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News Release from: Copper Development Association
Edited by the Engineeringtalk Editorial
Team on 24 June 2003
More to brass than meets the eye
Talking recently with design consultant Ken Kempson about the family of copper/zinc alloys collectively known as "the brasses", the discussion centred on the principal benefits of these metals.
Talking recently with design consultant Ken Kempson about the family of copper/zinc alloys collectively known as "the brasses", the discussion centred on the principal benefits of these metals Kempson has a particular brief within Copper Development Association's Cupro-Technology educational programme to organise quarterly symposia at various venues in the UK covering the engineering aspects of "Brass in focus"
This article was originally published on Engineeringtalk on 22 Aug 2000 at 8.00am (UK)
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When discussing the full range of these alloys there is a trap that catches designers and engineers time and again.
It is the use of the singular word "brass" as a basis for comparing the relative advantages over, for example, the use of mild steel, stainless steel, aluminium or plastics.
There exists a perception of brass as one material.
Perhaps it is thought of sometimes by engineers and designers as existing either in a free machining or a casting grade, but a comprehensive understanding of properties however is usually only found among the existing users of brasses in large quantities and for specific uses.
If one includes the casting brasses there are in fact over 70 different alloys in the range, all sufficiently original to require defining in British/European (CEN) Standards.
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The general mechanical properties of these brasses vary widely, indeed it is this wide range that makes these alloys so important as engineering materials.
Good news for the designer, however, is that each of the defined alloys is well documented and was formulated to confer certain advantages in specific applications.
For example, there are the 60/40 (60% copper and 40% zinc) brasses, which are very plastic at 700-800C enabling the ready forming of intricate shapes by extrusion and stamping.
There exists a choice of free-machining brasses (metal removal rate up to three times that for mild steel), some with built-in ductility to permit varying degrees of cold working, eg riveting, knurling etc.
Hot stamping brasses can yield a near "net" shape for complex items such as pneumatic control valve bodies.
If the stamping die is well designed, then side cores can be included leaving the very minimum of post operations and rendering the manufacturing process extremely rapid and cost-efficient.
There are also brasses with a touch of tin in the alloy to enhance corrosion resistance in marine environments.
Higher copper, 70/30 (70% copper and 30% zinc), cartridge brasses, as the name implies, can be deep-drawn by cold working to suit the requirements of the defence and container applications.
All brasses are non-sparking, and this property is made use of in high-tensile brasses for critical applications in mining, oil and gas industries.
And as one final example among a myriad of others there are the wear resistant brasses.
These unique alloys contain silicon, giving the product an enhanced degree of face-to-face lubrication by reducing frictional drag.
Brasses occur everywhere you look in everyday life - electric plugs, light bulb fittings, precision medical instruments, cable glands, bearings, gearwheels, household and plumbing fittings, aircraft, locomotive and car components - the list is virtually endless, proving beyond doubt that alloys chosen from the brass range are essential in many applications.
If there existed any other material more cost effective, or with better properties, then that material would have been chosen at the design stage.
There is, however, one very significant justification for thinking "brass" in the singular in that, irrespective of the sophistication of the individual alloys, the three main benefits deriving from the use of brasses are common to all the alloys.
First comes cost-effectiveness: although the copper/zinc alloys are more expensive than say mild steel, they machine up to three times faster and to better finishes.
They do not need plating or painting for corrosion protection and the swarf produced by high speed machining commands a premium price, often significantly reducing the final component price.
Secondly, because the materials are so readily worked, sheet - bar - tube - extruded sections - plate - wire - and other stock and custom forms represent an easy and rapid manufacturing step.
Add the machinability detailed above, and the near shape facility of stamping and die-casting, and their versatility becomes apparent.
Finally comes probably the most important property, which in itself can often justify the use of, or in some cases a switch to, brass, is its recyclability.
Over 95% of brass produced is made from recycled brass and copper (swarf, clippings, scrap and obsolete products).
Brasses can be recycled time and time again without any loss of properties.
These materials have traditionally been recycled for centuries and the infrastructure to ensure this practice continues is firmly in place.
Delegates who attend the symposia organised by Ken Kempson are brought up to date on all aspects of these cupro-zinc alloys.
The symposia are combined either with a comprehensive table-top engineering exhibition carrying practical examples of stamping, casting, machining and surface coating or, where the venue is a manufacturing company, the host company is invited to hold an industrial open day giving an upbeat degree of industrial focus to an education-rich presentation.
Details of the next event can be obtained from the CDA.
Brasses are as vital now as they have been throughout the ages, from Roman times (brass coins have been found dating from 20 BC) through several industrial evolutions and revolutions, to the present day.
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