Kaiserblick Knowledge

Dry Milling Equipment

9 min read

Dry Milling Equipment

Sources: Pinhalense (website); Cimbria (website); Oliver Manufacturing (website); El Arte del Café by Sébastien Racineux & Chung-Leng Tran (Lunwerg, 2017)

After drying to 10–12% moisture, coffee must be hulled (parchment or husk removed), cleaned, graded, and sorted before it is ready for export. This stage — the dry mill (beneficio seco) — is the final quality control step in the production chain. See Green Coffee Selection and Export Preparation for the full selection workflow. See Pinhalense and Cimbria for the primary manufacturers referenced here.

Hulling

Hulling removes the outer protective layer from dried coffee:

  • Parchment coffee (washed/honey process): the endocarp (parchment layer) is stripped away
  • Natural/dry process coffee: the entire dried cherry — skin, pulp, and parchment — is removed as a single unit

Combined Coffee Huller (CON / Compacta)

Pinhalense’s flagship hulling machine, performing 5 processes in a single pass:

  1. Pre-cleaning — removes loose debris before hulling begins
  2. Destoning (CON models only) — Flutu-Ar system removes stones and heavy impurities integrated before hulling
  3. Hulling — removes parchment or natural husk from the bean
  4. Automatic repassing — un-hulled beans are automatically re-routed through the huller
  5. Weight sorting — beans separated by weight after hulling

Cold huller technology: the hulling mechanism operates without heat generation, protecting bean integrity. This design processes naturals, washed (parchment), and honey coffees without heat damage — important because heat at this stage can damage aromatics in the green bean.

Additional features:

  • Electronic adjustment for precise oscillation settings optimising bean separation
  • Some models: perforated oscillating screen for dual-layer size classification (combines hulling and size grading)
  • Reinforced structure, low power consumption
  • Available in multiple sizes for different dry mill throughput requirements

Model families:

  • CON — includes Flutu-Ar integrated destoner; the comprehensive choice for full dry mill operations
  • Compacta — compact form factor; suitable for smaller operations or farms with space constraints

Parchment Coffee Huller

Designed specifically for washed/parchment coffee. Can be attached to the Combined Huller (CON model) when a farm processes both natural and parchment lots in the same facility, optimising the hulling channel for each type.

Mini Coffee Huller

Small-scale hulling; appropriate for on-farm micro-lot processing, sample preparation, or very small production volumes.

DEPOS Coffee Huller Polisher

Combines two functions: hulling parchment coffee and removing the silver skin (inner seed coat / silverskin / chaff) from the bean surface. Produces cleaner, shinier green beans that meet international export quality standards. Particularly relevant when buyers or export quality inspectors expect clean, chaff-free green coffee.

Destoning

Stones and soil clods enter the coffee at harvest and during drying. Even small stones can damage hullers and pulpers downstream and cause quality claims at import. Destoning must occur before or during hulling.

Coffee Destoner (CPFBNR series)

Pinhalense’s standalone destoner using the Flutu-Ar System: combined air flotation and vibration separates stones (dense) from coffee beans (less dense) with high precision.

  • Works with green coffee, parchment coffee, and dry cherries — can be placed at multiple points in the processing line
  • Aspiration system with dust hood available
  • Low noise and energy consumption
  • Models: CPFBNR 1 through CPFBNR 5

CPFBNR 1 dimensions: 2.35 m H × 1.3 m W × 2.85 m L; 810 kg; 5 + 0.5 HP motors CPFBNR 1 capacity: 2,800–3,800 kg/h parchment / 3,200–4,500 kg/h clean coffee

The Flutu-Ar System is also integrated into the Combined Coffee Huller (CON models) so that stones are removed within the hulling process itself.

Gravity Separation (Density Sorting)

After hulling, green coffee beans vary in density depending on development level, ripeness at harvest, and defects. Gravity separators (densimetric tables) sort beans by density, separating defective (hollow, light, under-developed) beans from dense, well-developed ones.

Gravity Separator (MVF series)

Pinhalense’s Flutu-Ar System gravity separator combines:

  • Vibration — deck vibration moves beans across the table surface
  • Air flotation — upward air current through the deck keeps lighter beans suspended while denser beans sink to the surface
  • Inclination — the tilted deck causes light beans to move upward and dense beans to move downward

Electronic control of deck vibration enables precise fine-tuning. Air flow direction is also adjustable. The result is a continuous fan-shaped separation of beans from most dense (heavy, high-quality) to least dense (light, defective), with split points set by the operator.

Optional aspiration system with dust hood.

MVF-0 specifications:

  • Capacity: 900–1,200 kg/h / 20–26 quintales/h
  • Motors: 3 HP (fan) + 0.5 HP (vibration)
  • Dimensions: approx. 1.87 m H × 1.64 m W × 1.98 m L; 430 kg

Model range: MVF-0, MVF-1, MVF-2, MVF-3, MVF-3S (larger capacity at each step)

Gravity separation is one of the most impactful dry milling steps for specialty coffee: it directly removes hollow, insect-damaged, and poorly developed beans that cannot be detected by colour or size sorting alone.

Oliver Hi-Cap and Voyager Gravity Separators

Oliver Manufacturing (La Junta, Colorado; est. 1930) is the international benchmark for gravity separator construction — the reference brand against which other gravity tables are evaluated. Two product families are relevant at Kaiserblick’s scale:

Hi-Cap (HC51–HC241) — manual controls; 3–7 fan zones; entry point for production-scale gravity separation. The HC51 (26”×59” deck, 3 zones) and HC81 (32”×84”, 5 zones) are the likely scale match for a specialty micro-mill. Published capacities reference corn and brassica — exact coffee throughput should be confirmed with Ian Ely (Central America contact).

