Monday 19th Aug, 2019

The advantages of flexibility in the bagging of bulk products

Incorporating real flexibility into an automatic bag-filling operation can allow a wide range of formats to be handled, while avoiding the high labour costs and low productivity associated with multiple manual systems.

Incorporating real flexibility into an automatic bag-filling operation can allow a wide range of formats to be handled, while avoiding the high labour costs and low productivity associated with multiple manual systems.

As bag filling companies grow and develop, it usually means moving from manual operations to fully automatic lines, often trading higher outputs for a more limited product range.

But productivity gains don’t need to be compromised, even when it comes to very short job runs, provided the new line has flexibility at its core. The ability to handle the widest possible product range isn’t just a desirable feature, it can be key in justifying the initial investment.

By applying experience and innovation, replacing manual adjustments by servomotors, linking individual elements into a single integrated network and harnessing programmable logic controller (PLC) power to aid line management, it is possible to provide a highly versatile automatic system that makes switching between formats both quick and trouble free.

Dosing

In circumstances where several products or an extended weight range up to 10 to 1 are involved, feed system design becomes vital. Using brushless motors to control aperture size, servomotors to adjust bed depth along with variable speed drives, it becomes possible for changes to the dosing rates for different products to be programmable. This reconciles speed and accuracy across the entire product and weight range. Even separate feed devices for free and non-free flowing materials can be provided.

Cleaning down to avoid cross-contamination can be done by quick access panels or automatic cycles using either hot water or air jets for hard to reach places, minimising downtime between grades.

Bag types and sizes

Different bag types, such as polyethylene or paper, with different closure methods can be handled on the same line. Heat sealing, sewing or hot-melt closure methods can be fitted in combination, selectable by program, and changeovers made automatically without the need for handwheel adjustments.

Hybrid systems are available where bags from a tubular film reel can be produced and filled together with pre-made PE and paper bags. This is common in dry pet food.

Changes in bag length are made by motorised adjustment to the sealing conveyor height, although width changes tend to be more problematic. The filling spout usually has to be sized for the smallest bag which can restrict the filling rate on larger sizes and create dust suppression issues when fine powders are involved, potentially limiting the range.

Automated packaging company Concetti has overcome this for granular products by using a variable-geometry spout, which adapts to a wide range of bag widths and with the opening size set by servomotor under PLC control.

Palletising and complete lines

A complete line will normally include a number of discrete elements, each with an individual PLC or controller. These are often systems for product dosing, filling, closing and palletising, but also could include optional items such as printing, labelling, weight checking, and pallet wrapping.

Individual machines work together easily when operating in automatic mode on a single format, but making changes is not always straightforward. Each may need programme or physical adjustments, placing an additional responsibility on the operator to set-up everything correctly, adding non-productive time and risking problems on restart.

But linking the PLCs and control devices through a local area network (LAN) can produce an integrated system where changes are made automatically from a single operator position through a keypad or directly from the user’s plant control system. Programmes are linked through the network and whole-line changes can be made in less than two minutes.

Product type, dosing weight, bag width and length, closure method, print details, weight check target and palletiser layer pattern are all adjusted or updated automatically without tools and consistently to the correct settings.

The network also enables data to be gathered from the lines, which can be used to log and review historical performance data and trends to help reduce plant shutdowns and raise productivity.

Support

Modern automatic lines are complex, and consideration must be given to maintenance and technical support. This is especially important in Australia with huge distances between urban centres.

To account for this, Concetti has a dedicated telephone and email hotline support service, which includes a teleservice facility. A recently developed application allows for real-time sharing of data and video. Local servicing has been augmented by collaboration with Melbourne based Automaint Solutions, located in Keilor Park. The companies work together to guarantee both telephone assistance managed directly by specialised Concetti technicians in Italy, and field interventions within a few hours, by Automaint engineers.