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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.

32 terms

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.

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.

The orifice ring and shears assembly that controls gob shape and weight at the gathering.

The first element after the gob former — receives the gob and directs it into the trough.

Channels the gob from the scoop to the deflector. Coating and surface condition matter for gob shape preservation.

Final element of the delivery train — directs the gob into the funnel of the assigned blank mould.

The entry port of the blank mould; centres and seats the gob before settle.

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.

The first mould in the IS forming cycle — forms the parison from the gob via either pressing (PB) or settle/counter-blow (BB).

The second mould — receives the parison and final-blows it into the finished container shape.

Forms the finish (sealing surface, threads, lip) of the container; transferred between blank and blow mould carrying the parison.

Closes the top of the blank mould during forming; on the blow side, seals the top of the parison during final blow.

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.

On blow-and-blow, settles the gob into the bottom of the blank mould via low-pressure air; controls bottom-of-bottle thickness.

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.

The mechanism that lifts the finished container from the blow mould onto the dead plate.

Cooling station between the blow mould and the conveyor; ware sits briefly before being pushed onto the conveyor.

Mechanism that transfers ware from the dead plate onto the cross conveyor. Timing here affects ware spacing.

One gob delivered to one section per cycle — the simplest gob configuration.

Two gobs delivered to one section per cycle, doubling output but requiring tighter mould equipment matching.

Three gobs per section per cycle.

Four gobs per section per cycle — top output configuration; demands very precise gob delivery and section timing.

An individual mould forming station within a section (single-cavity = 1 gob; quad-cavity = 4 gobs).

Targeted cooling within an individual cavity — typically via vertiflow, axial or stack cooling.

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.

25 terms

The transfer step where the parison is rotated 180° from the blank mould (top-down) into the blow mould (bottom-up).

The reverse of invert — used in some forming sequences.

Conveyor running across the IS machine output, carrying ware from each section to the lehr loader.

Distance between adjacent containers on the cross conveyor — critical for downstream handling without contact damage.

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.

The cylindrical-vs-tear-drop profile of the gob, set by orifice geometry and trough condition. Affects parison loading and wall distribution.

How the gob enters and seats in the blank mould; correct loading is the foundation of consistent parison formation.

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.

Low-pressure air pulse that seats the gob in the bottom of the blank mould (BB process).

On BB process, air introduced through the neck ring after settle to form the parison's interior cavity.

The high-pressure air that final-forms the parison against the blow-mould walls.

Vacuum applied at the blow mould to improve glass-to-mould contact during final blow; common on premium and complex shapes.

Active cooling of blank and blow moulds to extract heat from forming glass; vertiflow, axial or stack architectures.

Mould cooling architecture with vertical airflow through internal cooling fingers; high cooling rate, well-suited to high-output and lightweighting.

Cooling architecture with airflow through axial channels in the mould body.

Cooling via stacked plates around the mould; older but still used architecture.

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.

The sequence and duration of each forming step within a section; the master variable that ties all forming actions together.

The first half of the IS forming cycle — gob delivery, settle/press, parison formation in the blank mould.

The second half of the IS forming cycle — invert, parison reheat, final blow in the blow mould, takeout.

The frequency and duration of mould swabbing within a campaign — typically every 10–30 minutes depending on mould equipment and SKU.

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.

10 terms

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.

Alternative cold-end coating chemistry; applied as an emulsion or solution.

The annealing oven through which ware passes after forming to relieve internal stress through controlled cooling.

Mechanism that transfers ware from the cross conveyor onto the lehr belt with correct spacing and orientation.

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.

15 terms

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.

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).

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.

The physical swap of blank and blow moulds (and supporting equipment) between SKUs.

A campaign-level change between glass colours (e.g., flint to amber) — typically requires forehearth and feeder transition plus cullet management.

Synonym for SKU change in some industry usage.

A continuous run of a single SKU (or a colour/family) on a forming line — typically days to weeks long.

Synonym for job change — emphasises the SKU dimension over the equipment.

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.

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.

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.

24 terms

A heat-exchanger structure that pre-heats combustion air using waste heat from flue gas — the dominant furnace efficiency technology.

An alternative heat-exchanger to a regenerator; less common in container glass.

Furnace combustion using pure oxygen instead of air — eliminates nitrogen, reduces NOx, improves thermal efficiency. Common decarbonisation pathway.

Partial oxygen enrichment of furnace combustion (not full oxy-fuel) — incremental efficiency gain.

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.

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.

The mixed raw materials charged into the furnace — silica sand, soda ash, limestone, dolomite, feldspar, and other inputs.

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.

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.

Contaminating non-glass material in cullet (ceramics, metals, plastic) that causes defects if not removed.

The building and equipment where raw materials are weighed, mixed and conveyed to the furnace charger.

The mineral inputs to the batch — silica sand, soda ash, limestone, dolomite, feldspar, and minor additives.

Primary glass-forming raw material; typically 70–75% of soda-lime container glass batch.

