FEA

finite element analysis (+)

 

Flow-induced vibration

a phenomenon that occurs when turbulence or vortex shedding causes excessive vibration

 

Hand-arm vibration syndrome (HAVS)

prolonged exposure to excessive vibration, as from hand tools, causing reduced circulation, numbness and loss of fine motor control in the fingers (+)

 

Harmonics

integer multiples of a resonant frequency

 

Modal analysis

determining resonant frequencies, damping, and mode shape using the measured vibrational response to a given input force (+)

 

Operating deflection shape (ODS)

the shape of a structure during operation.  The shape may be determined for all frequencies combined, or for a specific frequency (+)

 

Pressure pulsation

pressure variations in a fluid

 

Predictive maintenance

regular, systematic equipment monitoring to predict when maintenance should be performed, to prevent unplanned shutdowns and expensive or catastrophic failures (+)

 

Resonance

the condition wherein a vibration amplitude is much higher for a given input force (+)

 

Self-excited vibration

a structure’s resonance, combined with a vibration feedback mechanism, may result in vibration occurring without an apparent source

 

Speed sweep analysis

mapping vibration amplitude and frequency in relation to machine speed to determine the source(s) of transient vibration (+)

 

Strain gauge testing

application of strain gauges to component parts to determine a material’s stress from static and dynamic strains

 

Torsional vibration

angular vibration of a shaft along its rotation axis, best analyzed using strain gauges with a telemetry system

 

Transient vibration

intermittent vibration typically associated with speed or process changes, and often due to resonance

 

Transient vibration analysis

see: speed sweep analysis

 

Vibration analysis

vibration analysis measures machine vibration at various operating conditions in order to anticipate (and prevent) damage (+)

 

Vibration audit

survey of current vibration to determine if a problem exists now or at potential future operating conditions (+)

 

Basis weight

mass per unit area, syn. grammage (+)

 

Calender barring

a self-excited vibration, in the audible range, that results in excessive vibration and caliper variations (+)

 

Calender stack

hard pressure rollers used to increase the smoothness and printability of paper; calender stacks reduce caliper (+)

 

Caliper

thickness of paper (+)

 

CD

cross direction; direction perpendicular to the path of paper. Compare 'machine direction' (MD)

 

Cockling

non-uniform sheet shrinkage resulting in visible patterns on the paper (+)

 

Crepe wrinkles

wrinkles that form in the interior of a paper roll (+)

 

Density

mass per unit volume (basis weight/caliper)

 

Grammage

mass per unit area, syn. basis weight (+)

 

Hard paper edges

hard edges arise from thick paper, insufficiently calendered at the roll ends due to overinsulated roll ends that have a smaller diameter than the remainder of the roll

 

MD

machine direction; direction parallel to the path of paper. Compare 'cross direction' (CD)

 

Misregister

misalignment of ink on paper product due to non-uniform paper characteristics

 

Oxbow effect

growth in end diameter of friction-heated calendar rolls

 

Press section

wet fibre web passes between large rolls loaded under high pressure to press as much water out of the material as possible

 

Process variability

the quality of a finished paper product is affected by variations in raw material, and in the manufacturing process itself due to equipment

 

Soft nip calendar vibration

a self-excited vibration typically caused by cover temperature variations or cover creep, resulting in caliper variations (barring) and increased roll maintenance

Soft paper edges

soft edges arise from thin paper, overcalendered at the roll ends due to overheating and expansion of the roll end diameters (oxbow effect)

Speed increase

an increase in machine speed is often desirable to produce additional product; a speed sweep analysis can enable optimization and avoid costly damage. it is wise to first predict the results of such an increase by performing a speed sweep, to determine the vibration characteristics of the structure (transient vibration analysis ) whereby the rotating elements of a machine are assessed for vibration response under change of speed conditions. (speed sweep analysis)

 

TAPIO testing

analysis of MD & CD product strips by TAPIO analysis helps find a correlation between the paper and print quality using long statistically significant sample sizes, solving cross direction variation, machine direction variation, random variation and printability problems

Throwout

excessive vibration may cause a process roll to be ‘thrown out’ of the pocket of a winder in which the axis of the roll sits (+)

Transient vibration analysis

see speed sweep analysis

 

TNT

tension, nip, and torque (TNT) are parameters that control wound roll structure (+)

 

Uniformity

uniformity of product is of fundamental importance to final product paper quality: in paper production, basis weight and caliper uniformity are most important. Without this uniformity a host of problems arise, including wrinkles, cockling, breaks, and misregister in the pressroom

 

Wet end audit

an evaluation focused on the design of the components of the wet end of a paper machine

 

Wet end survey

in-depth study of process components relevant to basis weight formation in paper production (+)

 

Winder vibration

winder vibration may cause slower than desired operating speeds, and may lead to roll throwouts(+)

 

Wound roll structure

paper on a roll must is subject to various stresses during unwinding, therefore the paper must be wound onto the roll according to precise controls to ensure quality and consistency (+)

 

Autogenous mill

An autogenous mill makes use of the self-grinding action of ore.  A rotating drum throws the ore in a cascading motion, which causes impact breakage of larger rocks, and compressive grinding of smaller particles. (+)

 

Ball mill

A ball mill uses steel (or rubber) balls to grind material.  A rotating drum carries balls up the rising side of the rotating shell, where they the fall upon the raw material below. (+)

 

Headframe

A headframe is the structural frame over an underground mineshaft, which allows people and materials to be hoisted between levels (+)

 

Jaw crusher

A jaw crusher breaks down material between a stationary 'fixed jaw' and a reciprocating 'swing jaw'. Oscillations can be small, as material is broken down with multipe impacts. A flywheel creates an eccentric motion with enough interia to crush the ore. (+)

 

Rod mill

A rod mill uses steel rods to grind material.  Jostling action induced by a rotating drum causes attrition of ore pieces against the steel. (+)

 

SAG mill

A Semi-Autogenous Grinding (SAG) mill uses both the self-grinding action of ore, and the impact of steel balls, to break down large pieces of ore into finer particles. (+)