Frequently Asked Milling Questions

Founded in 1976, Quadro has earned the respect and trust of customers worldwide via our commitment to improve the performance of powder processing and milling operations. We are recognized as manufacturers of specialized process equipment, with over 40,000 machines installed globally as well as decades of experience with problem-solving and product innovation. We set the standards by which others are measured.

Quadro support manufacturers worldwide through a combined network of regional offices and expert partners.

As well as our own IDEX-affiliated regional offices, we are supported by a network of Agents & Distributors, who enable us to provide quality customer service anywhere in the world.

With customers in more than 80 countries, we have both the ability and competency with which to provide whatever level of support may be required.

Quadro services support process validation and long-term equipment performance.

Process / Application Testing

Quadro^® has an extensive database linking to our equipment capabilities with various processes and applications, across a broad range of industries.

Our industry-leading global test facility is located at our Head Office in Waterloo, Canada, and features a full range of the latest lab equipment, a product preparation area and a state-of-the-art analysis area. Testing is also available at our facilities in India and China.

Our knowledge, expertise and facilities are available to evaluate all potential applications.

In addition, our rental fleet enables customers to test their application prior to purchase, thereby ensuring the suitability of our equipment for specific process requirements.

Site Acceptance Testing / Start-up Assistance

We offer full on-site start-up assistance for both purchased and rental machines to enable you to get your Quadro^® equipment up and running. This service includes machine set-up, standard IQ/OQ (Installation Qualification/Operational Qualification) Performance Qualifications and Site Acceptance Testing, all of which aid in the validation of your process.

Technical Training

Focused, professional training programs are  available either at our facility or yours for engineers, technologists, operators and maintenance personnel. Training is comprehensive, covering everything from basic equipment operation and best practice to more advanced programs relating to equipment theory, optimization and troubleshooting.

Quadro has a dedicated aftermarket team who will assist you promptly with any requests for Quadro replacement parts or technical service support in order to keep your equipment running smoothly and efficiently, thereby reducing unscheduled downtime and minimizing impact on production.

Contact our Aftermarket Team to learn more.

A Comil cone mill delivers controlled, consistent particle size reduction for powders and wet materials.

The Quadro Comil® (conical mill) is a gently operating size‑reduction and screening machine that uses a rotating impeller inside a conical screen to achieve uniform particle sizing, deagglomeration, sieving and homogeneous dispersion. Originally developed by Quadro Engineering in 1976, the Quadro Comil® has become an industry standard for both wet and dry milling applications in pharmaceutical, food, chemical and personal care manufacturing, where precise, repeatable particle size is critical to product performance.

The Quadro Comil^® delivers optimum process efficiency and product consistency and is fully scalable from R&D to large production volumes with accuracy and repeatability of results.

Typical applications include:

• Granulation of dry powders
• Size reduction and milling of wet/soaked products to produce liquid with wet suspended particulates
• Powders into paste
• Wet blending
• Uniform sizing of wet granulation for tablet manufacturing
• Lump-free homogenous blending to precise size requirements
• Reducing sticky agglomerates into uniformly-sized powders
• Product reclaim

Overdriven and Underdriven Comils differ in drive location, layout and how they fit into your process.

The Overdriven Comil is the simplest and most economical Comil to maintain and operate.

Available in four models, the Overdriven Comil has the widest capacity range - up to 120,000 lb/hr (54,500 kg/hr). And with the largest number of screen and impeller options available in the market and many specialized tools, almost any process requirements can be achieved.

The Underdriven Comil has a smaller footprint, inline design and extremely short head height, easily integrating into processing environments where space is limited. A large diameter infeed and 'straight through' housing promote unhindered inline product flow for quicker discharge.

With four models to choose from, the Underdriven Comil is scalable in capacity from several ounces to 35,000 lb/hr (15,900 kg/hr). The innovative spacer less design allows for quick changeover of impellers and screens.

The Quadro FlexSift functions as both a high‑capacity screener and an inline sifter. 

