MFN had the opportunity to talk to Mr. Wang Qi, the general manager of Jiangsu Daqi Metal Surface Preparation Co., Ltd..

(?) MFN: Mr. Wang Qi, first of all, thank you very much for accepting our invitation. Would you please introduce to us the brief history of DAQI for producing and developing cut wire shot?

(!) W. Q.: Thank you for having me! Ever since its establishment in 1998, DAQI has specialized in producing various materials used in the shot-peening process for more than 20 years. In fact, even earlier than 20 years ago, when I knew very little about the peening media, many of customers, especially the joint ventures, inquired about these kinds of products, which encouraged me to make a series of explorations and perform research on such products.

After close investigation and study on the cut wire shot market home and abroad, I realized that most of the peening media in our domestic market were imported from abroad, and that almost 90% of the peening media produced by Chinese manufacturers were not up to standard; they practically couldn’t meet the technical standards required in the peening industry. At that time, the market of cut wire shot was well developed overseas, especially in Europe and America, while the market in China was just at its starting point! Therefore, we expected a tremendous market opportunity and a promising future in China.

Together with my R&D team, we initiated the project by visiting many research institutes and universities in the country, including Beijing Institute of Aeronautical Materials and Shanghai Jiao Tong University. We also worked with a number of steel wire manufacturers for joint production and technical research possibilities. It took us about three years of trial-and-error before the first generation of DAQI cut wire shot was available in the market.

The industrial application first began with our domestic customers right after the availability of DAQI’s peening products. We then obtained some important opportunities to provide our products abroad. The feedback and suggestion we received from the industrial users during this cooperation really helped us to learn and grow, so we kept improving and making continuous progress of our cut wire shot and became more and more confident in providing materials. Eventually, our cut wire shot product conformed to various international norms and standards, such as VDFI 8001 (Germany), AMS 2431 and SAE J441 (USA) as well as ISO11124-5: 2019. You may find the following attributes in DAQI’s peening media:

1. High uniformity of hardness and size;
2. Longer service life with lower breakage rate;
3. High maintenance of intensity while in usage.
4. Less dust and environmentally friendly.

We have also participated actively in drafting and applying for a number of domestic industrial and national standards, such as National Standards for Shot Peening of Springs, National Standards for Shot Peening of Gears and Industrial Standards for Shot Peening of Aerial Parts.

Apart from the peening industry, our media has also been widely used by many large-scale shipyard and steel manufacturing enterprises for cleaning and blasting applications.

Practically speaking, in both peening and blasting fields, we are seeking to provide tailor-made and high-performance surface preparation solutions for customers with different requirements. We insist on providing customers with not only the products, but also the values and services that could help them to save costs and be more environmentally friendly. To achieve this goal, we are dedicated to enhancing the performance of the products during industrial application through focusing on the technical features of our media and the proficiency of our sales team.

(?) MFN: Thanks for the briefing! I guess you must have gained some breakthroughs after years of in-depth exploration and development in the industry. Would you please share with us some of the technical or production experience?

(!) W. Q.: Yes, you are right. Throughout the years, we have indeed obtained some experience and breakthroughs in terms of the technical and production aspect. Firstly, one of the exciting news items I would like to share is that we eventually drew steel wires for cutting by ourselves, which means that we are now in control of our raw materials to an even greater extent. At the end of the day, our customers will also benefit from our involvement in the supply chain in their value for money.

Back to 2012, in order to have better control over the supply of raw materials, we decided to invest a large sum of nearly one hundred million yuan in setting up the plant and equipment for producing steel wires. DAQI has now become a cut wire shot producer with not only a well-established wire drawing plant but an experienced cut wire processing factory as well!

More importantly, to realize our corporate social responsibility and to respond to the national call for environmental protection, DAQI has successfully replaced the conventional lead quenching technique by a more environmentally friendly water-quenching technique in the heat treatment process.

Please allow me to give a brief introduction on the main production lines and equipment used in our wire drawing plant:

• Coarse Wire Drawing Production Line:

Straight-Line wire drawing machine provided by Changxin Technology is adopted, whose frequency converter is automatically controlled. This type of machine that is characterized by fast speed and stable operation can be used for the drawing of phosphate- and boron- coated steel wires.

