Foundry defects pdf

As most of the foundry factories are small or medium — size plants, it is substantial for them to create such system that is less cost and administration pretentious: integrated management system. Quality of production, protection of environment, safety and protection of health in working conditions are integral part of modern management systems. At the simples level, they manifest as rework costs or casting scrap costs.

These charges may be significantly more than the cost of the casting itself. Elementary tools of quality assurance serve to assembling operating data about production process. It can be said, that these tools are methods to observe and diagnoses production process. In this chapter is given a proposal for Integrated Management System — Quality Management System in foundry an example of continous improvement process in iron and steel foundry: research of casting defects occurence in iron and steel castings.

Metal casting industry process Foundries produce ferrous and non-ferrous metal castings. Ferrous castings comprise iron and steel, while non-ferrous castings primarily include aluminum, copper, zinc, lead, tin, nickel, magnesium, and titanium. Castings are produced by melting, pouring, and casting the ferrous and non- ferrous metals. Many foundries cast both materials. Many different casting techniques are available.

All involve the construction of a container mold into which molten metal is poured. Two basic casting process subgroups are based on expendable and non- expendable mold casting. Lost molds are separated from the casting and destroyed during the shakeout phase, while permanent molds are reused. A variety of techniques are used within these two mold casting processes depending on the melting, molding and core-making systems, the casting system, and finishing techniques applied.

Different types of melting furnaces and metal treatments are used to produce ferrous and non-ferrous materials depending on the type of metal involved. Cast iron is typically melted in cupola furnaces, induction furnaces IF , electric arc furnaces EAF , or rotary furnaces.

Cast steel is typically melted in electric arc furnaces or coreless induction furnaces. Cast steel metal treatment consists of refining e. Before metal casting can take place, a mold is created into which the molten metal will be poured and cooled.

The mold normally consists of a top and bottom form, containing the cavity into which molten metal is poured to produce a casting.

The materials used to make the molds depend on the type of metal being cast, the desired shape of the final product, and the casting technique.

Molds can be classified in two broad types: - Lost molds single use molds. Pouring the melted metal is the most significant activity in the casting process. Different pouring systems are used depending on the mold and metal type used for casting.

The mold can be filled with the liquid metal by gravity lost mold or by injection under low pressure or high pressure die- cast or by centrifuga forces. After pouring, the casting is cooled to allow for solidification first cooling and it is then removed from the mold for further controlled cooling second cooling.

In sand casting foundries, sand castings enter the shakeout process to remove the mold after solidification. All remaining operations necessary to yield a finished produkt are conducted in the finishing shop. Depending on the process used, different steps may be required such as removal of the running and gatting system, removal of residual molding sand from the surface and core remains in the casting cavities, removal of pouring burrs, repair of casting errors, and preparation of the casting for mechanical post-treatment, assembly, thermal treatment, coating.

Integrated management system in foundry Concept of integrated management system is based on compatibility of principles of management systems set by the standards ISO , ISO and OHSA1 Because the organizations use different ways of management systems, applications and each organization has its own history of introduction and development of the systems, its unique environment, workers, culture of the organization, different forms of the management systems exist in different organizations.

Integration rate will depend on complexity of present management level also on will to integrate. In following text fully integrated model is discussed. Close ties exist among three management systems, though each of them is focused on different aim: a Quality management system — fulfillment of customer needs. Though the standard ISO does not contain all requirements specific for the other management systems, the organization can adjust its quality management system ISO A lot of similarities exist among the three above mentioned systems: - Control of documentation and records.

For establishment of effective and operative integrated management system, following requirements must be met: - Integrated management system and his principles must be included in all documents of the organization. Analysis of casting defects Quality can be perceived in accordance with requirements, costumer needs. An that means how, on the ground of this inspection, to improve quality of articles and services. To speak about possible usage of repairing methods in firm, it is necessary to mention exact qualifications of criteria usage of quality improvement tools.

Separations of quality criteria takes place to investigate all spheres of formation and usage of products: preproduction, production and after production phase. Each of these phases is characterized by occurrence a sequence of information about quality, quality features evidenced in certain forms.

Result assembled criteria of production can be used for effective application of different kinds of analytic tools. Casting defects can negatively impact the bottom line of a foundry OTT D. At the simplest level, they manifest as rework costs or casting scrap costs. Their meaning comes from the fact, that without honest and full information about process it is difficult to speak about undertaking whatever efficient activities in management.

