Wallwork Heat Treatment CEO discusses composites

Materials World magazine
1 Jun 2016

Khai Trung Le talks to Peter Carpenter, CEO of Wallwork Group, on how the growth of composites impacts the UK heat treatment sector.

Tell us about your background prior to joining Wallwork.

I completed a condensed sandwich HND Metallurgy course at Sheffield City Polytechnic – now Sheffield Hallam University, UK – with the industrial part spent as a Special Apprentice at Mather and Platt Ltd in Newton Heath, Manchester. The apprenticeship there was very structured and I gained good experience in various departments.

From there, I moved to the Metallurgy department of the Scientific Services Division of the Central Electricity Generation Board (CEGB), where I had the opportunity to gain further experience in failure analysis as well as investigating the properties of the then-new titanium/nickel shape-memory alloy the CEGB used to plug boiler tubes. 

It was from here that I answered an advert in 1982 for a ‘young enthusiastic metallurgist’ to work at Wallwork Heat Treatment in Bury – at the time a single-site company employing just 30 people.

Wallwork has worked extensively with Rolls-Royce, Airbus and Bombardier. How does their move towards using composites impact the heat treatment work conducted by Wallwork?

Obviously, composites will replace metal parts in some cases. Currently, this is happening extensively in the bodies and wings of aircraft where the fatigue resistance and strength-to-weight ratio of carbon fibre is superior to aluminium. In most cases, these parts are not heat-treated, or are so large that they need to be treated by the manufacturer.

As a contract heat treatment and coating company, most of the aerospace parts we see for processing are engineering components that require high strength and uniformity, such as engine components, undercarriage parts, hydraulics and actuators. Many of these parts also require wear and strength resistance, so are unlikely to be replaced by composites in the near future.

What challenges do you expect the UK heat treatment industry to face in the coming years?

Heat treatment is becoming increasingly specialised, particularly in the aerospace and motorsport sectors. The equipment required to carry out these processes is of high value, and we are frequently seeing that older equipment cannot be upgraded to meet the more stringent specifications required to produce a uniform product. Only the largest of manufacturers will be
able to justify investment in such specialised equipment. The sub-contract sector will need to invest heavily to provide these services to British manufactures.

The more enlightened manufacturers value their supply chain and make an effort to communicate well with them so that they can plan capacity for the future. But, unfortunately, there are still many companies who let very little information flow down, making it difficult for heat treaters and other sub-contractors to make long-term investment decisions. In a static market, this is not too much of a problem. But as the market hopefully starts to grow, it may well cause restrictions in the supply chain as new equipment is often on long lead times.

Have there been any recent technological developments within heat treatment that have caught your eye?

The big development starting to make an impact in many aspects of engineering is additive manufacturing (AM), also known as 3D printing. This is well established in plastics manufacture and is now moving into metal components. The good news for us is that virtually all AM metal components require some form of heat treatment. The highly stressed nature of the parts inevitably requires stress relieving, which is straightforward. But, when it comes to heat-treating to increase strength, toughness, and fatigue resistance, among others, the AM components respond quite differently.

Many designers assume that because a metal has the same chemical composition as a wrought component, the properties will be similar. This is not the case. The microstructure of AM materials is completely different and very little information is available regarding suitable heat treatments. At Wallwork, we started a research project over 18 months ago to test the properties of common grades of metal used in AM with different heat treatments. The results have been interesting and will enable us to specify heat treatment of such components in the future with confidence. 

We increasingly find manufacturers turning to us for advice – as metallurgists in industry appear to be a dying breed – so we need to be in a position to be able to offer informed advice to them on the latest treatments and coatings available. As such, Wallwork technical staff will be available on stand G121 in Hall 4 at the 2016 Farnborough International Air Show, held on 11-15 July.

Spotlight products:

1. USA-based Grieve Corp has released the No. 886 dual-chamber electric bench furnace. Comprising two chambers – an upper chamber with operating temperatures up to 2,200˚C and a lower chamber up to 1,250˚C – Grieve has positioned the No. 886 as suitable for a variety of heat treatment applications.

Each furnace has six inch-thick walls made from two inches of ceramic fibre and four inches of block insulation. Ceramic hearth plates also help to support the workload in each chamber.

2. The GENESIS High Temperature Fluid Generator line has been released by Victory Energy Operations. Suitable for use in the energy, pulp and paper and chemical industries among others, the GENESIS line is able to provide thermal medium and operating pressure for any suitable oil, glycol-water mixture or water.

Output ranges from 5–200MBTU/hr, and a membrane wall furnace offers structural integrity and minimal refractory. Moving on from previous tangent wall technology allows the GENESIS line to accommodate high differential temperatures while eliminating hot spots in the generator by controlling fluid flow evenly through the tubes.

3. To combat the issue of distortion within the heating and cooling process, Germany-based PhoenixTM GmbH has developed the Oil Quench System, able to monitor the temperature profile of products by moving through the furnace along with the product and relay information to the end user.

Distortion problems in the furnace can be related to flow patterns and temperature variations, among others. However, monitoring component temperature through a data logger outside of the furnace has not proven possible. The Oil Quench System is capable of traveling through the entire process with the products.

The Oil Quench System is able to monitor temperatures up to 950˚C throughout the process and fixed to production parts to measure core and surface temperatures.