Q) What is quality recycling?
A) Quality regrind may look different for different applications. However, a good rule of thumb is to look for a consistent, uniform particle size with minimal sharpness and low dust. Material density will determine whether the recycled material is flakes or pellets. Although screen size may determine particle size, the ultimate goal is to recover as much quality, usable regrind material as possible to minimize additional virgin material and to recycle and reduce waste during the process.
Q) How many rotor knives should I use and why?
A) This usually depends on the size and density of the part. The goal is to use enough cutters to maximize output without sacrificing part access to the cutting area. More knives means more cuts per minute, however, after a certain threshold the part/material will bounce in the chamber instead of letting the knives "bite" on the downstroke with diminishing returns .
Q) What determines how many bed knives to use?
A) Typically, material properties and yield requirements will dictate how many knives are used and in what configuration.
Q) When is a steep-angle knife design used?
A) Maximize the cutting capabilities of energy absorbing softer materials and elastic resins. Also suitable for many custom engineered compounds. For example, elastic thermoformed skeletons/wastes, sheets, films and fibers PE and rubber-like materials.
Q) When is a radial knife design used?
A) Used to maximize strength for strong wedge fracture of the toughest high-impact materials. Usually underslung in the rotor, providing extra strength. Proven technology, not always the most efficient/effective cutting technology. Currently, typical applications are limited to wire/metal pelletizing requirements.
Q) When to use the straight cutting knife design?
A) This parallel configuration is generally limited to applications requiring uniform, precise knife clearance over the length of the knife or cutting chamber. Requires more force to cut and tends to be noisy as the full length of the knife can cut at any time.
Q) When to use the inclined rotor + straight bed cutter design?
A) The angled rotor knife provides a scissor-type cutting action that requires less cutting force and potentially produces less noise. This configuration is typically used in applications where knife clearance is not critical. Knife gaps in the center of a knife or machine are usually slightly larger than others.
Q) When to use the inclined rotor + inclined bed cutter design?
A) Similar to the inclined rotor knife configuration, this configuration provides a shearing or scissors cutting action. By oppositely tilting the bedknife at equal and opposite angles, large gaps at the center of the knife are minimized.
Q) When to use a high shear knife design?
A) Also known as a "short cord", this is usually a high strength design with a thicker knife profile. This is the best choice for high-impact, cut-resistant applications such as thick-walled materials, hard resins, heavy mass and/or rubber. For example: Profiles, Profiles, Forms, Sheets, and Light Purge with wall thicknesses up to 2 inches.
Q) What is pig rotor design?
A) In this configuration, the knives are short segments positioned on the rotor in a helical or staggered pattern, providing small individual cut segments, thereby limiting occlusion of the machined material. Ideal applications are usually energy absorbing process materials and thick blocks or purges.
Q) When to use water-cooled rotors?
A) For high temperature applications, water-cooled rotors prevent bearing overheating. No heat build-up is allowed indoors, which helps create a radiator.
Q) What is the purpose of the rotor flywheel?
A) The rotor flywheel adds extra inertia to the cutting system. Therefore, it helps save energy by requiring less horsepower in the cutting system.
Q) What is a crosscut rotor?
A) The rotor and bedknife have equal and opposite inclination angles in the crosscut rotor. As the rotor knife moves downward relative to the bedknife, the two scissor cutting action points converge toward the center. The entire knife has an even edge. This configuration provides improved bite to process materials, lower power requirements, lower noise levels, and balanced loads on the rotor bearings.
Q) Tangential, offset or straight descent chamber?
A) Tangential allows larger parts to be machined with smaller machines. A three-blade rotor complements most of the ingested tangential geometry. Offsets are suitable for thick wall parts and long extrusions. A straight sinker chamber is used for applications with heavier part cross-sections, as it minimizes "seizing". There is also a combination chamber for better uptake while limiting occlusion.
Q) When to use a screenless grinder?
A) Screenless granulators are ideal for sprue pieces, runners and small parts that require low noise and low dust. They are low-rpm systems, easy to move, and the goal is to recover more regrind for reuse back into the process.
Q) Do I need a pulverizer before my granulator?
A) The shredding stage helps protect the granulator and, once pre-shredded, reduces the load during regrinding. It is best to use a shredder to handle large volumes of heavy material. Shredder types may vary by material type (eg single shaft vs multi shaft). Most shredders can be used for continuous shredding in-line.
Q) How can I extend the life of my downsizing device?
A) It is very important to keep the granulator and shredder in maintenance. Make sure to sharpen and change knives regularly when necessary. Dull knives produce poor quality regrind and increase vibration, which can lead to more frequent maintenance. Check out "Service Tips" for more advice.