I need to buy a waste shredder. What kind should I choose?


Source: Tana Oy

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Buying a waste shredder can be quite a challenging rehearsal. There are plenty of technologies and manufacturers and all claim to provide the best solution. The needs of today can change quickly and nobody wants to end up finding out having invested a lot of money in a machine that is not fit for purpose. We'd like to bring up some aspects worth considering when buying a shredder.

I need to buy shredder… but what kind? Today’s market is overwhelmed by different kinds of shredders, grinders, fast-speed, slow-speed, chippers, pre-shredders, primary shredders, tub grinders etc. Choosing the right one for your business can be extremely difficult. They all come with their own basic technology, horse power, rotors and settings. All these features will typically take you off the track when thinking about what this machine needs perform and how does it make you money.

Let’s start off with making money! First you need to look in to the investment costs and operational costs before actually calculating your cost per ton. The cost per ton is a simple figure that helps to understand your end product selling price and gives you a chance to calculate your profits. This is also the easiest way to compare different shredding processes and systems to eachother. Below is a cost calculation comparing two different solutions. Shredding solution 1 requires only one machine to produce the wanted particle sizes and the second solution requires a trommel screen in addition to the shredder to produce the wanted end product.

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As you notice the shredding solution 1 will provide higher profits. You should base your decision making on the profitability that the machinery can provide. The waste shredding business is always simple maths between two different units.

The second issue when choosing a right type of shredder or grinder is the end product it can produce. As your customers are very particular with what kind of material they want in their recycling process, you should carefully examine the end products that the solutions can provide you now and in the future. As the recycling processes will change every year, the solution you choose needs to adapt to this process now and in the future. Even though the process may look perfectly suitable for you this year, the oncoming years may make your investment useless as changes in your customers processes take place. This requires flexibility and versatility in the solutions to adapt to future needs and keep you in the game in the changing environment.

Technologies vary a lot between different waste shredders. The shredders could roughly be categorized in three distinct levels: pure pre-shredders, fine-shredders and multi-use shredders. As the pure pre-shredders do not create the end product but only downsize the shredded material, they are typically very good at dimensional lumber and anything that only needs only breaking the material in half. Typically these pre-shredders (such as Doppstadt, Hammel, Komptech) are of the old technology that get the work done when end particle size is not of importance.

Fine-shredders or fast speed grinders (CBI, Doppstadt, UNTHA) are the second category in this field. These machines typically shred only clean materials without impurities cutting against the screen and thus creating the wanted end product. When investing in these machines you need to be sure your waste stream is pure and homogenous all the way. You can imagine what happens if metal or any impurity ends between the fast moving blades. Hardly ever are these fast speed shredder/grinders acquired separately without any other type of equipment. Typical processes for such machines are clean wood projects where the machine solely shreds logs, stumps or green waste.

The third category is the one using the latest 21st century technology, i.e. the multi-use shredders (TANA). These shredders combine the good parts of both fast speed shredders and pre-shredders. These machines can be adjusted to any type of material and particle sizes. This technology allows material to be shred and cut in one pass to create the wanted particle sizes. The machines can be also fitted with a screen that creates the wanted end product particle size. This type of multi-use shredder can match the capacity of any slow speed shredder when needed. Used correctly they can cut off one or several units from the investments and be used as sole shredders.

Calculation example of an old technology investment vs. a multi-use waste shredder investment costs:

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Choosing the right shredding system and technology for your processes can save you easily hundreds of thousands Euros. The investing costs of a multi-use waste shredder are low and the flexible process creates you the same quality product with higher margins,the versatility of a TANA Shark makes your business more stable and tangible to meet the needs for the ever so changing recycling business.

Customer comments

  1. By Thomas Schmid on

    Hi, I just wanna to tell you, that your text is well written. But there is one point I want to point out. As you mentioned, it depends on the requirements of the customer, which end particle size he needs. If you want to get RDF/SRF output material of smaller 30 mm, what is a common particle size, you will need a secondary shredder. It all depends on the market needs. Kind regards Thomas Schmid (UNTHA shredding technology)

  2. By Olli Honkamäki on

    @Thomas Schmid Thank you for your comments. You are totally right. Typically producing under 30 mm product size is likely to require at least two different machines (a multi-shredder + a screening unit or a pre-shredder + a screener + a secondary grinder). In a scenario where required particle sizes are lower than 30 mm, TANA Shark is not able to create one pass particles to 100%, but it surely can shred 60-70% of the material to match this size. From here your segregation units (such as a drum screen or a star screen) can easily work with this waste flow and any oversizes (30-40% of the shredded waste) can be returned to the TANA Shark a for another shredding. If you want to keep the production process as simple and reliable as possible you only need two units. Typically fast speed grinders or secondary shredders are the bottle necks in existing waste processes. They cannot handle any type of metal, rocks, concrete or other hard materials and once damaged the repairing and servicing are time consuming and expensive. This would require you to set up even more units to separate and segregate the impurities from your waste stream before hitting your grinder. We recommend to build your SRF system as reliable and efficient as possible to maximize your production every working hour rather than using a system where any impurity will cause full stop to your production for hours, even days. Setting up a TANA Shark with a correct process-tuned screening system allows you to maximize the production with lowest operational costs but also provides the most careless system. The fewer easily damageable low capacity machines you have in your waste handling process, the higher profit margins and less downtime you get.

  3. By Thomas Schmid on

    @Olli Honkamäki Thank you for your answer. You are right, that the secondary shredder can be damaged from unshreddable items. Fot this case we (UNTHA) have an effective protection from foreign matters. But normaly for particle size smaller 30mm you have additional separation units (like drum screen,ferrous metal sparator, air separator, eddy current separator) to shift out all unshreddable items before the secondary shredder. With those or similar units you will get a very high availability of the shredders. The big advantage of the separation units is, that in the end of the process, the customer will have high quality RDF/SRF without foreign objects or non-combustible items. For higher quality you will get more money. I´m with you, that fewer machines means fewer investment costs. It all depends on the marktes and customer needs.

  4. By Ali Hashem on

    We have waste second hand shoes to shred and possibly recycle to another use. We are looking for a consultant to help get this done . We appreciate any information. Thanks