What does the intrinsic quality inspection of castings include?

1) Familiar with the drawings, according to the standards and process requirements, correctly grasp and understand each process.

2) Check raw materials and semi-finished products as required. Adjust the equipment, tools, measuring tools and instruments used in accordance with the regulations, so that

It is in perfect condition. Strictly abide by the process regulations

3) Research and analyze the process capacity, eliminate abnormal factors, and make the process in a stable control state, for key parts.

Focus control is required.

4) Research and improve operational skills to meet the needs of quality requirements.

5) Strictly do a good job of "three presses and one control". Three press refers to strictly according to product drawings, according to process regulations, according to technology.

The standard of technical documents is produced, and a control refers to the accuracy of self-control, which is the ratio of the number of qualified self-inspection of the operator and the number of qualified special inspection.

percentage. The accuracy of self-control should be reached! ’’

6) Adhere to civilized production, maintain a good production environment, and eliminate all factors that cause product defects in a timely manner.

7) Do a good job in the management of unqualified products, strictly prevent shoddy, and treat unqualified products as qualified products.

8) Adhere to balanced production and correctly handle the relationship between quality and quantity.

9) Actively participate in product quality management.

Crystalline phase, chemical composition, mechanical properties, etc. Crystalline phase mechanical properties will be measured at specific parts Fire: special test blocks and test rods Chemical composition measurement requires a special spectrum measuring instrument.

Inspection of relevant technical conditions. Including the chemical composition of castings, mechanical properties and other inspection contents. The inspection of mechanical properties and the inspection of technical conditions such as metallographic and chemical composition inspection must be carried out in accordance with the relevant national standards (omitted here).

Surface quality inspection. The inspection of the casting blank by the front-line personnel of mechanical processing and production in the process is mainly the inspection of its appearance casting defects (such as whether there is trachoma, sand holes, looseness, insufficient pouring, casting cracks, etc.); and whether the machining allowance of the blank meets the processing requirements.

Geometric dimension inspection of finished castings. The main one is to use the scribing method to check whether the machining allowance of the blank is sufficient. Another way is:

A relative measurement method that uses the reference datum of the blank (also known as the process datum) as the test datum of the blank (it is necessary to measure the size of the relative datum and perform a simple conversion).

The detection of castings mainly includes dimensional inspection, visual inspection of appearance and surface, chemical composition analysis and mechanical property test, for castings that are more important or easy to produce problems in the casting process, non-destructive testing work is also required, and non-destructive testing technologies that can be used for quality testing of ductile iron castings include liquid penetration testing, magnetic particle testing, eddy current testing, radiographic testing, ultrasonic testing and vibration testing.

Extended information: 1. Liquid penetration detection is used to check various opening defects on the surface of castings, such as surface cracks, surface pinholes and other defects that are difficult to find with the naked eye. The commonly used penetrant test is coloring detection, which is to soak or spray the colored (generally red) liquid (penetrant) with high permeability on the surface of the casting, the penetrant penetrates into the opening defect, quickly wipes off the surface permeate layer, and then sprays the easy-to-dry display agent (also called developer) on the surface of the casting, and after the penetrant remaining in the opening defect is sucked out, the display agent is dyed, so as to reflect the shape, size and distribution of the defect. It should be pointed out that the degree of penetrant detection decreases with the increase of the surface roughness of the inspected material, that is, the better the surface detection effect is when the surface is overlooked, and the surface detection degree of the grinding machine can even detect intergranular cracks.

In addition to coloration detection, fluorescence penetrant detection is also a commonly used liquid penetrant detection method, which requires the configuration of ultraviolet light for irradiation observation, and the detection sensitivity is higher than that of coloring detection.

2. Eddy current testing is suitable for inspecting defects below the surface that are generally not more than 6 7mm deep. There are two types of eddy current testing: the placement coil method and the through-coil method. When the specimen is placed near the coil with alternating current, the alternating magnetic field entering the specimen can induce a current (eddy current) flowing in the form of eddy currents in the direction perpendicular to the excitation magnetic field in the specimen, and the eddy current will produce a magnetic field opposite to the direction of the excitation magnetic field, so that the original magnetic field in the coil is partially reduced, thus causing a change in the impedance of the coil.

