Upgrading glass tempering machines for improved performance, quality and uptime
Glass Technologies Control Systems Ltd of Derby, UK, specialises in the renovation and upgrading of glass tempering machines. Glass tempering processes have evolved to meet the new requirements for sophisticated tempered glass products for architectural use. This requires and justifies a radical upgrade to the heating and cooling technology in the machines and in the way that the glass is presented during the process. Glass Technologies Control Systems (GTCS) is a long term user of ABB control and drive products for this work, the specification being based upon availability, advanced functionality and, above all, reliability.
Glass tempering was for many years undertaken using radiant heat sources, however, new multi-layered and more demanding architectural uses requires a higher level of control in both heating and cooling stages. The inherent non-uniformity of the radiant heating process cannot meet the demanding technical specifications and expectations of modern glass application uses. This has resulted in the adoption of convection heating to enhance the radiant heating. To meet specifications the glass sheet must be uniformly tempered to high tolerance, producing high quality tempered product consistently, and at the same time production costs have to be controlled in this energy intensive process; new heating and cooling technology combined with improved control achieves these two objectives.
GTCS finds itself fulfilling a vital role for the user as in many cases the original equipment supplier has no viable commercial offer to make to upgrade legacy machines, which are still thought to have long inherent life, thus after a GTCS upgrade the user finds an economical path to increased competitiveness. GTCS retains what is functional and also takes special care to utilise any existing robust software and even sometimes control hardware by, where appropriate, interposing an ABB controller into the existing scheme and retaining machine wiring where this is on good condition.
Technology and Vendor selection
GTCS selected ABB AC800 process controller, Panel 800, ABB Inverter Drives, ABB motors and ABB switchgear products for these applications; one-stop sourcing and guaranteed interoperability being important to this decision said GTCS co-director Paul Young. Additionally the world wide availability of ABB products and local support allows GTCS to trade confidently throughout many parts of the globe, from USA to Africa and UK to the Far East. Local ABB UK customer service allows enhanced logistics support whenever and wherever this is needed.
The new scheme
The upgraded tempering machines feature four main sections, the in-feed and out-feed areas and the heating and cooling systems. The in-feed and out-feed comprises a fully motion controlled conveyor which passes the stock glass sheet to the heating and cooling section, the motion for this is controlled accurately from motion recipes within the AC800M control system and executed through the ABB Inverter drives via ABB’s high speed, high bandwidth, fibre optic motion bus, which allows a seamless integration of the AC800M control with the Inverter Drives. Throughout the heating and cooling cycles (again under control of the ABB AC800M) the glass sheet is in constant motion, when the glass is in position it follows an oscillating path to ensure uniform and high quality tempering.
All sequences and machine visualisation are provided to the operator through a 15” ABB Panel 800 HMI. The control algorithms require complex loop control which is readily facilitated through ABB’s Compact Control Builder software in the AC800M. In some cases a third party SCADA system is also used, integration is easily made through the AC800M’s universal connectivity; this also has the provision of a real time data repository which captures production data for quality assurance and providence requirements.
In many case the upgrade is most readily seen in the in-feed, out-feed and oscillatory motion during the heating process with the unique GTCS heating control programme. The existing arrangements for blower control for cooling are converted to inverter drive control as opposed to throttling the airflow, the existing fan motors typically being retained.
The user receives benefits of higher and consistent quality, and higher throughput. Augmented with ABB’s legendary product reliability which ensures high uptime, these benefits address all three parameters of OEE to vastly improve OEE, which invariably leads to improved schedule adherence and resulting customer satisfaction. The use of highly energy efficient Inverter drives of course reduces the energy bill, which, depending upon the machine size can be between £15,000 and £50,000 per year depending on shift patterns, glass types and volumes.
Quoting his experience with ABB, Steve Kimmitt, MD GTCS, said, ‘working with ABB is easy, they understand my company’s needs and have established and tested processes that greatly eases procurement and support’, adding, ‘the equipment is highly reliable and allows us to take a modular approach which provides our customers with high functionality in the upgraded machines and at the same time simplifies any support role.’ GTCS provides a planned maintenance service which usually requires a preventative maintenance task to be scheduled twice per year.
A recent project in Ireland
Raymond Douglass, MD, Ideal Glass and Stone, Co. Monaghan, Ireland said, “With the improvements made to our plant control by GTCS we reduced costs and increased throughput. This machine is on the critical path in our operation and is essential to our order fulfilment. As reliability and local support is key, the ABB-based system gives us the peace of mind that machine availability is at its highest level, a factor which is critical to our business, this, combined with the energy saving that the new heating system, reduces costs and improves margin across the business. We operate in a highly competitive environment and improvements to our operational effectiveness such as the ABB-based system delivers make a great deal of difference to our viability and profitability.”
Steve and Paul are especially impressed with the robust nature of the ABB products that GTCS uses, the environment in glass tempering is demanding yet the equipment, and the entire upgraded machines, have proven to be consistently reliable – measured as vastly improved uptime, and improved OEE. Steve added that he continues to deliver his solution with ABB systems onboard because of the “Fit and Forget” reliability of the control system and has a six year history of zero failures and good service in applying these systems throughout the world, which bodes well as GTCS is currently undertaking its 27th glass tempering machine upgrade.