Brass in design

BRASS IN DESIGN

Esther Maganga

What is BRASS? •

An alloy of copper and zinc + additions of other metals to enhance different properties

•

Other alloying elements added to brass

Elements

Material

Property Improved

Lead (1.0 t0 4.0%)

High-speed machine brass

Machinability

Manganese, Aluminium, Silicon, Nickel, Iron (0.75 to 2.5%)

High tensile brasses

Yield strength up to 500MN/m2

Aluminium, Arsenic and Tin (0.4 to 1.5%)

Aluminium brass, denitrification-resistant brass, Naval brasses

Corrosion resistance especially in sea water

•

Brass covers a wide range of materials with different field of applications

•

Wide variety of forms and sizes available that minimise costs of machining to final dimensions

Copper Development Association Inc

Brass Rods, profiles and wire (Delta Extruded Metals Company Limited)

Properties of Brass q Weather resistance § § § § §

Do not degrade in sunlight Do not suffer from rapid softening above ambient temperatures Do not embitter below ambient temperatures.

Do not rust Do not corrode under plating

q Strength § § § §

Medium strength engineering materials Fixable and strong when softened or in an anneal condition When hardened by cold working their strength doubles Has good impact resistance and does not shatter or crack when subject to a high impact load

q Conductivity § §

Good electrical and thermal conductivity Do not spark when struck by other materials and are approved for use in hazardous environments

q Surface finishes §

§

Easily toned to almost any desired colour – from a gold-like yellow, through dull yellows and amber browns, to chocolate brown and black One of the few metals that can be successfully polished to either a high gloss or mirror finish

q Excellent machinability § §

Sets the standard by which other materials are judged Slight reduction in ductility when lead is present

Types of Brass q Over thirty-five different standard brasses q Each has unique properties that makes it particularly suited to specific applications q Free Cutting Brass: q Contain 60% copper, 2-3% lead and 37% zinc

q Architectural Brass: q Especially resistant to atmospheric corrosion q Unlimited lifespan q Develops a durable and attractive chocolate brown colour q Self-healing over superficial scratches

A household faucet stem machined from Free-Cutting Brass

Shapes and Forms of Brass • 

Brass can be purchased in: (i) hard, half hard, and dead soft tempers, (ii) Different shapes and sizes

Applications of Brass in Architecture

Applications of Brass in Architecture

Brass Fabrication Techniques Readily Cast q Sand and Shell q Permanent die q Gravity q Pressure

Sand Cast Breather Valve Guard

q Investment q Centrifugal q Continuous (Logs for extrusion/slabs for rolling)

Pressure Die Cast Components

Cored shell moulded valve

Investment Cast Clarinet Keys

Good Hot & Cold Formability Hot Forming q Extrusion (direct and indirect) q Hot stamping/forging q Hot rolling

Examples of Hot stampings

Cold Forming q Drawing (sections, wire, tube) q Heading and thread rolling q Stamping/Pressing

q Deep drawing q Spinning q Machining

Wire and tube examples

**Source: Copper Development Association Inc

Brass Fabrication Techniques Machining q Free Machining Brass q Fine chips of swarf q No lubricant q Minimal wear on cutting and Machine tool

q Non-Free Machining Metal q Spirals of swarf slow to clear q Excessive Lubricants Examples of machined components

Joining q Brass can easily be joined to itself and all other copper alloys, by: q Mechanical fasteners e.g rivets, screws, etc q Adhesive bonding q Soldering q Brazing q Welding **Source: Copper Development Association Inc.

The flux goes clear and watery as the component reaches brazing temperature 550-600C

The flux protects the brass component during heating.

100-200C

The silver brazing alloy melts and flows as it is touched onto the joint area.

700-750C

Relative Cost q Brass products are relatively lower in price than those made from other common metals such as aluminium, steel, etc.

Brass

Aluminium

Raw materials Cost

45%

21%

£3.50

Machining Cost

63%

66%

£0.00

£2.50

Finishing Cost

0%

29%

Drilling & threading

£7.90

£11.70

Sub Total

108%

116%

Plating

£0.00

£1.41

(8%)

(1%)

Total

£14.12

£21.46

Minus scrap value of machining swarf

Total saving

£7.34

Total Cost

100%

115%

High Tensile Brass

Steel

Raw material cost

£6.22

£2.35

Pre machining cost

£0.00

Milling

MECO International

Vickers Systems Division, Trinova Ltd

q Lower fabrication cost q Well established recycling tradition (infrastructure in place), and high scrap value q Well established aftermarket tradition (infrastructure in place) q High quality reputation q And finally brass has a longer service life, freedom from corrosion, which means that maintenance or replacement of the product will be either lower or non-existent.

Ecological Issues Environmental q Recycling is essential for the economics of the brass industry q Brass is recycled without loss of properties q Almost 100% of brass manufactured in the UK is made from recycled copper and brass q Process scrap has a high value approximately 40% of the virgin alloy q Nearly half a billion pounds are generated from recycling of brass scrap each year in the UK

Ecological Issues Health

q Brass is the perfect material for use in clinical environments such as hospitals where the biocidal action of the copper will inhibit the growth of most micro-organism – i.e fight against hospital-acquired infections such as MRSA and Clostridium difficile. q It has been shown that these pathogens, which can be spread by touch, will die in a few hours on copper/brass surfaces. This does not happen on stainless steel or plastic

MRSA – Methicillin-resistant Staphylococcus aureus

Summary

Brass is cost-effective q Close tolerance manufacturing processes give near-net shapes q High-speed machining q Swarf/scrap commands premium price with high quality reputation q No plating or painting required

Brass is recyclable q Without loss of properties q The recycling infrastructure is already in place

Useful Links

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http://www.copperinfo.co.uk/alloys/brass/downloads/pub-177-brass-in-focus.pdf http://www.copper.org/applications/automotive/radiators/no_flux.html www.copperinfo.co.uk/alloys/brass/presentations/lecture/lecture.ppt http://www.copper.org/publications/newsletters/innovations/1998/07/brass360.html http://www.secretvintageportland.com/?cat=11 http://www.comptonsmith.co.uk/architectural-ironmongery.htm http://www.cococozy.com/2009/03/ugly-or-pretty-weekend-furniture-hunt.html http://mp3lejatszo.info/?p=16 http://www.manitobacorp.com/ https://www.admiralmetals.com/AdmiralMetals/wp-content/uploads/2012/08/Getting-Down-toBrass-Tacks-on-Quality.pdf http://www.architectural-review.com/buildings/copper-awards-commended/8621689.article http://machinedesign.com/article/comparing-brass-versus-stainless-steel-threaded-inserts-1117