Make your own free website on Tripod.com

gold_logo.gif (4083 bytes)Ved Exports
 Brass Parts Manufacturing and Trading Company....            

 

Phones:

+91-288-679215

+91-288-679216

+91-288-664709

Fax:

+91-288-664707

 

                        webmaster

Brass the Yellow Metal.....

The generic term "brass" covers a wide range of copper-zinc alloys with differing combinations of properties, including: 

 

 

 

 

 

 

 

 

Machinability of Brass:

Machined components can be cheaper in brass than in mild steel.

  • All brasses are intrinsically easy to machine

  • The addition of small amounts of lead to brasses further improves this property

  • 'Free machining brass' sets the standard by which other materials are judged when machinability is being assessed

  • Higher machining speeds and lower rates of tool wear mean the overall production costs are minimised

  • Tolerances are held during long production runs and surface finish is excellent.   

 

 

 

 

 

 

Conductivity of Brass:

Brasses have good electrical and thermal conductivities and are markedly superior in this respect to ferrous alloys, nickel-based alloys and titanium.Their relatively high conductivity, combined with corrosion resistance, makes them an ideal choice for the manufacture of electrical equipment, both domestic and industrial. Condenser and heat exchanger tubing also require the good thermal conductivity of copper and its alloys.

 

 

 

 

 

Cost Effective and Recycling of Brass:

Introduction

Most people recognise the high price commanded by brass scrap.   Indeed many of us, after a DIY project such as installing a new kitchen or bathroom, collect together the old brass taps and fittings and sell them to our local scrap merchant in an attempt to recoup some of our expenditure. The reason such a premium price is paid for brass scrap is because it is essential to the economics of the brass industry.

Brass for extrusion and hot stamping is normally made from a basic melt of scrap of similar composition adjusted by the addition of small amounts of virgin copper or zinc as required to meet the specification before pouring. The use of brass scrap bought at a significantly lower price than the metal mixture price means that the cost of the fabricated brass is considerably less than it might otherwise be. How many designers consider this when designing new products or seeking cost savings in existing products.

Brass machined parts and stampings

Free machining 60/40 brass with small additions of lead is particularly cost-effective and environmentally friendly when used for the manufacture of machined parts and stampings. Firstly, the swarf produced as a result of high speed machining (typically metal removal rates are two to three times those of mild steel) can be sold as scrap. Secondly, when brass components reach the end of their long and useful life they too can be readily recycled. The stamping temperatures for brasses are lower than those required for ferrous alloys making it an energy efficient process; the low stamping temperature also gives an increased die life. Stamping is a near-net-shape process but the small amount of swarf produced by machining is again recyclable. Brass is also cost-effective and kind to the environment because it does not normally need plating or painting to prevent corrosion.

Special purpose alloys

Brass swarf arising from machining operations can be economically remelted but it should be substantially free from excess lubricant, especially those including organic compounds that cause unacceptable fumes during remelting. The presence in brass of some other elements such as lead is often required to improve machinability so such scrap is frequently acceptable. Besides the common free-machining brasses, there are many others made for special purposes with properties modified to give extra strength, hardness, corrosion resistance or other attributes, so strict segregation of scrap is essential.

When brass is remelted, there is usually some evolution of the more volatile zinc. This is made up in the melt to bring it back within specification. The zinc is evolved as oxide that is drawn off and trapped in a baghouse and recycled for the manufacture of other products.

Brass sheet, strip and wire

The 70/30 brass to be made into sheet, strip or wire form must be significantly free of harmful impurities in order to retain ductility when cold. It can then be rolled, drawn, deep drawn, swaged, riveted, spun or cold formed. It is normal therefore to make it substantially from virgin copper and zinc, together with process scrap arising from processing that has been kept clean, carefully segregated and identified.

Conclusion

Brass is a cost-effective engineering material ideally suited for the manufacture of machined and stamped items. The need for plating or painting to prevent corrosion in normal circumstances is eliminated, but when required for cosmetic purposes or to give additional protection against corrosion it is easily plated. Brass is readily recycled without loss of properties and the infrastructure to do so has been proven over many years.

 

 

 

 

 

Brass is readily joined:

Brasses may readily be joined to other copper alloys or to other metals by most of the commercial joining processes such as:

  • Riveting
  • Soft soldering
  • Brazing
  • Friction welding
  • Modern adhesive joining practice

 

 

 

 

 

Maleable and Ductile:

  • Brasses with a copper content greater than 63% can be extensively deformed at room temperature, and are widely used for the manufacture of complex components by pressing, deep drawing, spinning and other cold forming processes.

