Dr. Mark Cross
Commercial Sales Director, Ultraseal International Group Ltd
Case Study Recycling Technology Improves Productivity
Honeywell consulted Ultraseal International, a global specialist in porosity sealing, to assess its existing system and make recommendations for improvements. The results were very positive with increased productivity and cost savings.
As a manufacturer of combustion control valves, Honeywell - Environmental and Combustion Controls NA (North America) has been championing a vertical integration approach to its manufacturing process for many years. Producing millions of valves per year, Honeywell carries out all machining and secondary operations in-house, operating eight die casting machines (ranging between 500 – 945 US tonnes) which supply 100 % of the company’s die casting requirements.
Mr Morray Ysaguirre, the division’s Principal Manufacturing Engineer, has worked for the company for over 40 years and is responsible for six machining work centres and an impregnation system. For more than 18 years, the facility in Dublin, CA has been sealing porous castings using an automated impregnation machine that processes more than 2,000 castings per day.
As a global brand operating across a wide range of industries, Honeywell has a corporate focus on improving productivity and efficiency and a commitment to reducing costs and the inefficient use of resources. The plant's casting impregnation process, unchanged for many years, had ongoing issues with post impregnation product quality, which reduced productivity, and with the environmental costs associated with the process. To find a solution to these issues that met Honeywell’s improvement goals, Mr Ysaguirre called on Ultraseal’s experienced engineers to conduct a site survey to understand their component impregnation needs, current systems and processes.
Analysing the manufacturing system data, the Ultraseal America team found the impregnation system was consuming about 200 gallons of sealant per month and 1000 gallons of water per day on the wash tank alone. Due to restrictions on discharging, the contaminated process water was treated on site, then filtered. An evaporation system was also required, adding an additional effluent treatment cost of $0.21 USD per gallon of process water.
In addition to the high volumes of water and sealant usage, Honeywell was experiencing issues with parts becoming sticky following impregnation. This meant they were having to use even more fresh water in the tanks for cleaning, which increased process downtime and reduced productivity. At this point in time, the system was only capable of processing five carriers per shift.
Following a full system review and assessment, Ultraseal America recommended converting the conventional impregnation system to Ultraseal recycling technology and using Ultraseal Rexeal 100 recycling sealant.
The Ultraseal recycling system is fully closed loop on the cold wash operation and requires no changes in the application of the impregnation process. The Sealant Recovery System (SRS) provides cost effective processing while avoiding the significant challenge of process chemical effluent treatment costs, as well as eliminating solids disposal and greatly reducing the associated evaporation costs.
The conversion to Ultraseal recycling technology was achieved by adding the SRS module and modifying two of the wash and cure tanks to meet more modern specifications and improve component washing, eliminating the previous post impregnation problems with “sticky” components. This meant Honeywell could also eliminate one of its three wash tanks which reduced the time required for processing.
Ultraseal engineers were able to reuse most of the existing equipment in the system conversion and also updated the programs in the PLC and CNC controllers. The PLC updates led to much faster processing cycle times, made possible by the faster gel time and improved process stability of Ultraseal Rexeal 100 recycling sealant. The conversion work was completed within a two week window.
Since implementing the system, Honeywell has benefitted from significant cost savings, productivity improvements and environmental benefits. These include:
- Reduced water consumption: Most significantly, the business has seen a 98 % reduction in water usage generating a cost saving valued at $172,000 USD per year
- Reduced sealant consumption: In total, monthly sealant consumption has reduced by 93 %
- Reduced cycle times and processing costs: The cycle time reduced from 110 minutes to 40 minutes per carrier and the number of carriers processed per shift has increased from five to nine. This has reduced the impregnation cost per part by 37 %
- Reduced wastewater treatment costs: By eliminating the need to treat waste offline, the cost for flocculation chemicals, filter paper, trucking etc. were eliminated completely, saving an additional $70,000 USD annually.
- Sub-contract cost savings: Because the system no longer has sealant building up on process equipment, a further savings of $16,000 USD per year was realised by eliminating the need for an outside contractor to clean the process tanks twice a year.
Overall, conversion to Ultraseal recycling technology has delivered Honeywell consolidated cost savings of $19,000 USD per month while also significantly improving productivity and environmental performance. This approach to die casting impregnation highlights the importance of optimizing the choice of component impregnation strategy.
Good to Know: How Does the Impregnation System Work?
There are three key stages to the impregnation process. First, sealant is applied to the casting under vacuum in an autoclave. Once components are immersed in sealant the vacuum is released, allowing the sealant to penetrate into the micro-porosities and leak paths within the casting through the resultant change in pressure, which draws the sealant into any micro-porosities and leak paths. Application of sealant to the casting can take as little as 30 seconds to two minutes for components such as engine blocks or up to 30 minutes for compressor parts.
Second, a cold wash module removes excess sealant from external component surfaces and tapped holes.
The third process stage is a hot cure cycle. This exposes components to heat for a predetermined time period using a hot water bath which polymerizes the sealant, changing it from a liquid state to solid polymer by applying heat.
Both the cold wash and hot cure stages produce an effluent stream. During the cold wash stage with conventional, non-recycling sealants, up to 90 % of the sealant consumed is lost to effluent, which is a chemical pollutant that needs to be disposed in accordance with local environmental legislation. After a relatively small number of cycles the wash water must also be replaced to prevent unwanted sealant contamination of components. The emulsified wash water cannot be discharged into the public sewer system and requires disposal by specialised waste management companies. The result is wastefully high and expensive process water and sealant consumption and associated environmental treatment and disposal costs.