The solution for the cleanliness inspection of automobile mechanical transmission assembly
1 Introduction
1.1 Concept of cleanliness of transmission assembly
The cleanliness of the transmission assembly refers to the degree of cleanliness of the transmission assembly that has completed the performance test, expressed by the quality, quantity and maximum particle size of foreign particles. According to different prescribed methods, the cleanliness of the transmission assembly is divided into two types, one is the cleanliness of disassembly and the other is the cleanliness of non-disassembly. The cleanliness of disassembly is to detect the cleanliness of the specified parts; the cleanliness of non-disintegration is to detect the cleanliness of all lubricating oil or working fluid inside.
1.2 Purpose
Through cleanliness detection, it can greatly reduce the damage caused by particle wear, improve the operating life and reliability of the whole machine; prevent and reduce the harm to the whole machine by impurities in parts; blockage, damage, and failure of the filter element, filter, and oil injection port Such as the damage of the synthetic resin shell; the decrease in flow due to sediment in the circuit; the friction due to the sediment causing poor work and spring damage; the abnormal wear and damage of the sealing material and diaphragm are of great significance.
1.3 Scope
Cleanliness inspection of automobile mechanical transmission assembly and its parts.
2 Test overview
2.1 Testing environment requirements
Dry and ventilated, the temperature is between 15～30℃, and the humidity is not more than 70%RH; there are good dust-proof measures in the laboratory, and the indoor 24-hour dust reduction is ≤0.04g/m2.
The cleanliness laboratory should provide a working area that can be operated independently for dismantling, cleaning, filtering, drying, weighing, and analysis of the transmission.
2.2 Test preparation
The filter device, collection device and disassembly tool used in the cleanliness test process need to be cleaned with a cleaning agent before the test, especially when the disassembly cleanliness test is performed, the cleaning of the disassembly tool will affect the experimental results The impact of the disassembly tool is particularly important. If the disassembly tool is not cleaned, it is easy to introduce foreign impurities during the disassembly process.
The filter membrane used in the test has the characteristics of uniform pore size, fast filtration rate, not easy to fall off, easy to constant weight, etc., no pinholes, no translucent spots, and no streaks. And the porosity is not less than 80%.
Before use, the filter membrane should be washed in a cleaning solution and dried on both sides. At present, the laboratory uses nylon membrane, which can be taken out after drying at 80°C for 30 minutes. Place in a desiccator to cool and weigh. The filter membrane needs to be dried for two consecutive times and the difference in quality after cooling is not more than 0.0004g to reach a constant weight, then it can be used.
The cleaning fluid should be selected to not cause damage to the tested transmission, harmless to the human body, and not cause chemical reaction and damage to the filter membrane used in the test to collect impurities. And before cleaning the tested transmission, the cleaning agent used in the test needs to be filtered with a filter membrane smaller than 1/10 of the pore size of the measured filter membrane before it can be used to clean the tested sample.
Blank experiment
1) The particle mass value and particle quantity of the blank test should be less than 1/10 of the cleanliness limit of the transmission assembly;
2) The maximum particle size of the blank test should be less than 1/2 of the particle size limit of the cleanliness of the transmission assembly;
2.3 Cleaning of disassembled cleanliness parts
The cleanliness of disassembly requires disassembly of the parts of the transmission assembly to be cleaned. The degree of disassembly must be confirmed with the customer before disassembly. Before the confirmation is clear, the test personnel shall not disassemble at will. In the process of disassembling the sample, it is premised not to affect the function and performance of the disassembled parts, and to ensure that the transmission can be used normally after the experiment is completed, so as to observe the comparison of the transmission before and after cleaning. The disassembly process should prevent damage to the parts, thereby introducing foreign particles, which will affect the experimental results.
Use pressure to wash the surface of the sample to be tested. If the customer requires it, ultrasonic cleaning can be performed, or pressure cleaning and ultrasonic cleaning can be combined with each other. During the cleaning process, for the residues that cannot be washed off the surface of the tested sample, such as the sealant used to bond the sample, after the sample is disassembled, there are still some residues on the surface of the sample. At this time, it cannot be carried out artificially. Hard rejection, even if the filter membrane collects impurities, the residue in this part is not used as the test result of the cleanliness assembly.
The impurities are collected, dried and weighed, and then calculated, the particles are counted for microscopic analysis, and the maximum particle size is measured.
2.4 Cleaning of non-disintegrating cleanliness samples
The undisassembled cleanliness of the tested transmission does not need to be disassembled. Collect all the lubricating oil or working fluid inside the tested transmission. After the collection is completed, use a volume smaller than the lubricating oil or working fluid to rinse or continuously shake the inside of the sample to rinse twice. And collect the cleaning fluid.
There are two ways to collect impurity particles. One is full-liquid filtration, in which all the cleaning liquid collected from the sample to be tested is collected by a filter membrane. One is sampling filtration. The volume of the test liquid to be sampled and filtered is not less than 3L. Before sampling, the collected test liquid needs to be stirred evenly and randomly sampled under agitation. The sampling volume is 1/10 of the total liquid volume. The accuracy is not less than 0.5mL.
The filter membrane collects the impurities, is dried and weighed, and then counts the particles for microscopic analysis to measure the maximum particle size.
Applicable Products：
DJ-CA100 Cleanliness Analysis System DJ-CC767 Cleanliness Cabinets DJ-CCCX Custom Cleanliness Cabinets