For the characteristic criterion of quality level measuring it assumed quantity of defects in one year. These areas are: accepted technology — in investigated firm casting is realized by means of sand mould with partly automatized production-line and by manual pouring of mould; this technology, as every other, possesses its own advantages and defects which are responsible for formation of foundry defects, man-qualifications, experience of workers, engagement in works which in significant manner influences final product quality, machine — outfit and its defectiveness, ease of use etc.

Represented diagram shows only a little part of the graph, which in reality is more complicated. The most common castings defects Several types of defects may occur druring casting, considerably reducing the total output of castings besides increasing the cost of their production.

It is therefore essential to understand the causes behind these defects so that create a deficiency or imperfection contrary to the quality specifications imposed by the design and the service requirements.

Under practical circumstances castings, like all metallurgical products, contain voids, inclusions and other imperfections which contribute to normal quality impairment. Such imperfections begin to be regarded as true defects only when the satisfactory function or apperance of the product is in question. In such cases, the possibility of salvage, if worse, rejection and replacement should be considered. The decision should be based upon not only the defect itself but also upon the significance in relation to the service function of the casting and the quality and inspection standards being applied.

A defect may arise from a single clearly defined cause which enables the remedy to be more specific and straightforward. It may, however, result from a combination of factors, so that the necessary preventive measures are more obscure.

All men are familiar with the persistent defects which defies explanation and finally disappears without clarification of its original cause. Close control and standardization of all aspects of production technique offers the best protection against such troubles.

More specific precautions can be taken in those cases where there is a known susceptibility to a particular defect, whils the radical approach of design modification may need to be considered in the extreme cases which do not respond to changes in foundryy technique. One the most common defects in castings are inclusions, which can be found on the casting surface or inside the casting. Some inclusions are separate particles, whereas other inclusions agglomerate into compact clusters.

Some inclusions are not bonded to the alloy microstructure and others concentrate in intergranular spaces. Depending on all this, the negative effect of inclusions can manifest itself in various ways. Removing such defects is expensive and, moreover, it requires considerable machining allowance. As a consequence of the inclusions reacting with the mould material, both the amount of burned-on sand and the surface roughness can increase.

Deterioration of mechanical properties — an inclusion is a foreign particle that interferes with the metal matrix. Inclusions make the mechanical properties deteriorate, in particular ductility and fatigue strength. Considerably reduced is mainly the low-cycle fatigue strength. Apart from the quantity of inclusions, the significance of this effect depends on the volume and the shape of inclusions. Inclusions that form films have an adverse effect.

They damage large areas of the metal structure and they also cause the notch effect. Click here to sign up. Download Free PDF. IOSR Journals. Avinash Juriani. A short summary of this paper. Download Download PDF. Translate PDF. I Nov. Castings are the major inputs for most industrial products hence foundry industry is most indispensable. The challenges of casting defects are to be identified and minimized for effective castings. This study provides an intense knowledge of critical casting defects and their root cause analysis.

In this paper efforts are made to achieve technically feasible remedies for minimizing several casting defects and improving the quality of castings which will serve as control measures for quality control professionals with zero defect concepts. Introduction Defects formation in castings is one of the most vexed topics of foundry industries. Foundry industries mostly rely on different process parameters to control such defects ensuring high efficacy of casting with an optimum yield hence controlling of such parameters becomes necessary by sound knowledge of possible causes, for this the probable defects should be analyzed and their root causes have to be studied.

This paper brings out the industrial case study of castings having prominent defects. The work was carried out based on production trials. An attempt has been made to analyze the critical defects and possible remedial measures are suggested for cast masters to have a sound knowledge about such defects with an aim to minimize rejections rates. The data was collected to take decisive action for quality improvement with reduced rejection in castings.

Methodology Cause and Effect diagram is a powerful tool that aids in determining the control factors on quality output. The data was analyzed using Ishikawa Cause and Effect Diagram. Casting Defects The major casting defects are classified as follows: 3. Blowhole Blowhole is a type of casting defect mostly prevalent in castings, further divided into pin holes, endogenous and exogenous blowholes.

Entrapment of air resulting due to pouring of liquid metal takes the form of rounded contours or spherical cavities. Surface blows or inter granular cavities appear in cope of the mould. Pinholes result when the hydrogen present in liquid metal evolves due to less solubility during solidification resulting in triangular appearances, prevalent mostly in thinner castings which are revealed after machining.

Blowhole 3. DOI: Vent Holes and Riser Placing 3. Shrinkage Shrinkage is a type of casting defect resulting due to formation of shrinkage cavity as such due to lack of design and insufficient feed metal. Shrinkage results due to formation of a closed loop at a specific point during solidification which creates a cavity because of absence of feed of molten metal.

Open shrinkage appear on the exterior of casting surface resulting due to volume contraction from liquid to solid state.

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