Glass Glossary
The Lean Glass glossary — every term that matters in container glass manufacturing.
190 industry terms, written by operators. Use it on the floor, send it to a new hire, cite it in a tender. Built for the people who actually work the hot end.
Forming & IS machine
Individual Section machine, gob delivery, mould equipment, takeout.
IS machine
The Individual Section machine — the dominant container glass forming machine. Each section forms ware independently, allowing one machine to produce multiple containers in parallel and offering redundancy when one section is taken offline.
Individual section
A self-contained forming station within an IS machine. Each section runs an identical forming sequence on its own timing cycle, decoupled from neighbouring sections.
Gob
A controlled drop of molten glass cut from the gathering and delivered to the IS machine for forming. Gob weight, temperature uniformity and shape are the foundational inputs to forming quality.
Gob delivery system
The mechanical system that transports gobs from the gathering to the blank moulds — distributor, scoops, troughs, deflectors and funnels in alignment.
Gob distributor
The rotating mechanism that allocates each gob to the correct section's blank mould in sequence around the IS machine.
Gob former
The orifice ring and shears assembly that controls gob shape and weight at the gathering.
Scoop
The first element after the gob former — receives the gob and directs it into the trough.
Trough
Channels the gob from the scoop to the deflector. Coating and surface condition matter for gob shape preservation.
Deflector
Final element of the delivery train — directs the gob into the funnel of the assigned blank mould.
Funnel
The entry port of the blank mould; centres and seats the gob before settle.
Parison
The intermediate hollow shape formed in the blank mould before being transferred to the blow mould for final shaping. Parison quality dictates final ware quality.
Blank mould
The first mould in the IS forming cycle — forms the parison from the gob via either pressing (PB) or settle/counter-blow (BB).
Blow mould
The second mould — receives the parison and final-blows it into the finished container shape.
Neck ring
Forms the finish (sealing surface, threads, lip) of the container; transferred between blank and blow mould carrying the parison.
Baffle
Closes the top of the blank mould during forming; on the blow side, seals the top of the parison during final blow.
Plunger
On press-and-blow, the plunger presses the gob to form the parison. Plunger setup is the highest-leverage variable in PB and NNPB processes.
Plunger mechanism
The actuator system driving plunger motion (servo or pneumatic). Controls press timing, profile and position.
Settle pin
On blow-and-blow, settles the gob into the bottom of the blank mould via low-pressure air; controls bottom-of-bottle thickness.
NNPB
Narrow Neck Press and Blow — a forming process using a plunger to form the parison; standard for lightweight beverage containers (returnable beer, lightweight wine).
BB (Blow-and-Blow)
Traditional process — gob is settled and counter-blown into a parison in the blank mould, then transferred and final-blown in the blow mould.
PB (Press-and-Blow)
Press-and-Blow (wide-mouth) — used for jars and wide-mouth containers; plunger forms the parison.
Wide-mouth press and blow
PB process variant for wide-mouth containers (food jars), with plunger forming the parison directly to size.
Takeout
The mechanism that lifts the finished container from the blow mould onto the dead plate.
Dead plate
Cooling station between the blow mould and the conveyor; ware sits briefly before being pushed onto the conveyor.
Pusher
Mechanism that transfers ware from the dead plate onto the cross conveyor. Timing here affects ware spacing.
Single gob
One gob delivered to one section per cycle — the simplest gob configuration.
Double gob
Two gobs delivered to one section per cycle, doubling output but requiring tighter mould equipment matching.
Triple gob
Three gobs per section per cycle.
Quad gob
Four gobs per section per cycle — top output configuration; demands very precise gob delivery and section timing.
Cavity
An individual mould forming station within a section (single-cavity = 1 gob; quad-cavity = 4 gobs).
Cavity cooling
Targeted cooling within an individual cavity — typically via vertiflow, axial or stack cooling.
Servo IS
An IS machine with servo-actuated motion control instead of pneumatic, enabling tighter timing and precision (NIS, AIS, SpeedLine variants).
Hot end operations
Process control, swabbing, mould cooling, ware spacing, timing.
Invert
The transfer step where the parison is rotated 180° from the blank mould (top-down) into the blow mould (bottom-up).
Revert
The reverse of invert — used in some forming sequences.
Cross conveyor
Conveyor running across the IS machine output, carrying ware from each section to the lehr loader.
Ware spacing
Distance between adjacent containers on the cross conveyor — critical for downstream handling without contact damage.
