Bottle making: Difference between revisions

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The very first article on compressors in PETplanet Insider came from LMF Austria (issue 1/2000). The company had developed and brought onto the market a new compressor design, delivering from 353-1,413 cfm (600-2,400 m³/h FAD). The basic aggregate consists of either a 3-stage VC type compressor for 353 cfm (600 m³/h) or a VCL type for 706 cfm (1,200 m³/h). Its total capacity can be doubled by adding a Roots blower as a booster. It is possible to adjust the blower motor capacity via a PLC control system to produce exactly the amount of air required at any one time (e.g. when the size and/or number of bottles per hour is not constant).  

In issue 4+5 AF Compressors explains why they chose an L-shape design for their compressors. The “L” shaped layout makes it possible for the number of moving parts to be reduced to a minimum. There are only two cross-head assemblies with two piston rods and associated bearings. The fact that the pistons at stages two and three are single-acting also means that a minimum number of valves are required. Having pistons 2 and 3 on the same piston rod means that the 40 bar stage (piston 3) does not require piston rod air packing seals between the 40 bar compressed air and atmosphere.

When Atlas Copco introduced their Petpack compressed air system in 2000 they took a novel approach by combining oil-free screw and piston technologies. In issue 4/2002 the company announced a new standard in cost effective bottle blowing with the introduction of Petpack VSD. The Variable Speed Drive technology in both the screw compressor and the piston booster introduces power savings.

Kaeser has created a system solution to satisfy the requirements for control and blow-moulding air at different pressures with the “Sigma PET Air” system, which consists basically of a low pressure stage (at least one fluid-cooled rotary screw compressor with a refrigeration dryer for the control air) and a high pressure stage (at least one booster with a high pressure refrigeration dryer) plus the necessary filters and condensate treatment equipment (issue 12). The screw compressors are fitted with modulating control, which ensures that the compressor’s air delivery always matches the air demand from the blow-moulding machine.

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A centrifugal compressor for PET bottle blowing was highlighted as a world first in issue 1+2. It is Ingersoll Rand who make compact centrifugal compressors available for PET bottle blowing at 40 bar. Reasons for that were their long life, due in part to an inherently simple and rugged design (there are only four basic moving parts – a bull gear and three rotating impeller assemblies); the dynamic compression process in which the air is compressed by converting velocity energy, imparted by the impeller, to pressure energy without any contact between mechanical components, ensuring oil and particle free air; the energy efficiency through the use of multiple stages in conjunction with constant pressure control operation.

1998 saw the introduction of the LMF EcoPET range of compressors with smooth speed regulation. Seven years later we reported in issue 9 on the extension of some models (from 950-2,700 m³/h) and the development of Eco-Speed-Control for efficient use of compressed air. A single-stage, oil-free, rotary blower is used as what LMF call their booster (the term booster normally being applied to the latter, i.e. piston stages of a multi-stage system). Its strong point lies in its ability to compress large quantities of air at low pressures. To cater for the periods under partial load, typical of a blowing air compressor, LMF developed and introduced the Eco-Speed-Control. The advantage of this system is that only the booster (rotary blower) is controlled by a frequency converter that matches it to the final pressure of the unit as a whole. This means that the piston compressor downstream is fed with less air, so reducing its power requirement proportionally.  

In issue 11+12, LMF Austria discussed the topic of air recovery and demonstrated the possible savings if the compressed air is fed directly back into the blowing compressor using the patented EcoPET C.A.R. (Compressed Air Recovery) after the stretch blowing process. The pressure level of the return air, which is available for further use, is between 6 and 18 bars, and the amount of air fed back into the compressor can be between 0-80%. This optimised air control system is made possible by the use of “smart” valves integrated in the compressor control circuit.

At the 2008 edition of Brau Beviale, Kaeser Kompressoren featured a powerful booster used to deliver air at up to 45 bar as well as the compact “Sigma PET Air” complete compressed air system for stretch blow moulders. Also on show was the Kaeser screw compressors and the “Sigma Air Manager” which controls and adjusts the flow and pressure from several compressors for maximum economy and efficiency (issue 10).