Sodium carbonate — flux that lowers the silica melting point. ~12–15% of soda-lime batch.

Calcium carbonate — stabiliser in soda-lime glass. ~10% of batch.

Calcium-magnesium carbonate — adds magnesium oxide for chemical durability.

Aluminium silicate — adds alumina for chemical and mechanical durability.

Sodium sulfate — fining agent that helps remove bubbles from molten glass.

Conditioning

Forehearth, refining, gob temperature uniformity.

12 terms

The reduction-oxidation balance of the molten glass; controls colour development and bubble formation. Quantified by FeO/total iron ratio.

Stage of glass-making where bubbles (seeds, blisters) are removed via fining agents and elevated temperature.

Compounds (salt cake, NaCl, antimony) added to release gases that scavenge smaller bubbles to the surface.

Sodium sulfate, the most common fining agent in container glass.

Submerged channel between the melter and the working end — protects the working end from radiative heat from the melter.

Section of the furnace downstream of the throat where conditioning begins; feeds the distributor.

Channel that splits glass flow between the multiple forehearths feeding multiple IS machines.

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.

The cooling air feed positioned along the forehearth roof; controls top-to-bottom thermal profile.

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.

8 terms

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.

Pull rate divided by furnace area (TPD per m² of melter) — efficiency metric for benchmarking furnace utilisation.

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.

Repair work performed during operation (without cooling the furnace) — limited scope, used to extend campaign life.

Major repair requiring cooling of the furnace; smaller than a full rebuild but more disruptive than a hot repair.

The vertical exhaust passage from regenerator to atmosphere; emissions monitoring point.

Defects

Defect taxonomy and root-cause links.

24 terms

Solid inclusions in the glass — typically refractory, batch material that didn't melt, or recrystallised glass. Major rejection mode.

Visible streaks in the glass caused by chemical inhomogeneity in the melt.

Large gas bubbles trapped in the glass — typically from fining failure.

Small gas bubbles in the glass — visible but smaller than blisters; common at high pull rates.

Localised undissolved batch in the glass — a chemical inhomogeneity defect.

Surface or sub-surface stress fractures, often on the finish or shoulder. Result of inadequate annealing or thermal shock.

A small fracture or surface flaw, often on the finish.

Defect from ware sticking to the mould or to itself during forming or post-forming handling.

Visible mark on the bottle shoulder caused by misaligned baffle; cosmetic and weakening defect.

Cosmetic defect with a cage-like pattern, typically caused by mistimed settle blow during BB process.

Restricted internal opening at the bottle neck — affects fill rate. Usually a neck-ring or settle-pin issue.

Bottle that doesn't stand vertically — typically a result of invert-side timing or push-up issues.

Wavy pattern on the bottle wall caused by inconsistent settle pressure; BB-process defect.

Visible mark from gob cutting that propagates through the parison and into the final ware.

Ware sticking to the mould or to itself — typically a swabbing or mould temperature issue.

Wavy texture on the bottle wall — typically a blank-side cooling issue.

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.

Variance in fill height when liquid is added — driven by wall-thickness distribution and capacity variance.

How vertically the bottle stands — affects line handling and palletising.

Out-of-round bottle cross-section — typically a takeout or invert timing issue.

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.

7 terms

The thickness of the bottle wall, typically varied by zone (shoulder, body, base) and measured against a target spec.

Thickness of the bottle base — typically thicker than the side wall for thermal-shock resistance.

The concave indentation on the bottle base — provides vertical stability and increases base strength.

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.

Helical or rolled-on profile on the finish for screw-cap engagement.

Checks (stress fractures) appearing in the lehr — typically from inadequate annealing.

Cold end & inspection

Testers, scanners, palletising and packaging.

15 terms

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).

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.

Automated scanner inspecting the bottle base.

Automated scanner that inspects finish dimensional and cosmetic specs.

Automated detector for sub-surface stress fractures (checks).

Stress polariscope

Polarised-light test used to verify residual stress (annealing quality).

End-of-line packing of finished bottles into pallets ready for shipping.

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.

Packed pallets of unfilled containers, typically with layer pads and shrink wrap.

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.

18 terms

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.

Output rate of saleable packed ware (units per hour or per day).

Percentage of forming output accepted at cold-end / pack — closely related to pack-to-melt ratio but expressed at line level.

Mean Time Between Failures — reliability metric for forming equipment.

Mean Time To Repair — recovery metric for forming equipment.

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.

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.

Visual or audible signal that surfaces a problem in real time — typically a stack light at the line or a digital alert.

Workplace organisation discipline: Sort, Set in order, Shine, Standardise, Sustain.

Total Productive Maintenance — operations-and-maintenance discipline focused on reliability and operator-driven maintenance.

Continuous, incremental improvement — operationalised as kaizen events, daily kaizen, and structured improvement loops.

Single-page structured problem-solving format — problem, target, root cause, countermeasures, sustain.

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.

Distribution-based prioritisation — the 80/20 rule applied to defects, downtime, or improvement actions.

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.

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