Gob weight
Mass of an individual gob, controlled by orifice ring and shear timing. Variance in gob weight propagates directly to wall-thickness variance in the final container.
Gob temperature
Temperature of the gob at delivery to the blank mould — typically 1080–1180 °C depending on glass colour and process. Variance ±5°C is acceptable; ±10°C+ degrades pack rate.
Gob shape
The cylindrical-vs-tear-drop profile of the gob, set by orifice geometry and trough condition. Affects parison loading and wall distribution.
Gob loading
How the gob enters and seats in the blank mould; correct loading is the foundation of consistent parison formation.
Parison reheat
The interval between blank-mould forming and blow-mould forming; the parison's surface heats from its core during this period — controls final blow viscosity.
Settle blow
Low-pressure air pulse that seats the gob in the bottom of the blank mould (BB process).
Counter-blow
On BB process, air introduced through the neck ring after settle to form the parison's interior cavity.
Final blow
The high-pressure air that final-forms the parison against the blow-mould walls.
Vacuum assist
Vacuum applied at the blow mould to improve glass-to-mould contact during final blow; common on premium and complex shapes.
Mould cooling
Active cooling of blank and blow moulds to extract heat from forming glass; vertiflow, axial or stack architectures.
Vertiflow
Mould cooling architecture with vertical airflow through internal cooling fingers; high cooling rate, well-suited to high-output and lightweighting.
Axial cooling
Cooling architecture with airflow through axial channels in the mould body.
Stack cooling
Cooling via stacked plates around the mould; older but still used architecture.
Timing drum
Mechanical or electronic drum that controls valve timing across the IS machine forming sequence.
Electronic timing
Digital control of valve timing; replaces mechanical drums on modern IS machines and enables servo-precision.
Section timing
The sequence and duration of each forming step within a section; the master variable that ties all forming actions together.
Blank side
The first half of the IS forming cycle — gob delivery, settle/press, parison formation in the blank mould.
Blow side
The second half of the IS forming cycle — invert, parison reheat, final blow in the blow mould, takeout.
Swab cycle
The frequency and duration of mould swabbing within a campaign — typically every 10–30 minutes depending on mould equipment and SKU.
Swab programme
Documented spec defining swab cycle, swab material, application method and quality check per SKU.
Automated swabbing
Automated swab application systems that replace manual swabbing on selected mould areas — improves consistency but does not eliminate the need for operator inspection.
Coatings & lehr
Hot-end and cold-end coatings, annealing.
Hot-end coating
A vapour-phase coating applied to ware at the hot end (typically tin tetrachloride SnCl₄ or monobutyltin trichloride MBTC) — creates a tin-oxide substrate that improves scratch resistance and primes the surface for cold-end coating.
SnCl₄ (tin tetrachloride)
Inorganic precursor for hot-end coating; reacts with hot ware surfaces to form a thin SnO₂ layer.
MBTC (monobutyltin trichloride)
Organotin precursor for hot-end coating; alternative to SnCl₄ with different thermal and emission profiles.
Cold-end coating
A polyethylene wax or oleic-acid-based emulsion applied to ware at the cold end (post-lehr) — reduces scratching and improves conveyor handling.
Polyethylene wax
Common cold-end coating chemistry; emulsion applied via spray onto cooled ware.
Oleic acid
Alternative cold-end coating chemistry; applied as an emulsion or solution.
Annealing lehr
The annealing oven through which ware passes after forming to relieve internal stress through controlled cooling.
Lehr loader
Mechanism that transfers ware from the cross conveyor onto the lehr belt with correct spacing and orientation.
Lehr profile
The temperature-vs-position curve through the annealing lehr; defines stress-relief quality and energy use.
Annealing checks
Surface or sub-surface stress fractures caused by inadequate annealing; visible defect mode.
Job change
Changeover discipline, SOPs, lifecycle, KPIs.
Job change
The transition between manufacturing one container SKU and another — including mould equipment swap, plunger setup, swab programme, forehearth re-tune, and first-ware capture. The single largest controllable source of hot-end downtime.
Job Change Tool
Lean Glass's purpose-built software combining SKU Library, Live Execution and KPI Tracking — the world's first systemised Job Change Tool for container glass.
Job change checklist
Documented step-by-step task list executed during a job change. Paper checklists are the legacy approach; digital, role-aware checklists (Job Change Tool) are the systemised replacement.
