A Successful Conversion from Liquid to Powder

Posted on Thursday, September 24, 2020

By Corinna Hellwig 

In 1951, Joe Kinnear and his son Peter combined ingeniously designed slotted steel angles with matching clamping plates to form an extremely stable and versatile configurable shelving system. They founded “The Handy Angle Company,” which since 1966 has operated under the Link 51 brand name. Today Link 51, part of the Whittan Group, is one of the largest manufacturers of steel storage products in the United Kingdom, processing 1,000 tons of steel each week.

Link 51’s journey of bringing the powder coating process in-house involved converting a liquid paint line at their shelving plant in Brierley Hill, England, to a powder line. The high line density line, an electrostatic liquid paint system with rotary atomizers, delivered high paint application efficiency and the finish quality their customers expected. However, the system had seen better days, required hours of weekly maintenance, and created environmental concerns.

“In 2015, our sister plant, Link Lockers, installed a new Nordson spray system with dense-phase pumps and significantly improved their powder usage,” explains Tom Clayton, Link 51’s powder coating line manager and a member of the project team. This helped Whittan Group decide it was time to get away from liquid and convert to powder. “First, we defined our goals,” recalls Christopher Walker, operations director with Whittan Group, “and agreed that if we were to improve the paint system, it would need to deliver not only environmental benefits but also improve our operating efficiency and finish quality.”

In early 2018, Link 51 began a search for a powder coating system tailored to their production needs. “We were used to our liquid system applying 25 microns of coating. One of the concerns with powder was the ability to match that thickness consistently, without daily fine-tuning, and to reduce the overall applied coating and operating costs,” recalls Peter Charles, engineering and maintenance manager at Link 51, who also led the upgrade of the Link Lockers’ line back in 2015.

“The nature of our product is such that it allows us to load the line quite densely, with minimum gaps between the products. Because of this, the old liquid system delivered a rather high application efficiency and material utilization,” said Christopher. “However, each day we came to work smelling solvent in the air. Although all cleaning and disposal procedures were closely followed, we have a high level of environmental awareness and it was time to do the right thing—convert to a more environmentally friendly finishing method.” To maintain the highest quality surface technology, the Link 51 Shelving plant installed a custom-designed Nordson powder coating booth equipped with advanced dense-phase spray systems.

The Expectations for the New System Were Set High
The Link 51 team wanted to push the limits of how the new system would perform.

  • Four-meter-tall products with a line speed of up to 3.5 m/min.
  • Highly efficient powder application.
  • Consistent and uniform 25 microns of coating thickness.
  • Full, automatic coverage of the shelving corners.
  • Fast color change for flexible production.
  • Clean, environmentally friendly workplace.

Once the specifications were defined, the team started the supplier selection process. “We knew our requirements were challenging, so we were looking for a supplier with demonstrated abilities to design a system to match our needs and reliably support our production,” says Lyndon Woodfield, senior team leader, manufacturing, who has extensive powder coating experience with Link 51’s old line.

The Link 51 team knew about the positive experience at their two sister-plants, Lockers and Pallet Racking, which were already using dense-phase powder delivery technology. So, the team headed to the suburbs of Dusseldorf, Germany, to experience the new spray systems first-hand at the Nordson demonstration center. “It’s nice to test the equipment with our products and powder,” says Tom. “Since I was to operate the new system, having a chance to work with it without the pressure of running production was important.”

“After a few days of testing we gained confidence in the attainability of our goals. Their solution was easy to work with and was proven to apply highly- controlled coating thickness with no operator intervention. Process control was important for our production efficiency,” recalls Christopher. Because of the close teamwork, demonstrated abilities, and the special booth solution, Link 51 moved forward with their new powder coating system with the target to install in late December 2018 and begin production on January 6th—just 3 weeks later.

“Those were intense weeks,” recalls Lyndon. “In only one week we had to take out the old system, fill the pit, seal the floor, and have the area ready for Nordson’s installation team. A large booth with 20 automatic guns had to be ready for production just two weeks later.”

