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Green Tire Uniformity Systems

The Starrett Bytewise Green Tire Uniformity Systems (GTU) are a family of laser sensor systems used for checking the dimensional precision of components applied during tire building. GTU is configured for checking components on Belt/Tread Drums, Carcass Drums, and Shaping Drums.

Scroll down for details on each system, or download the complete GTU Brochure below!

The Green Tire Uniformity System for Belt Drums (GTU-B)

The Green Tire Uniformity System for Carcass Drums (GTU-C)

The Green Tire Uniformity System for Shaping Drums (GTU-D)

The Green Tire Uniformity System for Belt Drums (GTU-B)

What Is It?

The Green Tire Uniformity System for Belt Drums (GTU-B) is a laser measurement system that scans belts as the they are applied on the TBM drum.  GTU-B monitors 100% of production on the TBM for belt centering, width, snaking, splice and edge step-off so you can make sure every tire is a good one and get a better understanding of why things go bad.

How Does It Work?

Sensors are mounted on the left and right sides of the drum to scan belts as they are applied. Scan data is encoded as the drum rotates.  The resulting data set is automatically analyzed to extract the measurement parameters.  Parameters are graded as pass or fail.  All data is recorded to a log file.  Results are also exported the TBM PLC so you can pause the TBM operation when alarm conditions are detected. All data can be exported to your host system for analytics.

Why Does It Matter?

Tire Building is the most complex operation in the tire factory. Multiple components are centered, applied, spliced, turned-up, inflated, and stitched. Component stock variations combine with machine variations to produce green tires with variations in radial runout, belt and tread snaking, lateral runout, and splice quality. Green tires with the largest geometric variations invariably produce tires with the worst cured tire uniformity and balance performance.

Since GTU records measurements for every green tire, that data can be mined to compare each run with prior runs so you can recognize changes.  With large-scale data analytics you may be able to attribute changes to assignable causes.   

Belt geometry has associations with several cured-tire uniformity parameters:

  • Off-center and snaking belts are associated with conicity, LRO, LFV, and couple imbalance.
  • Overlapping belt splices are associated with radial effects.
  • Dog-ear belt splices are associated with lateral effects.
  • Belt 1 to belt 2 edge step-off is associated with lateral effects.
  • Open belt splices risk failure after curing and inflation.

Since belt splices are at a bias angle their RRO effect starts on one side of the tire as the splice enters the footprint, and traverses across to the other side, causing complex lateral and radial effects.

Measurement Parameters:

These parameters are measured in 8 places in 45 degree intervals around the drum:

  • Belt 1 width and center
  • Belt 2 width and center
  • Belt 1 an 2 edge step distance

These parameters are measured once per belt:

  • Belt 1 and 2 splice open distance (left, center and right positions)
  • Belt 1 and 2 splice overlapping distance (left, center and right positions)
  • Belt 1 and 2 snaking (difference between maximum left and maximum right values)
  • Belt 1 and 2 dog-ear splice distance
  • Radial runout

The Green Tire Uniformity System for Carcass Drums (GTU-C)

What Is It?

The Green Tire Uniformity System for Carcass Drums (GTU-C) is a laser measurement system that scans inner liner and ply components as the they are applied on the TBM.  GTU monitors 100% of production on the TBM for splice overlap so you can make sure every tire is a good one.

How Does It Work?

Sensors are mounted on the left and right sides of the drum to scan components as they are applied. Scan data is encoded as the drum rotates.  The resulting data set is automatically analyzed to find the leading and trailing edges of each component.  Edges are associated to the corresponding encoder count to determine the amount that each splice is overlapping or open.  When a splice is determined to be out of specification, the TBM can be set to pause for an operator inspect the tire and make a disposition to approve, repair, or quarantine the green tire.   The operator logs the action for statistical tracking and trend monitoring.

Why Does It Matter?

Tire Building is the most complex operation in the tire factory. Multiple components are centered, applied, spliced, turned-up, inflated, and stitched – all in ever-shorter cycle times, and in many cases with no human eyes present to monitor the assembly.  Component stock variations combine with machine variations to produce green tires with variations in radial runout, belt and tread snaking, lateral runout, and splice quality. Green tires with the largest geometric variations invariably produce tires with the worst cured tire uniformity and balance performance.

Since GTU records measurement for every green tire, that data can be mined to compare each run with prior runs so you can recognize trend changes.   

Since overlapping splices are two-layers deep across the overlap area the result is always a high bulge across the width once the carcass has been combined with the belt/tread package, inflated and stitched.  This localized RRO has associations with several cured-tire uniformity parameters:

  • Excessive overlapping splices are associated with RRO and RFV and static imbalance
  • Open splices risk tire failure in use.

Angles matter too.  GTU data can be mined to look for changes in splice angle, an indication of a process change.

Measurement Parameters:

  • Splice overlap for inner liner, ply 1, and ply 2 for left and right channels.

The Green Tire Uniformity System for Shaping Drums (GTU-D)

What Is It?

The Green Tire Uniformity System for Shaping Drums (GTU-D) is a laser measurement system that scans the final green tire after shaping and stitching.  GTU monitors 100% of production on the TBM for RRO, LRO, tread splice bulge, and circumference so you can make sure every tire is a good one. 

How Does It Work?

A single Starrett-Bytewise line laser sensor scans the green tire on the TBM drum after the completion of the shaping and stitching operation, and before the carcass is deflated.   Scan data is encoded as the drum rotates.  The resulting data set is automatically analyzed to extract the measurement parameters.  Parameters are graded as pass or fail.  All data is recorded to a log file.  Results are also exported the TBM PLC so you can pause the TBM operation when alarm conditions are detected.

Why Does It Matter?

Tire Building is the most complex operation in the tire factory. Multiple components are centered, applied, spliced, turned-up, inflated, and stitched. Component stock variations combine with machine variations to produce green tires with variations in radial runout, belt and tread snaking, lateral runout, and splice quality. Green tires with the largest geometric variations invariably produce tires with the worst cured tire uniformity and balance performance.

Since GTU records measurement for every green tire, that data can be mined to compare each run with prior runs so you can recognize trend changes.   

Since RRO and LRO of the green tire have the strongest associations with cured tire uniformity most agree that a check of the final shaped green tire provides the most comprehensive way to verify quality before sending the green tire to curing.

Measurement Parameters:

  • LRO of the center groove
  • RRO left and right and overall
  • Circumference left and right or each rib
  • Tread splice bulge
  • Runout values include harmonics and angles

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