Job change SOP
Standard Operating Procedure governing the job change — defines roles, sequence, timing, and quality checks.
Job change lifecycle
The end-to-end discipline around a job change — planning (T-72h), pre-job SOP (T-24h), preheat (T-2h), execution, first ware, stabilisation and post-mortem (T+24h).
Job change KPI
Measured outcomes of a job change — typically changeover time, first-ware quality, percent-pack and OEE recovery.
Job change downtime
Time from final saleable ware of the previous SKU to first saleable ware of the next SKU — the headline KPI for changeover discipline.
Mould change
The physical swap of blank and blow moulds (and supporting equipment) between SKUs.
Colour change
A campaign-level change between glass colours (e.g., flint to amber) — typically requires forehearth and feeder transition plus cullet management.
Article change
Synonym for SKU change in some industry usage.
Campaign
A continuous run of a single SKU (or a colour/family) on a forming line — typically days to weeks long.
SKU change
Synonym for job change — emphasises the SKU dimension over the equipment.
SKU Library
The locked-in best-known-state spec set per SKU — gob weight, mould cooling, swab programme, plunger setup, takeout timing, hot-end coating dose, lehr profile, target changeover time. Core component of the Job Change Tool.
Live Execution
The live, role-based, timed execution of a job change driven by the Job Change Tool — every role sees their next step at the right time, with target timings and quality checks.
KPI Tracking
Real-time target-vs-actual tracking of changeover time, first-ware quality, percent-pack and OEE during and after a job change.
Furnace & melting
Furnace types, batch, cullet, raw materials.
Regenerator
A heat-exchanger structure that pre-heats combustion air using waste heat from flue gas — the dominant furnace efficiency technology.
Recuperator
An alternative heat-exchanger to a regenerator; less common in container glass.
Oxy-fuel
Furnace combustion using pure oxygen instead of air — eliminates nitrogen, reduces NOx, improves thermal efficiency. Common decarbonisation pathway.
Oxy-boost
Partial oxygen enrichment of furnace combustion (not full oxy-fuel) — incremental efficiency gain.
Electric boost
Electrical heating elements added to a fuel-fired furnace to supplement melting capacity. A common decarbonisation step.
All-electric melter
A furnace melting glass entirely with electricity — the deepest decarbonisation technology, but limited by network capacity and cost.
Hybrid melter
A furnace combining fuel-fired combustion (typically oxy-fuel or natural gas) with substantial electric boost — the practical mid-range decarbonisation pathway.
End-fired furnace
A regenerative furnace with burners on one end of the melter; common configuration.
Cross-fired furnace
A regenerative furnace with multiple burner pairs across the melter — used for high-pull capacity.
U-flame furnace
An end-fired regenerative furnace where the flame loops in a U-shape across the melter.
Batch
The mixed raw materials charged into the furnace — silica sand, soda ash, limestone, dolomite, feldspar, and other inputs.
Cullet
Recycled glass added to the batch — reduces energy use proportionally to its share. Internal cullet (own production) and external cullet (post-consumer) are distinct streams.
Cullet ratio
Percentage of cullet in the total batch; higher ratios reduce energy use but require quality control on contamination.
External cullet
Post-consumer recycled glass cullet sourced from kerbside collection or industrial returns.
Internal cullet
Cullet from the plant's own rejected ware — higher quality and easier to manage than external cullet.
Foreign cullet
Contaminating non-glass material in cullet (ceramics, metals, plastic) that causes defects if not removed.
Batch house
The building and equipment where raw materials are weighed, mixed and conveyed to the furnace charger.
Raw materials
The mineral inputs to the batch — silica sand, soda ash, limestone, dolomite, feldspar, and minor additives.
Silica sand
Primary glass-forming raw material; typically 70–75% of soda-lime container glass batch.
Soda ash
Sodium carbonate — flux that lowers the silica melting point. ~12–15% of soda-lime batch.
Limestone
Calcium carbonate — stabiliser in soda-lime glass. ~10% of batch.
Dolomite
Calcium-magnesium carbonate — adds magnesium oxide for chemical durability.
Feldspar
Aluminium silicate — adds alumina for chemical and mechanical durability.
Salt cake
Sodium sulfate — fining agent that helps remove bubbles from molten glass.
Conditioning
Forehearth, refining, gob temperature uniformity.
Redox
The reduction-oxidation balance of the molten glass; controls colour development and bubble formation. Quantified by FeO/total iron ratio.
