Action analysis is an important method to improve production line. Taking the assembly line of a company’s body radio frequency controller as the research object, the operation time of the production line’s bottleneck position was measured by the method of time measurement (MTM). The problems in the production process were analyzed and found. Aiming at the bottleneck of the assembly line, the improvement measures of action analysis were put forward, which reduced the production line rhythm and improved the workers’labor. Dynamic strength improves the production capacity and efficiency of the whole production line. A company is a Sino-German joint venture automotive parts manufacturing enterprise, mainly engaged in automotive controller related parts development and production related business.
The car body RF controller product project is imported from Germany. The project is compact from project establishment to batch production. For equipment and process technology development, the concept of German company’s production line design is fully referenced and duplicated. No further research on its process has been carried out. As a result, after mass production, the bottleneck of the production line is prominent and the production line is balanced. Not high.
In the initial stage of mass production, the production capacity of the production line can meet the low demand of customers. After one year of mass production, due to the strong market demand, the demand of customers has risen sharply. Whether the production capacity of the production line can meet the needs of customers or not, the production line workers need to work overtime frequently, which increases the production cost of enterprises. Therefore, it is necessary to analyze the existing production lines, find out the main influencing factors, and take measures to improve production capacity. In the whole process of analysis and improvement, the related theory of job analysis is mainly applied. Aiming at the bottleneck position of the body RF assembly line, the procedure analysis, operation analysis and action analysis are carried out. ECRS analysis method (elimination, merger, reorganization and simplification) is used to optimize the layout of the production line, reduce the movement of operators and body movement. The incoming materials are defined, the material placement is standardized and the operation is standardized. At the same time, through MTM (method time measurement) measurement, the author analyzed the operator’s motive, reduced the invalid action of operation, and improved the work efficiency. At the same time, combined with MTM measurement and the related theory of human engineering, the related production equipment was improved, which effectively shortened the equipment’s rhythm and improved the operation.
At present, thermostatic element the assembly line is a special production line, which only produces body RF controller. The production process of RF controller includes two main processes, the front-channel electronic component patch process and the back-channel assembly test process. The SMT process section belongs to the standard process, and other production departments of the company directly supply circuit boards with well-attached components. The equipment of assembly test line is composed of non-standard equipment, which is also the object of improvement of this assembly line. According to the position rhythm measured by IE department, it can be seen from Figure 2 that the first bottleneck of production line rhythm is 32.6 seconds for operator 3, and the second bottleneck is 18.4 seconds for circuit board clamping at station 1. Operator No. 3 is mainly human-oriented, there is a lot of room for improvement, and when the demand for production rises, it can share the work of Operator No. 3 by adding an additional person. However, unit 1 is the working rhythm of individual single equipment. Improvement measures must be taken to effectively reduce the working rhythm of the station. Therefore, the analysis focuses on the selection and analysis of No. 3 operator and No. 1 workstation. The layout of production line is unreasonable, which leads to excessive movement; the moving distance of No. 3 operator between workstations exceeds 3 meters, and invalid moving time is more than 3 seconds in each round operation; the size of equipment and material rack is too large, which increases the movement of operators; No. 3 operator needs to take the upper cover and circuit apart from two equipments when assembling products. Semi-finished board; finished product testing, from functional testing to the next label station, need No. 3 operator with the product to move past; No. 1 operator needs to take three pieces of material each round of operation, but the distance of the material box is unreasonable; take the circuit board needs to stand forward; take the spring needs to turn around and bend to take, take the bottom cover, need to. Turn around and move to pick up; there are redundant actions; No. 3 operator needs to perform dot marking work in the operation process, the action is only in the early stage of mass production in order to mark the visual inspection of weld location.
Secondly, according to the four basic rules of action economy, every motive element of No. 1 station of the production line is analyzed. The No. 1 position is the circuit board pressing station. The operator pre-assembles the circuit board, the bottom cover and the spring antenna. After putting them into the equipment, the equipment automatically completes the pressing of the circuit board and the connector terminals. Laser code is placed on the bottom cover to facilitate the product traceability of the subsequent positions. The left hand takes the bottom cover from the turnaround box, the right hand takes the spring antenna from the other turnaround box, completes the pre-assembly of the two antennas in the hand, and places them on the operating platform; the right hand takes the circuit board, sends it to the scanning gun, adjusts the angle, reads the two-dimensional code on the circuit board; the two hands complete the pre-assembly of the bottom cover and the circuit board; the left hand flips to open the clamp of the equipment. Fixture, and take out the finished product, put it in the next position; put the pre-assembled product in the right hand, and flip the clamp; press the start button with both hands at the same time, close the safety door of the equipment; the equipment automatically completes the pressing and laser coding. After removing the bottom cover from the left side, it needs to change to the right hand for assembly; taking the spring needs to adjust the direction; taking the PCBA needs to adjust the direction; taking the whole board turntable needs to adjust the direction; needing to operate and maintain the two hands switch; needing to manually turn over the pressure shell tooling after placing the product; needing to move to the next position and place the product in the scanning; When the two-dimensional code on the circuit board, it is necessary to adjust the position of the circuit board. On the basis of adhering to the principle of work economy and the four principles of ECRS, the work station is improved. After the reallocation of the real estate line, the production line was changed from L to U.
