Bright Bars are steel or metal bars that are produced by one or more cold finishing processes. The processes outlined below are known as Cold Finish processes or the end products are known as cold finished because there is no or very little heat applied in the entire operation of converting them from hot rolled bars (also known as black bars) to cold finished bars or Bright Steel Bars.
Cold Drawing: Hot Rolled bar is descaled, pulled through Tungsten Carbide or High Speed Steel die, straightened & cut-to-length. Improves dimensional tolerance and shape, straightness, surface finish, strength and machinability.
Turning and Polishing: Remove bar surface of Hot Rolled bars with revolving cutting tool, rotate bar through rolls to straighten and polish, then cut-to-length. Improved dimensional tolerances and removes surface defects and decarburisation.
Grinding: Abrasive wheel grinds off surface metal. Improves surface finish and achieves very close dimensional tolerances.
Cold Rolling: Descale, pass through series of rolling stands, strengthening and cut-to-length. Improves dimensional tolerance and shape, surface finish and strength.
Stress Relieve Anneal: Sub-critical thermal treatment applied after cold drawing. Removes residual stresses in the bar and may also increase yield strength.
Straightening: Bending applied to bar through a set of rolls. Improves straightness.
Cutting: Separates into desired lengths by cold shearing or sawing. Improved length tolerance.
Chamfering: Cutting a taper and end-facing the bar. Eliminates end distortion and improves bar feeding.
Annealing: Heating above the critical temperature and slow coating the bar. Controls microstructure and softens the bar.
Normalising: Heating above the critical temperature and air cooling the bar. Improves uniformity of microstructure.
Quenching and Tempering: Heating above the critical temperature and quenching the bar in oil or water followed by a tempering operation increased strength, hardness and toughness.
A vast range of process combinations are available to meet different quality characteristics. Some of the most common process classifications are:
1. Cold Drawn
2. Cold Drawn, Stress Relieved
3. Turned & Polished
4. Ground & Polished
5. Turned, Ground & Polished
6. Cold Drawn, Turned & Polished
7. Cold Drawn, Ground & Polished
8. Cold Drawn, Turned, Ground & Polished
9. Cold Drawn, Stress Relieved, Turned, Ground & Polished
Cold finished steel bars possess improved mechanical properties, greater dimensional accuracy, better surface integrity and higher machinability. These superior product qualities provide a number of significant design advantages & benefits:
1. Mechanical Properties: Cold drawing increases the hardness, yield and tensile strength, which can:
a. Serve to reduce design mass (weight)
b. Eliminate costly heat treatment
c. Allow the use of a less expensive grades
d. Provide increased fatigue strength and longer service performance
e. Provide better wear resistance
2. Dimensional Accuracy: A cold drawn and/or turned, ground and polished bar offers more precise and consistent cross-section geometries, straightness and bar-end conditions, which can:
a. Reduce or eliminate machining.
b. Reduce strain on collets, pusher and fingers during machining
c. Improve work-holding and fixturing compatibility
d. Reduce scrap and yield loss during manufacture
3. Surface Integrity: Cold drawing or grinding and polishing greatly improves the surface texture, which can:
a. Reduce or eliminate machining.
b. Ease manual handling and machine loading.
Turning and/or grinding rids a bar of its surface anomalies, which can:
a. Eliminate decarburisation
b. Provide a defect-free surface
c. Reduce need for all-over machining
4. Machinability: The increased beam strength, reduced ductility, clean surface and improved dimensional accuracy of a cold drawn bar can positively affect machining performance by:
a. Allowing the use of rapidly activated, precision collecting
b. Increase work-holding security with larger bearing contact areas
c. Improve the machined surface finish through reduced tool-edge weldments on ductile grades
d. Improve part size control through less lateral deflection
e. Increase tool life through more stable tool-edge weldments on ductile grades as well as from reduced abrasion with oxide-free, bar surfaces
f. Reduce wear on machine parts and collets and less lubricant contamination due to the absence of hot mill surface scale and/or corrosion products
g. Allow the use of higher spindle speeds with the reduced propensity for vibration
h. Reduce screw machine maintenance
In summary, cold finished steel bars enable design engineers to reduce manufacturing costs and time and produce superior performance components. Cold finished steel bars are the value-added engineering material of choice for a universe of precision components in almost every industry.
|Auto Industry||Agricultural Implements||Health & Sports Equipment|
|Textile Industry||Food Processing Industry||Fasteners|
|Machinery Manufacturers||Decorative & Furniture||Stampings|
|White Goods||Hoses & Fittings||Cold Headed Components|
|Tools & Fixtures||Bearings, Hinges & Gears||Material Handling & Storage|
|Oil & Petroleum Sector||Mining|