The „Experimental Station for Special Cultures“ in Wies in southwest Styria in Austria, is a renowned institution of the province of Styria. For more than five decades the experimental station has been a reliable partner of vegetable and horticultural businesses. Practical experimental work provides results for vegetable producers, commercial gardeners and herb companies. A further focus is the preservation of old, rare crop varieties. The product range comprises around 700 species and varieties of herb and vegetable seeds.
Sorting of seeds is time-consuming and costly

The work of the experimental station is characterised by practical experiments, special cultures are examined in small quantities and many different batches make the process complex. In addition, the seeds to be processed are differentiated according to size, colour and shape as well as to different degrees of contamination. The manual sorting of the seeds is time-consuming and causes very high personnel costs.
Highly modern colour sorting technology for small seed quantities

Sesotec ASM supplied the intelligent optical sorter QUASAR 1000 for the sorting of small seeds quantities. Thanks to the high-resolution true-colour cameras, the device can detect the finest colour differences with the highest precision and eliminate off-colours. This guarantees maximum purity with minimum loss of good material.

The sorter is very compact, the operation is easy to understand. Additional benefits are the good price-performance ratio and the excellent quality.
High-quality seed with less time and personnel costs

The installation of the intelligent optical sorter QUASAR 1000 has significantly improved the cleaning process in the test station in terms of accuracy and speed. The pre-cleaning is still carried out with simple devices, the post-sorting is no longer necessary and saves personnel costs. The whole process takes less time and gives a very high seed purity.
„Until now, we have sorted the seeds by hand and our team was busy with it for days. Definitely, the new sorter makes our work easier, which we are very pleased about,“ emphasises test station manager Doris Lengauer. "We are also very satisfied with the machine in terms of price-performance, operability and product results, as well as with the support provided by the Sesotec staff“.

There are many reasons to use recyclates, and thereby close the plastic cycle. However, the right process technology is needed to do so profitably. In the following, we explain the impact of impurities in recyclates, and how they can be avoided and eliminated.

Why recyclates increase profitability

Recyclates have many advantages – for processors, consumers and the environment. Although the price of recyclates fluctuates, it is generally lower than the cost of new materials. There is also a long-term trend towards greater environmental consciousness in society at large, which make it more important that companies actively address environmental issues. Customers notice the proportion of recyclate materials used, and some even demand their use, so companies are increasingly committing to using certain ratios of recyclates.

Recyclates accounted for approximately 12.3% of the total volume of plastics processed in Germany in 2017. An industry comparison shows that significant quantities of recyclates were used in agriculture (34.9%), construction (21.5%) and packaging applications (9.1%).* That is a win for the environment, because using recyclates preserves resources. It is clear that the circular economy is becoming an important megatrend. But to make use of recyclates and truly close the plastic cycle, they have to be constantly available in sufficient quantities, and meet certain quality standards. That still isn’t always the case.

“The recyclates available on the free market may contain a variety of polymers and even metals,” says Tim Hencken, CEO of Sitraplas GmbH, a producer of engineering-grade plastic compounds, who buys and uses recyclates every day (> Read our Case Study about Sitraplas here). But where do the impurities come from?

 A closer look shows that there are many sources of impurities in delivered recycled goods. One reason is that today’s packaging and products are often made from various types plastic, in a variety of colours and a range of materials. Beverage bottles and their lids are often made from different types of plastic. And plastic soap dispensers usually have a metal spring. If the different materials are not correctly identified, separated and sorted in the plastic recycling process, then they are mixed and shredded, and end up in recyclates.
What is the potential impact?

If the recyclates are impure, it has consequences. For example, foreign plastics can change the physical properties of products made from recyclates. That has a negative impact on product quality, leading to complaints. Incorrect colours result in discolouration, another reason for complaints. Metal impurities are the most common type of contamination in recyclates.

 They can damage machinery – resulting in downtime, production outages and financial losses. And they increase the use of replacement parts and maintenance work, which significantly reduces the service life of parts that come into contact with the product. In short: production becomes less efficient. “Impurities can, for example, clog screens or damage plasticising screws. We have to avoid that at all costs,” says Hencken.

How can metal impurities be avoided?

