Top gong for Sterling

Pump users don´t often get a peek at how the components for their pumps are made. One factory opened its doors to Pumps Magazine and explained its high-tech, wire-erosion process for machining the equipment you use every day.
Harper and Simmons is a specialist subcontracting machinist company working with the likes of SPX Valves and Heatric, which are manufacturing experts, and, in cases such as Heatric, the only suppliers of their products to the pump industry. Harper and Simmons´ wire erosion manufacturing process is highly flexible and versatile, fulfilling the needs of the heat exchange, fluid dynamic, valve, pump and automotive industries.
The company currently operates six large Hitachi bridge-type wire eroders including a Hitachi 8Q, one of the largest wire eroders available in the world, cutting tools up to 1000x800x520mm. With five other wire eroding machines, all capable of cutting 1000x600x520mm, and with 45kg wire spool dispensers for maximum continual 24 hour/day operation, customers are assured of machine availability on even very large-scale jobs. Overhead crane accessibility to all machines has also enabled the handling of huge impellors and valves which often have weights in excess of 3 ton per component.
But it´s not simply size that´s putting wire erosion at the forefront of pump industry tooling. "The production of large impellors and valves has changed in recent years with the introduction of diffusion-bonded components," explains Harper and Simmons General Manager, Robert Simmons. "The precision cutting of these components and other exotic alloy materials used by the industry, as well as the complexity of some of the over-size components associated with large fluid dynamics, can only be achieved by wire erosion. Not only is it extremely accurate but it also provides true chipless machining (producing no swarf), a critical factor in cutting diffusion bonded materials."
Michael Yorke, Manufacturing Manager at Heatric in Poole, Dorset, manufacturers of chemically etched and diffusion bonded Printed Circuit Heat Exchangers agrees: "Wire eroding is the only means to shape diffusion bonded material without damaging the apertures or perforations. It produces clean holes and a clean cut and at the present time there is no other way to cut it in a precise manner." Heatric is already seeing a growth in the use of diffusion bonded materials by the pump industry and predicts continued growth. "And wire eroding is the only way to provide stress-free cutting and shaping of this material," he adds. Originally developed by Rolls Royce and described by Heatric as a "solid-state joining" process, diffusion bonding involves pressing metal surfaces together at temperatures below the melting point to promote grain growth between the surfaces. Under carefully controlled conditions, explains Heatric, diffusion bonded joints reach parent metal strength and stacks of etched plates required in the production of their Printed Circuit Heat Exchangers are, as a result, converted into solid blocks containing the fluid flow passages. The compatability of the chemical etching and diffusion bonded process with a wide range of materials means that Heatric´s PCHEs are suitable for a range of corrosive and high purity streams.

Today´s use of wire erosion as a high tech cutting device is enabling valve and impellor designers to change their approach to certain components to now take advantage of the 0.4mm cutting slot that wire erosion can produce. "It´s opening up new possibilities for designers within the pump industry, so that, as the next generation of techno-logy becomes more readily available, so the designs for pumps and impellors are also there to move the industry forward," says Robert.
As a result of this ability to cope with the specialised alloys, Harper and Simmons is already seeing an increase in the cutting of the very modern component designs on large-scale pumping installations. "The wire eroders ability to cut exotic alloys, stainless steel, titanium and diffusion-bonded components with ease, as well as cope with complex 2-axis and 4-axis shapes, has put it well and truly on the map as far as the pump industry is concerned," Robert explains.
But he adds that it´s also about having a team of experienced engineers who are prepared to think outside the box: "Many companies don´t have the skilled staff to work beyond 2mm thick standard materials. On a regular basis, particularly with the complex power station valve work, we´re working with exotic alloys up to 500mm thick. At these thicknesses and complexities, it´s a combination of the bridge-type Hitachi wire-eroder supported with high pressure EDM drilling, CNC hard metal turning, water jetting and state-of-the-art toolmaking that´s essential. As a result of being able to provide this technology, Harper and Simmons has carved itself a market niche for the large and unusual components used in today´s high-tech pumping industry."
Specialising for over sixty years in the press tool industry, Harper and Simmons aims to continue to prioritise traditional toolmaking skills alongside its expanding state-of-the-art hardware. It is a combination of investment in high-tech processes alongside our core business - which will always remain focused on skilful toolmaking - that I believe will help us to move with this industry," says Robert. "Our expansion means we can now continue to develop a range of unique and state-of-the-art processes. But our focus isn´t just about buying another high-tech machine. It´s about committing to a full service, and being able to efficiently turn over the work as the customer needs it. This move to a bigger site is to ensure we can tackle and accommodate all supply demands including oversized and specialized jobs such as diffusion-bonded impellors, impellor housings and large valve work."