Startup Four Days Ahead of Schedule
All involved worked like clockwork. From demolition to installation to startup, Link 51 and Nordson teams worked double shifts. On January 2, four days ahead of schedule, the first batch of powder coated shelves came off the line and everyone could breathe a sigh of relief. Lyndon feels the time spent in Germany learning to work with the equipment was time well spent. “We passed the learning curve at high speed, and as a result, on day one we were ready to hit the ground running with full production,” remembers Lyndon.

The new system included a custom engineered, 6.5-meter-tall ColorMax® booth with a Spectrum® HD powder feed center and advanced controls. The booth is designed to provide reliable powder containment while also ensuring soft airflow in the spray area. Special high-level openings with platforms enable operators to clean the booth walls from the top down. This way, no powder is blown in the direction of the conveyor opening against the booth airflow. The automatic floor cleaning system keeps the powder in the booth to an absolute minimum.

The high line density combines with efficient powder application resulting in minimum overspray. Any airborne powder is efficiently recycled through a twin-cyclone system and screened through an ultrasonic sieve prior to being returned to the fully enclosed feed center. The new system also delivers a fast, contamination-free color change. “The step-by-step color change instruction on the main controller and many of the color change tasks being fully automated makes my work much easier,” Tom remarks.

The New System Operation
Since commissioning of the powder coating plant, the Link 51 team took full ownership of the process. With the support from local Nordson personnel, the applied coating and application efficiency were perfected over the first few weeks of operation. Peter says conversion to powder helped in other areas as well. For example, the liquid paint pots had to be stirred 24/7, requiring their air compressors to run non-stop. Now, the compressors run only during the 8-hour production shift. They calculate that change alone saves approximately £2,000-3,000 (USD$2,500-3,700) per month. Additionally, about 2,500 liters of water had to be treated and discharged to waste every six months, which is no longer necessary. They also discovered significant gains evident in finish quality and rework rates. “We worked diligently to minimize rework on our liquid system,” recalls Lyndon, “yet paint runs and solvent boils, so resprays were part of our daily life. All of these issues are eliminated with the conversion to powder.”

Additionally, the liquid system required three to four hours of service and maintenance each week. In the months of production on the new powder coating system they have experienced zero maintenance or service downtime. “Our maintenance team hasn’t been called to the new system  once,” confirms Peter. Lyndon recalls, “We were used to changing venturis inside the pumps every three to four  weeks while tweaking our pump settings weekly to keep the desired coating thickness. None of this on the new system. No adjustment is needed as there are no wear parts inside the dense-phase pumps, which affect the powder output.”

The combination of the high line density, excellent powder application efficiency, and the use of thin-film powders allowed Link 51 Shelving to halve their applied coating cost. “We used to coat about 15 m2 of metal per liter of liquid paint, yielding an applied cost of £0.47 (USD$0.59) / m2. Today, we achieve the same 15 m2 of coverage but with only one kilogram of powder. This brings our applied coating cost to £0.23 (USD$0.29) / m2. That’s a 50 percent cost reduction,” says Peter.

After the first nine months of operation, the benefits of switching to a powder line included:

  • 50 percent reduction in the applied material cost.
  • Operating, disposal, and environmental compliance cost reduction.
  • 70 percent reduction in rework and quality costs.
  • Increased production capacity due to zero downtime for maintenance.
  • High color change flexibility with less than 15-minute color change time on a 6.5-meter-tall booth.
  • Zero consumption of replacement parts.
  • Clean, environmentally friendly operating conditions.
  • Expected 14-month return on investment.

From its inception back in 2015, the overall project took several years to implement. “The good news is that we got the latest equipment and technology. Plus, the new local Nordson team is supporting us every step of the way with their powder application expertise. Everybody worked hard and smart on this project and the results are fully reflective of this,” summarizes Christopher. “We can definitely say that moving from liquid to powder coating was an excellent investment for Link 51. Our high expectations for a quick payback and numerous operating benefits have been fully met or exceeded.”

Corinna Hellwig is marketing communications manager at Nordson.