Plastics processors must consider how metal impurities can be reliably removed from recyclates. Since metal is often hard to identify in product flows, that is a significant challenge. Metal particles are virtually invisible when mixed in with granulate. However, there are other ways to detect them.
Recognising and interpreting signs
Specific signs that recyclates contain metals include the constant clogging of screens in extrusion or injection-moulding machines with metals, or the need to regularly clear screen changers of included metal or melt.

 Frequent blockages of injection-moulding tool channels by metal parts also indicate the presence of metals in the product flow. Metal inclusion in finished products is also a clear sign of contamination.
Implementing detection and separation
Plastics processors have a number of ways to prevent metal impurities. They can assess the quality of material from recyclers by inspecting incoming goods through the installation of material analysis and metal detection systems. Material analysis systems automatically examine and document the composition of incoming material, allowing the plastics processor to immediately determine and survey recyclate quality.

There are many reasons to use recyclates, and thereby close the plastic cycle. However, the right process technology is needed to do so profitably. In the following, we explain the impact of impurities in recyclates, and how they can be avoided and eliminated.

Why recyclates increase profitability

Recyclates have many advantages – for processors, consumers and the environment. Although the price of recyclates fluctuates, it is generally lower than the cost of new materials. There is also a long-term trend towards greater environmental consciousness in society at large, which make it more important that companies actively address environmental issues. Customers notice the proportion of recyclate materials used, and some even demand their use, so companies are increasingly committing to using certain ratios of recyclates.

Recyclates accounted for approximately 12.3% of the total volume of plastics processed in Germany in 2017. An industry comparison shows that significant quantities of recyclates were used in agriculture (34.9%), construction (21.5%) and packaging applications (9.1%).* That is a win for the environment, because using recyclates preserves resources. It is clear that the circular economy is becoming an important megatrend. But to make use of recyclates and truly close the plastic cycle, they have to be constantly available in sufficient quantities, and meet certain quality standards. That still isn’t always the case.

Why is quality testing necessary?
“The recyclates available on the free market may contain a variety of polymers and even metals,” says Tim Hencken, CEO of Sitraplas GmbH, a producer of engineering-grade plastic compounds, who buys and uses recyclates every day (> Read our Case Study about Sitraplas here). But where do the impurities come from?

A closer look shows that there are many sources of impurities in delivered recycled goods. One reason is that today’s packaging and products are often made from various types plastic, in a variety of colours and a range of materials. Beverage bottles and their lids are often made from different types of plastic. And plastic soap dispensers usually have a metal spring. If the different materials are not correctly identified, separated and sorted in the plastic recycling process, then they are mixed and shredded, and end up in recyclates.
What is the potential impact?

If the recyclates are impure, it has consequences. For example, foreign plastics can change the physical properties of products made from recyclates. That has a negative impact on product quality, leading to complaints. Incorrect colours result in discolouration, another reason for complaints. Metal impurities are the most common type of contamination in recyclates.

Plastic: part of the problem...part of the solution - Part 4: Efficient use of recyclates

They can damage machinery – resulting in downtime, production outages and financial losses. And they increase the use of replacement parts and maintenance work, which significantly reduces the service life of parts that come into contact with the product. In short: production becomes less efficient. “Impurities can, for example, clog screens or damage plasticising screws. We have to avoid that at all costs,” says Hencken.

How can metal impurities be avoided?

Plastics processors must consider how metal impurities can be reliably removed from recyclates. Since metal is often hard to identify in product flows, that is a significant challenge. Metal particles are virtually invisible when mixed in with granulate. However, there are other ways to detect them.
Recognising and interpreting signs
Specific signs that recyclates contain metals include the constant clogging of screens in extrusion or injection-moulding machines with metals, or the need to regularly clear screen changers of included metal or melt.

Frequent blockages of injection-moulding tool channels by metal parts also indicate the presence of metals in the product flow. Metal inclusion in finished products is also a clear sign of contamination.
Implementing detection and separation
Plastics processors have a number of ways to prevent metal impurities. They can assess the quality of material from recyclers by inspecting incoming goods through the installation of material analysis and metal detection systems. Material analysis systems automatically examine and document the composition of incoming material, allowing the plastics processor to immediately determine and survey recyclate quality.

Installing metal detectors with integrated separating units at the start of the production process, and at other critical points, protects products and systems by removing metals. State-of-the-art detection systems can identify and separate even the smallest metal particles. That is decisive, because the smaller the particles that are detected and eliminated, the better the protection against damage and complaints.