Refining
Stage of glass-making where bubbles (seeds, blisters) are removed via fining agents and elevated temperature.
Fining agents
Compounds (salt cake, NaCl, antimony) added to release gases that scavenge smaller bubbles to the surface.
Sulfate
Sodium sulfate, the most common fining agent in container glass.
Throat
Submerged channel between the melter and the working end — protects the working end from radiative heat from the melter.
Working end
Section of the furnace downstream of the throat where conditioning begins; feeds the distributor.
Distributor
Channel that splits glass flow between the multiple forehearths feeding multiple IS machines.
Forehearth
The conditioning channel between the working end and the IS machine that delivers thermally uniform glass at the gob delivery point. The most critical conditioning element.
Forehearth conditioning
The thermal management of glass through the forehearth — temperature setpoints, cooling air distribution, riser configuration. Variance here propagates directly into forming defects.
Riser
The cooling air feed positioned along the forehearth roof; controls top-to-bottom thermal profile.
Gathering
The point at the end of the forehearth where the gob is formed and delivered to the IS machine.
Gob temperature uniformity
The variance of gob temperature across consecutive gobs and across sections — the headline KPI of forehearth performance. ±5 °C is good; ±10 °C+ degrades pack rate materially.
Furnace KPIs & life
Pull rate, campaign life, rebuilds.
Pull rate
The mass of glass melted per day from the furnace — typically expressed in tonnes per day (TPD).
Tons per day (TPD)
Standard furnace capacity unit. Container glass furnaces typically range from 100 TPD to 600 TPD.
Specific pull
Pull rate divided by furnace area (TPD per m² of melter) — efficiency metric for benchmarking furnace utilisation.
Campaign life
The operating life of a furnace between rebuilds — typically 8–14 years for container glass.
Furnace rebuild
Major capital event at the end of campaign life — refractory replacement, regenerator rebuild, electrical/control upgrade. Capital event of $20M–$60M+ depending on scale.
Hot repair
Repair work performed during operation (without cooling the furnace) — limited scope, used to extend campaign life.
Cold repair
Major repair requiring cooling of the furnace; smaller than a full rebuild but more disruptive than a hot repair.
Stack
The vertical exhaust passage from regenerator to atmosphere; emissions monitoring point.
Defects
Defect taxonomy and root-cause links.
Stones
Solid inclusions in the glass — typically refractory, batch material that didn't melt, or recrystallised glass. Major rejection mode.
Cords
Visible streaks in the glass caused by chemical inhomogeneity in the melt.
Blisters
Large gas bubbles trapped in the glass — typically from fining failure.
Seeds
Small gas bubbles in the glass — visible but smaller than blisters; common at high pull rates.
Knots
Localised undissolved batch in the glass — a chemical inhomogeneity defect.
Checks
Surface or sub-surface stress fractures, often on the finish or shoulder. Result of inadequate annealing or thermal shock.
Tear
A small fracture or surface flaw, often on the finish.
Sticker
Defect from ware sticking to the mould or to itself during forming or post-forming handling.
Baffle mark
Visible mark on the bottle shoulder caused by misaligned baffle; cosmetic and weakening defect.
Bird-cage
Cosmetic defect with a cage-like pattern, typically caused by mistimed settle blow during BB process.
Choked neck
Restricted internal opening at the bottle neck — affects fill rate. Usually a neck-ring or settle-pin issue.
Leaner
Bottle that doesn't stand vertically — typically a result of invert-side timing or push-up issues.
Settle wave
Wavy pattern on the bottle wall caused by inconsistent settle pressure; BB-process defect.
Shear mark
Visible mark from gob cutting that propagates through the parison and into the final ware.
Stuck ware
Ware sticking to the mould or to itself — typically a swabbing or mould temperature issue.
Washboard
Wavy texture on the bottle wall — typically a blank-side cooling issue.
Wavy finish
Distorted finish profile — typically a neck-ring alignment or temperature issue.
Dimensional defects
Out-of-spec dimensions on height, weight, capacity, or finish profile — caught at cold-end inspection.
Capacity (defect)
Bottle internal volume out of spec — affects customer fill operation.
Fill height
Variance in fill height when liquid is added — driven by wall-thickness distribution and capacity variance.
Verticality
How vertically the bottle stands — affects line handling and palletising.
Ovality
Out-of-round bottle cross-section — typically a takeout or invert timing issue.
