The main characteristics of casting management in developed countries are: many process control items, standardized and meticulous process management, and strict quantification of control scope; Carry out the process without any deduction; Focus on development and creativity, and continuously develop high-tech castings with higher intangible value.
1. There are many process management control items, the process management is standardized and detailed, and the scope is strictly quantified
The goal of casting production is to use * * * high efficiency and * * * low cost to produce castings with qualified and consistent quality. Qualified refers to qualified casting size, no surface and internal defects, and material properties meet requirements. Consistent quality means that each batch of castings and castings of different batches have the same performance and quality, and have good consistency.
1.1 Process management control
In order to achieve this goal, a complete set of processes and equipment are required. All equipment serves the process, and the process required for any process of production shall be controlled. Foundries in developed countries have established strict control scope for all projects that have been proved to be in need of control in production by science and technology and where they can control them. Raw materials are strictly inspected and controlled, including the composition and specifications of various metal materials and non-metallic materials. The parameters in the process are also strictly controlled, such as the compaction rate, wet strength, dry strength, moisture, crushing index, air permeability, effective clay content, volatile matter, loss on ignition, dead clay content, temperature, sand mold hardness, etc. Many domestic foundries do not detect the effective clay content, and the dead clay content in molding sand is high, so the moisture content is high. For another example, the general control range (mass fraction, the same below) of foundries in developed countries for the chemical composition of ductile iron molten iron: ± 0.05% C, ± 0.1% Si.
The author has inspected other European nonferrous metal and superalloy foundries, and their control processes and parameter requirements are also strict. Without the consent of the competent department, it is not allowed to change the detection and control parameters at will. In addition, the implementation of each process has original document records, which cannot be changed at will
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1.2 Selection and matching of instruments and equipment
In order to achieve the control goal, there must be corresponding equipment and instruments. Electric furnace smelting or duplex smelting shall be adopted, and carbon content shall be detected by carbon analyzer, and the remaining ten components shall be detected by spectrometer. If there is no electric furnace smelting and spectrometer rapid analysis, foreign customers will not generally buy your products. The spheroidization rate was tested with diamond polishing paste, and the sample quality was close to the photographic level; Check the white mouth depth with a sample plate; The mechanical properties can be measured accurately with the equipment configured by microcomputer; The casting sample shall be inspected by the three coordinate inspection bench; The cleaned castings shall be inspected with special measuring tools and special fixtures. Each process has original documents. The spheroidization rate and internal defects shall be inspected by ultrasonic, and the surface cracks shall be inspected by X-ray. The coupling agent for inspection is specially used for inspecting castings.
In a word, all equipment required to ensure the process must be repaired and purchased.
In order to achieve production with high efficiency and low energy consumption, production shifts shall be arranged so that production can continue as long as possible to reduce material and energy consumption. For example, enterprises with cupola and electric furnace are arranged to work 12 hours a shift and 4 days a week. The process shall also consider the convenience and safety of workers. For example, the wax mold for production of superalloy investment castings is light green, which protects vision and is conducive to production; The worktable of the cleaning department shall be at the proper height.
1.3 Quality management
Due to the complexity of the production process, no matter how advanced the quality certification is, no matter how good the management is, no matter how strict the implementation is, waste products will inevitably occur. The problem is the attitude towards waste products. What a good quality system says is that everyone is a quality officer, and never let a waste product escape from his own hands, never let a waste product leave the factory, and never let a defective product pass for a good one. International quality certification (IS09000) and various special certifications are very strict, and fraud is not allowed. The inspection of quality certification is not about whether there is a problem, but whether there is a reputation. If there are problems, they can be improved to meet the certification requirements. If you practice fraud, you will lose credibility and will not be authenticated. In developed countries, it is rare for foundries to give any special treatment to certified units and personnel, and there is also little fraud. Even so, some customers also stipulated that a third party must be present to witness the mechanical property inspection and jointly fill in the mechanical property inspection report, which shows that their requirements are strict.
Where instruments and tools can be used to control, instruments and tools shall be used to control. All instruments and meters are regularly inspected, calibrated and recorded.
In order to achieve high productivity, the configuration and management of equipment should be systematic and supportive. The author has visited many European and American enterprises, and found that not every enterprise's equipment is advanced, but it has good matching and high reliability. In this way, the lost time caused by the shutdown of the whole line due to a certain equipment failure is reduced, and the entire equipment system can also meet the requirements of producing high-quality castings. There are many manufacturers in China, many of which are very advanced in the world, but some of them are very poor, unreliable and have poor equipment matching. For example, many well-known domestic foundries do not have a three coordinate inspection table and other advanced testing equipment, resulting in insufficient testing equipment and data to support the product quality even if good castings are produced. European and American enterprises also have strong maintenance teams.