  • If the copper content is below 63% and no other alloying elements are present, the room temperature ductility is reduced, but such alloys can be extensively hot worked by rolling, extrusion, forging and stamping.

  • Strength, ductility and formability are retained at low temperatures, making the alloys ideal for cryogenic applications.

  • Brasses do not spark when struck and are approved for use in hazardous environments

 

 

 

 

 

Finishing and Plating of Brass:

  • Brasses may be polished to a high surface finish which can then be either easily repolished when required or lacquered to preserve the natural colour, enamelled or plated with chromium, nickel, tin, silver, gold, etc. as required. Alternatively, the surface can be toned to a range of colours, from "bronze" through various shades of brown, to blue-black and black, using commercially available toning chemicals. These coloured finishes are frequently used for decorative and architectural metalwork.

  • All types of common plating processes may be used. For many other metals it is usual to use a copper plate underlayer. This is not required on brass because it is easily polished and does not need the expense of an initial copper strike. To give extra corrosion protection to steel when used against brass, cadmium plating of the brass was traditional but this has now been generally replaced by zinc.

 

 

 

 

 

Corrosion Resistance of Brass:

Brasses have excellent resistance to corrosion that makes them a natural, economic first choice for many applications.

  • Atmospheric exposure of the brasses results in the formation of a thin protective green "patina", a visually attractive feature in buildings.

  • Brass will remain essentially unaffected for an unlimited period of time, i.e. it will not rust away like iron and steel.

  • Seawater can be handled successfully providing the correct alloy is chosen, and there is a long history of the use of brass tube and tube fittings, valves, etc. in domestic plumbing, central heating, seawater lines, steam condensers and desalination plant.

  • High tensile brasses containing manganese have particularly excellent resistance to atmospheric corrosion, continual exposure resulting in a gradual darkening of the bronze colour.

 

When exposed to the atmosphere, brass tends to form a protective tarnish film that impedes corrosion beyond a few micrometers into the metal surface. The tarnish will deepen in color from bronze to dark brown, and may eventually take on the green color of a patina in some environments. The important point is that brass's corrosion rate in normal atmospheric conditions is low and self-limiting, and the corrosion products that do form are not objectionable.

In addition to atmospheric corrosion resistance, brass also withstands exposure to a wide range of water compositions, including automotive coolant solutions. Brass is generally inert to organic liquids and gases, although it should not be used in mineral acids or acid salts. Alkaline salts are less objectionable.

Brass is susceptible to three types of corrosion. These include stress-corrosion cracking, which can arise in ammoniacal environments, amines, mercury compounds and nitrite solutions. Sulfides will promote pitting attack of copper and copper alloys, especially under alternating aerobic and anaerobic (sulfiding) conditions such as might be caused by episodic exposure to polluted seawater. Brasses are perhaps the least susceptible copper alloys to sulfide pitting. Also, road salt solutions contaminated with sulfide-laden exhaust emissions do not appear to affect brass. Brass can, immersed in acidic and mildly basic waters, corrode by dezincification, but this also has not been a problem in automotive applications. (For service in such environments brass compositions are modified by small additives of alloying elements that inhibit dezincification.)

 

 

 

 

 

Good Strength of Brass:

  • In the softened or annealed condition, the brasses are ductile and strong but when hardened by cold working techniques such as rolling or drawing, their strength increases markedly. Strong, stiff structures can be assembled from extruded-and-drawn sections. Bars and rolled sheet and plate can be fabricated into containers and other items of plant which work under pressure.

  • The strength of brasses is substantially retained at temperatures up to around 200oC and reduces by only about 30% at 300oC which compares favourably with many alternative materials.

  • The brasses are very suitable for use at cryogenic temperatures since the properties are retained or slightly improved under these operating conditions.

  • For applications demanding higher strengths the "high tensile brasses" are available. These contain additional alloying elements which further improve the properties.

 

 

 

 

 

Color of Brass:

Brasses are extensively used for durable decorative applications and for the manufacture of functional items where aesthetic appeal is a requirement in addition to a long service life.

  • In brasses, the red of copper is toned to a range of attractive yellow hues by the addition of varying amounts of zinc ranging from the gold-like colours of the 95/5, 90/10, 85/15 and 80/20 alloys (appropriately called "gilding metals") through the more subtle variations in the 70/30, 2/1 and 64/36 series of brasses to the stronger yellow colour of the 60/40 alloy, formerly known as "yellow metal".

  • Aluminium brasses have a distinctive silvery sheen.

