equipment;
• Technical vision systems.

Manual measurement

Manual measurement is still used for single measurements of objects of simple shape. In modern production, this quality control method is practically not used due to the low speed and the influence of the human factor.

Obtaining information about an object using hand-held 3d scanner for quality control  has more advantages than manual measurement, since it allows you to quickly and accurately collect complete data on the shape, size, color and texture of the surface of a part, immediately process and transmit the received data in digital form.

Measurement by stationary CMM – coordinate measuring machines

Coordinate measuring machines move the touch probe along several axes. Each time the probe touches the part to be inspected, the 3D coordinates of the point are measured and stored digitally. Based on the comparison of the obtained point cloud with the CAD model, a product quality check report is generated.

To obtain information about each point, physical movement of the stylus to it is required, which takes time – the process is quite long. CMM measurement enables you to measure deep holes and other hard-to-reach or inaccessible surface areas for optical scanners.

The main advantage of CMM is its high measurement accuracy, the main disadvantage is its low speed.

Measurement with optical or laser 3D scanner

3D scanners can acquire millions of points in seconds. The CMM collects multiple points and uses them to calculate the shape of the surface, while the 3D scanner creates a point cloud for the entire part.

Measurement using photogrammetry

Photogrammetry is a technology for obtaining information about an object based on its photographs taken from different angles – photogrammetry software automatically analyzes a large number of digital images to obtain a three-dimensional reconstruction. Manual intervention may be required to determine the position of photographs during processing.

Although photogrammetry can be used as a standalone quality control method, better results can be achieved when combined with 3D scanning.

3D scanner with probe

Portable optical coordinate measuring machines, a hybrid of a 3d scanner and a CMM, are a tool for combining the high accuracy and ability to measure hard-to-reach areas inherent in CMMs with the speed of non-contact optical 3D scanners.

To do this, they are equipped with a probe on the main body or a separate complete device, like the Scantech TrackScan-P22.

ConclusionsIt is worth remembering that quality inspection is important in any case. By and large, innovative 3D scanning technologies open up a lot of different possibilities. A digital model in a few minutes is not a fiction, it is reality. Moreover, the technology helps to implement the quality control definition, which greatly simplifies the work in many areas of human life.