John Parker, Chief Executive of the Cast Metals Federation (CMF) said “It was great to have the meeting at LBBC Technologies new facility and to see the impressive investment and work being done in future developments.”
Jeff Lantz, Director “This is a real benefit for our company, the new core leaching unit from LBBC Technologies enables us to confidently remove the cores, both simple and complex in a significantly shorter time than our previously sub contracted open bath method.”
Tech Castings are offering their new core leaching capability to other foundries in the USA.
As LBBC have over 100 years of experience of manufacturing pressure vessels, Howard was requested to present on Pressure Vessel Safety particularly on autoclave safety and the importance of good equipment maintenance.
LBBC pressure vessels are fully certified thereby providing a guarantee of exceeding the required quality and safety standards. The pressure vessels are manufactured with U stamp approval and adhere to rigorous inspection procedures throughout manufacture.
Work on the new 15,000 sq ft facility in Stanningley, Leeds, was completed at the end of August, following an eight-month build period managed by Triton Construction. The new premises feature 10,000 sq ft of manufacturing space for assembly, testing and development, plus 5,000 sq ft of modern office space.
The £1.5 million investment has been supported by a £130,000 grant from the LEP’s business growth programme. Funded through the Government’s Regional Growth Fund, the business growth programme is designed to help businesses expand and create jobs. It offers grants of between £10,000 and £500,000 to SMEs to cover up to 20% of the cost of capital investment in new premises, fit outs and equipment.
LBBC Technologies is a division of the £8.5 million turnover LBBC Group. It is a world leader in the supply of autoclave systems and related engineering activities used in a range of high pressure applications and environments.
The company recently supplied equipment worth over £1 million to Rolls-Royce for its new blades casting facility in Rotherham, one of the most advanced investment casting foundries in the world. Other clients include BAE Systems, and over 70 per cent of the firm’s sales go to export markets in the US, Russia, China, Asia and Europe.
Sister division LBBC Beechwood focuses on sub-contract activities of machining, dished heads and fabrication for the domestic market. With specialist capability and approvals to undertake pressure vessel manufacture and fabrication for the USA and China, LBBC Beechwood is well placed to work with UK partners as a key supplier to these markets.
Roger Marsh, Chair of the Leeds City Region Enterprise Partnership said: “The Leeds City Region is a major centre within the UK for advanced engineering and the LEP is delighted to support this investment in new testing and development facilities, which will enable LBBC to continue as a global leader in its field.
“As the largest manufacturing centre in the country, the sector has a key role to play in driving above-trend growth and jobs as part of our strategy to develop the Leeds City Region as a powerhouse for the UK economy.”
The group currently employs a workforce of 70 and managing director Howard Pickard sees scope for further growth across both divisions of the group: “We’re aiming for £10 million turnover and there’s potential to go beyond that. In the process, we expect to increase the number and calibre of the people we employ.”
“The new facility for LBBC Technologies is critical to our strategy going forward, with the need for continuous investment in product development and testing to support highly specialised projects and maintain our position as global leaders in sectors such as investment casting. The new premises are now home to LBBC Technologies, providing space for our sister division LBBC Beechwood to expand into existing facilities on the site.”
LBBC, originating as the Leeds and Bradford Boiler Company Ltd is a long-established family-owned business and has been located at its current site in Stanningley, Leeds, since 1876. Howard Pickard and his brother Robert are the fifth generation of their family to run the business.
Cllr Keith Wakefield, Leader of Leeds City Council and Chair of the LEP’s investment panel said: “Manufacturing remains an important sector for the Leeds economy, employing around 30,000 people and punching well above it weight both in terms of output and productivity. The investment by LBBC and its plans for continued growth are excellent news for the company and its workforce.”
As part of LBBC Technologies’ extensive R & D into the core leaching process, as presented in a paper at ICI 2013 by Howard Pickard, the company have developed a new ceramic core leaching model to extend the range of component and core geometry that can be efficiently leached. This unit now provides a solution for the commercial and medical sectors as well as low volume aerospace components.
The unit maintains the same basic processing system as has been proven on the many larger core leaching systems supplied to aerospace and IGT foundries throughout the world. As with all LBBC Technologies systems, the unit incorporates the highest levels of safety design. The new unit has demonstrated how ceramic cores, traditionally removed by other techniques in days, can be removed in hours in a safe and controlled environment.
LBBC who were founded in 1876 have invested in a new manufacturing and R & D facility at their Leeds site moving into the new facility at the end of July.
Our address and telephone number will remain the same.
Many thanks for your support and patience and we look forward to welcoming you to our brand new facilities.
by Howard Pickard, LBBC Technologies
EDITOR’S NOTE: This article is based on a longer paper presented at the investment Casting institute’s 60th Anniversary Conference and Expo in Pittsburgh, PA.
