• News

  • News
  • Notice

Abnen brings you the solution for the forefront of casting impregnation seals

Time:2016-09-29 00:00:00

     First of all, we need to understand why the casting should be sealed. Modern technology is advancing by leaps and bounds, but why castings involved cars, motorcycles, electronic components and aero-engines, especially colored light metal castings, are still inseparable from impregnation technology to improve quality and reduce costs?

Looking back at industrial history, the application of modern industrial impregnation processes can be traced back to the casting plugging process of the 1930s, when water glass was used to fill the casting voids via internal circulation. In the 1950s and 1960s, with the development of the automobile industry, the industrialized countries such as the United States, the former Federal Republic of Germany, and the former Soviet Union promoted the development and application of sodium silicate type impregnation, the first generation of impregnation sealant, for the sealing of pressure-bearing castings, and developed partial or atmospheric pressure impregnation process to vacuum pressure impregnation process.
    Since the 1970s, automobiles have become lighter, and many castings have been replaced by light metals such as aluminum, magnesium, and zinc, and their alloy materials, thereby reducing the weight of automobiles, reducing energy consumption, and improving the performance of automobiles. However, light metal castings are prone to micropores, resulting in leakage of pressurized castings. At the same time, the widespread use of powder metallurgy sintered parts further reduces material and machining costs. The leakage of porous materials urgently needs to be solved, which has promoted the demand for impregnation technology.

In theory, impregnation technology, which widely used to deal with casting defects, is limited to the field of micro-hole sealing technology. For example, for castings with a thickness of 5 mm, pores with a diameter of less than 0.254 mm are generally referred to micropores. It is difficult to find the micropores in naked eyes. In the castings of automotive power systems or pneumatic hydraulic systems, the presence of micropores will lead to the leakage of internal media, increasing the overall production cost directly and indirectly, failing to guarantee the product quality, and losing the product function in usage.

In the modern industrial system, the development of the chemical industry promotes the research and development of impregnation sealants. Thus, many types of impregnation sealant

 with a wide variety of applications and sound performance have been introduced, such as the second generation of polyester-type impregnation sealant and the third generation of anaerobic, thermosetting acrylate-type impregnation sealants. Since the 1990s, Nanjing Abnen has been involved in the field of organic impregnation, which is almost completely monopolized by major foreign companies. It is committed to continuous improvement in impregnation sealants, methods and processes by its own research and development. Its impregnation equipment also conforms to the requirements of large production, and has been continuously developed to be large, semi-automatic and fully automatic, which further promotes the wide application of the domestic impregnation process and promotes the thinning of many complex structural parts. Nowadays, many automobile supporting enterprises have adopted the impregnation technology as an indispensable typical production process in the production of castings based on the advanced impregnation technology provided by Abnen, and advocated full impregnation processing of the evaporative pattern castings. At present, Abnen develops the leading product 8690 organic impregnation sealant (environmentally friendly and recyclable) series, and its technology is on the cutting edge. Only the British super-sealing company owns this technology. Abnen possesses more than 70% of the mainland's impregnation sealing market, and its patented technology in this field exceeds any peer in the world. It is the pride and honor of Chinese national industry.

As a new generation of environmentally-friendly and recyclable acrylate resin, the impregnation sealant can be separated and recovered from cleaning water because of its lower density than water. The impregnation process can recover about 90% of the impregnation liquid washed away by water, thereby effectively reducing waste; at the same time, compared with the general non-recycled heat-curing resin impregnation process, its water consumption is reduced by more than 45%, so the wastewater disposal cost is saved and the pollution discharge of the resin is almost eliminated. The application equipment provided by Abnen to customers has evolved from the traditional type to the semi-automatic and fully automatic production line, and all of them are equipped with impregnation sealant recovery device. The whole equipment includes: Vacuum impregnation tank (the lower level is resin storage tank) , spin cans, cleaning tanks, rinse tanks and curing tanks, and recycling equipment. The recycling equipment is linked with the cleaning tank, and the cleaning water is automatically circulated between the cleaning tank and the recycling equipment to recover the impregnation sealant. The impregnation process is automatically controlled by a programmable controller (PLC). The touch screen display can dynamically observe every step of the impregnation process, covering the tank liquid level, pressure, temperature, and opening and closing of the valve. The casting basket is automatically transferred between the cans by the robot hand. The entire impregnation process does not require any personnel to participate, thus ensuring the consistency of the impregnation quality and improving the production efficiency.

The impregnation quality mainly depends on the sealing rate of the casting after impregnation, whether there is any residual glue in the threaded hole that affects the subsequent assembly, and whether the appearance is damaged or not, such as scratch or bump, corrosion, and oxidative discoloration.

The impregnation technique theoretically only seals the micropores because the resin has flowed out of the macropores, especially during the curing phase. Therefore, the size of the casting pores is a key factor affecting the impregnation sealing effect. For certain processes and impregnation sealants, long pores with small diameter mean long time the resin takes to fill them. The upper limit of the sealability of the new impregnation sealants and processes developed by Abnen has been close to 0.30 mm, exceeding the traditional limit of 0.25. For the impregnation technology itself, the impregnation quality is closely related to the impregnation sealant, the impregnation process, and the impregnation equipment. In order to ensure a high sealing rate, the quality of the impregnation sealants must be monitored daily.

If the resin in the threaded hole of the casting or other types of blind holes cannot be cleaned, it is difficult to remove after curing, which affects the subsequent casting assembly or other processing. The placement method of the casting, the cleaning method and time, the cleanliness of the cleaning water, and the centrifugation affect the cleaning effect of the casting. The concave and blind holes of the casting face downward or outward, which is beneficial to the resin being pumped out during the centrifugation process; replacing the water in the cleaning tank and the curing tank on time; increasing the cleaning time and frequency; increasing the centrifugation time and the rotation speed can improve the cleaning effect. In the improved impregnation process of Abnen, the casting basket will experience a 360-degree centrifugal process in the forward and reverse directions after the end of the process step in each tank, and the excess residue or water is extracted. The water quality of the rinsing tank (second cleaning tank) is monitored, the water is periodically replaced, and the tank wall is cleaned. A resin separation test was conducted once a week to check the content of water resin in the cleaning tank. If the resin layer above the water is larger than the 12% aqueous solution volume, it is necessary to perform a resin removal treatment on the cleaning tank, that is, remove excess resin from the cleaning tank to improve the cleaning effect. In the whole impregnation process, the castings are washed in water, and cured at high temperature, which are easily oxidized or corroded. Thus, anti-oxidants and preservatives must be added to the cleaning tank and the curing tank to prevent discoloration of the casting due to oxidation and corrosion.

     Abnen's impregnation system and process provide customers with a unique, fully automated impregnation solution. Its recyclable, environmentally-friendly 8690 Series impregnation sealants provide consistent quality and unmatched sealing performance. Abnen's efficient impregnation solutions enable customers to achieve higher levels of sustainability, reduce the use of impregnation sealants, lower energy costs, and reduce processing time; while reducing production costs, they are also more environmentally friendly, with low pollution emission. In this field, Abnen has more than 70 patent technologies, and this is the root cause that it occupies more than 70% of the mainland impregnation seal market.