Operator No. 3 was responsible for the operation of three workstations, and needed to move 4 meters per round. After improvement, the moving distance of each round was reduced to 1 meter. Most of the work could be completed by turning around. The shell pressing equipment modification is directly placed on the redundant area of the functional test operation surface, which effectively reduces the size of the equipment and the moving distance of No. 3 operator. After canceling operator 3 to check solder joints, do dot marking. The transfer of semi-finished materials between operators is changed from manual movement to fixed position to slideway transmission. The finished products can slide to the next working position only by putting them into slideway. The first material of No. 1 workstation is the bottom cover. Because the bottom cover material frame is too high, the parts are moved far away and the labor intensity is high. We have modified the structure of the bottom cover rack to make the front horizontal rack tilt to the operator. After modification, the operator can reach out and take it. The second material of No. 2 station is spring, which was mixed in the material box before it was put on line. The springs are easily entangled, and the direction is often reversed. It is not easy for the operator to separate the spring and take the spring. We inform the spring supplier that the packaging of the spring has been modified. The spring is positioned in the direction of the plastic tray. After this improvement, the operator can easily take the spring and the feeding direction of the spring does not need additional adjustment. The third lesson is circuit board, which is supplied by plastic tray from the inner workshop, but the circuit board is not defined in the direction of placement in the tray. After the operator takes it, it often needs 180 degrees to adjust the direction of the circuit board. There are 6 groups of trays in each turnover box, and the placement between the trays has no defined direction, so it needs to be adjusted during operation. Complete; The used tray has no defined placement position and requires the operator to turn around and place it behind the material rack. Through the improvement activities, we defined the direction of the turning box into the rack, the direction of the tray in the turning box, and the direction of the circuit board in the tray. After such positioning management, the operator took the circuit board without additional action. The used trays are placed directly under the modified material rack. Six empty trays are accumulated and put into the used turnaround box. No extra movement is needed to reduce the fluctuation of operation. After picking up the circuit board, we first need to read the two-dimensional traceability code on the circuit board. The scanning gun is installed below. When the operator places the circuit board, the position of the scanning gun is inaccurate due to the invisibility of the scanning gun. We often need to adjust the position. We make the placement bracket of the circuit board above the scanning gun to locate the placement of the circuit board and ensure each one. The sub-circuit boards are placed in the same position, and the scanning gun can be read accurately at one time. After putting the prefabricated circuit board into the fixture, the operator needs to manually flip the upper fixture to ensure the rough positioning of the upper and lower pressing fixture; after the internal structure transformation of the equipment, the upper fixture is fixed directly, and the lower fixture is moved by motor, which reduces the action of the overturning fixture.
After installing the spring and bottom cover, the circuit board is manually put into the equipment for pressing and laser coding. In order to be safe, the operator needs to operate the mechanical start button with both hands to ensure that the safety door is closed before letting go and proceeding with the operation of the next product. We have modified the structure of the equipment, cancelled the mechanical two-handed switch, added photoelectric switch and safety light screen. The operator’s action is simplified to put in the product and touch the photoelectric switch, then the next product can be operated. The device automatically closes the safety door and carries out subsequent actions. The safety light screen can ensure the operation safety of the equipment. 。 Through the above improvement activities, the rhythm of the bottleneck workstation decreased from 32.6 seconds to 19.9 seconds, the planned output of single shift increased from 960 to 1600, and the production efficiency increased by 66.7%. By adjusting the layout of production line equipment, about 20% of the space was saved. The above key improvement indicators, converted into single product, can reduce the manufacturing cost of each product by 3.3 yuan. At the same time, due to the implementation of 5S, visual management and customization management, the production line site environment has been greatly improved, the production site has become cleaner, the material transfer between workstations is more smooth, and the scrap of material transfer has also been reduced. The degree of automation of the equipment has been improved and the labor intensity of the operators has been effectively reduced. The design level of production lines often directly affects the production capacity of enterprises, especially many production lines often because of one or several bottleneck positions affecting the overall capacity of production lines. Improving the bottleneck operation, reducing the production line rhythm, and continuously improving the efficiency and productivity of the production line have become the focus of enterprise transformation of the production line mode. Aiming at the problems existing in the production line of a company’s radio frequency controller, this paper uses the theory of action analysis to analyze and improve the bottleneck workstation, which reduces the rhythm of the production line by nearly 13 seconds and greatly improves the production efficiency. The ultimate goal of action analysis is to identify unnecessary activities in production process and personnel operation, and take further measures to reduce or eliminate the time of inefficiency. In the conceptual design stage of production line, the method of industrial engineering is introduced to analyze and simulate the scene, so as to minimize unnecessary activities, which can effectively reduce the cost of subsequent production and improvement.