Granulation & Toll Processing Glossary
Definitions of the terms that come up in granulation, pelletizing and toll processing projects.
Plain definitions of the powder processing terms buyers and engineers use when they talk about granulation, pelletizing and toll processing.
Agglomeration
Joining fine particles into larger ones. Dry granulation and pelletizing are agglomeration processes that use pressure rather than liquid binders. Dry granulation →
Bulk density
The weight of a powder or granule per unit of volume, including the air between particles. Raising bulk density cuts freight and storage space and helps fill weights stay consistent. Dry granulation →
Caking
Fine powder clumping or setting into a hard mass in bags, silos or hoppers, often from moisture or pressure. Granules usually cake less because they have fewer contact points. Food ingredients →
Compact (flake or ribbon)
The dense sheet a roll compactor produces before it is milled and screened into granules. Dry granulation →
Densification
Increasing a powder's bulk density, usually by compaction or pelletizing. Dry granulation →
Dry granulation
Forming granules by compressing a dry powder, with no water, solvent or binder. Roll compaction is the most common dry granulation method. Dry granulation →
Dust-free form
A granule, pellet or flake that releases little airborne dust when handled. Plastics additives are often supplied this way for compounding. Plastics additives →
Fines
Particles smaller than the target size range. In granulation, fines are screened out and can often be recycled back through the compactor. Screening →
Flowability
How easily a powder or granule moves through hoppers, feeders and chutes. Poor flow causes bridging, rat-holing and uneven dosing. Dry granulation →
Granule
A particle built up from many smaller particles. Granules flow, dose and blend more consistently than the fine powder they were made from. Dry granulation →
Hygroscopic
Tending to absorb moisture from the air. Hygroscopic powders often cake and are good candidates for dry processes, which add no water. Dry granulation →
Liquid nitrogen injection
Cooling with liquid nitrogen during compaction, milling or pelletizing to keep low-melting or heat-sensitive materials from softening. Pelletizing →
Mesh size
A screen opening size used to describe particle size. Higher mesh numbers mean finer openings. Screening →
One-pack
Several additives blended and supplied as a single, often dust-free, ingredient so a compounder handles one material instead of several. Plastics additives →
Particle size distribution (PSD)
The range and proportion of particle sizes in a material. A granulation spec usually sets limits on the PSD, such as a percentage between two mesh sizes. Quality and certifications →
Pellet mill
A machine that presses material through holes in a die to form cylindrical pellets. D&A runs a 100 HP California Pellet Mill. Pelletizing →
Pelletizing
Forming dense, uniform pellets from a powder. Pellets dust less and dose more predictably than powder. Pelletizing →
Roll compaction
Dry granulation in which powder is pressed between two counter-rotating rolls into a dense compact, which is then milled and screened into granules. Also called roller compaction. Dry granulation →
Segregation
Separation of a blend's components by particle size or density during handling. Granulating a blend locks the components together. Blending →
Toll processing
Processing a customer's material for a fee, with the customer keeping ownership of the material. Also called toll manufacturing. How toll processing works →
Trial run
A small production run to confirm that a material processes well and meets spec before committing to a full order. How toll processing works →
Wet granulation
Forming granules by adding a liquid binder, then drying. D&A does not offer wet granulation; we use dry processes only. Roll compaction vs. wet granulation →
Have a material in mind?
Send it over and we'll tell you which process fits.