Quality of castings

Mainly includes appearance quality, internal quality and use quality. Commonly used in Ningbo Hexin die-casting, low pressure, gravity products of various non-ferrous metal casting quality analysis.

Range of casting quality:

Appearance quality

surface roughness: The smoothness of a casting surface is usually determined by comparing samples or instrumental measurements.

surface defectThese defects are not only affecting the appearance of the casting, but also the performance of the casting, such as sand eyes, sand holes, sticky sand, oxidized skin, pores, shrinkage holes, slag entrapment, succulence, lack of meat, cracks and so on.

Dimensional and shape deviations: The size and shape of the casting is usually evaluated by means of dimensional and shape inspections to assess whether the size and shape of the casting meets the design requirements.

weight deviation: Whether the weight of the casting is within the permissible limits.

intrinsic quality

Intrinsic quality is the core part of casting quality, which mainly includes the following aspects:

• chemical composition: Whether the content of various elements in the casting meets the design requirements directly affects the physical properties and mechanical properties of the casting.
• Metallographic Organization: The important factors determining the performance of a casting are the crystal structure and phase composition within the casting.
• mechanical property: These properties directly affect the use of castings, such as strength, hardness, toughness and so on.
• physical property: In certain specific applications such as density, thermal conductivity, electrical conductivity, etc.
• internal flaw: such as holes, cracks, inclusions, segregation, etc. These defects can seriously reduce the performance and service life of the castings.

Quality of use

The quality of use refers to the durability and process performance of castings under different conditions of use, including the following aspects:

• abrasion resistance: The castings are wear-resistant in use.
• corrosion resistance: Castings are corrosion resistant in corrosive environments.
• heat and cold resistance: Castings maintain stable performance under sharp temperature changes.
• Fatigue performance: The ability of a casting to resist fatigue damage under alternating stress.
• vibration absorption: The ability of a casting to absorb and disperse energy upon impact.
• machinability: Difficulty of cutting castings during machining.
• solderability: Difficulty of welding castings to other materials.

What is the effect of castings on performance?

Wear resistance and dimensional stability of machine tool castings directly affect the accuracy of the machine tool to maintain life

The dimensions, shape line accuracy and surface roughness of the internal cavities of housings and hydraulic components have a direct impact on the efficiency of pumps and hydraulic systems, energy consumption and the development of cavitation.

Internal combustion engine cylinder block, cylinder head, cylinder liner, piston ring, exhaust pipe and other castings of the strength and resistance to agitation directly affect the working life of the engine.

Factors affecting the quality of castings

There are many factors that affect the quality of castings, including the following:

design processability

Design process. In the design, in addition to determining the geometry and size of the casting according to the working conditions and the properties of the metal material, it is also necessary to consider the reasonableness of the design from the point of view of the casting alloy and the casting process characteristics, i.e., the obvious dimensional effects and solidification, shrinkage, stress, etc., in order to avoid or minimize the defects of the casting such as the compositional segregation, deformation, cracking, and so on.

Reasonable casting process

Reasonable casting process. That is, according to the structure, weight and size of the casting, the characteristics of the casting and the production conditions, choose the appropriate parting surface, shape and core method, and reasonably set up the casting reinforcement, cold iron, outlet and pouring system. To ensure that high quality castings are obtained.

Excellent casting materials

Good quality of casting raw materials. Metal furnace materials, refractory materials, fuels, fluxes, densifiers, casting sand, sand binder, coatings and other materials whose quality does not meet the standard will cause defects such as porosity, pinholes, slagging, sand sticking, etc., affecting the appearance of the casting quality and the internal quality of the casting, and seriously scrapping the casting.

Excellent process operation

Excellent process operation, to develop a reasonable process operation procedures, improve the technical level of workers, so that the process procedures are correctly implemented. In casting production, the quality of castings should be controlled and checked. First of all, formulate process specifications and technical conditions, from raw materials and auxiliary materials to the control and inspection of each specific product. Strictly follow the process specification and technical conditions to control and inspect each process.

Castings quality inspection

Finally, quality inspection of finished castings. Reasonable inspection methods and suitable inspectors should be equipped. Generally speaking, for the appearance quality of the castings, the surface roughness of the castings can be judged by comparing the sample blocks; the fine cracks on the surface can be inspected by coloring method and magnetic particle method. For the internal quality of castings, audio, ultrasonic, eddy current, X-ray and γ inspection and judgment rays can be used--Ningbo Hexin