A defect, which is also a manufacturing defect, can be found in almost all products. In short, these are products that are not allowed to the consumer due to non-compliance with the requirements. For example, leaky packaging, insufficient strength of the weld and so on. Let's talk in more detail about what defects are, and also consider the types of defects of various materials.
General information
Any industry to one degree or another produces defective products, that is, defective. As a rule, marriage is determined after sending it to the warehouse or to the consumer. In this case, the manufacturer can both withdraw its products and leave it. For example, a packaging defect for household sponges cannot be considered critical, but a defect in the brake system of a car can lead to the death of the driver. Therefore, you need to understand that defects are different: some are acceptable, others are not. We can say that any product that has at least one deviation from the established standards is considered defective, while the rest belongs to the suitable category. And here it doesn’t matter at all which industry they are talking about. As you already understood, any production has its own defects. Types of defects are divided into correctable and incorrigible. The products belonging to the first group can be made suitable (if it is economically feasible), the second - not.
Types of defects in construction
Sometimes on the news we hear information that a house collapsed somewhere, brickwork collapsed, etc. Often, the fault is some kind of defect that was not revealed during the verification check. So, in the construction industry, any discrepancy with the terms of reference (TOR) or established rules is called a structural defect. If we are talking about the inconsistency of the technical documentation for the manufacture of products, this is called a manufacturing defect. But this is not the whole list. The fact is that there are other defects in construction. The types of defects here are classified as follows:
- a clear defect is determined by external inspection, that is, visually;
- latent defect does not provide for control standards. It is usually detected after sending the goods to the consumer.
We can say that a clear defect is less dangerous for the consumer, since it is much easier to detect and eliminate. However, far from always obvious defects are eliminated by the manufacturer. Often you can buy products that visually do not meet the norm, for example, having chips on its surface, leaky packaging, etc.
Critical, major and minor defect
All these types of marriage can conditionally be placed in one group, since they are interconnected. The fact is that such discrepancies, one way or another, affect the efficiency of product use, but to a different extent. For example, critical marriage suggests that the effectiveness of the product, depending on the scope, will be much lower. Usually, the intended use of the product in this case is impossible or prohibited. An example is a broken kitchen knife, an unpressurized compressor for supplying compressed air , etc.
A significant defect is one that is not critical, but has a significant impact on the durability and efficiency of the intended use of the product. For example, a microcrack in a metal sheet is considered a significant defect. Such defective products can be used, but not so long and not under such a heavy load. A minor defect is one that practically does not affect the durability and efficiency of product use. For example, shabby paint on a heating radiator is considered a minor defect.
Types of welded defects
It is difficult to underestimate the importance of welded joints. Agree, they determine the quality of the product as a whole. For example, a well-welded solid fuel boiler body looks much better than the one on which defects are detected. Types of welding defects are divided into internal and external defects. The first is determined visually, and the second can be detected only when conducting flaw detection.
In addition, in this case we can talk about acceptable and unacceptable defects. A group of products with acceptable defects can be used with an efficiency of less than 100%, the second group is not allowed to the consumer. However, the defect itself is already something abnormal that needs to be eliminated. Today, defects in welds are eliminated using modern welding technologies and allowing only qualified craftsmen to work. In addition, they add special filler materials, use welding equipment and much more. Let's take a closer look at the types of defects of the product (welded) and how they affect the efficiency of use of products and safety for the consumer.
Outdoor marriage
Any violation of the geometry of the structure is called an external defect. These include the influx, lack of fusion, undercut, etc. Almost all of this is determined by eye. For example, the main cause of lack of penetration is a small penetration into the metal of the arc. This is due to insufficient current. Correcting such a defect is extremely simple: they try to increase the dynamics and reduce the length of the welding arc. In addition, this marriage is often found due to too fast work, so sometimes it makes sense to make the weld more measured.
Another typical and frequently encountered defect is undercut. This is a marriage, which is a groove (recess) in the base metal near the welded joint. Usually formed due to improperly selected current and welding speed. In principle, much depends on the human factor.
Burning is also quite common. This defect is a through hole in the weld. There is a marriage due to too slow welding and high current. As a result, the weld pool leaks.
The influx occurs as a result of the appearance of scale on the surface when the welding mode is incorrectly selected. Such a marriage is the leakage of an additive on the base metal without fusion.
