Optimising the Contiform
Increasing production output by technical upgrades

The production output of existing stretch blow-moulding machines from the Contiform S series can be retrospectively upgraded by a series of appropriate measures. With additional features and technical upgrades, all second-generation Krones blow-moulding machines can be optimised at costs that can be recouped in a relatively short timeframe. Some of these measures ensure faster product change-overs, others increase the output per cavity, and others in their turn extend the machine’s useful lifetime while enhancing its overall availability.

PET containers still on the advance
The global market for PET containers is continuing to grow. According to calculations from the market research institute Euromonitor, the number of PET bottles produced will rise by around seven per cent a year up to 2009, when the volume will total almost 350 billion units (350,000,000,000), compared to 278 billion in 2005 and an estimated 288 billion in 2006. As the quantity of containers produced rises, the market for beverages bottled in PET containers expands to keep pace. So it’s all the more important to produce these PET containers as cost-efficiently as possible.

Front-runner in output upsizing
In the ten years of the Contiform’s history since 1997, Krones swiftly developed into a front-runner on the market. In 2002, Krones was the first manufacturer able to offer an output of 1,600 containers per hour and cavity. The same thing happened in 2004, when Krones was the first machinery manufacturer to successfully upgrade the hourly output per cavity still further, to 1,800. Now comes the good bit: this output of 1,800 containers per hour and cavity is available not only on new machines. On the contrary, with an upgrade job clients can modify their existing machines to achieve the current maximum speed of 1,800 containers per hour and cavity.

In parallel to this, Krones has developed some additional features as optional extras. Early in 2002, the first PreformCheck preform inspector was installed, followed the next year by the premiere of the Prejet preform rinser for cleaning the interiors of the preforms with ionised air, either as a single machine or in combination with the PreformCheck. Another additional feature introduced was the PET-View bottle inspector, integrated into the Contiform.

Fast change-overs
Contiform stretch blow-moulding machines will usually produce disparate formats for the clients concerned, involving different container sizes, shapes or colours. To ensure that the machines are quickly back in action despite frequent change-overs, Krones has developed a variety of upgrades, all designed to increase overall efficiency:

• A quick-change five-clamp gripper reduces the make-ready times for the grippers by up to 40 per cent, while at the same time enhancing the dependability of preform handling, since the inner diameter of the preform’s mouth may deviate by up to ± 0.2 mm from the nominal diameter. Any ovality in the mouth’s inner diameter can be compensated for within a harmless tolerance using the five-clamp gripper, thus upgrading the dependability of preform handling.
• With quick-change transfer clamps, the make-ready time per gripper can be cut by about 80 per cent.
• The make-ready time can be very substantially shortened by changing from the former screwed-on stretching stopper to the new plug-in version, calculated to produce time savings of approximately 90 per cent.
• Time savings of approximately 30 per cent can be achieved by a “Base Quick Change” upgrade. The mould base is replaced without any tools using Base Quick Change, merely with the assistance of a clamp lever, thus easing the operator’s workload.

Pressure curve recorder
When a Contiform is retrofitted with a pressure curve recorder, the reproducibility of the blow-moulding process improves at every single station. Any process deviations at a particular station are detected at an earlier stage. If a bottle is incorrectly blow-moulded, the blow-moulding process can be switched off prematurely, thus reducing the number of bottles rejected. This monitoring feature enables even small holes to be detected, and worn blow-moulding or snifting valves to be easily located. If the limit values are correctly utilised, this produces very good bottle quality control.

Preform rejection unit in the oven
When the machine is upgraded to include a preform rejection unit in the oven, it will remain in production mode even in the event of fit-on errors – there will be no emergency stops, thus minimising production downtimes and the resultant losses of preforms and containers, with concomitant cost savings, of course. What’s more, damage inside the machine is avoided, from staggering preforms, for example. Rejected preforms can be checked and a complaint passed to the manufacturer where appropriate.

Further technical upgrades

• Thanks to additional lubrication in the main cam, the lifetimes of the cam rollers and the main cam have been extended.
• Reduced noise levels at the oven extractor enable noise emissions to be cut by approximately three dB in the Contiform, referenced to the extraction system as the most significant source of noise.
• Earlier monitoring of the stretching rod ensures enhanced operational reliability for the machine. Lengthy downtimes can be avoided, thanks to early detection of wear and tear, which enables resultant emergency stops to be precluded.
• An intelligent automatic restart feature ensures a more consistent heating process after a stand-by phase. This helps to avoid preform rejects and disparate bottle qualities due to different preform temperatures.
• The Temperature Wizard is designed to ensure a substantially more constant heating process, and thus more consistent bottle quality thanks to consistent wall thicknesses, even under changing environmental conditions. Once it has been installed, too, the requirements for the operator’s specialist qualifications are significantly reduced.
• In the blow-moulding process for PET containers, high-pressure compressed air is a significant cost factor. So Krones has developed the Air Wizard concept to reduce the amount involved.

All these upgrades are designed to improve the cost-efficiency of the Contiform stretch blowmoulding machines and enhance the benefits for their users.