Some peers in the technology and management departments of domestic foundry enterprises worry whether such strict process procedures and their strict implementation will cause production stoppage due to problems in a certain link, affecting the production rhythm and productivity. In developed countries, there is no production stoppage due to strict process procedures and their strict implementation, which affects productivity.
In fact, the implementation of loose and less strict process procedures cannot improve productivity, but is harmful to the improvement of productivity and product quality. On the contrary, it is precisely because of such strict and meticulous process procedures and their thorough implementation that the energy consumption of castings in developed countries is far less than that in China, while the labor productivity and total output value are far higher than those in Chinese foundries.
A foundry in Germany has adopted strict process management system to produce as cast low temperature high impact ductile iron without heat treatment. The attached test bar and casting body meet all the mechanical property requirements of low temperature and high toughness ductile iron. It is no exaggeration to say that the optimized process procedures and their strict implementation are actually the fundamental reason, or the know-how, for the entire industrial system of developed countries to continuously produce high-quality products.
1.4 Personnel Training and Post Setting
The training of personnel focuses on actual results, and what needs to be trained. The main methods are training classes (industry training classes, university training classes), and mentoring between old employees and new employees. The training is very targeted and practical. Training is not a diploma, not a certificate, but only for work needs.
If the process can be completed by machinery, people will never be employed; One post needs one person, never two. For example, one worker in a foundry is responsible for the sand treatment system of two green sand production lines, responsible for all feeding, pulverized coal, new sand, water, etc., checking and controlling the properties of molding sand, recording data, and also responsible for sample sorting; A specially assigned person in the cleaning workshop is responsible for inspection, including scribing inspection of samples, dimensional inspection of castings, ultrasonic inspection of spheroidization rate, internal defects, X-ray inspection of surface cracks, management of inspection tool library, etc.
2. Strictly implement the process
Process is regarded as the production law of the enterprise. Once the process is formulated, everyone from workers to management and technicians has the responsibility to implement the process. Although the education level of the workers is not high, the quality of implementing the process is not low, and the process regulations are implemented to the letter. If the process conditions are not met, the workers will never operate. For example, if the temperature and composition of the molten metal are unqualified, the furnace worker will never leave the furnace; If the temperature of molten metal in the ladle exceeds the specified pouring temperature range, the pouring worker will not pour; Would rather be cast into ingots; If the molding sand temperature exceeds the specified temperature, the molding worker will not mold; Products with unqualified hardness, dimension and surface quality will not be released.
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The equipment and raw materials are all for the process. In order to enable the process to be carried out without compromise and at any cost. For example, the spheroidization rate of ductile iron is tested by polishing with diamond polishing paste, and the sample quality is close to the photographic level; Three coordinate inspection table is used for dimensional inspection of casting samples. Other advanced inspection equipment for internal defects inspection is necessary for samples such as X-ray and ultrasonic flaw detection.
3. Focus on development and creativity, and develop high-tech castings with higher intangible value
In recent years, foundries in developed countries have made great efforts to improve customer service, actively participated in the development, design and production of high-tech castings and high profit castings with higher added value. In recent years, due to the continuous improvement of the properties of cast metal materials, the improvement of casting methods and the emergence of new casting methods, new development fields have been provided for new castings and casting design. Some metal castings have even replaced plastic shells.
The famous Intemational Waukesha foundry in Portland, Oregon, which produces auto castings in the United States, redesigned the assembly consisting of four steel castings from its competitors and produced one ADI casting. From 1991 to 2003, it has produced more than 40000 tons of ADI castings. In 2003, the truck rear spring seat was redesigned as ADI casting, and the weight was reduced from 34 pounds to 27 pounds.
Smith Foundry in Minneapolis in the United States changed the originally designed caterpillar drive wheel assembled from 84 steel parts into a single ADI drive wheel casting, reducing the weight by 15% and the cost by 55%. Users save $190000 annually. Compared with the original assembly parts, the assembly time of 30 min is saved, the wear resistance is improved, and the appearance is more beautiful. This shows that the casting design has great potential, and the design, innovation and improvement of castings are endless.
According to the author, many foundries in Europe and America are cooperating with users to design, innovate and improve castings. Some companies have more than ten such projects every year. As illustrated by the above examples, at present, the main work of developing new castings by using new processes and new alloy materials is realized by combining foundries and users. However, there have been companies in developed countries that take casting design as their business. These emerging companies use computer solidification simulation technology, computer casting design technology, combined with casting users and casting manufacturers, to develop new castings at a fast speed. It can be said that the castings in the future will have more functions, better performance and cheaper price. China's foundry industry should understand the development of the international foundry industry, seize the opportunity to further develop and improve the level of China's foundry industry.
