Metal Crushing Machine

Scrap metal is categorized into two types: ferrous and non-ferrous. Here’s the difference between the two:

Ferrous Metals
The term “ferrous” is derived from the Latin word for iron and refers to both iron and steel. Iron is the second most commonly occurring metal in our planet’s crust. Its natural magnetism is what gives the Earth a magnetic field. Because nearly all ferrous metals are magnetic, metal scrap yards often use massive electromagnets mounted on excavators to load and unload ferrous scrap from trucks and move it around the yard.
‌The largest sources of scrap ferrous metals in the U.S. are found in durable products such as appliances, tires, and furniture. According to the Environmental Protection Agency, 27.8% of all recycled ferrous metals in 2018 came from these durable goods, which equals a whopping 4.7 million tons.
The following items are also made of ferrous metals:
● Construction and building materials such as I beams, ductwork, rebar, and electrical wiring
● Transportation parts and products such as cars, railroad scrap, rotors, drums, and motor blocks
● Containers and packaging
● Scrap metal is also a byproduct of steel manufacturing. This type of scrap — including clippings, busheling, and skeletons — is easy and valuable to recycle back into the same stream it came from, because it isn’t altered and therefore doesn’t require as much processing.

Non-ferrous Metals
Because non-ferrous metals don’t lose their chemical properties during the recycling process, they can be endlessly recycled. There’s a long list of non-ferrous metals, but some of the most common base metals include aluminum, copper, nickel, lead, tin, and zinc. Precious metals like gold and silver also belong to the non-ferrous category. Each of these has a wide variety of uses.
‌Although non-ferrous scrap makes up only 10% of the total material recycled in the U.S., it provides half the total value of the scrap recycling industry’s earnings. For example, the U.S. exported $10.4 billion worth of non-ferrous scrap metal to more than 95 countries in 2018 alone.
Because recycling operations purchase non-ferrous scrap on a per-pound basis, it’s usually more valuable to recyclers. However, prices for non-ferrous tend to fluctuate more than for ferrous metals.

Non-recyclable Metals
Unfortunately, not all scrap metal can be recycled, but the list of non-recyclable metals is exceptionally short. It includes radioactive metals like uranium and plutonium as well as toxic metals like mercury. However, there are some metals or metal items that scrap yards will not take, often for liability reasons. Other items they may charge to take because it takes extra steps to process them. It’s wise to check with a yard before you bring something in if you’re not sure.

Function
While you might already know a thing or two about metal shredding, it’s good to be clear on what these devices can be used for so you get the most out of your shredder. A metal shredder can be used in the following applications:
(1) Reducing your business’ metal waste to more movable material (e.g. strips or small particles)
(2) Destroying sensitive information stored on electronic devices
(3) Assisting with recycling
(4) Allowing metal to be reused or repurposed
(5) Disposing of metal properly

Shredding Materials
Next, determine what exactly you will be shredding. This takes into account the following components:
(1) The type of metal
(2) The type of objects and their shape
(3) Whether the metal contains sensitive information
Certain shredders are more appropriate for different types of materials. For example, if the metal being fed into the machine is a hard alloy, a stronger shredder will be needed. On the other hand, a standard metal shredder can handle items such as thin strips of aluminum.

Shredding Capacity
There are two sub-questions to be asked in regards to metal shredder capacity:
(1) Will you be shredding a lot or a little?
(2) How often will you be shredding?
If your business produces large amounts of metal waste on a daily basis, you’ll want a machine with a higher capacity, meaning you will be able to feed more metal into the machine at a higher rate.
You should also check out the cool-down time of the shredder. Shredders use a lot of energy as they heat up very quickly. Make sure that the shredder you want is going to be able to be used as often as you want.

Safety Features
The safety features you need will likely depend on who will be using the machine and what is being shredded.
If the people using the machine are inexperienced, it’s a good idea to get one that can be used easily. However, if you are shredding large or complex items, this may not be possible. Safe metal shredders will have features such as protective screens and auto-shutdowns.

Space Constraints
This one might seem obvious, but it’s an essential factor to consider. If you are operating a small warehouse, you may only have room for a small shredder. If that’s the case, hopefully, you aren’t shredding bulk materials.
Before you purchase a shredder, do an audit of your current business space, and see how your available space can be optimized. Once you’ve worked out how much space you have to spare, you will know the maximum shredder size you can get.

Shredding Method
There are four main ways that a metal shredder will cut:
(1) Grind: A metal grinder will destroy the metal completely and transform it into dust.
(2) Strip-cut: A strip-cut shredder reduces the metal into strips, much like a standard paper shredder.
(3) Cross-cut: A cross-cut shredder works by making two separate cuts. It will make one cut one way (e.g. vertical) and then cut again the other way (e.g. horizontal). As a result, the pieces coming out on the other side will be small pieces, often in the shape of squares or diamonds.
(4) Particle-cut: The particle-cut shredder uses multiple cuts to create a more specific shape than the cross-cut shredder.

Extra Features
There are a lot of different metal shredder features that go beyond the considerations outlined above. For example, some metal shredders will also work with other materials, such as wood and plastic.
Other metal shredders will come with features that impact the ease of use, or give you greater control over its operation. To determine which extra features you might want, it’s best to look at the available shredders and see what they offer.

Segregation
The first step in the metal recycling process is segregation. During this time, the collected scrap metal is separated. This type of organization is necessary to ensure that the recycling process goes smoothly. The metal is separated by size and weight. The different densities of material will be taken into consideration when they are being sorted. Sometimes products get trapped in the metal and they will need to be removed.
For example, plastic may get trapped in between the metal. This is a foreign object that will need to be removed before the recycling process begins. The removal of raw materials such as plastic ensures that the finished product is pure. In the past, segregation was done by hand, but this is no longer the case. Now there are several machines available that automatically detect the type of metal and the size and separate them automatically.