Parallelism
How parallel the sealing surface (top of finish) is to the base — critical for vacuum integrity on twist-off and crown-finish bottles.
Glass distribution
How glass mass is distributed through the bottle wall — uneven distribution increases breakage and degrades dimensional consistency.
Container specs
Dimensional, structural and finish specifications.
Wall thickness
The thickness of the bottle wall, typically varied by zone (shoulder, body, base) and measured against a target spec.
Base thickness
Thickness of the bottle base — typically thicker than the side wall for thermal-shock resistance.
Push-up
The concave indentation on the bottle base — provides vertical stability and increases base strength.
Finish
The top of the bottle — sealing surface, threads or crown profile, and lip. Critical to closure performance.
Sealing surface
The flat top edge of the finish that contacts the cap or crown closure for seal integrity.
Threads
Helical or rolled-on profile on the finish for screw-cap engagement.
Lehr checks
Checks (stress fractures) appearing in the lehr — typically from inadequate annealing.
Cold end & inspection
Testers, scanners, palletising and packaging.
Squeeze tester
Cold-end test that compresses the bottle radially to detect weak spots.
Vertical load tester
Test that loads the bottle vertically to verify it can withstand stacking and handling forces.
Internal pressure tester
Test that internally pressurises the bottle (used for carbonated beverage and pressurised pharma).
Thermal shock
Test that subjects the bottle to a rapid temperature change to verify it can survive pasteurisation, hot-fill or freezing.
Dimensional gauging
Automated measurement of every container dimension at the cold end — height, width, finish profile.
Sidewall scanner
Automated optical scanner that inspects the bottle sidewall for cosmetic defects.
Base scanner
Automated scanner inspecting the bottle base.
Finish scanner
Automated scanner that inspects finish dimensional and cosmetic specs.
Check detector
Automated detector for sub-surface stress fractures (checks).
Stress polariscope
Polarised-light test used to verify residual stress (annealing quality).
Palletising
End-of-line packing of finished bottles into pallets ready for shipping.
Depalletising
The reverse — typically at the customer's filler, removing bottles from pallets onto the filling line.
Shrink wrapping
Plastic-film wrap applied to bulk-pack stacks for stability and dust protection.
Bulk pack
Packed pallets of unfilled containers, typically with layer pads and shrink wrap.
Layer pack
Pack format using inter-layer pads between bottle layers — common for premium cosmetic and spirits glass.
Lean & management
OEE, KPIs, leader standard work, problem-solving.
OEE
Overall Equipment Effectiveness = Availability × Performance × Quality. Plant-level rollup KPI used across container glass operations.
Pack-to-melt ratio
Saleable packed ware divided by total glass melted — the headline efficiency KPI of a container glass plant. Captures losses across forming, ware handling, lehr and packaging.
Pack rate
Output rate of saleable packed ware (units per hour or per day).
Percent-pack
Percentage of forming output accepted at cold-end / pack — closely related to pack-to-melt ratio but expressed at line level.
MTBF
Mean Time Between Failures — reliability metric for forming equipment.
MTTR
Mean Time To Repair — recovery metric for forming equipment.
SMED
Single-Minute Exchange of Die — discipline of structured changeover, adapted for container glass as the Job Change Lifecycle and operationalised in the Job Change Tool.
Gemba walk
Structured leader walk on the floor to observe work where it happens, surface issues, and reinforce standards.
Leader Standard Work
Documented daily/weekly/monthly cadence of activities expected of each leader role — what they do, when, with whom.
Andon
Visual or audible signal that surfaces a problem in real time — typically a stack light at the line or a digital alert.
5S
Workplace organisation discipline: Sort, Set in order, Shine, Standardise, Sustain.
TPM
Total Productive Maintenance — operations-and-maintenance discipline focused on reliability and operator-driven maintenance.
Kaizen
Continuous, incremental improvement — operationalised as kaizen events, daily kaizen, and structured improvement loops.
A3
Single-page structured problem-solving format — problem, target, root cause, countermeasures, sustain.
5-Why
Iterative root-cause analysis technique — ask 'why' five times to surface the underlying cause.
Root-cause analysis
Structured discipline of finding the underlying cause of a problem rather than treating symptoms.
Pareto
Distribution-based prioritisation — the 80/20 rule applied to defects, downtime, or improvement actions.
Standard work
Documented best-known method for performing a task — the baseline against which deviations are measured and improvements proposed.
30-minute call with a senior practitioner.
Bring a problem — leave with a direction.