The Quadro^® FlexSift delivers high capacity, inline security screening and gentle deagglomeration and delumping. This means that only uniform, appropriately sized particles can enter the processing stream. The Quadro^® FlexSift effectively deagglomerates materials without damaging the powder particles. Learn more with this overview.

A greaseless gearbox gives operators the flexibility to modify their maintenance schedules or save money by eliminating oil, lubricator components and system maintenance.

Ensuring that motors are regularly oiled can be costly, cumbersome and, in some applications, not even an acceptable option.

A greaseless gearbox provides the following application benefits:

• Mitigates product contamination.
• Low energy input reduces overall product temperature.
• Noise exposure levels reduced.
• Easily accessible to perform preventative maintenance.

Higher milling capacity depends on selecting the right mill configuration for your material and throughput targets.

To increase milling capacity, you first need to match the mill type and size to your application and material properties, including particle size, moisture content, temperature sensitivity, hardness and other physical or chemical characteristics. Quadro offers a wide range of mills from lab scale to full-size high‑capacity units, in both Overdriven and Underdriven configurations. A detailed assessment of your process, product and required particle size distribution allows the most efficient equipment and process set‑up to be specified.

Where very high throughputs are required, the Overdriven Comil provides the broadest capacity range, handling up to 120,000 lb/hr (54,500 kg/hr). Underdriven Comils are also scalable, from small‑scale development quantities up to 35,000 lb/hr (15,900 kg/hr). By combining the appropriate mill size with the right screen and impeller selection, you can significantly increase capacity while maintaining tight control of particle size and overall product quality.

A tight particle size distribution depends on matching the right mill set‑up to your target particle size.

To achieve a tight PSD, you first need to select the most appropriate milling technology for your target size range – typically cone milling (conical milling) or hammer milling. The choice of process is driven by the final particle size and distribution you need, as well as how sensitive your material is to heat, impact and moisture.  

Equally important are the details of the set‑up: screen type and hole size, impeller design, surface coatings (if required) and operating parameters such as RPM and tip speed. By using sizing tools such as the Quadro Particle Size Card to link target PSD to mill type and screen specification, and by fine‑tuning the impeller and speed to your specific powder, you can reliably mill to a narrow PSD while protecting product quality.

Particle size optimisation depends on the right combination of screen, impeller and operating conditions.

To optimise particle size, you first need to select the correct screen specification for your target PSD. This includes choosing the appropriate opening size (for example, from 0.150 mm up to 38 mm) and screen type, such as round or square perforations, wire mesh or grater/Conidur designs. In parallel, the impeller profile must match the application – from gentler round, square or bevelled arms through to more aggressive geometries – and can be further refined with specialist finishes or add‑ons where required.

Once the screen and impeller are defined, the next key factors are how the mill is fed and how it is run. By reviewing your feeding method (for example, gravity, screw or pneumatic conveying) and then setting the correct RPM and tip speed, you can achieve a consistent, scalable PSD. When this parameter set is established, it becomes straightforward to reproduce the same particle size results as you move from lab mills to full‑scale production, using the same operating conditions.

Fine grinding performance depends on the right mill design, tooling and operating parameters.

When precision grinding is critical, the core components are a suitable fine‑grind mill, correctly specified tooling (screen and impeller) and tight control of milling speed and energy input. Solutions such as the Quadro® F10 Fine Grind and the H20 High‑Energy Comil® are engineered to deliver D90 targets in the 20–60 µm range, with a high percentage of particles on target, often without the need for additional auxiliary equipment. Integrated variable‑frequency drives allow you to adjust speed and torque in real time, giving precise control over the particle size distribution (PSD).

Equally important is the application‑specific set‑up: selecting the right screen and impeller combination, and optimising the feeding method and tip speed for your product. The F10 offers high portability, process flexibility and low heat generation, while the H20 High‑Energy Comil® can achieve PSDs 30–70% finer than many conventional conical mills. With expert support to match tooling, RPM and feed conditions to your material, these elements work together to deliver consistent, scalable fine grinding results.