8855 Washington Blvd. Suite 4, Roseville, CA 95678

Advice for Shredder Buyers

Published on June 20, 2017

by Rafael Reveles, President at Converge Engineering


I have had the opportunity to work with many great shredder manufacturers over my 18 year career in the recycling market and I reached out to four true titans of the industry who have seen it all to ask them to share their insights on shredding. Some of them I know personally better than others, but I do know their sterling reputations and how they stand out as lifelong shredding enthusiasts and experts.



Sean Richter – Shred-Tech

Skip Anthony – American Pulverizer

Gary Moore – Untha UK

David Wilson – SSI Shredding Systems, Inc.


1. What is your advice for someone buying their first shredder? 

David – It certainly starts with the application. Clearly define “What Needs Shredding” and deal with reliable vendors that offer multiple shredding technologies. Be prepared to spend some time looking for the best solution. The capabilities of each technology have expanded significantly over the last several years, there are more choices and there is more product overlap. As a longtime customer recently relayed to me, you want to get heavy duty well designed equipment tailored for your application from a company that can provide good long term support.

Sean – Seek out the manufactures that have supplied machines for your exact application. Look at the track record, compare the top 3 with proven installations.

Skip – Make sure you do the research to fully understand the different options that make sense for your project. Do testing with your materials.

Gary – Understand your shredding requirements. As obvious as it sounds, you need to know what the machine must be capable of achieving.

Start by considering the furthest point in the supply chain and work back from there. Whether you’re producing a commodity and need to take ‘end user requirements’ into account, or whether you simply need to ensure the compliant disposal of materials, the final output criteria should drive your shredder purchase.

Think also about your material type, particle size and the need for fraction homogeneity. Then consider additional factors such as required throughput, available space and the extent to which your shredder will have to work alongside other separation equipment.

A list of essential and desirable criteria should then be carefully recorded. Don’t be tempted to rush this process – it will underpin the next-step success, efficiency and profitability of your plant.


2. Where do most people go wrong when they buy a shredder? 

Gary – There are a few key areas for me.

Some people fail to plan for the future. The majority of shredding requirements evolve over time so the equipment needs to be flexible to protect the longevity of the investment. If such a consideration isn’t made, organisations may find they lack the capacity or output sizing capabilities they truly need.

I’m also incredibly concerned when people focus only on the price tag, and don’t take into account the ongoing wear costs of the shredder. Of course, capital outlay is important, but there are so many other factors that can affect the overall affordability of a machine including uptime, longevity of component parts, power consumption, maintenance intervals, plus the price and availability of spare parts.

Any shredder manufacturer worth their salt will be willing to make these calculations for the customer, to provide them with a clearer financial picture of the investment.

Skip – Buy the right type and size shredder. We know cost is an issue, but equipment cost is a onetime investment. The cost to operate is forever. I have never had someone say they bought too big of a machine. But, have repeatedly heard the opposite and this cost them in profits.

Sean – Carefully analyze the core objective for adding the shredder. More often than I can count customers will try to buy machine to handle every material in every application. Initially they are looking for product destruction but them it morphs into “I need it to shred my pallets, oh and my left over steel drums” etc. Stick to the intended application as the machines are usually purpose built, purpose configured. Trying to buy a single shredder for all materials usually results in poor performance and shred size in the originally intended application.

David – One area where people can go wrong in purchasing a shredder is simply not allowing enough time for the project. Usually a shredder is part of a system and it takes time for a good system including the controls to be designed and built. Another area involves the system layout. You can have a great shredder but if the material handling system is not well designed it can be troublesome. For example, the transition from the shredder to the discharge conveyor needs to be adequate to avoid a buildup of material under the shredder.


3. When is used appropriate and under what conditions? 

Sean – Used machines must be looked at carefully from the following points:

  1. A) Age of the machine. Are parts and service still available?
  2. B) Is there a history on the machines? i.e. what application was it used in previously? Can the records be found at the manufacture or previous owner?
  3. C) Cutting chamber: Is it even configured correctly for your material? I.e. correct knife (hook height and width), pattern of hooks can make or break an application, Hp, Cutting force, Shaft RPM etc
  4. D) Testing: Never buy a used machine without testing your material on that machine. Mimic how you will feed/meter the material to the shredder so there are no surprises when implemented it in your plant.

Skip – Used is OK as long as the technology is current and of course the condition of equipment. We are always trying to improve our equipment and we use feedback from customers to continue to do so. This can mean that the used machines may be lacking either efficiency or reduced cost available with new equipment.

Gary – If the shredder has been designed and built by a reputable manufacturer, renowned for their engineering quality, a used shredder could prove a very sound investment – especially if the supplier will refurbish it. In some cases, the machines look and run like new!