If there is a defect on the surface of the casting, the electrical characteristics of the eddy current will be distorted, so as to detect the existence of the defect, the main disadvantage of the eddy current testing is that the size and shape of the detected defect can not be visually displayed, and generally only the surface position and depth of the defect can be determined, in addition, its detection sensitivity to the small opening defect on the surface of the workpiece is not as good as the penetration detection.

When the tensile properties of the casting sample need to be determined, what is recommended to avoid the influence of surface quality on the experimental results?

Hello, I am glad to serve you, here after the senior inquiry to the network publicity casting samples need to determine the tensile properties, in order to avoid the impact of surface quality on the experimental results, it is recommended to pass the tensile test results at room temperature, there are two main ways to test the mechanical properties of the workpiece, one is the tensile test, the other is the hardness test. The tensile test is the tensile strength, yield strength and elongation of the workpiece, the answer is for reference only, subject to the publicity, may be happy, with you, a successful career, happiness and happiness look forward to your praise <>

In order to avoid the influence of surface quality on the test results of the test results of the tensile limb flammability, the surface of the casting sample can be treated by the following methods:

Clean the surface: Use appropriate cleaning methods, such as solvent cleaning, surface polishing, etc., to remove dirt and oxides from the surface of the casting and ensure a clean surface during testing.

Surface treatment: For some special materials or situations of historical rocks, surface segmentation can be carried out to improve their properties, such as removing the oxide layer, electrolytic polishing, etc. This helps to eliminate surface defects and provides a consistent surface condition.

Surface lubricants: Apply an appropriate lubricant such as a thin layer of oil or paraffin wax to the surface of the casting before performing a test tensile test. Lubricants can reduce surface friction and provide more accurate test results.

Avoid mechanical damage: Avoid using sharp or rough tools when handling and mounting casting samples to avoid introducing scratches or other mechanical damage to the surface.

When the cast iron specimen is fractured, it is characterized by the fracture being oblique and shear stress.

When the fracture of cast iron is stretched, the cross-sectional area at the fracture hardly changes, and the normal stress causes the change. When the cast iron is compressed, the specimen suddenly fails under a small deformation, and the failure section is roughly inclination angle to the axis at an angle of 45°-55°, which indicates that the specimen is damaged by shear along the oblique cross-section, and the shear stress is caused.

Be caused by. Cast iron judgment Ling compressive strength.

4-5 times higher than tensile strength.

The properties of gray cast iron mainly depend on the properties of the matrix and the quantity, shape, size, and distribution of graphite. Among them is a fine-grained pearlite.

Gray cast iron, composed of a matrix and fine flake graphite, has the best performance and the widest range of applications. The tensile strength and plasticity of gray cast iron are much higher than those of steel with the same matrix, but graphite sheets have little effect on the compressive strength of gray cast iron, so Jingju gray cast iron is widely used as parts that bear compressive loads, such as machine bases, bearing seats, etc. Gray cast iron has good casting performance and cutting performance, and the presence of graphite can play a role in reducing wear and shock.

It is characterized by a cup-shaped port in mild steel, while a shell-shaped port in cast iron.

1. The mild steel fracture has a bright inclined surface caused by obvious plastic failure. The angle of inclination of the inclined plane is approximately equal to the axis of the specimen (known as the cup fracture). The middle part is a rough plane.

The greater the plasticity, the larger the cup fracture and the smaller the area of the central rough surface. Cast iron, on the other hand, is a typical brittle fracture without any inclined edges, and the fracture is flattened and perpendicular to the tensile stress.

2. The tensile fracture of the cast iron specimen at the temperature of the chamber is basically unchanged (or the circular section is slightly reduced), and the broken fracture coincides with the cross-section. The fracture is rough and concave and convex granular.

Performance indicators: Tensile tests can determine a series of strength and plasticity indicators of materials. Strength generally refers to the ability of a material to resist elastic deformation, plastic deformation, and fracture under the action of external forces.

When a material is subjected to tensile load, the phenomenon of obvious plastic deformation that continues to occur without increasing the load is called yielding. The stress at which yield is generated, called the yield point or physical yield strength, is expressed in s (Pa).

There are many materials in the engineering that do not have obvious yield points, and the stress value when the residual plastic deformation of the material is % is usually used as the yield strength, which is called the conditional yield limit or conditional yield strength, which is used to express the gear match. The maximum value of stress that a material can reach before it breaks, called tensile strength or strength limit, is expressed in b (Pa). <>