Ceramic cores have been used in castings for many years to assist in achieving ever more complex internal geometry. In the investment casting industry, ceramic cores have played an important part in the development of improved performance of blades and vanes in gas turbines.
In order to form the passageways within the components, cores with the same intended geometry as the cooling channels are positioned in an investment casting shell. Once the component is cast and the majority of the shell removed, a process known as caustic leaching is widely used for dissolution of the encapsulated core, thus leaving behind the empty cooling channels. Although widely used for many years, the fundamentals of the process physics and chemistry are little understood.
Following some initial experimental work performed in LBBC Technologies’ facility in 2010, Rolls-Royce PLC and LBBC Technologies agreed to cosponsor a Post Graduate Doctoral Studentship through the University of Birmingham’s four year engineering doctorate program with the project aim to investigate the physics and chemistry of the present investment casting core removal process in order to enhance its industrial application.
To recap on the process operation, components are loaded within a basket and the basket is placed in the autoclave. The autoclave is filled with a caustic base solution with approximate concentrations of typically 20% sodium hydroxide (NaOH) or 40% potassium hydroxide (KOH). This breaks down the bonds in the ceramic core which is typically made up of silica (70-100%) and zircon etc (0-30%). The solution is heated to around 320°F (160°C) under a pressure of around 90 psi (6-7 bar) to suppress boiling at this temperature. Through venting, dwelling and repressurizing of the autoclave at regular intervals the solution boils and creates a ‘flow’ of solution within the autoclave. This flow enables the alkaline solution to be replenished at the interface with the core as well as physically removing the core material that has softened or ‘broken away’.
Key Components of the Process
To understand what is happening during the leaching process, consider the three main areas of the process:
1. Caustic solution– Caustics are strong alkaline chemicals that destroy soft body tissues resulting in a deep penetrating type of burn, in contrast to corrosives, that result in a more superficial type of damage via chemical means or inflammation. Caustics are usually hydroxides of light metals. The
alkali metal hydroxides are the most basic of all hydroxides; sodium hydroxide (NaOH or caustic soda) and potassium hydroxide (KOH or caustic potash) being the most widely used caustic agents in industry.
2. Ceramic Core– The most commonly used core material in turbine blade manufacture is fused silica due to its chemical removability, well documented high temperature properties, abundance, and economic cost. The material development and complexity of future superalloys formed via directional
solidification or single crystal techniques is limited by the capability of conventional silica-based core and shell materials to withstand longer casting times at high temperatures (~1700 °C). Preformed cores fashioned from alumina, Al2O3, are suitable for investment casting application as they exhibit good dimensional tolerance, high strength and high refractory properties. The leaching of alumina is however often economically not feasible for production and manufacturing operations due to longer
dissolution rates relative to silica.
3. Boiling at Diffusion Layer– When a liquid is heated in an open vessel, the liquid vaporizes from its surface. The condition of free vaporization throughout the liquid is called boiling. The temperature at which the vapor pressure of a liquid is equal to the external pressure is called the boiling point at that pressure. Boiling does not occur when a liquid is heated in a rigid, closed vessel. Instead, the vapor pressure, and hence the density of the vapor, rises as the temperature rises. Factors which control the rate of a reaction are:
- Concentration of reactants in solution.
- Surface area of any solid reactants.
Initial experimental work was focused on determining the most effective chemical reagent and its optimum concentration to facilitate the dissolution of cristobalite and zircon. Observations have been;
- The higher leaching capability of NaOH compared to KOH.means or inflammation. Caustics are usually hydroxides of light metals. The alkali metal hydroxides are the most basic of all hydroxides; sodium hydroxide (NaOH or caustic soda) and potassium
- The plateau/dip in reactivity after concentrations 20 % w/v of NaOH. hydroxide (KOH or caustic potash) being the most widely used caustic agents in industry
Initial trials to investigate the optimum cycle parameters have been performed using an LBBC test unit. Studies were conducted using the core test piece shown below with 33 % potassium hydroxide (KOH) solution. The extent of core dissolution was determined by measuring the change in core depth on a number of different components with six identical cores, each with a diameter of two mm to give an average over 18 samples.
Experimental work has been undertaken to study the effect that different high and low pressure dwell times have on core removal. Observations have been;
- Varying the low and high pressure dwell time has little impact on leach effect.
- Varying the vent time has the greatest impact on leach effect .
- Lower temperatures reduce core leach but not as significantly as expected.
- Reducing suppression pressures only begins to effect leaching below 55psi when using this concentration of KOH.
The caustic leaching of ceramic cores involves a wide range of physics and chemistry concepts. Key aspects to the process have been illustrated here. Identifying and analyzing specific areas of caustic bases, core materials such as silica and zircon, boiling action, etc., is expected to result in a better understanding the process of caustic core leaching. Initial experimental work has begun to show the aspects of the process that need to be further investigated.
For more information, contact the author at firstname.lastname@example.org
From Incast Magazine, June 2014