However, it is important to assess the quality of the machine and its operational history. Reverting to my original point, it is crucial to consider whether the shredder can truly meet the organization’s requirements. If not, it doesn’t matter how affordable it is – the technology won’t solve the problem.

David – We get calls from clients looking at used shredders and they want to know if the used model is suitable for them. We spend time on these calls because we do not want the shedder to end up in the wrong application. Often what the client needs and what they are looking at on the used market is typically NOT a good match, not even close. The reason is the best systems are tailored for your application. You are rarely going to find one configured for your application on the used market. For example, you want a tire shredder and you find a 300 HP hydraulic shredder on the market. It will likely work, but a new electric drive 200 HP or 250 HP shredder is a better option because it is less maintenance and will deliver better performance.


4. What is the hardest material to shred typically?

Skip – That’s a tough question. Meatballs from ASR are a good test of equipment durability. Any product can be hard to process if doing so in equipment not really suited for process. This is where used equipment can pose a problem.

David – The applications are more challenging today and clients often want to process at higher volumes to justify the investment. Often a smaller particle size is also required. So processing higher volumes to a smaller particle size cost effectively can be a challenge. One of the ways we meet this challenge is to build larger shredders that can do more in one step. The T-160 for example is a very large 750 HP slow speed high torque shredder with an integrated sizing screen. The system weighs over 50 tons and can process high volumes of material to a controlled particle size in one step. In the past, this would have required two shredders and additional material handling equipment.

Sean – Toughest material we have seen to date is Titanium. Hardest material to shred is perhaps plastics as it comes in so many forms, types, shapes and properties. Issues with melting, dust, screens plugging, bearding, self feeding and more can be experienced if you don’t have the right set up!

Gary – We’ve engineered a four-shaft shredder – the UNTHA RS150 – to specifically tackle heavy duty, complex applications such as large-scale metals and bulky WEEE. These materials are notoriously difficult to shred, but this machine tackles them with ease.

Other waste streams present challenges because of their inherent construction. UNTHA extensively configured an XR waste shredder so that it could handle footwear production waste in Vietnam, for example. This was a very interesting – and far from easy – project because the waste contained rubber, textiles, plastics, metals, sponge, reinforcements and more. But, with clever engineering, what could have been considered an unshreddable waste, was processed successfully into a fuel for the cement industry.

It’s finally important to note that sometimes materials that seem incredibly easy to shred, at first glance, can actually pose significant challenges. With confidential documents, for example, the over-riding factor is often compliance and the robust destruction of data. But if the documents are paper based it’s also crucial to source a high torque, slow speed shredder as this reduces dust generation and therefore the risk of fire. Very few people would consider paper shredding a difficult job, but doing it safely and successfully is a different matter.


5. What is the most challenging job/application you have had in your career and what did you learn?

David – The most challenging job was a custom system that was not really a shredder at all. It was a “crusher”.  The challenge was to deform or crush the material while still maintaining the products integrity such as the serial number. We used common components from our shredder line but it was nothing like anything we had built previously.  It was designed to handle different sizes and types of products, count each product that was processed, and print out a bar code label for each batch. It was designed to operate in five languages and it was a totally self-contained system. This project started with a specific need identified by the client as well as the clients concept on what the system design might look like. The solution drew on all the in-house expertise we have developed over the years at SSI. Our expertise coupled with the clients input, knowledge, support, and cooperation resulted in this unique custom built system designed to do a specific job.

Gary – During a lengthy career, I have had many applications/installations that have proved to be technically, mentally and financially demanding. However, one project springs to mind that encompasses all these areas would be for a design & build solution that we supplied to Avanti Environmental Limited. The turnkey solution was a low speed-high torque shredding system capable of high throughput and handling a diverse, mixed and potentially hazardous wastestream which we then converted into a premium grade SRF that was to be used in the cement industries.

Throughout this project we had to maintain a strict project and design management ethos to ensure that we delivered the correct solution, which provided the correct product, on time and within budget to ensure that our client realized their return on investment from the point of final commissioning.

Sean – One of my toughest applications to date is with a major auto manufacture in the US. In this case I had to figure out how to receive and shred varying surge loads of stamped steel from multiple press lines. The goal was to increase the density the scrap steel for volume reduction in rail car shipping. The application required a specially configured 300 HP twin shaft shredder in conjunction with a variety of conveyors to load level, reverse when necessary, meter feed and finally discharge evenly to the customers rail cars. Special knives were developed for the shredder to prevent material pick up (galling) under the immense cutting forces generated when multiple layers of steel were sheared at one time. The system was designed and installed in an existing facility with virtually no modifications to the existing line or flow. The system operates 24/7 with little or no operator intervention, minor periodic online maintenance with knife changes pegged at 12 month intervals. Design of the system allows the shredder to be bi-passed at any time or during knife changes for uninterrupted line production. It all fit with 1” to spare I remember the millwrights saying….

