The ability to control costs and quality is critical when manufacturing high volumes of engine components, according to Ultraseal International. One automotive manufacturer used robotic vacuum impregnation to seal porosity, minimize scrappage, and increase throughput, while also significantly reducing costs, explained Bob Remler, technical sales manager in North America for the Coventry, U.K.-based company.
Trends and challenges
Demand for die casting is on the rise, with the market projected to grow to $94.1 billion (U.S.) by 2025. In the U.S., the automotive industry is a major user of die casting, with a high proportion of components—including cylinder heads, engine blocks, transmission cases, electric-motor housings, and structural parts—produced using high-pressure, die-casting processes.
With an increasing focus on creating greener methods of transport and meeting zero-emissions targets in cities across the globe, automotive manufacturers are looking to lighten vehicle parts and structures. By reducing the overall vehicle weight, manufacturers can increase fuel economy, deliver better performance, and reduce vehicle emissions. To achieve this, many automakers are use die casting to manufacture parts from lightweight materials such as aluminum and magnesium.
As well as being stronger and lighter, casting larger single-piece components means that there are fewer welded joints or fasteners, all of which normally add to the overall weight, noted Remler.
The drive for new and more efficient production methods has brought with it significant investment in research, development, and new technologies. As Industry 4.0 shapes the competitive landscape of manufacturing across the globe, industry is embracing digital transformation to drive efficiencies and improve production outcomes.
Despite the ongoing debate over automation versus humans, the need for skilled labor and the urgency of industry flexibility mean that the digitization of the automotive industry is well under way. This includes everything from harnessing production data to improve processes and digitizing supply networks to applying artificial intelligence and using robots in repetitive processes.
While technology and production methods are evolving to create operational efficiencies and meet market needs, one legacy challenge remains—that of porosity. Porosity is one of the defects most frequently encountered in aluminum die casting. Microscopic voids in the metal can lead to leak paths and reduce the density of the cast components.
Untreated, casting porosity leads to costly scrappage, creating waste inefficiencies in materials, energy, and production time. For parts that go into applications that need to be fluid- or airtight—such as in fuel or cooling systems—this can be an especially critical issue, explained Ultraseal.
The role of vacuum impregnation
For a leading U.S. manufacturer of engines, off-road vehicles, and motorbikes, creating best-in-class vehicles and achieving operational excellence is key to its continued success, said Remler. Despite an extremely strong focus on quality control, the company was experiencing high scrappage rates due to porosity in its die-cast engine components.
To combat the problem, the company was shipping parts to another state for vacuum impregnation processing. This specialist process is designed to permanently seal porosity by using a specially formulated resin to fill porosity in automotive castings. While this arrangement provided a solution, the process was time-consuming, often adding a week to production times.
To overcome lags in production, the company resorted to keeping a week’s worth of inventory on-site, taking up valuable production space and increasing working capital. Yet, despite the time, effort and financial investment in the process, the scrappage rate was still around 11%.
On-site automated vacuum impregnation system
The company turned to Ultraseal International, a leader in sealing porosity and leak paths in die-cast, sintered, and electrical components. Ultraseal said its engineers worked with the manufacturer to design and install a fully automated, robotic, vacuum impregnation system. The custom system offered fast cycle times, improved productivity, cost-effectiveness, more reliable sealing rates, and improved environmental performance, said the company. Crucially, during an initial system trial, the 11% scrappage rate was reduced to nil, and the one-week turnaround to a speedy 12 minutes.
By switching to automation, the manufacturer achieved 100% sealing effectiveness and improved output quality, said Ultraseal. Where the handling and processing process previously resulted in component damage, the parts now benefit from an impressive and consistent gloss black finish.
The addition of a multifunctional corrosion inhibitor means that the products remain resistant to rust, retaining their glossy appearance long beyond the point of manufacture.
In an industry where batch traceability and process control are vital, Ultraseal said its system software offers total process-control visibility and data logging. For added flexibility, the system can be pre-programmed to process components from two different production lines or alternate between both, while remote diagnostics help to optimize plant performance and minimize unplanned downtime.
With both shipping costs and time a huge issue with the previous outsourced setup, the small footprint of the system meant that it could be integrated into the customer’s existing manufacturing line without compromising on workflow or floor space.
Reducing costs and improving sustainability
While many industries are yet to fully embrace the potential benefits of Industry 4.0, elements of the smart factory are increasingly commonplace, said Ultraseal. For the automotive industry, where levels of digital adoption are high, smart technology and IoT-connected devices offer proven benefits over more traditional manufacturing processes, it added.
Despite the perception of Industry 4.0 as a revolutionary process requiring a huge level of capital investment, automation is increasingly affordable and available to organizations of every size. In fact, robotic systems often offer a fast return on investment, reducing floor space and allowing production processes to run for longer periods.
Ultraseal said that in the case of its robotic vacuum impregnation system, the equipment, chemicals and processes are more economical and environmentally sustainable than traditional alternatives, while also offering improved quality and increased repeatability.
Casting impregnation is usually carried out in three stages. Initially, parts are placed in an autoclave and a vacuum is used to draw air out of any voids before a liquid sealant is introduced.
The parts are then washed in a cold wash cycle to remove excess sealant from component surfaces as well as critical areas such as threaded holes.
The final step is the hot cure cycle, where heat is used to polymerize the sealant within the void, turning it from a liquid state into a solid polymer.
Like all other manufacturing processes, vacuum impregnation produces waste. In the standard impregnation process described above, around 95% of the sealant is washed off the components during the cold wash cycle. These non-recoverable chemicals must be handled as effluent. This adds considerable environmental management processes, as well as significant costs for both the processing and wastage of large volumes of chemicals.
The cold wash process in the Ultraseal Sealant Recycling System operates in a closed loop, claimed the company. As well as enabling the sealant to be reclaimed from the cold wash solution, the process allows both the sealant and the cold wash solution to be reused, with no need to continually replace the water.
With lower sealant and water consumption, less effluent discharge and no need to ship parts to distant suppliers, the customer has significantly reduced its environmental impact when compared to its previous vacuum impregnation process.
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Making porosity problems a thing of the past
As automotive manufacturers continue to embrace thinner-walled castings and lighter materials, porosity sealing technology will become an increasingly vital process, said Ultraseal. Incorporating vacuum impregnation into production lines can help the automotive industry to reduce scrap and material wastage while increasing component life cycles and improving environmental performance.
By “owning” the vacuum impregnation process, manufacturers can have peace of mind that they have given their best in terms of quality, efficiency, and environmental sustainability—at a fraction of the cost of scrapping components.
However, for those not equipped to install a completely owned and automated solution to their site, Ultraseal said it offers on-site managed services and external service centers, enabling customers to find the systems that best fit their operational requirements. The company offers more information about its equipment and sealant solutions, including recycling and automated systems at its Web site.
About Ultraseal International
Ultraseal International is a Quaker Houghton company. From the development and manufacture of best-in-class sealants and impregnation systems, through to a global network of service centers and the provision of fully managed on-site facilities, the company said it is focused on meeting its customers’ porosity sealing challenges.
Conshohocken, Pa.-based Quaker Houghton Corp. said it is a global leader in industrial process fluids. With operations in more than 25 countries, the company's customers include thousands specialized steel, aluminum, automotive, aerospace, offshore, can, mining, and metalworking companies. Quaker Houghton has 4,000 employees, including chemists, engineers and industry experts. It said partners with customers, using best-in-class technology, deep process knowledge, and customized services to improve their operations.
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