Brass - 'Showering Wishes on Designers'

A & J Gummers has been a leading manufacturer of thermostatic showers, taps and water controls since the 1950s. The company continues to design and manufacture original products for increasingly wider markets at their 40,000 sq ft Birmingham factory. The Gummers’ products use brass almost exclusively, although one could be forgiven for not realising this fact at first sight. The dazzling array of gold and chromium plated finishes offered in Gummers’ Sirrus range of products, especially the top of the range Grande Thermostatic Shower, part of the Renaissance Collection used in the illustration, lifts the visual impact and aesthetic quality to luxury levels.

If you divide each shower and valve product made by Gummers into its component pieces and then section them in groups by the respective engineering processes used in making them, a pattern emerges that reinforces their choice and extensive use of brass in a wide range of manufacturing techniques, each ensuring the optimum performance and underlying quality in every piece. In reviewing these techniques, it becomes clear also that ‘brass’ is actually a broad term used for a range of application-specific alloys, each with unique properties. The manufacturing operation behind the Sirrus shower, bath and water handling products represents the very best in brass utilisation, employing every process and application for which brass alloys are ideal. The designer’s ‘wish list’ is met at every level.

Why A & J Gummers chose brass:

• Brass is easily cast to intricate shapes
• Brass is a perfect substrate for chrome plating
• Brass has excellent machinabilty
• Brass has excellent corrosion resistance.

The Glamour Factor
The electroplating of metals such as gold and chromium onto brass is good news all the way. Most plated coatings have some degree of porosity and this cannot be avoided. Brass, however, has an inherent corrosion resistance, avoiding the early on-set of cracking or blistering that characterises the use of materially inferior, steel substrates. The surface structure of plating-prepared brass is totally compliant with the applied coating, ensuring a long product life with minimal maintenance beyond a mild detergent wash and a rinse-and-polish dry. Designers and manufacturing engineers at A & J Gummers have taken brass and used every available production technique to maximum effect and the result shows.

Water Resistance
Constant and continuous contact with water is obviously a requirement for shower components and special DZR (de-zincification resistant) brasses are specified by Gummers, ensuring longevity and minimal degradation in the various geographical water conditions met in worldwide use.

Deep Drawn Shapes
The elegantly designed showerheads are manufactured from 70/30 Cu/Zn ‘cartridge brasses’ in soft, deep drawing quality (DDQ). The cold rolling process that creates the sheet brass leaves the raw material ductile in all directions and ideally suited to accept the tremendous shape changes called for by the design and produced in presses by cold deformation.

Hot Stampings
Valve bodies and some of the ‘chunkier’ components are produced by forging pre-sized ingots of heated brass bar between dies in a hot stamping press. The resultant items display ‘near-net’ shape requiring the minimum of post operations. Close tolerances are held item-to-item, surface finish requires little polishing before plating and, most importantly, these high strength brass stampings are impervious to water and free from porosity.

Casting Intricacy
Die-casting of brass into steel dies, with intricate performed sand-cores in place, is a process that gives high consistency, yielding components of extreme complexity. Waterways with passages that could not be post machined or created in any other way give the designer complete freedom. As with stampings, the ‘near-net’ shape results, reducing post operations to a minimum.

Bar and Tube Stock
The ready availability of brass bar and tube stock, extruded and drawn to close tolerances makes this material ideal for bar-fed automatic machines and CNC lathes. Speed of manufacture, cost of machining time and material economy come together in a unique package with brass. It machines three times faster than steel in terms of material removal. With the speed comes a superior finish and, on economy, the swarf from machining returns 40% of the cost of virgin material.

Super-Tubes... The ‘Alpha’ Secret
Highly relevant to the design of thermostatic shower units is the requirement for special components unique to the design employing non-standard, high-strength, thin-walled tube. The so-called ‘Alpha’ brasses, those containing less than 35% zinc are cold drawn for Gummers, using custom dies, into thin-walled tubing of greatly enhanced strength. Both internal and external surfaces are of high quality answering the designers’ threefold need for: free flowing water passages, plating-ready outer faces and strong, unsupported lengths without excess mass.

Production Director, Jeff Shade comments: “Our primary skills have always been in design and manufacture. In the early 1990s the innovative introduction of multi-pressure compatible, with or without pressure-boost, thermostatic shower controls with compensation for differential hot and cold pressures, took us into a lead position in the UK’s commercial shower market. This ‘one-for-all-applications’ product permanently changed the stocking and supply pattern of the UK, simplifying the installation specification. Ten years later and with a chain of successful products introduced we are rapidly becoming the UK’s largest supplier of showers, taps and controls for both commercial and domestic use. Throughout the period from the founding of Gummers in the mid 1800s to the present day, the copper based alloys have been favoured materials, starting with bronze valves and moving to the sophisticated products in a range of brasses as the markets and the materials developed. Our in-house capabilities are world-standard and even advanced developments such as no-touch controls, minimalist taps and vandal proof units will continue to depend heavily on the properties of brass.”