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Salt spray test:

The salt spray test is an environmental test that mainly uses the artificial simulated salt spray environmental conditions created by the salt spray test equipment to assess the corrosion resistance of products or metal materials. It is divided into two categories, one is the natural environment exposure test, and the other is the artificial accelerated simulated salt spray environment test. The artificial simulated salt spray environment test is to use a kind of test equipment with a certain volume space-the salt spray test box, in the volume space of the artificial method to create a salt spray environment to assess the quality of the salt spray corrosion resistance of the product.


Corrosion is the destruction or deterioration of materials or their properties caused by the environment. Most of the corrosion occurs in the atmosphere. The atmosphere contains corrosive components and factors such as oxygen, humidity, temperature changes and pollutants. Salt spray corrosion is a common and most destructive atmospheric corrosion. The corrosion of the salt spray on the surface of metal materials is caused by the electrochemical reaction between the chloride ion contained in the oxide layer and the protective layer and the internal metal. At the same time, chloride ions contain a certain amount of hydration energy, which can easily be adsorbed on the pores and cracks of the metal surface to squeeze out and replace the oxygen in the oxide layer, turning insoluble oxides into soluble chlorides, and turning the passivated surface into an active surface.

Salt spray test is an environmental test that mainly uses artificially simulated salt spray environmental conditions created by salt spray test equipment to assess the corrosion resistance of products or metal materials. It is divided into two categories, one is natural environmental exposure test, and the other is artificial accelerated simulated salt spray environmental test. The artificial simulated salt spray environment test is to use a kind of test equipment with a certain volume space-the salt spray test box, in the volume space of the artificial method to create a salt spray environment to assess the quality of the salt spray corrosion resistance of the product. Compared with the natural environment, the salt concentration of chloride in the salt spray environment can be several or tens of times the salt spray content of the general natural environment, which greatly increases the corrosion speed. The salt spray test is performed on the product and the result is obtained The time is also greatly shortened. For example, if a product sample is tested in a natural exposure environment, it may take 1 year for its corrosion, while the test under artificially simulated salt spray environment conditions can get similar results within 24 hours.

Types of salt spray test

Artificial simulated salt spray test includes neutral salt spray test, acetic acid salt spray test, copper salt accelerated acetic acid salt spray test, and alternating salt spray test.


Neutral salt spray test

It is the earliest accelerated corrosion test method with the widest application. Under normal circumstances, it uses 5% sodium chloride salt aqueous solution, the pH of the solution is adjusted in the neutral range (6.5 ~ 7.2) as the spray solution. The test temperature is 35℃, and the sedimentation rate of the salt spray is required to be between 1 and 3ml/80cm2.h, and the sedimentation volume is generally between 1 and 2ml/80cm2.h.


Acetate spray test

It was developed on the basis of the neutral salt spray test. It is to add some glacial acetic acid to 5% sodium chloride solution to reduce the pH value of the solution to about 3, the solution becomes acidic, and the salt mist formed finally turns from neutral salt mist to acid. Its corrosion rate is about 3 times faster than the NSS test.


Copper salt accelerated acetic acid salt spray test

It is a kind of rapid salt spray corrosion test recently developed abroad. The test temperature is 50℃. A small amount of copper salt—copper chloride is added to the salt solution to strongly induce corrosion. Its corrosion rate is approximately 8 times that of the NSS test.


Alternating salt spray test

It is a comprehensive salt spray test, which is actually a neutral salt spray test plus a constant damp heat test. It is mainly used for cavity-type complete products. Through the penetration of the humid environment, the salt spray corrosion is not only generated on the surface of the product, but also generated inside the product. It is to alternately switch the product under two environmental conditions of salt spray and damp heat, and finally check whether the electrical and mechanical properties of the whole product have changed.

Review criteria:

The salt spray test standard is a clear and specific stipulation for the salt spray test conditions, such as temperature, humidity, sodium chloride solution concentration and pH value, etc., and also puts forward technical requirements for the performance of the salt spray test chamber. Which salt spray test standard is used for the same product should be selected according to the characteristics of the salt spray test, the corrosion rate of the metal, and the sensitivity to salt spray.