Preparation
The next step of the metal recycling process is preparation. During this time, the materials are put in a metal shredder to cut down on the recycling process time. This is why the segregation process is so important. It ensures that the materials being shredded are as similar as possible.

Shredding
To be as efficient as possible with your scrap metal recycling, you’re going to want to purchase the right shredder. There are different shredders that can dispose of materials in different sizes. These materials include bulk waste solids, liquid and solid waste, as well as sludge and biosolids.
What’s even better about the shredding process when you have an industrial shredder is that there is minimal work required. So not only are you going to ‌shred scrap metal on-site, but you’ll have a system that’s easy to use. The shredding part of this process also ensures that there are smaller amounts of emissions used during the next stage of the scrap metal recycling process, which is burning.

Burning
Once the material has been segregated and shredded, it is time for the burning process to begin. The burning process ‌makes all the scrap metal have the same density. The metal is put in a furnace and then put under high heat. The heat ‌binds the metal together.
Different metals have varying melting points. The melting point will determine how long it takes for shredded metal to become molten metal. For the process to go faster, the amount of the shredded metal being processed ‌can be reduced. The bottom line is that the melting point of the metal is critical in creating molten metal. For example, iron has a higher melting point than zinc.

Formation
The next step in the metal recycling process is formation. At this point, all the metals are taken out of the furnace and are created as ingots. When the material is in an ingot format, it is in its purest form. These ingots are shaped to form bars of metal. The ingot can also be transported as a liquid and sometimes powder to manufacturing plants where they are transformed into products.

Minimal Downtime
The first challenge that machine builders face in shredding applications is ensuring that the machine has minimal downtime. These machines are designed to process a lot of material in a short amount of time, and any downtime forces delays in the overall system. If a shredder were to go down for maintenance, it can sometimes be offline for days and cause large backups of material. For example, users have the ability to program torque limits in the drive to protect the mechanical components in the drivetrain, including shafts, gearing, and the motor. Actively monitoring both the VFD and motor temperatures ensure the components do not overheat and fail.

Jam Detection
Jam Detection is a unique function built into our drives to help avoid downtime. If a shredder were to jam because of material blockage, a mechanic would need to shut down the machine, then disassemble and clear the blocked material. This usually means the rotor stops, reverses and clears the material, and then quickly reverses again and returns to normal speed. This Jam Detection article goes into more details on the setup and operation. In short, this function clears a jam condition in a matter of seconds compared to hours or days to manually clear it.

Lower Starting Torque
The motor control algorithm has proven effective many times over in shredder applications. A line fed current will draw approximately 500-600% of motor rated current during start-up, which can cause issues with the mains and other connected electrical loads. By contrast, a VFD-started motor will ramp up the voltage and frequency in a controlled manner, thereby keeping the current to a minimum.

Locked Rotor Scenario
As the shredder loading is increased, the induction motor will slip more and more until it reaches the breakdown torque. At that point, the motor will lose torque, and the speed will quickly drop to 0 rpm. This is now a locked rotor situation, and the motor will draw an extremely high current until the system is shut down or faults. It is likely that the shredder jam needs to be manually cleared, which requires human intervention in the process and downtime.

Contamination Issues
Another challenge that companies face in these types of applications is the amount of contamination that can enter the electrical enclosure of the machine. Depending on the process, it is possible that conductive metal shavings and oils are released into the air as the material is being processed. Ensuring these contaminants are not able to get into the electrical components of the machine is critical. Several VFD heatsink options include the ability to push the heatsink outside of the panel while sealing it from outside contamination. In this arrangement, the sensitive power electronics can be sealed inside the enclosure while the air or water flow is external.

Avoiding Overfeeding the Crusher
Overfeeding is not the right solution when you’re trying to process more materials in one day. Instead of greater production, you’ll only end up with reduced efficiency. Adding more material will only end up stalling the crusher. The manufacturer of your crusher will include a manual on how to operate it properly. This includes the proper feeding method to prevent blockages. You need to set up the right feeder speed and adjust the other settings or you’ll end up with an overloaded situation and a blocked crusher.

Prevent Entry of Other Materials
Stalling and bridging can happen when a foreign material enters the crusher. This might be excessive clay or wood. Metal parts such as bucket teeth and dumper wear plates might also break off and enter the crusher, therefore causing a blockage. These can damage not just your crushers, but also your conveyors and other process equipment.
To prevent tramp metal from entering your crusher, you can consider using a tramp metal detector to protect your investment. Another good practice is to regularly inspect the metal parts to spot early signs of damage and prevent them from breaking off.

Reduce Entry of Oversized Material
Crushers are made to reduce the size of materials, but blockages can occur especially if you feed your equipment with oversized material. Ensure that the size of the raw material is matched to the opening of the crusher to prevent this incident. If you need to process an oversized material, consider using other tools and equipment to reduce its size first.

Blockages Cleared by Professionals
When you encounter a blockage, you might be at a loss at what to do. There are a few tools you might need, but only trained and competent persons can do the clearing. This is important especially if manual removal is needed. In this case, make sure that the crusher and the associated plant are stopped and isolated.
When you attempt a clearing, there are risks involved. Some examples are being struck by material, slipping, sudden movement from the crusher components, and more. Stalled crushers can cause fatal accidents because of material being ejected, so don’t attempt to do the clearing if you’re not suitably trained. Don’t hesitate to call for help if the situation calls for it.