Magnet separators are also used, but are not sufficient on their own – because they only remove magnetic metals. They cannot eliminate stainless steel and other non-magnetic metals, such as copper, brass or aluminium. A magnet separator should, therefore, always be used in combination with a metal detector – to sort out iron in advance and thereby relieve the burden on the downstream metal detector.

Conclusion
The use of recyclates is increasing, making material analysis systems and metal detectors more important. The limited availability of recyclates forces plastics processors to acquire them from a variety of suppliers. That means uniform quality is usually not guaranteed. However, extremely precise analysis and detection systems allow plastics processors to purchase recyclates without risk, further increasing the profitability of their production processes. Ultimately, material analysis systems and metal detectors make an important contribution to cost-effectively closing the plastic cycle.

White Paper: Important factors when buying a metal detector for plastics processing machines
How easy is it to install the metal detector in the production line – and how easy is it for your staff to operate the device? In our white paper, we will take a closer look at these two factors and show you why you should take them into account when making your decisions.

All over Europe, electrical and electronic scrap is the waste stream showing the highest growth rates. Since electronic equipment contains the most varied kinds of materials, the recycling of such waste involves high demands with respect to separation and sorting processes. The German plant manufacturer MeWa builds state-of-the-art recycling plants for large international waste management companies.

In the United Kingdom MeWa realised a plant where old refrigerators, computers, vacuum cleaners, Hi-Fi systems, and other kinds of electrical waste are processed on two separate lines. For the recycling of high-quality plastics such as ABS (acrylonitrile butadiene styrene) or PC (polycarbonate) and of printed circuit boards MeWa uses three VARISORT N sorting systems made by S+S. "The decision to use S+S systems was based on the high output quality of these VARISORT systems. Only absolutely pure fractions can be sold at a good price in today's difficult times", explains Peter Mayer, sales manager - sorting technology at S+S Separation and Sorting Technology.

Innovative technology for outstanding value creation

Polymer separators of type VARISORT N are based on near-infrared technology. At the MeWa facility these systems in fully automatic operation separate plastic types from precrushed electrical waste. Optimally scattered on a fast-running conveyor belt this waste reaches the detection area of the near-infrared detector which determines and locates the plastic types of the passing pieces. The electronic evaluation unit determines the exact position of the unwanted types, and with accurate timing and positioning activates the corresponding nozzles of the air-blast unit. The user can freely select which types of polymers should be separated.

In one VARISORT sorting system the near-infrared sensor is combined with a colour sensor. With this multi-sensor system design the colour of the particle and its plastic type can be combined as sorting criteria, which results in an even higher separation accuracy for the pcb-fraction.

Recycling materials are economically efficient and environmentally friendly

S+S VARISORT N polymer separators are characterised by highest throughput capacities. Sorting is performed at a speed of up to 3m/sec. Air-blast valves that have been specifically developed for this application keep the loss of good material at an absolute minimum. In the recycling of electrical waste VARISORT N separators are an economically efficient solution for the reclaiming of high-quality plastic fractions and of the pcb-fraction. The resulting pure plastics can be profitably returned to the production cycle again, and valuable (precious) metals can subsequently be reclaimed from the separated printed circuit boards.

Flexible and future-proof solutions provided by S+S

Says Peter Mayer, sales manager - sorting technology at S+S: "Recycling companies that produce clean, economically-priced material have the biggest competitive advantage. Because of their outstanding flexibility VARISORT sorting systems are ideal for the sorting of electrical waste. No matter what type of electrical waste should be sorted in the current job, a VARISORT will always optimally perform the sorting task by employing different kinds of sensors. Since the markets for recycled materials are rapidly changing especially in the field of electrical waste, and since quality requirements for recycled materials are high, and recycled material has to compete with the price of new materials, the VARISORT sorting system with its flexibility is a future-proof investment here because the employed technologies are highly sophisticated and the systems provide high-purity material fractions."

S+S - an overview

S+S Separation and Sorting Technology GmbH of Schönberg, Bavaria, manufactures machines and systems for the detection/separation of contaminants, for product inspection, and for the sorting of material flows. Product sales primarily focus on the food, plastics, chemical, pharmaceutical, wood, textile, and recycling industries. S+S is one of the world’s leading suppliers with subsidiaries in Great Britain, France, China, Singapore, and in the USA, a representative office in India, and more than 40 agencies all over the world. The main factory in Schönberg presently employs 200 people.

