Independent hot end audit: what it examines and what it reveals

An independent hot-end audit gives the technical director, production manager and maintenance team a shared basis for deciding what to do next. It does not begin with a proposal for a new machine. It begins by defining the operational problem, its possible causes and its effect on quality, throughput, energy use and line availability.

Why a hot-end audit looks for the causes of losses

The hot end runs from the forehearth through gob delivery and forming to the point where bottles or jars enter the annealing lehr. Variations arising along this part of the line may later appear as defects, rejects or unstable output.

Depending on its scope, a hot-end audit may examine gob weight and shape, delivery into the mould, section timing, mould cooling and product changeovers. It may also review downtime, maintenance history and how the forming machine interfaces with the conveyors and annealing lehr.

A supplier that assesses a plant while also selling its own equipment may face a conflict of interest when recommending replacement. An independent hot-end audit considers the equipment, process data and operating practices together, without assuming the answer in advance. The outcome need not be a new machine: it may be a settings change, additional measurement, replacement of a worn component or a retrofit of one part of the line.

How a hot-end audit works, step by step

The first step is to define the problem. Before the site visit, the glassworks provides information on its product range, capacity in tonnes per day, shift pattern, forming processes and breakdown history. Recipes, defect records, energy-use data, maintenance records and available drawings are also useful. On site, the audit team observes the line in operation and compares what it sees with the supplied information.

1. Define the brief: Identify the specific variation, how often it occurs and its operational impact.
2. Check gob formation: Assess the feeder, plunger, shear mechanism and gob cut-off timing.
3. Inspect gob delivery: Check the scoops, troughs and deflectors in the delivery system.
4. Analyse forming: Review section synchronisation, the forming cycle and mould cooling.
5. Check downstream interfaces: Assess the cross-conveyor, servo stacker and entry to the annealing lehr.

At the feeder, the team checks how consistently gobs are delivered to each section. The audit therefore looks beyond the feeder itself to its settings, timing and interaction with the delivery system and the rest of the forming line.

Beyond the forming machine, the assessment continues with container spacing and arrangement ahead of the lehr. Poor coordination between the cross-conveyor, servo stacker and lehr entry can affect the conditions under which containers are annealed. That interface belongs within the audit’s scope.

What the audit examines in BB, PB and NNPB processes

Blow and Blow (BB), Press and Blow (PB) and Narrow Neck Press and Blow (NNPB) are established container-glass forming processes. NNPB can support lightweight bottle production. A hot-end audit therefore cannot rely on a single checklist: it must assess parameters against the particular container, mould set and process recipe.

• BB: Assess gob consistency, glass distribution, cycle stability and mould-cooling conditions.
• PB: Check movement timing, the pressing stage and its transition to subsequent forming.
• NNPB: Review the stability of narrow-neck pressing, glass distribution and the process conditions needed for lightweighting.

The same visible defect can have several causes. It may be linked to gob weight, the delivery system, section timing or mould cooling. Cold-end inspection can detect the defect; a hot-end audit aims to establish where the variation is most likely to originate.

Technical consultancy for a glassworks brings defect records together with recipes, equipment condition and observations of the forming cycle. That connection helps distinguish a symptom from its process cause. Without it, an intervention may address only the visible fault.

How to turn audit findings into an investment decision

Hot-end audit findings can be ranked by urgency, expected operational impact, cost and the downtime required to act. Plant management can then weigh immediate operating changes against work that needs planned investment.

• Adjust settings: Change the recipe, timing, cooling or equipment synchronisation.
• Replace components: Renew worn parts that affect process consistency.
• Upgrade a unit: Retrofit the feeder, controls or container-handling equipment on the existing line.
• Modernise the line: Replace equipment where targeted changes will not remove the main operating constraint.

Recommendations can be expressed in plant measures such as reject rate, downtime hours, compressed-air consumption, throughput and maintenance costs. A substantial investment should be supported by a total cost of ownership (TCO) calculation based on the glassworks’ own data, rather than a generic savings claim.

A structured audit report can also help procurement and central engineering teams compare options, prepare a technical specification and assess suppliers. An initial audit may be followed by a feasibility study.

What a useful hot-end audit report contains

The final report sets out the current operating position, principal bottlenecks, available evidence, existing problems and development plans. T&T, Turnov s.r.o. presents its findings and recommendations to the glassworks team in a report and management presentation. Depending on the scope, it may also include a diagram of the gob-delivery path, a list of critical units, photographs or a proposal for further measurement.

T&T, Turnov s.r.o. specialises in hot-end audits and BB, PB and NNPB processes. Work can continue through external or on-site consultancy within an agreed scope. For an initial assessment, you can send a description of the bottleneck, operating data and available documentation through the T&T enquiry form. An audit is a first step in assessing the operation; it does not commit you to buying T&T equipment. You can discuss the next steps via the contact page.