Skip – Processing unexploded ordinance so they can be recycled safely. There is such a large spectrum of materials and some of these products can still contain live explosives. We found that there isn’t one machine to do all types and equipment needs to be able to handle detonations if they occur.


6. What is your favorite type of machine and why (single rotor, 2-shaft, etc?)  

Gary – This is a tough one. For me, it’s the way that single shaft shredding has revolutionized the alternative fuel production market. The throughputs, flexibility, energy efficiency and low noise of the XR, for example, is like nothing I’ve ever seen before in the industry. It is a machine I feel extremely proud to work with, and the fact that we’ve just sold our 150th unit is a testament to how much it has changed the face of waste shredding.

Skip – The ringmill has always been the most versatile and rugged machine we have manufactured for the specialty shredding areas. We have more ringmills in the field than all other types combined. Our slow speed shredders are the heaviest in the industry and designed for tough applications.

Sean – Twin shafts would be my pick 90% of the time. Recent advances in cutter design, cutter materials and more importantly the way we power these machines (VFD’s, DC Drives, hydraulics etc) have opened up new applications that were once too tough or unthought-of for this type of machine. Typically their lower cost, lower HP and lower maintenance make them the better choice

David – I would have said the Dual Shear years ago because it is hard to beat for overall price, performance, reliability and low maintenance. However, as we have broadened our product line over the years to include the Single Shaft Uni-Shear, Quad and Pri-Max type of shredders, I realize that I don’t have a favorite, it is a matter of what is best for the application. However, what we have done with electric drive shredders and the SSI Smart Drive has amazed me the most. One example is processing bales of textiles. Previously a hydraulic drive shredder could do the job but not at high rates. Today, an electric drive shredder with the SSI Smart Drive can do the job at less cost, require less maintenance, and produce higher throughput!


7. How do you decide how large of a HP machine to buy? 

David – It’s a combination of many factors that determines the size of system. The infeed opening, torque, particle size, and feed rate are all evaluated to determine the appropriate size system. We rely on our extensive database of applications and our years of experience to make recommendations. We also rely on customer input, customer data and field service data. We also do extensive testing.

Sean – For most of our machines, in most of these applications it’s not about HP, it’s about Knife Tip Cutting force, Torque and throughput. First I analyze the application to determine the machine type and its initial size, from there I ask the question of throughput. For example, in a paper shredding application the same machine can be driven with 60 HP, 80 or 100 HP assuming it is geared to produce the same required cutting force. The only difference then is speed. Cutting force (constant) + Speed (Hp)(varies) = Throughput. I then ask “what kind of throughput do you need” and match this to known values of HP/Speed/Throughput.

Skip – We base it on the following which also can determine what type machine:

  • What is the material to process?
  • What is the largest size pieces we will see going into mill?
  • What is the size of the final product?
  • How many tons per hour?

Gary – Several criteria will need to be considered when calculating the power required, not least; Type of material to be processed, required output, capacity, operational considerations, feed type. Once we have evaluated this information we can readily provide a suitable recommendation. However, the over-riding aspect to ensure we have the correct power-to-process mix is to shred-test the customer’s material. Every client’s material is different and likewise every shredding solution is (just a little) different.


8. What is your philosophy and style with your customers? 

Skip – We want to understand fully what the customer’s needs are. We want to be a part of their team and work together for best solution for particular needs. We strive to offer the best support and service for all of our systems.

Our vast inventory of parts and quality of our manufacturing plants assure customer that we will be there for the life of equipment.

Sean – Right off the bat I can usually tell them either a good or a bad story about the application they are looking at. If I know the application has merit, we have successful installations, happy customers etc., I then show them photos, videos and drawings for proof and further discussion. If it’s an application nightmare, I am the first to warn them or steer them towards the correct type of equipment (ours or others).

Gary – I listen, ask questions and am genuinely passionate about the shredding challenge they must solve. I’m also incredibly honest about the shredder that I think will solve their needs, and the direction they need to take their investment in. I’ve even been known to advise clients to explore different output markets, which has resulted in them overhauling their business models – for the better, I’m pleased to say.

David -We are problem solvers. We like to work together with the client to solve the “What Needs Shredding” challenges they bring us. The solution ranges from a standard system to totally custom systems. We have a simple goal of creating and maintaining loyal and satisfied customers. We engineer and build the systems for reliability and work hard on the front end of the sales process to make sure we apply the technology correctly to achieve the goal.



I would like to thank Sean, Skip, Gary, and David – and their companies for agreeing to be interviewed and contribute their incredible stories. This was a rare treat and the answers are insightful and full of great tips and advice. I hope you enjoyed this feature and gain useful knowledge in your pursuit of shredding. Remember, there is no need to guess – enlist a professional when buying a shredding solution. All 5 of us are willing to help and each have unique experiences to share!

Rafael Reveles

Converge Engineering