The purpose of the salt spray test is to evaluate the salt spray corrosion resistance of the product or metal material. The result of the salt spray test is the judgment of the quality of the product. Whether the judgment result is correct and reasonable is to correctly measure the salt spray resistance of the product or metal. The key to corrosion quality. The methods for judging the results of the salt spray test include: rating judgment method, weighing judgment method, corrosive appearance judgment method, and corrosion data statistical analysis method. The rating method is to divide the percentage of the corrosion area to the total area into several levels according to a certain method, and a certain level is used as the basis for qualified judgment, which is suitable for evaluation of flat samples; the weighing judgment method is through the corrosion test before and after The method of weighing the weight of the sample to calculate the weight lost by corrosion to evaluate the corrosion resistance quality of the sample. It is especially suitable for assessing the corrosion resistance quality of a certain metal; the appearance determination method of corrosive substances is a qualitative determination method , It judges whether the product has corrosion phenomenon after salt spray corrosion test. This method is mostly used in general product standards; the statistical analysis method of corrosion data provides the confidence of designing corrosion test, analyzing corrosion data and determining corrosion data. The method is mainly used to analyze and count the corrosion situation, rather than to determine the quality of a specific product

Temperature and humidity test:

The purpose of Humidity Test is generally to determine the degree of influence of humidity on the product, and to ensure that the product can still meet the specifications under high humidity conditions. This kind of test usually belongs to the scope of accelerated test, generally to find out whether the product has weaker components, components, or process problems or failure modes as soon as possible, so as to provide a reference for product quality design improvement . In order to ensure the performance of the product, various temperature and humidity components and time intervals are used in the test, during which each stage of the test must pass and meet the specifications.

Some materials that easily absorb moisture (such as printed circuit boards, plastic injection parts, packaging parts, etc.) will absorb moisture in proportion to the pressure and time of exposure to water vapor. When the material absorbs too much moisture, it will cause expansion or Pollution can even damage the function of the product. For example, leakage current can be caused between some more sensitive circuits and cause the product to fail. Some chemical residues can even cause serious corrosion of circuit boards or cause metal surfaces due to moisture. Oxidation and other reactions.


When conducting humidity tests, it must be noted that the ceiling of the environmental test machine must be designed to prevent frost to prevent the possibility of water dripping onto the product, especially for certain materials that are not water resistant (such as wood products, chemicals). The condensed water in the environmental testing machine must be discarded and cannot be recycled. Pure water or distilled water must be used to form water vapor. Minerals and ions must be removed. The pH value should be between 6.0 and 7.2 at 23°C. The resistance value of water must be greater than 150,000 ohms-cm.

Test steps

Initial Performance Test (Initial Performance Test)

At the beginning of the test, put the product in the temperature and humidity test machine, record the results of the performance test, and confirm that it meets the specifications. The conditions at the beginning of the test are 25°C±3°C and a relative humidity of 50%±10% (approximately indoor environment).

Minimum Operating Humidity (Minimum Operating Humidity)

According to the market demand of the product, the low humidity test environment is set to 15%RH±10%, and the test time at this stage is 24 hours. For some products (such as CRTs, printers, drawing chickens, magnetic tape recorders, etc.), they may be more sensitive to this environment. Record the performance test results at the beginning and end of this phase.

Maximum Operating Humidity (Maximum Operating Humidity)

The test at this stage measures the effect of adsorption (surface leakage current). The EUT (Equipment Under Test) before and after the "Non-Operation" step belongs to the "Maximum Operating Humidity" environment. The "Maximum Operating Humidity" in the first stage has 17 hours, and the second stage has 11 hours. The purpose of the test at this stage is to accelerate the absorption of excessive water on the surface of the product, will it cause product leakage and electrolysis effects and other defects. Most of the dendrites of electron migration also appear at this stage, and they grow when the power is turned on. Record the performance test results at this stage.

Non-Operating Humidity

The purpose of this test is to measure the effect of absorption (absorption, penetration of moisture into hygroscopic materials).

Important: When testing at this stage, remember to remove consumables such as audio (video) media from the product.

When the product successfully completes the first stage of the "Working Humidity Test" (48 hours), turn off the power of the product and start to enter the "Non-Operation" step. According to different product categories, there will be different "non-operation" step time, there are three options: 12 hours, 24 hours and 72 hours. This high-humidity environment may accelerate metal corrosion, deteriorate moisture absorption and porous materials.

At the end of the humidity cycle of "Non-Operation", the environmental test opportunity returns to the conditions of "4.3 Maximum Working Humidity". Record the performance test results at the beginning of this phase.

