How does Miraplast achieve consistent part quality in multi-cavity injection moulding, and why is the non-return valve crucial?

Miraplast Kunststoffverarbeitung GmbH – a company established over 60 years ago with sites in Würmla (Austria) and Hungary – is one of the first companies worldwide to use the latest product in the ENGEL inject AI portfolio in live production: iQ weight control plus.

The first deployment of iQ weight control plus on an ENGEL victory 80 demonstrated exactly what production professionals strive for:

• significantly simplified trial runs

• improved and reproducible injection-moulded part quality

• optimal balancing for multi-cavity moulds

• efficient injection moulding production despite a shortage of skilled workers

The results, expressed in figures, surprised even experienced set-up engineers:

• Production-grade quality achieved after just the second parameter iteration – Simplified trial runs using just two injection moulding process parameters, even without specialist staff

• 10% reduction in energy consumption per cycle – thanks to pressure-optimised and material-friendly process control

• 50% reduction in the decompression stroke during the injection moulding process – thanks to a non-return valve that closes reliably and repeatably

Consistently high injection-moulded part quality is crucial for the production of pipe clamp components using a 4-cavity mould. At the same time, process variations and the closing behaviour of the non-return valve make it difficult to achieve repeatable injection moulding production.

Typical challenges in day-to-day production:

• Surface defects and venting problems at corners and ribs

• Time-consuming sample testing requiring a high level of skilled labour

• Gradual process fluctuations caused by temperature changes, batch changes or the addition of masterbatch lead to process instability

• Unreliable closure of the non-return valve compromises the reproducibility of injection-moulded part quality

The key question was: How can process fluctuations be minimised, the closing behaviour of the non-return valve be stabilised and, at the same time, component quality ensured, without increasing set-up effort?

Miraplast Kunststoffverarbeitung GmbH employs around 80 staff at its main site in Würmla and operates 23 injection moulding machines, including 17 ENGEL machines. With a deliberately diversified product portfolio, the company cushions the impact of market fluctuations, for example in the automotive sector.

Using the iQ weight control plus software, the ENGEL victory 80 automatically adjusts the injection speed during injection moulding in real time to match the current flow resistance. The system makes targeted use of the physical characteristics of the process.

This results in an effect in the injection moulding process that has received little attention to date, yet is impressive: a significantly improved function of the non-return valve.

At the start of the injection phase – during the decompression stroke – there is virtually no flow resistance. iQ weight control plus utilises this time window to achieve maximum screw acceleration (up to approx. 80 cm³/s). This makes optimum use of the inertia of the stop ring: the non-return valve closes more quickly and reliably.

As a result, the decompression stroke was reduced by 50 per cent, giving Miraplast significantly more flexibility with the injection moulding unit.

Following this rapid initial phase, the system reduces the screw speed and fills the cavities gently under pressure control.

The results were fewer surface defects and cleaner moulding of corners and ribs thanks to improved venting. An improvement in quality that is immediately apparent from a simple visual inspection.

1) Improved part quality in injection moulding – visible without the need for measuring equipment

• Reduced risk of surface defects

• Cleaner moulding of corners and ribs thanks to improved venting

• Improved quality already verifiable through visual inspection

2) Rapid trial moulding – less reliance on skilled personnel

• Just 2 setting parameters for tuning the injection movement: injection pressure + switch-over point

• Production quality achieved after the second iteration

• High tolerance to insufficient balancing in multi-cavity moulds

• Pressure-controlled injection moulding: a cavity failure does not immediately lead to rejects in injection moulding production

3) Sustainable process stability and energy efficiency

• –10% energy consumption per cycle thanks to a smoother, pressure-optimised operating mode

• Automatic compensation for gradual process fluctuations such as temperature, batch changes or masterbatch thanks to integrated flow time control

• Long running times without manual readjustment

4) More reliable non-return valve function

• Faster and reproducible closing of the non-return valve

• Decompression stroke reduced by 50 per cent

• Greater flexibility and scope for manoeuvre with the injection moulding unit

The test results at Miraplast impressively demonstrate the potential of iQ weight control plus in real production environments, right from the very first use.

Read more about iQ weight control plus in an interview with development engineer Matthias Hüttler: How does iQ weight control plus simplify injection moulding?.