Gardner Denver Ltd used Drinktec to show its new VH25 oil-free compressor for PET bottle blowing and a new, low-maintenance, shaftless and water-cooled motor, as reported in issue 10. In common with other compressors in its VH range, the VH25 features its AirPET air recovery system, which is designed to accommodate a returned pressure from the blow moulding machine that can be recycled back through the compressor.  

Compressor coordination and regulation: In issue 4, ABC Compressors presented its works on savings in compressor central units and made recommendations to guide distribution line set-up. Coordinating the work done by all the compressors together helps to provide energy savings in a number of ways: it minimises the number of compressors running idle and the number of start-ups; it helps to stop machines that are not required and identify which compressors should be adapted to total air demand at any time; and covers possible compressor stoppages due to maintenance requirements or breakdowns.

The name is Vito. In PETplanet 1+2 we introduced Siad’s new compressor technology, the result of a complete re-think both of the design and production of an entirely new compressor concept. The new model should be suitable for all performance categories above 1,200m3/h, with variable speeds to ensure flexibility in production. Covering all performance ranges with just one compressor generates cost savings in the manufacturing process: a number of identical parts can be used. This of course includes the pistons, piston rod and crankshaft.  

With the launch of a new machine, the WH35 high-pressure reciprocating compressor, the celebration of Gardner Denver’s 45-years anniversary festivities at its Redditch, UK site, hit its peak, as we reported in issue 9. The oil-free system offering 2,120m3/hr at 40barG was claimed to bridge the gap between their WH29 model, with its output of 1,800m3/h and the WH40, with its output of 2,300m3/h.

Improved volumetric design and optimally balanced compression ratios were introduced in issue 3 by ABC Compressors and their Horizon models’ cylinders. To avoid losing energy in the transmission between the electrical motor and the compressor shaft, a direct coupled configuration has been constructed. Reducing the moving parts of the cylinders by 33% also affects the maintenance costs in a positive way.  

Induction motors, as used in compressors, have a very high starting current; often many times the nominal current. This can cause problems with plant power networks if, for example, several motors in the factory start at the same time. Using standard electric motors, AF Compressors addressed this problem in issue 1+2 with its SIS (Smart Inverter Starter). Developed by Ateliers François Liège, this inverter system for starting purpose only, ensures that the starting current never exceeds the nominal current and that the full load power never exceeds 100%. Another way to save energy is to adjust the air flow in cases where less than full air capacity is needed. AF’s Adjustable Air Flow System (AFS) does this by deploying a special working protocol around the acting compressor cylinder.

[[1 blow]] |

[[Arburg]] |

[[Atlas Copco]] |

[[Automa]] |

[[AVE Technologies]] |

[[Awanti Polymoulds]] |

[[Bahubali Group]] |

[[Bevazar]] |

[[BJY]] |

[[Boge Kompressoren]] |

[[Büsser Formenbau AG]] |

[[Caiba]] |

[[Maag]] |

[[MAG Plastic Machinery S.A.]] |

[[Mahathanee]] |

[[Manjushree Technopack]] |

[[PEGASO]] |

[[Petainer]] |

[[PETCO Gulf]] |

[[PET Engineering]] |

[[Saniton Plastic]] |

[[Samkin]] |

[[Schoettli AG]] |

[[Serac]] |

[[Torus]] |

[[TPS Tooling Preform Systems]] |

[[UAB Putoksnis]] |

[[Urola]] |

[[Vanta]] |

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'''Market survey are available for the following categories:'''  

{| class="wikitable sortable"

! Category !! Company !! Issue   

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| Compressors || [[Siad]] || [https://petpla.net/archive/PP202123?pp_page=28 Issue 07+08/2023]

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| SBM Moulds || [[Röders]] || [https://petpla.net/archive/PP202005?pp_page=33 Issue 05/2020]

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| [[Compressors]] || [[Siad]] || [https://petpla.net/archive/PP201907?pp_page=24 Issue 07+08/2019]