Traction Basics

• What is traction?
• What causes scratching?
• How is scratching measured or quantified?
• What is coefficient of friction (COF)?
  
• How is COF measured?
  
• What is micro-slip?
• What is the friction circle?

• How much traction is needed on a idler roller?
• What are typical bearing drag torques?
• What bearings are used for idler rollers?
• How much traction is needed on a driven roller?
• When will the web slip on a wrapped (unnipped) roller?
• When will the web slip through nipped rollers?
  
• How is vacuum used to increase traction?

• What is air lubrication?
• Can a nip roller eliminate the boundary air layer?
• What is the coefficient of traction (COT)?
• How is COT measured?
• How does roughness or grooving affect COT?
• What are the best groove patterns?

• How far should rollers be spaced?
  
• How is an idler roller specified?
• What is a cantilevered roller?
• How big should a roller be?

Alignment

• What is level and tram?
• How is roller alignment measured?
• How should a roller be mounted to the equipment?
• How often should equipment be re-aligned?
• When should a equipment and rollers be manually adjustable?
• How do you keep a moving roller aligned, such as a nipping or dancer roller?
  

Nipped Roller Basics 

• What is the pressure between a tensioned web and roller?
• What is the pressure between nipped rollers?
• Why do nips usually include a compliant roller?
• How should nip load be controlled?
• How does nip load affect rubber and web speed?
• What is the best web path to enter a nip?

Rubber Covered Rollers

• What is Durometer?
• What durometer used by application?
• What are the most common rubber compounds?

Nip Pressure Variations

• What cause pressure variations in nipped rollers?
• How are nip pressure variations measured?
• How can nip pressure variations be corrected?
• How does Durometer affect nip pressure variations?
  

Air Flotation and Drag Bars

• How is forced air used to handle a web?
• What is a web turn bar?
• Why are turn bars used?
• What is air flotation?
• Why is air flotation used?
  

Introduction to Web Tracking

• What are your lateral position needs?
• What is the most accurate web positioning system?

• What is the parallel entry rule?
• How much will a misaligned roller shift the web?
• How do roller diameter variations shift the web?
• How does web bagginess shift the web?
• How is traction important to web tracking?
• What passive ways are used to guide a web?

• Where are web guides used?
• What are the components of an automatic web guide?
• How is web edge, center, or pattern detected?
• What is the best location for the web position sensor?
• How is a web guide actuated?
• What determines a web guide's accuracy?
• What are the limits of a web guide?
• How can a web guide be used proactively?

• How does a sidelay unwind guide work?
• How does a sidelay rewind chaser work?
• How does a displacement guide work?
• How does a steering guide work?
• What is understeering? Oversteering?

• What is a trough? A wrinkle? A crease?
• What causes a shear wrinkle?
• What causes a tracking wrinkle?
• What causes an expansion wrinkle?
• What causes an accumulation wrinkle?

• Why is traction important to wrinkling?
• How do span length and wrap angle affect wrinkling?
• What is a kiss roller?
• How are wrinkles measured or detected?

• What is a spreader roller?
• What is an anti-wrinkle roller?
• How much spreading is required to prevent wrinkling?
• Can you spread too much?
• What the best way to spread slit strands?
• What is the best anti-wrinkle roller?
  

More on Anti-Wrinkle Rollers

• How does a bowed roller work?
• How does an expanding surface roller work?
• How do biased edge nips work?
• How does a flex expander work?
• How does a concave roller work?
• How does a hyper crowned roller work?
• Do spiral tape bands, grooves, or ridges spread a web?

Introduction to Winding

• What is the purpose of winding?
• What is a good roll?
• What is a roll's buildup ratio?
• How can I calculate roll size or length?
• What are the torque requirements of winding?

The Winding Process

• What are the key process variables of winding?
• What is center winding? (and center unwinding?)
• What is surface winding? (and surface unwinding?)
• What is taper tension?
• What is nip-induced tension?

• What are the advantages of using a gap roller?
• What are the advantages of using a winding nip?
• Does a nip roller exclude air from a winding roll?
• How do web roughness and porosity affect winding?
• What is the best geometry for wrapping a winding nip roller?

• How does pressure build up as roll size increases?
• What are the key web and roll properties of winding?
• What is the stack or radial modulus of a roll?
• How is stack modulus measured?
• How is internal roll pressure measured?
• How much pressure is needed in a roll?
• How does core stiffness affect internal roll pressure?

• What are the most common winder designs?
• When is center winding used?
• When is surface winding used?
• When are winding shafts vs. chucks used?
• What is the best way to load or unload a roll?
  
• Why is winding two rolls on one axis difficult?
• What is differential winding?
• What should be included in a winder specification?

• How are automatic roll transfer completed?
• What is a zero speed splicer?
• What is a flying knife or stationary knife transfer system?

Cinching and Telescoping

• What is torque capacity and how much is needed?
• How is torque transmitted though the layers of a winding or unwinding roll?
  
• What causes cinching in a roll?
• How is torque capacity improved?
• What causes shifted layers in winding?

• What causes starring or spoking in a roll?
• What causes dimples in a roll?
• What causes knots in a roll?
• What causes roll dishing?
• What cause MD lines or ridges in a roll?

• What is roll hardness?
• How and why is roll hardness measured?
• How do crossweb thickness variations affect a roll?
• What is oscillation winding? Why do it?
• What makes winding difficult?