Which criteria are decisive when selecting an industrial mixer for plastics, meaning masterbatch and additives?
Selecting a suitable industrial mixer for masterbatch and additive applications is decisive for homogeneity, process reliability, product quality and the economy of plastics compounding. What matters is that the mixer achieves the desired distribution of colour and functional components reproducibly, without damaging material or encouraging segregation.
1. Material properties and bulk solids behaviour
Type of components: powders, granules, pellets or flakes behave differently in the mixing process.
Bulk density, particle size distribution, grain shape and flow behaviour: these variables influence blending, the tendency to segregate and dosability.
Moisture content and hygroscopicity: they increase the tendency to lump and can impair flow behaviour.
Abrasiveness: fillers such as talc, calcium carbonate, glass fibres or mineral flame retardants increase wear.
Temperature sensitivity: the mixer must be designed so that the material is not damaged thermally or mechanically.
2. Mixing task and target homogeneity
Distributive mixing: even spatial distribution of additives and pigments.
Dispersive mixing: breaking up agglomerates, for example with pigments or finely distributed additives.
Target homogeneity: the required mixing quality should be defined in advance, for example via a coefficient of variation.
Mixing ratio: with ppm or per mille additions in particular, the requirements for precision and reproducibility increase.
3. Mixer type and design
The appropriate technology depends on recipe, throughput and mixing objective:
- Horizontal ploughshare or paddle mixers for intensive, predominantly distributive mixing tasks.
- Vertical conical or tumble mixers for gentle, gravimetric blending.
- High-speed or intensive mixers for dispersive tasks and rapid incorporation of additives.
- Heating/cooling mixing systems for temperature-critical dry blends.
- Twin-shaft or continuous mixers with defined residence times and higher throughputs.
Appropriate dimensioning, a sufficient drive reserve and a suitable fill level are also important, so that the mix is reliably captured and moved evenly.
4. Mode of operation and scalability
Batch or continuous: the choice depends on throughput, variety of recipes and the need for flexibility.
Batch size and cycle times: filling, mixing, discharging and cleaning influence the real plant performance.
Scale-up capability: laboratory and pilot-plant values should be transferable to larger plants; geometric similarity and stable process parameters make scaling easier.
5. Temperature management and energy input
Rotational speed and circumferential speed: they determine the mechanical energy input.
Heating or cooling: jacket or double jacket systems help to keep the product temperature below critical limits.
Temperature measurement and control: they prevent degradation, caking and sticking.
6. Construction and materials
Choice of materials: wear-resistant and chemically resistant materials are important with abrasive recipes.
Surface quality: low roughness reduces build-up and makes discharge easier.
Low-dead-space construction: it minimises material residues and cross-contamination.
Sealing systems: a dust-tight and, where applicable, ATEX-compliant design is required depending on the product.
7. Cleaning and product change
Good accessibility: inspection doors and easily removable components shorten downtimes.
Cleaning concept: dry cleaning, manual cleaning or WIP/CIP options depending on product and frequency of change.
Colour and additive changes: with colour masterbatch in particular, low residual quantities and short cleaning times are important.
8. Safety and explosion protection
Dust explosion risk: MIE, KSt and other characteristic values must be assessed.
ATEX requirements: earthing, relief or inerting may be necessary.
Extraction and filter technology: they protect personnel and plant from dust emissions.
9. Dosing and automation
Interfaces to dosing and weighing equipment: with micro-dosing in the ppm range in particular.
Process synchronisation: dosing must be matched to the mixing cycle.
Control system integration: recipe management, batch tracking and connection to higher-level production and control systems.
Process monitoring: torque, power consumption and temperature serve as condition and quality indicators.
10. Economy
- Specific energy consumption.
- Service life of wear parts.
- Maintenance effort and spare parts availability.
- Cleaning and product change times.
- Effect on OEE and plant utilisation.
How amixon® moves from product data to a well-founded mixer recommendation
The selection of a suitable industrial mixer is of decisive importance for homogeneity, process reliability, product quality and economy in masterbatch and additive applications. At amixon®, the design does not begin with a standard mixer but with a structured analysis of the product data and the process objectives. Bulk densities, particle size distributions, flow behaviour, moisture, temperature and shear sensitivity as well as, where applicable, dust explosion characteristics form the basis for a well-founded recommendation.
1. What amixon® does better: from the requirement to the appropriate technology
From the product and process data, amixon® derives the appropriate category of mixer, such as vertical and conical mixers for precision mixing tasks, units for particularly fragile materials, continuous systems for constant operating regimes or special solutions for vacuum, temperature control and reaction processes. Mixing technology is therefore not chosen across the board but matched precisely to recipe, batch size, hygiene requirement and discharge requirements.
For very large volumes, the Gyraton® silo mixer extends this spectrum: it is designed for large-volume mixing tasks and combines the function of a silo with that of a precision mixer. Large batches can thereby be homogenised with very low drive power without impairing mixing quality.
2. What distinguishes amixon® in the application
- Mixing quality independent of fill level: even results across a wide fill level range make design easier with fluctuating batch sizes.
- Adjustable mixing intensity: one and the same apparatus can homogenise gently or deagglomerate intensively.
- Very good residual discharge: this reduces product losses and improves colour and recipe purity during product changes.
- Gentle processing without unnecessary heat input: this is of particular importance with plastics, masterbatches and additives in order to avoid melting or degradation.
- ATEX-compliant design: for fine dusts the mixing chamber can be executed for Zone 20.
- Construction according to the URS: the choice of materials, the surface quality and the hygiene functions are consistently adapted to the specific application.
3. Why the Gyraton® silo mixer is relevant
The Gyraton® silo mixer is particularly interesting where large mixing volumes (up to 100 m³) have to be homogenised economically and yet precisely. It requires only a very low electrical connected load, works very gently and is also suitable for moist or poorly flowing materials. According to amixon®, even mixing ratios of up to 1:100,000 can be distributed ideally in this way. That can be very important for the base raw materials where they come from different suppliers.
4. Why this is decisive with masterbatch and additives
With plastics, additives are often present only in very small quantities, while the requirements for homogeneity are high. Accordingly, the homogeneity of the macro raw materials is of great importance. For the precision mixing of disperse solids, amixon® points to reproducible mixing qualities, even at very large mixing ratios. That is of particular importance for masterbatch applications, since pigments, fillers and functional additives have to be distributed reliably without impairing the material properties.
5. Verification instead of assumption
Paper data are not sufficient: amixon® verifies the selection in the pilot plant with original products. Mixing quality, product protection, energy input, cleanability and reproducibility are examined on test units and evaluated jointly. A robust basis for the investment decision is thereby created and the project risk considerably reduced.
6. Hygienic design, cleaning and operation
Even though hygiene requirements with plastics are usually weighted differently than in the food and pharmaceutical sectors, clean discharge, good accessibility and controlled cleaning remain decisive, particularly during colour and product changes. amixon® relies for this on constructions with few joints, readily accessible inspection doors and low-residue discharge. Where required, wet cleaning solutions are also used. This makes safe and economical operation easier, even in a demanding plastics environment.