- 9 February 2007 -

Pump toolmaking goes high-tech

Pumps users don't often get a peek at how the components for their pumps are made. One factory opened its doors to World Pumps 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, and 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 impellers and valves, which often have weights in excess of three tons per component.

But it's not simply size that is putting wire erosion at the forefront of pump industry tooling. "The production of large impellers 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," says Simmons.

Michael Yorke, manufacturing manager at Heatric, a manufacturer 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. 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.

"Wire eroding is the only way to provide stress-free cutting and shaping of this material," Yorke 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. Stacks of etched plates required in the production of Heatric's printed circuit heat exchangers are, as a result, converted into solid blocks containing the fluid flow passages. The compatibility 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.

High-tech effect

Today's use of wire erosion as a high tech cutting device is enabling valve and impeller 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 technology becomes more readily available, so the designs for pumps and impellers are also there to move the industry forward," says Simmons.

The new technology employed by Harper and Simmons is having a ripple effect, enabling complete pump redesigns and a new look at the capabilities and efficiencies of the industry as a whole. New developments such as diffusion bonding are creating a cascade effect down the supply chain. The only way to cut diffusion bonded materials is via chipless cutting, for example, and the only chipless cutting method available is wire erosion.

This evolution of modern machining methods and pump/valve design is pushing new manufacturing methods forward. Harper and Simmons points to their work for SPX Valves, which is producing next-generation gas valves for the elimination of steam in power stations. The petrochemical and power generation industries are benefiting most from these large scale abilities as well as the company's ability to manufacture large-scale turbines and diaphragms for the power station industry. Those valves being manufactured for SPX are 350mm thick.

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 eroder's ability to cut exotic alloys, stainless steel, titanium, and diffusion-bonded components with ease, as well as cope with complex two-axis and four-axis shapes, has put it well and truly on the map as far as the pump industry is concerned," Simmons explains.

Success with this technology is 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 the standard thinner materials. On a regular basis, particularly with the complex power station valve work, we're working with exotic alloys up to 500mm thick," says Simmons.

"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," says Simmons.

A company on the move

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 Simmons. Harper and Simmons' recent move to a new 18,000 square-foot factory in Redditch has enabled the company to continue to build on its already significant position in European toolmaking and wire eroding, which has seen particularly strong growth in the large valves and impellers market.

"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 specialised jobs such as diffusion-bonded impellers, impeller housings and large valve work," says Simmons.

Contact

Robert Simmons

Harper and Simmons

Howard Road , Park Farm Industrial Estate

Redditch , Worcs

01527-518-121

www.harperandsimmons.co.uk

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