RecyPET AG was established in 1998 and has operated Europe’s first bottle-to-bottle PET recycling plant in Fraunfeld, Switzerland, since September 2000. The PET recycling plant operates in accordance with the URRC technology developed by the United Resource Recovery Corporation (USA) together with Coca-Cola and has an input capacity of approx. 18,000 tonnes per year. Four further plants in Europe now use this technology.

 In Switzerland the collected beverage bottles are sorted in five sorting plants according to colour and quality, compressed into balls and delivered to RecyPET AG, among others, for processing. RecyPET’s goal is to close the material cycle for PET beverage bottles. The recyclate produced is used among other things for the production of new PET beverage bottles, food packing films, other films, etc.

S+S Separation and Sorting Technology supplied a metal separator of the type PETMAG to RecyPET as long ago as 2001. The PETMAG separates metal contaminants of all kinds from PET flakes. Since the flakes are also to be sorted according to colour, S+S, in close cooperation with RecyPET, adapted a colour sorting machine originally used in the glass recycling industry to the requirements of PET recycling. The result was the SPECTRUM colour separator. By means of double-sided inspection it was possible even to separate flakes contaminated with the slightest glue residues.

In 2010 the PETMAG metal separator, which during its ten years of operation caused service and spare part costs of barely 2000 Euros, was replaced by a combined system of the latest generation, the VARISORT COMPACT. Colour and metal sensors are combined with one another in this device.

The material to be examined is fed by means of specially adapted vibrating trough conveyors and unites the advantages of chutes and belt systems. This also makes it possible for the first time to remove rubber pieces from the material stream that are difficult to separate using chute technology due to varying friction. The superiority of VARISORT COMPACT over chute systemswith channels lies in the fact that the equipment is easy to clean and blockages due to larger flakes can virtually be ruled out. Even in the case of irregular parts or materials with different
coefficients of friction, the belt feeding system provides for pinpoint ejection in free fall at the end of the belt, after the material has been classified with the sensors. After evaluation of the relevant information, high-speed valves for the material discharge are activated with an appropriate time delay. By means of powerful compressed air pulses, the particles to be separated are diverted from their original drop parabola into a separate shaft.

In comparison to conventional belt sorting systems, the VARISORT COMPACT sorting system is characterised by a compact design requiring little space. Retrofitting in existing plants and the adoption of already existing chute devices is easily possible. The use of high-resolution sensors and state-of-the-art signal processing technologies allows high detection accuracy and the analysis of up to 500,000 parts per second. By means of the free-fall inspection, a very precise blow-out procedure can be realised even with high rejection rates. This is made possible by the large number of high-speed valves, which can perform up to 500 switching cycles per second.

For Kornel Büsser, production manager at the Swiss company RecyPET AG, the long-standing cooperation with S+S has proven its value: “The reliability and ease of maintenance of the S+S units convinced us, together with their performance, particularly in the separation of difficult contaminants.”V

At the K 2010 trade fair S+S presents contaminant detectors and separators for production and recycling

Schönberg, August 2010
At the K 2010 plastics trade fair in hall 10, stand 10E60, S+S Separation and Sorting Technology GmbH presents comprehensive separation and sorting solutions for the complete life cycle of plastics. The systems that are presented comprise metal detectors and separators as well as magnet systems for all production stages and conveying types in plastics processing, and contaminant separators for plastics recycling. With the main subject of "All about PET" S+S here focuses on PET processing and recycling. All the systems presented at the trade fair are highly sophisticated solutions that represent the result of 30 years of experience.

Reliable processes in PET processing and in the production of caps and closures
At the K 2010 S+S presents innovative solutions for the problem of protecting high-performance injection moulds for preforms or caps and closures against metal contaminations to increase the economic efficiency of the complete production process. In this field S+S presents two new systems:

With the Protector-XHT S+S has successfully developed a metal separator in high-temperature version for processing temperatures of up to 200ºC. The separator is installed directly at the inlet of the injection-moulding machine or after the drier and thus inspects all the fed materials at the last chance control point.

High-performance moulds, e.g. for bottle caps with up to 96 cavities (moulding nests) and more require metal separators with highest scanning sensitivity to protect the delicate hot-runner systems. For this application S+S has developed the Protector-HR metal separator.