  • The addition of manganese to certain brasses gives them an attractive bronze colour when extruded.

  • High tensile brasses, some of which are otherwise known as "manganese brasses" or previously "manganese bronzes" are particularly suitable for architectural applications since they can also be patinated to a range of durable brown and bronze finishes.

 

 

 

 

 

Wear Resistance of Brass:

The presence of lead in brass has a lubricating effect that gives good low friction and low wear properties utilised in the plates, pinions and gears used in instruments and clocks. Special brasses are available with additions of silicon that make the material ideal for use in heavy duty bearings.

 

 

 

 

 

Brass is Cost Effective:

 

There are many factors, sometimes overlooked, that contribute to low costs of brass components.

  • Close tolerance manufacturing techniques can be employed so that finishing costs are minimal.

  • Tooling costs may be significantly lower than for other materials or processes.

  • Ease of machining means that production costs can be minimised.

  • The good corrosion resistance of the brasses means that the cost of protective finishing is lower than for many other materials.

  • In addition to these benefits the high value of any process scrap can be used to reduce production costs significantly.

  • The long service life normally expected of well-designed brass components means that the costs of service failures are minimal.


 

In today's cost conscious component parts industry, the difference between a "good buy" and a "good bye" is often bottom line cost. In this case, free-cutting brass is 17% less expensive than its 12L14 steel counterpart!

It's simple math. While up-front costs for brass may be higher, once you factor in machining costs (brass is up to five time more machinable), turnings value (steel scrap is worthless), and the need to plate steel (brass naturally resists corrosion) - the bottom-line cost for free-cutting brass is significantly lower per finished part.

And is doesn't stop there. As automakers extend warranty warranty periods and cover additional systems, down-the-road costs to remove rusted, corroded steel parts can be significant. As the photo shows, brass stands the test of time far better than zinc-coated steel.

For information on vendor sourcing and what makes free-cutting brass the "good buy," call the Copper Development Association at 800 CDA-DATA; fax: 212-251-7234

Automotive Hydraulic Tube Fitting/1,000 parts*

 

C36000



12L14 Steel


$92.46


Raw Material Cost

$35.92


-44.84


Scrap/Turnings Value

+0.00


$47.62


Net Raw Material Cost

$35.92


+28.44


Cost of Machining

+47.78


+0.00


Zinc Electrocoating

+6.09


$76.06


Total Finished Parts Cost

$91.79


* Based on June 1994 costs.

After only 314 hours exposure to salt-spray (fog) corrosion testing (ASTM B 117), the zinc-coated steel fitting (right) failed to meet customer specification.

C36000 12L14 Steel

 

The numbers say it all. In terms of finished part cost, brass is a whopping 19.9% less expensive than 12L14 leaded steel.

Surprised? Don't be. Brass may cost more up front, but brass turnings can be reclaimed for 75-85% of the original brass value (steel scrap is worthless). And while brass easily meets the yield strength requirements for small auto component parts, it's five times more machinable than steel. That means higher productivity and lower per-part cost. What's more, brass naturally resists corrosion, eliminating the need for costly protective plating.

 

Transmission Cooling Fitting/1,000 parts*

12L14



C36000


$121.80


Raw Material Cost

$339.12


-0.00


Scrap/Turnings Value

-196.24


$121.80


Net Raw Material Cost

$142.88


+126.39


Cost of Machining

+68.06


+15.12


Zinc Electrocoating

+0.00


$263.31


Total Cost

$210.94


* Based on mid-1991 costs.

 

 

 

 

 

Summary:

Here are the important points to bear in mind when considering Brass for machine products:

  • Brass is widely available and in plentiful supply.
  • Brass' quality is assured by adherence to numerous standards;
  • Brass's mechanical properties in service are adequate for the majority of parts produced on automatic machines;
  • Brass's extremely high machinability translates into lower product costs, compared with leaded steel;
  • Brass's close dimensional control and high surface finishes will be reflected in higher product quality;
  • Brass's natural corrosion resistance eliminates the need for expensive electroplating. Customers perceive and appreciate the quality inherent in solid brass components.
  • Brass gives the designer freedom to conceive parts that would not be economical in steel.


Finally, it is important that the designer takes into account the added design freedom Brass makes possible. Brass lets the designer specify deep blind holes without concern for tool breakage and high rejection rates. Brass also accepts fine detail and excellent surface finishes without extracting a cost penalty for slow cutting speeds and expensive tooling. Brass can simplify designs, and simpler designs can lower costs while improving product quality.