Internal defects
This kind of marriage is detected less frequently, since not everyone can detect it with the naked eye. That is why often there is a breakdown of the welded structure, which can be very dangerous for humans. One of the most common and dangerous defects is hot cracks. They can be both longitudinal and transverse. They arise in the intermediate period of melting and solidification of the metal, as well as due to an error in the choice of filler material and its chemical composition. Responsibility for such a defect lies entirely with the welder. There are also cold cracks. They arise after the solidification of the metal and cooling of the seam. Usually appear due to excess load on the seam.
Pores - a defect that appears during all types of welding work. It is safe to say that every welder faced such problems. If you list all the main types of defects in welded joints, then this will be in first place. It occurs due to insufficient protection of the bath with welding gas. As a result, pores are formed that differ in size and randomness of distribution.
About tissue defects
In the process of manufacturing any product, marriage occurs. Weaving is no exception. There are a wide variety of types of tissue defects that we will try to examine now. The most common marriage is close. It implies the absence of one or more threads over a certain length. Often, this defect appears due to a broken thread during the execution of work. This happens due to a faulty lamella device or as a result of an error of the operator who stopped the machine later than necessary. Interestingly, this kind of defect is not taken into account if it is located on the closed parts of the product. At the same time, products with close 10-20 cm in two threads are not allowed on sale.
Often there is a plinth. Such a defect is a break in one or two threads and their incorporation into the fabric. As a result, the product acquires an irregular shape at the embedment site. Such a defect is unacceptable in products of the 1st and 2nd grade. A defect called "thread failure" affects the quality of the product in the same way as plinth. The defect lies in the fact that the main threads are not interwoven with weft threads, as a result of which they appear on the surface of the fabric, changing its shape. Marriage associated exclusively with improper operation of the weaving unit is called undershot. It consists in the availability of permitted stripes by duck.
Other tissue defects
There are other types of defects in goods made from fabric. But first, it is worth noting that the vice is local (local) and widespread. The first is usually small and is located only in a certain area of the product. To such defects can be attributed close, plinths. But defects that spread along the entire length of a piece of tissue are called common. These usually include weediness, banding, etc. Another interesting point is that all these defects can occur at different stages of production. So, a defect may appear even during spinning due to insufficient quality of the feedstock or already during finishing. All this suggests that careful monitoring is required at all stages. In addition, it is necessary to purchase only high-quality raw materials. The same applies to weaving equipment and, in fact, the qualifications of employees.
For example, the presence of dirt and oil stains depends on the abundance of machine lubrication. And since modern equipment is automatically lubricated, it makes no sense to blame the operator. The same applies to holes, perforations, as well as holes on the product that appear due to incorrect operation of the machine. Such products do not pass quality control and are immediately rejected. It is worth paying your attention to the fact that in the weaving business there are removable defects. Local defects in any case reduce the grade, however, when cutting fabric, they can be circumvented by supplying premium products.
Defects in metal and metal products
To date, there are no defect-free metal samples. This suggests that, to one degree or another, marriage is present. But it is interesting that as a result of certain processes and mechanical operations, the quality of the metal can significantly decrease, as a result of which the product will become completely unsuitable for further use.
The most common defects occur during the deformation of a metal in a solid state. The smaller the deformation, the less defects will appear. Some steel grades have good elasticity, this allows you to take its previous shape after a slight deformation. However, if you constantly increase the load, then a tipping point will come when it will be impossible to restore the metal. In any case, it makes sense to say that here, as in weaving, some types of metal defects occur even during casting, while others are already in the final processing of the product.
For example, casting defects are very common. In the metallurgical industry, they are constantly struggling with them, developing ever new ways of casting. The uneven cooling and solidification of the liquid metal leads to the formation of pores and shifts of the inner layers. There are also various types of defects in parts that undergo secondary mechanical and heat treatment. There is a marriage that occurs during the transportation or storage of a metal product.
Conclusion
As you can see, there are a wide variety of defects. We examined the types of defects in metals, welded joints, and fabrics. But you must understand that marriage is present in both the food and chemical industries. Here you can’t even talk about the human factor, since machines also sometimes fail, which leads to a similar result. Nevertheless, some types of product defects can be eliminated by partial or full automation of the technological process, which is currently being done.
As for the buyer as an end user, it is not worth buying defective products. Often they are offered at a discount and other attractive offers. This makes sense only when the purpose of the product is not responsible, in other cases, any defects can lead to the most unexpected and even sad consequences. Therefore, before you purchase something, make sure the quality of the product, as well as its serviceability. After all, even a slight error in the production process can cost you health, and often life.