All-electric double stage stretch blow moulding series for high quality bottles

India’s Shyam Plastic Machinery has expanded its Pristine series further and added a 16-cavity, 400 bpm blowing variant in the beginning of 2023. The all-electric double stage stretch blow moulding machine christened as SP-Pristine 16-0.25 series-II - which was designed and manufactured indigenously - emerged as a highly reliable line to efficiently manufacture high quality PET bottles. The new model was unveiled and earned positive reviews at India’s premier plastic exhibition, Plastindia 2023, held in New Delhi in February. With the introduction of the high-capacity model Shyam Plastic emerged as the first Indian company that produces all-electric machines for PET bottles ranging 6,000 to up to 24,000 bottle per hour.

High efficiency levels

The Pristine line uses multiple servo axes, in synchronous mode to optimise mechanical movement and timing, resulting in reduced mechanical functions time and allowing more process time to achieve higher productivity. The preform loading system and heating conveyor is based on continuous movement, which removes the conventional pneumatic reciprocating movements. As a result, it eliminates abnormal wear and tear of moving parts whilst also reducing air consumption.

According to the Ahmedabad-based Shyam Plastic, the servo Pristine series machine is not using any hydraulic or pneumatic technology in moving operation, resulting in at least 25% to 30% energy efficiency levels compared to competing machines in the market using hydraulic or pneumatic moving operation. Moreover, there is no need for low-pressure air in the Pristine series due to its air recovery feature, thus saving energy.

The entire machine is based on Neck Hold system, right from preform entry to bottle ejection, which has great advantage against Body Holding of preforms and blow bottles. It enables a reduced number of change parts and mould change over time and efforts.

The Penetration Zone followed by precise power-controlled zones provides accurate and efficient heating of preforms; while auto-controlled variable speed ventilation blowers also greatly contributes to precise heating control. This Close Loop Heating System is a unique feature in its segment.

The machine offers Servo Stretching system, with individual fast responses blowing valve sets per cavity for precise stretch-blow process control, which is a primary requirement for better material distribution.

Interestingly, reduction of pneumatic components and reciprocating movements, together with the use of servo motors for all major functions, result in reduction of impact and noise levels.

The machine is enclosed on all sides and also from top to prevent dust from setting in to machine components. Reduction of dust level reduces maintenance requirements and increases life of all moving components. Machine covered from top is again a unique provision in the segment.

Ease in mould change over and maintenance is one of the primary criteria taken care while designing the machine. The ergonomically designed machine provides a safe and convenient working level for the operators and maintenance personnel. Necessary safety features like easily visible emergency mushroom buttons, machine mode switch limit switches in guards are part of standard equipment.

Low energy consumption

Blow air recovery is provided in all cavities so that part of high-pressure blowing air is re- collected back before exhaust. The same air can be used either for pre-blow or supplied back to the booster compressor as designed and desired. The usage of servo motors replaces major pneumatic components that consume enormous compressed air, resulting in negligible air consumption, and hence highly reducing production cost. The operation air is less than 8 CFM (which is 1/5 th as compared to conventional machines) is easily recovered by the blow air recovery feature, still leaving extra air for the other re-use.

Reduced pitch in the oven allows for greater number of preforms in the given heating area, and hence efficiently heat preforms using less heat, with minimal heat loss.

Functioning of machine

A preform hopper is connected to the elevator conveyor, which takes preforms to unscrambler (orientation unit). The roller type unscrambler orients perform and send into the loading channel. The loading channel supplies preforms to loading tunnel wheel, which in turn loads preforms to

oven mandrels.

Loaded preforms are heated using 6 heating modules, each comprising 6 heating lamps with modules 1-3 are penetration zones and modules 4-6 are distribution zone. Perform spreading is done by servo-controlled spreader assembly. While preform transfer and bottle ejection are done by servo- controlled transfer mechanism. Servo-operated mould clamp system, together with blow air compensation ensures fast movement of mould platens and also minimal parting line. Blown bottles are inserted into an air conveyor connected to a machine.

Container and preform specification for 16 Cavity/0.25 Liter

As per company, the machine operates on 400 bpm speed at 24,000 bottles/hour production capacity. Shyam Plastic claims to be the first company in India to introduce a high speed all- electric pet blowing machine with production capacity of up to 24,000 bottles per hour.

For such a high output machine, there was only an option to go for a rotary blowing machine which involves huge investment and not affordable to all. Therefore, Shyam Plastic has developed high speed linear blowing machine which is cost-effective in terms of capital investment, running and maintenance cost as compared to rotary machines.

The machine has application in water, CSD, juice and liquor industry. The 16-cavity variant has nominal bottle volume (max) of 250 ml, max. bottle height (H) 250 mm, max. bottle dia (D) 56 mm, max. preform neck diameter (D1) 30 mm, max. preform support ring (D2) 34 mm, max. preform neck height (H1) 21 mm and max. preform body height (H2) of 120 mm.

It could produce 24,000 water bottles per hour of 250 ml water bottle (in 16 cavities) and 12,000 water bottles per hour of 500 ml (in 8 cavities) with output varies with bottle design and preform weight and design. The company also offer guaranteed production efficiency levels of 95%.

According to the company, quality of blow moulds contributes to the bottle quality and production rate and hence it recommends that blow moulds are manufactured by Shyam or one of the registered suppliers of the company. Material of mould provided by Shyam is Aluminium HE 20 Grade as standard supply on customer’s request. While Alumec 89 can be used by Shyam at additional cost.

The interactive user interface allows the authorized user to use the machine interface to order spares, access machine manuals and also track spares order status. Machine interface can also be used by the operator to communicate online for support. The company is also developing interface feature that will provide reminders for preventive maintenance based on usage hours of the machine.

Future plans

Shyam Plastic’s next target is to introduce rotary blowing & filling combi line in the range of 500 bpm by 2024. Currently, its Gujarat site produces 90 to 100 multi-cavity fully-automatic blowing machines per year. It has more than 130+ Pristine series machines installed and are successfully running for various PET bottle packaging solutions. The clientele includes various prominent corporate brands like Bisleri, Parle Agro, Reliance, Coca-Cola, Archian Foods, Megha, Dawat and many more. The company has global presence in 42 countries across the globe which includes Europe, UK, Middle East, Africa etc.