Commissioning an Extrusion Blow Molding Machine

A new extrusion blow molding machine arrives with a factory acceptance test certificate, a parameter book and a set of drawings. Three weeks later it is running, but nobody can say which parameters were settled on, which settings were changed during the night shift to get a stubborn part to release, or whether the machine ever ran continuously for long enough to prove it can hold a dimension. That is how a commissioning project becomes a warranty argument.

The cost of an informal commissioning is paid twice. First, a defect that would have been visible during a structured dry run — a chattering cylinder, a slow pressure build on a long air main, a temperature zone that hunts instead of holding — is absorbed into production and blamed on the material. Second, when something fails in month eight, there is no documented baseline to compare against, so every conversation about root cause starts from scratch and every claim about performance is unprovable.

Sailwin has built extrusion blow molding machines for 15+ years, with 500+ machines delivered into 60+ countries, CE marking, ISO 9001:2015 manufacturing and a 2-year whole-machine warranty, running from 0.5 L to 1000 L container capacity. Every machine is load-tested at the factory before shipment, and on-site installation and commissioning typically take 3 to 7 days with 7×24 remote support afterwards. This article sets out the commissioning sequence that protects both the machine and the warranty, and the evidence each stage should leave behind.

1. Why Commissioning Order Matters More Than Commissioning Speed

Extrusion blow molding machine commissioning is a sequence, not a checklist, and the order carries information. A dry run performed before any material is loaded isolates mechanical and electrical behaviour: valve timing, clamp motion, pressure build, temperature control. Once resin is in the machine, the same faults produce defects instead of clean measurements, and the engineer has to separate machine behaviour from material behaviour at the same time.

That distinction matters commercially. Most warranty disputes on blow molding machines are not about component failure; they are about whether a machine ever met its specification. A plant that commissioned informally has no answer, because the only figure anyone recorded was the cycle shown on the HMI on the day the last engineer left.

There are four conditions a commissioning sequence exists to establish, and each one has a stage where it is proven:

• The machine is mechanically and electrically sound before material is introduced, established during the dry run.
• The utilities are inside the machine’s envelope — air pressure, chilled water temperature, power quality — established during installation.
• The process can make a good part repeatedly, established during the mould trial and capability run.
• The plant can reproduce that process without the commissioning engineer, established at handover and training.

2. The Commissioning Sequence Stage by Stage

Sailwin schedules on-site installation and commissioning at 3 to 7 days for a standard machine, which is enough time for all seven stages when the utilities are ready before the machine arrives. The single most common cause of an overrun is not the machine: it is a compressed air supply that reaches 25 bar instead of the 30–40 bar the blowing system expects, discovered on the day the first parison is due.

3. The Dry Run: What to Prove Before Material Goes In

The dry run is the stage most often compressed to save a day, and it is the cheapest day in the whole project. With no resin in the machine, every observation is unambiguous. Cylinder motion is either smooth or not. The blow valve either opens and closes cleanly or chatters. Mold closing and clamping either build tonnage progressively or shock the frame. Heating zones either hold setpoint or hunt.

Cycle the machine through a complete sequence repeatedly and watch three things. First, valve and cylinder response — Sailwin machines use FESTO combi blow valves and SMC cylinders, and sluggishness at this stage is a pneumatic supply problem, not a valve problem. Second, pressure build and decay on the blowing circuit; a slow build is almost always an undersized or long air main, and it will look like a mould problem once parts are being made. Third, temperature control, which should hold about ±1 °C with barrel heating in the 90–115 °C band for typical polyolefins.

Record what you changed. The corrections made during a dry run are the first entries in the machine’s history and belong in the handover pack. One pattern stands out across 500+ delivered machines: machines with a written dry-run record spend less time in the first year chasing intermittent faults, because a comparison between “as commissioned” and “as found” exists.

A warranty covers components. It does not cover a process that was never defined. The parameter sheet you sign at handover is the document that makes both the warranty and every later optimisation project possible.

4. Mould Trial, Capability Run and Handover

The mould trial develops the process window for one specific part. Die gap and screw recovery are set against measured parison weight and wall distribution rather than by eye, melt temperature is set as low as the material’s processing window and weld line quality allow, blow pressure is established within the 25–40 bar range, and cooling is tuned until the part leaves the mould straight and stable. Every one of those decisions has a number behind it, and the numbers belong in the controller, saved per mould.

The capability run is where commissioning turns from opinion into evidence. Run the machine continuously at the target rate for a defined period with the actual material and the actual mould, and measure the output rather than watching it. Record cycle time, container weight at intervals, critical dimensions, wall thickness distribution and the reject count with the reason for each reject. That record is what a supplier and a customer can both sign, and it is the baseline against which every future complaint is judged.

Handover decides whether the plant needs the commissioning engineer again next week. Walk the operators through a real task: change a parameter and change it back, change a mould, start from cold, and interpret an alarm. Sailwin machines log 40+ parameters in real time, so training should include where that history lives and how to export it. A plant that can send a parameter history over 7×24 support channels gets a faster answer than one describing symptoms by telephone.

5. Case Study: A 30 L Machine Commissioned Without a Dry Run Record

A supplier of industrial containers took delivery of a machine for 30 L parts and put it straight into production. Weight variation appeared in week two and was attributed to the material.

Scenario based on a Sailwin customer project; site-specific figures available on request during engineering review.

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