Robotic vacuum impregnation reduces scrappage due to porosity

Small footprint of workstation integrates into existing workflow

By Bob Remler April 9, 2021

It is no surprise to learn that the automotive industry in the United States is the single largest user of metal die casting. In today’s vehicles, a high proportion of components — including cylinder heads, engine blocks, transmission cases, e-motor housings, and structural parts — are produced using high-pressure die-casting processes.

The automotive industry wants to reduce environmental emissions, increase fuel economy, and deliver better performance. Automotive suppliers constantly seek ways to reduce vehicle weight or accomplish other efficiencies. Ways can include combining thinner walled castings with lighter-weight metals such as aluminum and magnesium.

Hand in hand with continuing research and new casting processes and techniques, is growing process automation. Industry 4.0 points the way toward smarter factories that include — over and above automation of repetitive processes — incorporation of cobotics (involving collaboration between a person and a robot), digital supply networks and artificial intelligence.

While some industry pain points may disappear as manufacturing technology and processes evolve, one legacy challenge remains — that of porosity. Porosity is one of the defects most frequently encountered in aluminum die casting. These microscopic voids reduce component density, leading to leaks. For parts that go into applications that need to be air- or fluid-tight, such as fuel or cooling systems, this can be a critical issue.

Untreated, casting porosity formation wastes materials, energy and production time, and results in costly scrappage.

Challenges faced

A leading U.S.-based maker of engines, off-road vehicles and motorbikes found its production of die cast engine components was plagued by high scrappage rates due to porosity and leaks.

With supply chains under increasing pressure, treating porosity has become an important part of the manufacturing process. Previously, the company addressed the issue by shipping parts to another state for vacuum impregnation processing. That process used a specially formulated resin to fill porosity in automotive castings.

However, this arrangement was far from ideal. Besides shipping costs, 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 needs. Yet, despite the time and effort, the scrap rate was still around 11%.

Automated, on-site solution

To mitigate the issues and find a more efficient and cost-effective solution, the company turned to Ultraseal International. A leader in sealing porosity and leak paths in die cast, sintered and electrical components, Ultraseal proposed an automated process using robotic component handling that offered improved productivity, greater cost-effectiveness, more reliable sealing rates and improved environmental performance.

Ultraseal engineers worked with the company to design and install a fully automated, robotic vacuum impregnation system. The bespoke solution offers fast cycle times combined with best-in-class performance, reducing the 11% scrappage to nil during the initial trial, and the one-week turnaround to a speedy 12 minutes.

The small footprint of the workstation enables it to be integrated into the existing manufacturing line without compromising on workflow or floor space. The system is designed to process parts from two different production lines. It can be pre-programmed to treat components from either line, or alternate between both, offering complete flexibility.

Automation use results in improved output quality. Besides offering 100% sealing effectiveness, the solution also addresses issues with component damage resulting from handling and processing, by using a consistent gloss black finish. It eliminated corrosion issues by employing a multifunctional corrosion inhibitor.

The Ultraseal system is integrated with software that offers process control visibility and data logging. Besides ensuring batch traceability and process control, the system can be used for remote diagnostics, optimized system performance, and minimized unplanned downtime.

Reducing costs with robotics

While Industry 4.0 adoption is still an evolutionary process, elements of the smart factory are increasingly used in production lines, as smart technology and IoT connected devices replace or improve traditional manufacturing processes.

Once only achievable for larger enterprises with large budgets, robotic automation is now more affordable and available to organizations of every size. It reduces floor space and allows production processes to run for longer periods. Automated systems offer increased repeatability. In the case of Ultra seal’s robotic vacuum impregnation system, equipment, chemicals, and processes are more economical and environmentally sustainable than the traditional alternatives.

Typically, casting impregnation is carried out in three stages: first, parts are placed in an autoclave and a vacuum applied to draw air out of any voids before a liquid sealant is introduced. Second, parts are washed in a cold wash cycle to remove excess sealant from component surfaces and critical areas such as threaded holes. Finally, parts undergo a hot cure cycle where heat polymerizes the sealant within the porosity, turning it from a liquid state into a solid polymer.

Like other manufacturing processes, vacuum impregnation produces waste. In a standard impregnation process, around 95% of the sealant is washed off the components during the cold wash cycle. These chemicals are not recoverable. They must be handled as effluent that needs to be treated or trucked away for disposal off site, adding replacement chemical costs to the process and considerable environmental management processes for the user.

The Ultraseal Sealant Recycling System allows the sealant washed off the parts to be reclaimed from the cold wash solution, allowing both the sealant and the cold wash solution to be reused. This makes the cold wash cycle operate in a closed loop, negating the need to continually top up with copious volumes of fresh water with the same volume going to drain.

This automated process offers best-in-class sustainability, lowering sealant consumption, reducing water consumption, and minimizing effluent discharge. Taking the system in-house further lowers the manufacturer’s carbon footprint by eliminating the need to ship components to distant suppliers.

Things of the past

As automotive manufacturers turn to lighter and thinner castings, porosity sealing technology will become an increasingly vital step in manufacturing. Incorporating vacuum impregnation into production lines can help the automotive industry reduce scrap and material wastage, increase component life cycles, and improve environmental performance.

Ultraseal provides a range of best-in-class equipment and sealant solutions, including recycling and automated systems that can deliver efficiency and boost environmental credentials. Customers can opt to work with Ultraseal in whichever way best suits their operational requirements, using on-site managed services, external service centers or completely automated owned installations.

By owning the vacuum impregnation process, manufacturers have peace of mind that they have given their best in terms of quality, sustainability, and environmental responsibility — at a fraction of the prohibitive costs involved in scrapping components.

For more about Ultraseal International’s complete range of vacuum impregnation products and services, please visit

Author Bio: Bob Remler is technical sales manager, North America, Ultraseal International.