Improve mold life and reduce mold costs
In the production of profiles, the mold has a very important meaning to realize the entire extrusion process. To improve the quality and service life of the mold is one of the important ways to achieve high yield, high efficiency, and high quality bottom consumption in the extrusion process. According to statistics, the cost of the mold accounts for 25%~33% of the total cost of the extrusion process.
The factors that affect the quality and service life of the extrusion die are numerous and complex, and must therefore be studied in a systematic project. In order to further tap potential and increase efficiency, special research is conducted on the quality and service life of extrusion dies: the scientific management system for molds has been further improved, external bidding has been implemented, internal storefronts have been implemented, and subcontractors have been strictly required by ISO9002 quality system requirements. Control, reasonably regulate the use and maintenance of molds, strengthen mold repair, optimize mold nitridation process, increase the number of nitridation. The above work has greatly reduced the number of molds purchased and the cost. The molding rate of the upper mold and the production yield of the mold are greatly improved, the life of the mold is improved, and the economic benefit is very significant.
1. Establish a sound scientific management system for molds and reduce procurement costs
An aluminum processing plant with an annual output of more than 5,000 tons of aluminum profiles uses about 1,000 sets of molds. To reduce the cost of molds, we must first of all reduce the purchase price on the premise of ensuring quality. At the same time, according to production requirements, reasonable inventory molds, in the guarantee of the production of the early period, reduce the number of purchases.
1. One Goods Comparison, Bidding Procurement
For more than a decade, aluminum processing plants and mold subcontractors have established long-term and warm cooperative relations, and the quality of molds has also been continuously improved. However, the procurement of three tenders to purchase goods, further reducing procurement costs is an inevitable choice.
According to the requirements of ISO9002 quality system, a qualified mold supplier shall be determined by comprehensive assessment of qualification, quality, price, service, delivery date, and credit status.
1. 2 Sound scientific management system
Acceptance, tryout, repair, use, storage, custody, distribution, scrapping, and replenishment of molds are the whole process of mold management. The management of the plant and workshop is implemented at the two poles, and each person is responsible for each link.
Set up mold files, revise and improve <extrusion mold acceptance requirements> and <test mold regulations>. Contents include: acceptance inspection conclusions, trial contents and conclusions, amendments to the content of the mold, each production situation, nitriding situation, and the amount of cause of rejection, etc., and comprehensive records of the raw data for each set of the whole process of the mold, based on the assessment of the situation , accumulate experience, improve and improve, and constantly improve the level of mold.
Establish a sound mold retirement supplementary system. The scrapping of molds is not just a matter of light and obsolete molds that cannot be repaired. The scrapping standard of the mould must be determined according to the quality standard of the profile. There are nearly 1,000 types of existing profiles, and a total of more than 3,000 sets of molds. The production quantity and frequency of use vary widely. The molds are stored in a classified manner, the inventory status is managed dynamically, the use of the molds must be predictable, and the supply cycle of the molds must be considered comprehensively. The new molds should be added to the storage before the large-volume molds are scrapped. Therefore, the scrapping of molds supplemented insists on the principles of dynamic management, classified storage, scientific foresight, multiple times, and reasonable inventory.
2. Optimize the use conditions and improve the life of the mold
The total weight of the product that passes through the extrusion die before being scrapped due to wear or other forms of failure resulting in irreparable damage is called the life of the die. Increasing mold life essentially means reducing failure. The reasons for scrapping can be divided into two types: over scrapped scrap and scrapped scrap.
2.1 Strict process conditions, standard and reasonable use of mold
During the extrusion process, the mold is subjected to high temperature, high pressure, high friction, repeated cyclic stress, impact load, and chilled heat for a long period of time. The working conditions are rather poor, and it must be ensured that the mold is under optimum process conditions when used.
(1) Strictly mold heating system, determine the heating temperature and time according to the mold type and size, and strictly prohibit the mold from squeezing out of warm car, and use the mold protectively.
(2) Regulate the relationship between temperature and enthalpy, implement low-temperature high-speed or high-temperature low-speed extrusion method, and slowly pressurize to prevent impact extrusion and reduce the number of blockages.
(3) Reduce the chilling and heat change of the mold, avoid cold water pouring directly onto the mold, and the unloaded mold is not allowed to put into the alkali etching groove above 200°C.
2.2 strengthen mold maintenance, improve the mold on the molding rate
The use of the accompanying card system to establish the mold, the details of the situation on the machine, unsatisfactory mold sawing a good head, to provide a reliable basis for repairing the mold. At the same time, technical personnel are trained in repairing molders to improve the level of repairs. For the common problems that exist, we must sum up laws in a timely manner and solve key problems.
The most common defects that occur in the production of bite marks in solid profiles are severely detrimental to production over a period of time. The analysis is due to the plastic deformation of the mold. For this purpose, more than 200 sets of gaskets are thickened in a circle around the die holes. Strengthen the support of the mold. At the same time standardize the use of the support ring, according to the shape of the profile choose the most suitable special support ring, timely replacement of the damaged deformation. After taking the above measures, the number of bite marks is greatly reduced.
The surface of the profile is scratched and bright, and solid and hollow profiles are treated separately. Solid profiles. Repair from the width of the guide trough, working belt drop, working belt entrance and exit angles: Hollow profile to solve the problem of whether the flow of the upper die split hole is consistent, whether the welding is sufficient, whether the metal flow has resistance points. After the measures were taken, the original scratches, two obvious defects were significantly reduced, and the finished product rate was increased.
2.3 Optimize the process of mold nitridation and improve the throughput
The nitridation process of the mold is urea plus formamide gas soft nitriding. This method has a thin nitride layer, low hardness, poor seizure resistance, and high cost. After many investigations, it was decided to use an ammonia gas plus alcohol two-stage gas soft nitriding process to perform multiple tests on the process parameters such as the ratio of the chemicals, the nitriding temperature, the time, the ammonia decomposition rate, and other process parameters. Process. At the same time increase the number of nitriding, the original two days a furnace to one furnace, the new mold on the machine to produce 10 ingots after the removal of polishing and nitriding, continuous nitriding 3 times to improve the work of the hardness, wear resistance and Anti-occlusion. After testing, the microhardness of the nitrided layer reaches HV1000 or more, and the throughput of the nitrided layer reaches 0.6 tons or more.
3. Conclusion
By continuously summarizing and optimizing the technical conditions for the use of molds and bidding and purchasing, the “aluminum processing plant tooling management and use technical standards” have been formed, so that the use of mold management is scientific, standardized, and institutionalized. The machine forming rate, the number of pass throughs, and the life of the mold are greatly improved, which can create direct economic benefits.
New and old nitriding process comparison table
Process Chemicals Insulation temperature and time NH3 decomposition rate/% Temperature of the furnace/°C Cost/set
Original Process Urea + Formamide (575+/-5)°C*4H / 400 31.45
New Process Ammonia + Alcohol 560°C*4H+540°C*2H 30%~45% 200 15.5