Dry-Out and Final Performance Test (Dry-Out and Final Performance Test)

At the end of the second phase of the "Maximum Operating Humidity" test, the temperature and humidity will return to the atmospheric environment, and the performance test must be repeated at this time. Record the results of the performance test. Compare it with the results of the "Preliminary Performance Test". Checking the difference between the two test results may reveal some potential weaknesses in product design.

Take the product out of the environmental testing machine and check for any signs of corrosion, rust, deformation, or any other abnormalities. Observe carefully and record. If any component or assembly no longer meets electrical or mechanical specifications, it will be recorded as a defect. If there is an appearance problem, it should be raised, and the team will evaluate whether it meets the customer's expectations.

This stage will last for 24 hours at room temperature. Any failure that occurs during this period must be evaluated to determine whether it was caused by the humidity test just completed.

Condensation and condensation

This test is used to measure the possible reaction of the product in the "condensation" state of water vapor. When the product is in an area with a sharp change in temperature, such as a warm environment suddenly entered from a cooler area, the surface of the product and the The surrounding water vapor may be condensed into water droplets due to the rapid warming of the temperature. Products of grades C1 and C2 are usually used in a normal environment, and there will be no "condensation", so this test can be omitted.

Other measurements:


2d or 3d measurement:

Use mechanical or manual measurement methods to check the size and tolerance of each part of the product for errors. The purpose of this measurement is that the workpiece is a precision part. If there are slight errors in the process of assembling the product, the product cannot be assembled. Success, so this process is a necessary process when each workpiece is manufactured


Microscope measurement:

It is based on the microscope to observe whether the metal surface has defects that are invisible to the naked eye or the metallographic state. Because the metal is heated in the process of casting into a workpiece, the length of the cooling time and the speed will affect the metallographic and material strength, and this problem is impossible Observed with the naked eye, you need to use a microscope to observe.


Surface roughness measurement:

If the customer has a certain degree of surface roughness requirements, our company will measure the surface roughness of the workpiece. The measurement method is as follows:

Comparative method

Compare the surface roughness of the sample block and compare it with the measured surface based on vision and touch to determine which value the measured surface roughness is equivalent to, or measure the change in reflected light intensity to evaluate the surface roughness (see laser length measurement technology) . A sample block is a set of metal blocks with a flat or cylindrical surface. The surface has different surface roughness after grinding, turning, boring, milling, planing, etc., electroforming or other casting processes. Sometimes a sample can be selected directly from the workpiece as a sample after being measured and qualified. Although the method of using the sample to evaluate the surface roughness based on vision and touch is simple, it will be affected by subjective factors, and the correct surface roughness value is often not obtained.

Stylus method

Adhesion is an important physical property of a coating, and related tests are often regarded as an indicator of proper bonding between the substrate and the primer and/or between the coatings. Adhesion testing may be a requirement for coating specifications, or it may be used in the laboratory to verify the performance of the coating system. Adhesion test can also be used to evaluate whether the coating system has been used for a long time, whether its performance has declined, whether it needs repair, whether the output coating should be strengthened with topcoat, in addition, it is also often used for coating Invalid investigation. Regardless of the purpose of the test, the adhesion test must follow its standard test method (procedure) in order to obtain consistent results

ASTM D3359 “Standard Test Method for Measuring Adhesion by Tape (Tape Method)” and ASTM D6677 “Standard Test Method for Evaluating Adhesion by Blade (Blade Method)” may be the most commonly used to evaluate the adhesion of coatings to substrates Two methods. Although it is generally considered that the tape method and the blade method are more subjective than the tensile adhesion test, the tape method and the blade method can indeed show the true adhesion properties of the coating. Experience has shown that sometimes coatings that are easily picked up by blades, tape or even fingers have high tensile adhesion values. It seems that the two seem to contradict each other. This is mainly caused by the different directional forces applied to the coating during the test. .

Introduce of assembly

FuChia Industrial has an automated assembly line for the assembly of workpieces, which can be assembled and packaged in an efficient manner. small plastic sealing bags or Tray trays are used for packaging. This method can effectively protect the goods from the transportation process. damage. After the assembly is completed, the shipping schedule will be determined according to the customer’s requirements, and the choice of air or sea transportation will be delivered to the designated location according to the customer’s requirements