1. The processing line of heat treatment adopts a natural gas open fire all-radiant furnace with high automation control degree. The furnace adopts a PLC servo actuator to realize automatic control of temperature. Both advanced relief and proportional valves are used to control burner gas, making the performance of heat-treated steel wire more stable.
2. The most advanced water-quenching process is employed, which is deemed as more environmentally friendly and easier in operation in comparison with the conventional lead-quenching process.
3. Advanced electrolysis phosphorization technology is adopted. Dense steel wire phosphorus layer is conductive to drawing; electrolysis phosphorization has high requirement for phosphating solution and will not produce much phosphorus slag, which can reduce environmental protection expense of phosphorus slag treatment; meanwhile, electrolysis phosphorization can shorten the length of the production line, which is more reasonable in arrangement.
4. Separate control per wire allows simultaneous production of wires with different specifications, which makes the control of lines more flexible.

• Wet Drawing Production Line:

Vertical wet drawing machine has been used. Fully automatic control of frequency converter and the automatic wiring make operation easy, safe and stable.

Our Wire Drawing Plant:

(?) MFN: As you have mentioned above, the conventional lead-quenching process has been successfully replaced by the water-quenching process. But how does this replacement happen and become practical?

(!) W. Q.: At the moment, our government is paying very intensive attention to environmental protection issues, which means most of the conventional environmental hazardous production process in industry should be disposed gradually. Since the conventional lead-quenching process could not be accepted under current environmental protection laws, we are urged to look for better alternative approaches to not only guarantee the technical attributes of heat-treated wires but also be more friendly to the environment. We realized that the water-quenching process was a good choice and nowadays it has already been widely applied in the domestic steel wire heat treatment industry as one of the matured quenching methods; moreover, in comparison with the conventional lead-quenching process, it saves more energy while in use and is more intuitive and easier to operate in production. Most importantly, it could avoid the problem of lead adhering to steel wires.

However, the water-quenching process requires higher technical control in production. The principle behind this process is to change the surface tension among solid, liquid and gas in water solution after the joining of water-soluble polymers. The film boiling state is artificially maintained and stabilized. By increasing the boiling time, the cooling speed at which the temperature of steel wire to be reduced from 650°C to 500°C in the solution could be decreased, so the time required for sorbitic transformation is guaranteed, which assures the same or similar treatment effect to be realized in comparison with the lead-quenching process. In the water-quenching process, steel wire and water solution do not contact with each other directly; instead, heat exchange happens between steel wire and water via a steam film in order to slow down the cooling velocity of the steel wire and to obtain sorbitizing of the steel wire in the end.

(?) MFN: Thank you for the illustration of breakthroughs in terms of the production aspect. Shall we continue to talk about the development in products?

(!) W. Q.:We have developed and released a wide range of cut wire shot with various technical attributes. For example, service life of the newly developed high durability cut wire has been increased at least 60% compared with conventional products. Also, if 0.5mm or 0.6mm HRC60-65 peening media are used for the shot peening of gears, you may find the depth of the residual compressive stress can reach 1200Mpa; moreover, our fine size cut wire of 0.2mm, whose hardness can be up to HV700 and HV800, has been approved by customers due to its stability in quality. Furthermore, we have also developed steel cut wire with ultra-low hardness (e.g. as low as HV60) to replace copper shots in the coating industry to help our customers save on production costs.
At the moment, we are focusing on one kind of particulate shot, whose sizes range from 0.15 to 0.175mm with a hardness of HV1200. It will be mainly applied for the composite (secondary) shot-peening process. We have passed the experimental stage and it will not be long before mass production is realized.
In the next few years, we will continue to innovate and progress to expand the portfolio of our products and meet the diverse requirements of customers.

(?) MFN: Congratulations on your achievements! Hope DAQI will make continuous progress to contribute to the industry! All the best to DAQI!

(!) W. Q.: Thanks for your kind words. There’s no way back if you choose to run an enterprise. The only way out is to persist and be ready for challenges. I believe DAQI will always be down-to-earth and strive to move forward in the future!

MFN would like to thank Wang Qi for this interview!

For Information:

Daqi Metal Surface
Preparation Co., Ltd.
No.6 Daqi Road Dafeng City Jiangsu Province China 224100
Tel. +86.515.83793000
E-mail: eav@daqigroup.com
www.daqiabrasive.com.cn