Heat Treatment

Materials World magazine
1 Jun 2017

Richard Bilson, Director of Engineering at Carbolite Gero, UK, talks to Ellis Davies about the GPC 13/300B retort furnace.

What is Carbolite Gero?

Carbolite Gero is a manufacturer of high-temperature furnaces and ovens from 30°C to 3,000°C with a focus on vacuum and special atmosphere technology. Established in 1938, our products are used in research laboratories, pilot plants and manufacturing sites worldwide. 

Could you explain the function of the GPC 13/300B retort furnace?

The furnace, as with all our general-purpose chamber furnaces, is suitable for a variety of laboratory, pilot scale and industrial applications that require heat treatments up to 1,100oC. The product is designed with a modified inert atmosphere for annealing and sintering for additive manufacturing applications, particularly direct metal laser sintering (DMLS). The retort-equipped furnaces can also be optionally fitted for compliance to AMS 2750E Class 2 Type B Instrumentation.

What does this furnace offer to the user?

The range of retort furnaces for additive manufacturing can hold one-to-four bed-plates and reduce O2 levels to below 30ppm, as well as providing easy loading and unloading via a swing door, continual monitoring of inert gas flow volumes and forced cooling for faster cycle times. With unrivalled temperature uniformity, a DMLS ‘impossible part’ can be annealed to ensure the final product acquires the correct metallurgical composition.

Furnaces come in a variety of litre chamber volumes, ranging from 131–350 litres, allowing the user to choose the product best suited to their needs. Other features include a programmable controller, free radiating coiled wire elements on two sides and roof and low thermal mass insulation for high-energy efficiency.

How does the furnace work?

The GPC furnace design uses an optimised heating element principle to ensure uniform heat distribution. It combines with a robust retort design to ensure gas tightness at high temperatures, and also offers the security of O2 monitoring.

Do you think the heat treatment industry will be working a lot with additive manufacturing in the near future? 

‘Impossible parts’ and rapid prototyping are a blossoming global market and those who use the DMLS technique, where a laser binds metallic powders together using data from a 3D CAD model, must heat-treat their parts to remove stresses and ensure the final product acquires the correct metallurgical composition. As production volumes rise, particularly in the aerospace sector, we envisage many more collaborative projects, but all advanced manufacturing sectors are looking to speed up prototyping, and ‘powder-to-part’ offers this speed advantage. 

What benefits can be gained from monitoring oxygen content? 

With O2 levels below 30ppm the material will not oxidise, therefore ensuring a high-quality surface finish.

Could you give me some examples of the furnace’s applications? 

Small batch sizes, rapid prototyping, forward base/small scale production that requires temperature uniformity, a modified inert atmosphere and, potentially, forced cooling.

Heat treatment complete

General Atomics (GA), USA, recently completed the heat treatment of the first module of the ITER Central Solenoid, a milestone in its fabrication. Once completed, the Central Solenoid will stand at around five storeys tall and be the worlds most powerful pulsed superconducting magnet. The Central Solenoid will be part of ITER’s new fusion facility.

GA engineers placed the module in a large 1.5MW furnace to carry out the treatment. The furnace functions in a similar way to a convection oven, shortening the overall process but maintaining uniform heating. The temperature of the furnace could only change at a rate of 5–6oF per hour because the process for creating the superconductive materials is highly exacting. This meant that the treatment was time consuming, requiring one week for each module winding. 

The module as a whole spent a total ten and a half days at 571oC, and an additional four days at 649oC. The modules were tested at the National High Magnetic Field Laboratory, USA, where the heat treatment was deemed successful.

SECO/WARWICK patents new heat treatment solution

Engineers at SECO/WARWICK have designed a way of exercising continuous control over heating and cooling during a heat treatment cycle in multi-chamber furnaces. This solution addressed the inclusion of thermocouples during the cycle, which move between chambers attached to the tray. 

A special construction allows operators to monitor temperature in both chambers, providing full temperature control of the processed parts throughout the treatment. This has been used in a two-chamber vacuum for case hardening in aerospace, automotive machinery, wind energy, transmission and commercial heat-treat facilities. 

The company says that this patent is a unique solution with the potential to revolutionise the heat treatment process, and will be able to exceed the high standards of the aerospace sector.

Wallwork Group gets Rolls-Royce approval

The Manchester site of Wallwork Group, UK, has recently gained approval from Rolls-Royce for its vacuum brazing development laboratory, which features a high concentration of modern vacuum heat treatment furnaces. 

The aerospace thermal processing specialist has invested significantly in the site over the past few years, gaining other approvals for mainstream heat treatment processes from a range of other aerospace companies. The vacuum-brazing laboratory is the latest addition to the site, and is used for joining metal components in small assemblies and more complex fabrications. 

Optomec expands to full solution

Additive manufacturing (AM) systems supplier Optomec has announced a strategic alliance with Taiyo Nippon Sanso Corporation (TNSC) to resell its LENS 3D printers as a total AM solution, which would include metal heat treatment techniques. 

TNSC holds expertise in metal heat treatment that can be drawn on to help lower costs, streamline production and eliminate defects for AM customers. Optomec hopes that the shift to a full solution will expand the sale of the LENS products through TNSC’s network in Japan, the USA and Asia.

Kobe Steel invests to meet demand

Global materials and product qualification testing company Element Materials Technology has gained Nadcap accreditation at its Houston lab for radiography, ultrasonic inspection, liquid penetration and magnetic particle inspection.

The accreditation is the second achieved by the site for materials testing, and is accredited under audit criteria AC7101, spanning hydrogen analysis, micro- and near-surface examinations, impact and temperature tensile testing and standard specimen machining.

The company says that the achievement will allow them to further serve aerospace clients by offering a complete range of testing and inspection services approved at the highest level.

T7 Global Bhd and KOV join forces

T7 Global Bhd, Malaysia, and KOV Ltd, owned by Kilgour Metal Treatments Ltd, UK, have signed a joint venture to pursue high-value metal treatment manufacturing, offering a range of services, including heat treatment. 

The pair say the collaboration will mainly focus on the aerospace sector, but also provide services for oil and gas, automotive and biomedical industries. Metal treatment plants will be built and operated by the partnership in Malaysia. 

Ipsen reaches new countries

Heat treatment systems manufacturer Ipsen, USA, has expanded its reach by providing eight vacuum heat-treating systems to customers in Costa Rica, India and Germany. Ipsen says that the equipment will be used to support a range of industries, including additive manufacturing, aerospace, medical, MIM and tooling. The company has also provided training, spare parts kits and installation. 

Furnaces shipped included a vertical MetalMaster furnace with a 2,268kg capacity, a custom-built furnace for debinding and sintering, horizontal MetalMaster and TurboTreater furnaces, a TITAN DS (debinding and sintering) furnace and several H2- and H6-sized TITAN vacuum furnaces equipped with the PdMetrics software platform for predictive maintenance.