Clean production to cure "stubborn disease" -- Record of the Southwest Aluminum business department overcoming the difficulty of "black strip" of tank cover material

West Aluminum - West Aluminum Industry Telecom: The defect of "black strip" is a common technical problem in the aluminum processing industry. It was also a "big worry" of the tank cover products of the high precision plate and strip business department (hereinafter referred to as the business department) of SWA, which has troubled the civil product market of SWA for more than 10 years.

In order to completely get rid of the adverse effects caused by the "black bar" defect, the business unit set up a research team in 2018 to carry out special research. Through the implementation of effective measures such as cleaner production, equipment transformation and upgrading, they have finally changed the rating of enterprise product quality from "d" to "a", and the loss of customer complaints has been reduced from nearly ten million per year to zero.

Behind the elimination of the "stubborn diseases" that have plagued the production for many years, is the confidence and determination of the business division to keep up with the world's first-class standards, carry out precise management and improve product quality, and is the wonderful story of all cadres and employees who are united in a city, facing difficulties and striving bravely.

Find "cause"

On March 6th, with the roar of equipment operation, the smooth and clean aluminum plate and strip on the production line were transmitted from the end of the rolling mill, then gathered into a roll, and then lifted away... Walked into the hot continuous rolling manufacturing center of the division, and the rolling mill was in full swing.

Just a year ago, the large hot-rolled roll of tank cover material produced on the production line that once won the first prize of national science and technology progress had "black strip" defects from time to time, which caused great user opinions and once broke the minds of technicians.

The "black strip" defect refers to the irregular black strip defect in the rolling process of aluminum sheet, which damages the integrity, uniformity and aesthetics of the aluminum surface. This is also a common quality problem in the industry.

The surface quality of the can cover pull ring material of the business unit has been seriously affected by the "black strip" defect. The internal control rating has been between level C and level D (level a is the best and level D is the worst). The direct impact is that the process scrap is large, there are many customer complaints, the market image is damaged, and the brand of sinal aluminum is damaged.

Since 2017, with the fierce competition in the civil products market, customers have higher and higher requirements for surface quality. Due to the influence of "black strip" defect, the pull ring material of the tank cover of the business unit has gradually failed to meet the requirements of the mainstream market. From 2017 to 2018, the number of customer complaints and process scrap of the business unit accumulated to thousands of tons, resulting in a huge loss of quality and a sharp contraction of the market.

How to solve this problem from the root? The business unit has a lot to think about.

In 2018, the business unit set up a research team, and many technicians first cleaned up the equipment, but the effect was not significantly improved, and the product quality was still unstable. At the same time, the business unit also went to a number of advanced peer enterprises for study and research.

During the visit, we found that even if some enterprises use older equipment, the "black bar" defects of products produced by them are not serious. However, the factories that produce high-quality products are very clean without exception, and there are few thick sludge on site. This discovery made many technicians of the business unit realize that clean production is the key to solve the "black bar" defect.

At the end of August 2019, the research group investigated the related factors of hot rolling production one by one, and found that there were serious deficiencies in the cleaning condition of the hot-rolled emulsion and the rack, resulting in the residual aluminum dust and aluminum powder on the strip surface after rolling, forming a "black strip" on the surface of the strip during the subsequent rolling process.

In order to thoroughly clean the frame, the research team upgraded the washing equipment with a spray pressure of more than 10 kg, and replaced it with a new equipment with a spray pressure of about 200 kg. In addition, the production line was shut down for 2 days, and a scaffold was built to enter the top and the inside of the rolling mill for washing.

In Chongqing in August, the heat wave hit people. When I stayed in the factory, I felt the air was sultry, let alone the inside of the rolling mill. When the operators enter the rolling mill for washing, they should put on raincoats, and use equipment with strong impulse and hard to control. When they are finished washing, the raincoats are mixed with water and sweat, and the clothes are all wet.

"After washing the frame completely, the dead angle of sanitation is eliminated completely, and the risk of contamination of the strip surface by the internal organs of the frame during rolling is reduced." Liu Lunyou, deputy chief engineer of hot rolling manufacturing center of business division, said.

The Ministry also regulates a series of standardization processes for cleaner production: take full advantage of the downtime of equipment, flush the top and inside of the rack before each production can cover the product, regulate the manual oil skimming operation of the emulsion, increase the number from the original shift to two times per class, and increase the time from 5 minutes to no less than 10 minutes, improving the cleanliness of the emulsion. The function of oil-water separator is optimized, the oil discharge port of the first level filter tank is added, the dirty oil on the emulsion surface is discharged timely, and the cleanliness of the emulsion is improved.

In addition to making great efforts in cleaner production, the Ministry also upgraded the thickness gauge and emulsion heater of the rolling mill, adjusted the formulation of the emulsion accordingly, rationally allocated the amount of the rolling mill under pressure, re selected the emulsion nozzles, improved the cooling ability in the rolling process, reduced the surface temperature of the work roll surface and strip, and effectively reduced the sticky aluminum.

Through a series of precise analysis and various measures, the business unit has thoroughly solved the problem of "black bar" defect. From October 2019 to now, the complaint of "black bar" from customers of the business unit is zero; the scrap amount of process black bar only accounts for 0.5% of the shipment amount, down 94% from 2018; the pending amount of process only accounts for 2.5% of the shipment amount, down 91% from 2018. The customer's product quality rating of the business unit is all above grade B, and part of it is Grade A

(Chongqing Xialu Xinda Aluminum Industry Co., Ltd. Publicity Department collates contributions)

Source: Network

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