Innovative technology for highest value creation in PET recycling
More than 80 percent of all the PET processing companies in Germany and more than 60 percent all over Europe use S+S separators for the reliable separation of contaminants. S+S sorting systems are ideal for PET flake sorting because they guarantee highest product quality that allows a further use of the recycled material in the food sector. Since quality requirements for recycled materials are high and such materials must be competitively priced against new materials, S+S sorting systems with their outstanding flexibility are a future-proof investment because they employ sophisticated technologies and provide high-purity material fractions.  

2011 was a good year for S+S Separation and Sorting Technology GmbH of Schönberg, Bavaria. With a growth of 15 percent S+S reaches a turnover of approximately Euro 34 million, the number of employees increased from 250 to about 300.

For 2012 S+S is planning some reorientation. At the beginning of the year the VTC group acquired a 70 percent interest in S+S, which formed the basis for the company's successful development. One important step is the organisational division into business units in line with the main operating sectors PLAST, FOOD, and SORTING. This allows S+S to even more focus on the requirements of the respective industry sector and to provide custom-made solutions for every individual application. In the year 2012 S+S furthermore plans to invest about Euro three million in building projects at the plant in Schönberg. For the first time in the company's history the number of employees at the company headquarters in Schönberg is expected to increase to clearly more than 300.

"Nine months after S+S became a member of the VTC group it is now clear that we have reached our objective of a healthy company that is optimally positioned for the future. S+S not only has ensured corporate succession, S+S also has established the basis for successful growth in 2012 and future years with the required investments in Germany and abroad", says S+S Managing Director Helmuth Frisch.

At the K 2016 plastics trade fair (hall 10, stand E60) Sesotec GmbH as highlights presents the RAPID PRO-SENSE metal separator and the RAYCON D x-ray inspection system – both fit for “Industrie 4.0” - to trade visitors. The Sorting Recycling business unit for the first time presents the modular FLAKE PURIFIER+ system for the sorting of plastic flakes.

“Industrie 4.0” a major topic in the plastics industry

The German VDMA association of the plastics and rubber machinery industry and its member companies, which also include Sesotec GmbH from Schönberg, at the K 2016 trade fair want to demonstrate “Industrie 4.0” by way of concrete

practical examples. They want to show to the trade which “Industrie 4.0” technologies are already successfully used to improve production efficiency in plastics and rubber machinery production, and what their advantages are for users.

Contaminant detectors networked in production facilities

Sesotec GmbH at the K trade fair presents the fit for “Industrie 4.0” RAPID PRO-SENSE high-performance metal separator. RAPID PRO-SENSE reliably detects and separates magnetic and non-magnetic metal particles even if they are enclosed in granulate and thus ensures the quality of plastic granulate and protects plastics-processing machines against damage and clogging. In terms of a "Smart Factory" the system can be integrated in networked production facilities.

For the quality inspection of finished plastic products Sesotec GmbH furthermore presents the newly developed RAYCON D x-ray inspection system.

This system x-rays injection moulded parts and inspects them for contaminations, incorrect shape, air inclusions, or missing components. The RAYCON D system also can be integrated in networked production facilities.

New generation of multi-sensor sorting system

At Sesotec's trade fair stand the new FLAKE PURIFIER+ sorting system is presented for the first time. Based on a modular concept this system allows the combination of all available sensors for contaminant detection: Sensors for metal separation, sensors for colour separation / sorting, and sensors for the separation and sorting by plastic types.

The "+" in the FLAKE PURIFIER+ system stands for optimised material infeeding for a more evenly distributed material flow and increased material throughput. The system also allows easier maintenance and integration. The "+" furthermore stands for the dust-proof system design and for the integrated connections for dust and label extraction which all provide increased efficiency in the recycling process.

For almost a year we intensively dealt with the requirements of DIN EN ISO 9001:2015 certification and particularly with our processes, and since 26 November 2019 it is an official fact: Sesotec received the DIN EN ISO 9001:2015 quality seal. We expressly thank all our employees for their support and for the work performed so far by every individual. Successful certification would not have been possible without this.

After certification is before certification
The DIN EN ISO 9001:2015 certificate is valid for three years starting from the time it is issued (with annual monitoring audits). After three years a re-certification audit is necessary to renew the certificate.