The heat is on … Charl du Plessis and Kevin Marle are chuffed with Purple Line’s new PP stretch blow moulding system; the preforms are heated in infrared tunnels before entering the blowing stations.

Purple Line goes 2-stage, again … this time with PP

PURPLE LINE PLASTICS, the Cape small container manufacturing specialist, has achieved another coup with the introduction of new technology for the 2-stage stretch blow moulding of polypropylene containers, possibly the first in South Africa to do so.

Purple Line MD Charl du Plessis and ‘lieutenant/sheriff’ Kevin Marle have been operating the company in Triangle Farm, Cape Town, since 2002 and at no stage has the improvement process slackened. It has in the process achieved a number of successes, the most recent of which prior to the current project was in 2015, when it commenced with the production of PET containers on a similar two-stage process. To manufacture two stage jars in PP, it was decided to request that the Machine Manufacturer develop and design dedicated technology for the PP work, where the melt point and heating parameters are different to PET.

The result of this was the commissioning recently of the new line. Although PP, even with clarifying agent, does not achieve the crystal clarity of PET, it does offer a number of advantages for specific cosmetic containers.

With the preforms being manufactured separately on-site, the advantage is that preform stock can be built up which takes less space than finished Blow Moulded Jars. The easy to start and operate blow moulding process can cater for smaller and quicker turn around times. The company continues to surprise it’s customers by turning large late orders, such as going into the Christmas season, with in-time turnaround and personal service.

Further advantages of using stretch blow moulding for the PP containers, as compared to extrusion blow moulding, is that seam lines are eliminated and there is no need to trim lost heads or flashing scrap.

In one of the first jobs run on the new machine are 500ml cosmetic jars. A further advantage is that no hydraulics are used, reducing the maintenance requirements.


Rejigged layout

Purple Line has also just completed the rejigging of its plant layout. Du Plessis, who has been involved in blow moulding for more than four decades, and Marle have continuously been working at improving the ‘flow’ through the factory. Mind you, they have also expanded into adjacent halls over the past few years. The team is now happy that efficiencies have been improved to the point that they are finally achieving close to maximum performance from their plant.

Purple Line is also using recycled PET in many of it’s containers and last year completed a first off Christmas order for a new brand of gin baubles in a record time. It was the only company that could supply this product into the market within six weeks of conception – mould manufacture and production in 5 different colours!