Voyager (GVX1020–GVX1050) — PLC touchscreen, 20 programmable recipes, VFD fan control. The GVX1020 (29”×60” deck, ~3,800 lbs/hr corn, 1,066 kg) adds recipe repeatability across lots and processing methods, useful in a multi-lot specialty mill.

No El Salvador distributor confirmed — contact Ian Ely (ian.ely@olivermanufacturing.com; Central America territory).

Gravity Separator Comparison

Three viable options for Kaiserblick; all use the same physical principle (upward air + deck vibration + inclination):

Pinhalense MVF-0Oliver HC81Oliver GVX1020 (Voyager)Cimbria GA 31
ControlsElectronicManualPLC / 20 recipesSiemens PLC / recipe DB
Fan zonesAdjustable5VFD variable—
Capacity900–1,200 kg/hConfirm with Ian Ely~1,720 kg/h (corn)Confirm with Cimbria
Weight430 kg435–771 kg (series range)1,066 kg—
ES distributorComercializadora El PotosíNone confirmedNone confirmedNone confirmed

Size Grading (Screen Grading)

Uniform bean size matters for roasting consistency: smaller beans roast faster than larger beans at the same heat, so mixed sizes in a roast batch produce uneven development.

Upward Flow Size Grader (PFA series)

A stack of perforated screens through which an upward air flow passes. Beans are sorted by their screen size — beans that pass through a given screen aperture fall to the next level; beans that do not pass remain on that screen.

  • Upward flow technology: the air current lifts beans, reducing retention on screens and improving throughput accuracy
  • Low retention rate: fewer beans trapped in or on the screen
  • Up to 9 sorting screens in a single machine — produces up to 10 size categories in one pass
  • Screen aperture selection customised by buyer
  • Low power consumption

PFA 1-2 specifications (smallest model):

  • Capacity: 300 kg/h; 0.5 HP motor
  • 1.85 m H × 1.0 m W × 1.7 m L; 150 kg; 2 sieves

Model range: PFA 1-2 through PFA II 6

For export, beans are typically sorted into a minimum of two or three size categories. Specialty buyers generally prefer larger screen sizes (higher density and development).

Coffee Sample Screens

Manual hand-held sieves (round or elongated hole patterns) used in the quality lab for grading green coffee samples. Standard sizes correspond to SCA and local export grade specifications. Available in wooden or metal frames.

Complete Dry Mill Sequence

Dried coffee (10–12% moisture, hulled form)
  → Pre-Cleaner PL (if large volume: removes large/small debris)
  → Combined Coffee Huller CON (hulling + integrated destoning + weight sort)
  → Gravity Separator (density sort: dense / light / defective; options: Pinhalense MVF, Oliver Hi-Cap/Voyager, Cimbria GA)
  → Size Grader PFA (screen size calibration)
  → Colour sorter (automated optical — not in Pinhalense catalog; third-party)
  → Manual sorting (final visual pass)
  → Bagging for export

For smaller operations, some steps are combined (e.g., Combined Huller handles destoning + hulling + weight sort in a single pass).

Quality and Export Grading Context

El Salvador’s SHG/HG/CS grading system is altitude-based (see El Salvador Coffee Quality Grades). However, export quality is also governed by defect count and screen size specifications set by the buyer.

Dry milling equipment directly determines:

  • Defect rate in the export lot (destoner + gravity separator + colour sorter)
  • Screen size uniformity (size grader)
  • Bean appearance and surface cleanliness (polisher)

Specialty buyers such as Tim Wendelboe and Nordic Approach set minimum quality thresholds (e.g., 86+ SCA score) that presuppose properly executed dry milling.

Cimbria HANSA SM — Alternative Huller/Polisher

Cimbria (Denmark, AGCO Group) offers the HANSA SM as an alternative combined huller + polisher for micro-mill scale. Key differentiator from Pinhalense: processes both dry parchment AND dry cherry (natural) in the same machine without changeover, with integrated polishing via “blunt hulling” (fluted broad hulling cheeks + friction under pressure).

AttributeHANSA SMPinhalense CON/COMPACTA
ModelsSM10, SM14CON series, COMPACTA
Coffee typesParchment + NaturalPrimarily parchment
PolishingIntegratedDEPOS separate unit (or integrated in some CON models)
DestoningSeparate TS unit requiredFlutu-Ar integrated in CON
ES distributorNone confirmedComercializadora El Potosí

Cimbria also offers the GA gravity separator series (GA 31 through GA 310) as an alternative to Pinhalense’s MVF series. The GA series features a Siemens PLC HMI with recipe database and remote connectivity. The GA 31 is the smallest standard model and may match Kaiserblick’s throughput scale.

Full specification comparison requires downloading data sheets from cimbria.com. No El Salvador distributor confirmed — contact via cimbria.com/en/contact/contact-us/.

Optical Colour Sorting

Automated colour sorting is the dry mill step that follows gravity separation, removing beans with visible colour defects — black beans, sour/yellow beans, over-fermented beans — that gravity separation cannot detect. This is a Phase 2 investment for Kaiserblick (not required for initial setup).

Scale reference for industrial optical sorting: Bühler SORTEX systems (SORTEX F: 20 t/h; SORTEX AI700 and SpectraVision series) define the industrial ceiling — built for plants processing 10,000+ tonnes/year. Not relevant at Kaiserblick scale.

Small-format option: RealTech (Anhui RealTech Machinery, China) makes a mini coffee bean colour sorter — AI-based, wide-spectrum HD imaging, designed for micro-producer scale. Sold direct and via Alibaba; no Latin America distributor confirmed. Full specs require a quote (ChinaColorSorter@126.com). Cimbria also offers SEA optical sorters as an alternative.

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