Packaging lines and machines

A typical packaging line includes several sections that are synchronized with each other, or work individually depending on the layout of the line and automation ratio. These sections can be the material feeding unit, consumer packaging machine, transportation packaging machine, single load unit and other devices related to lines which fulfill a process. Other devices in the packaging line can be for example the closing device, taping machine, sealing machine and labelling machine. Due to the complexity of the packaging line, it is very common that a line has one or more intermediate storages to maintain the production run with as low downtime as possible. A small storage before the most critical part of the packaging line can be a huge improvement in production volume. [1] Picture 1 shows the typical layout of a packaging line including several different sections.

Picture 1. Packaging line. [2]

1.2.1 Selection criteria

The package itself is a cost for the product manufacturer which drives them to make decisions on packaging selection. The possible alternatives in product packaging are [2]:

 Straight after the production line

 Packaging near consumer markets

 Using subcontracting in packaging

 Externalize packing

 Product without a package

The selection has to be made based on what is the most suitable location for packaging machinery, which in turn depends on the possible production facilities and products that need to be packed. If the packaging machinery is located directly after the production line, it has to be fast enough not to slow down the whole process. But with some products, such as in the food industry, it is necessary to pack the product immediately after the production line has accomplished manufacturing the product.

High expectations of quality and quantities set demands for the packaging line manufactures to meet the requirements of packaging companies, as well as of end users.

The greater the demands, the faster the machines are expected to create packages.

Therefore, mechanical durability plays a great role already during the packaging process and not only after the product has been packed. [5] Mechanical durability is necessary in order to maintain the desired production speed with as low downtime as possible.

Automation in packaging machines together with complex mechanics is also an essential part of the whole system.

The product itself is one of the main criteria in packaging line and machinery selection, in addition to the rate of production, logistics, market location, customer demands and the expertise of the packaging company [1]. In machinery selection, it is highly recommended to gain as much information as possible about the product itself. The importance of product specification is on as high a level as selecting the packaging materials [4]. Before starting packaging, a company has to form a deep calculation of the needed capital, operating expenses and possible waste expenses, not forgetting the

risk analysis for the machinery. Over time, operating costs in packaging transactions rise compared to what they are when the initial investment is made. The required amount of operators to run the machine is an essential part of the operating expenses, and it is fairly common that small companies use very simple machines that require more manpower. Fully automated packaging lines are dependent on the production volume, for the reason that a single investment is substantially higher than it is in less automated machines. A fully automated packaging line can be an enormous investment in the beginning but offers many benefits, such as better package uniformity and quality, improved hygiene and fewer downtime periods. [1]

Picture 2 represents the main criteria for packaging line selection in addition to the product features. As stated before, the package itself is one of the directive variables in the packaging line selection.

Picture 2. Selection criteria of a packaging line. [1]

Many packaging machine manufactures are rather small and specialized in a certain sector. Another common feature for packaging machinery is that packaging machines, products and packages are tailor-made according to the customer’s needs and required product features almost every time. Tailor made machines mean that there is no serial

Selection

production and the supplied machines are delivered in small batches, with a few exceptions in the industry.

A packaging machine covers multiple phases and separate axes for different tasks.

Frequently, the axes need to be synchronized with each other and in the past these were usually driven by one single mechanical power shaft wherefrom the ratios for different parts of the machine were implemented with levers. This means that when the power shaft is on the move the other phases are also moving with the defined ratio. It provides very accurate synchronization where the axes are always in the desired position. In modern packaging machines the control of different axes is done by using motion control products for controlling several induction or servo motors.

It is very common that a packaging machine is controlled from one computed system.

One common feature of modern packaging machine control is that all the axes are working in a closed loop. The definition of a closed loop is that a motor is equipped with a device that provides motor shaft position feedback to the system, which makes the process more accurate and faster. The controlling signals from the main system to the motor controllers are usually sent in digital, analog or fieldbus forms. [1]

Packaging speeds in modern packaging machines are respectably fast. For example, a wrapping machine wrapping sweets is able to wrap more than 1000 sweets per minute;

this cannot be detected with the human eye due to the high speed. The starting point in packaging machine design is to give a target speed defining how many packages or how many kilograms have to be packed during a given time frame. The target can be defined in pieces, weight or units requiring packaging in a given varying time period between a minute and one year. Despite the demanding targets on machinery speed, the designed maximum capacity is not always the setting that is used in production. A line is made up of several different parts which need to run together smoothly. [1] There might be sections or single tasks that are not as fast as the single packaging machine, so the production speed is limited to the lowest part of the line. If a single machine is working alone it can be ran at full speed, but seldom are machines running at the designed maximum speed. There are other important points to consider regarding production speed, such as a decrease in quality, and the number of incorrect packages; both of which are more likely to occur as the machine speed grows. [5]