High Plansifters in Flour Milling

A high plansifter is the machine that classifies ground stock into size fractions in the sifting section of a flour mill. In wheat and maize mills it grades flour particles and separates bran, germ and endosperm into different streams after the rolls have done their work. Three things decide how well it performs: the screen area and mesh you install, the way sieve frames are arranged in sections inside the body, and whether the feed rate through it is kept even.

Where the plansifter sits in the milling flow

Cleaning comes before grinding. A pre-cleaning sifter, sometimes supplied as a cylinder control sifter, removes straw, stones, dust and metal particles from wheat, rice, corn, soybeans, sunflower seed and rapeseed while the grain is still whole. It is described with customizable mesh sizes for different grain types.

Grinding comes next, and the plansifter sits immediately after it. Ground stock leaving the rolls is sifted and graded, so the sifter decides how many flour grades the mill produces and how cleanly bran and germ are kept apart from the endosperm.

The same screening job also appears in feed, food, chemical, sugar, pharmaceutical and building-material plants, where powders and granules have to be classified into size bands.

What a plansifter does and what it does not do

It does three things:

1. It separates flour particles by size, which is what produces a uniform, refined product.
2. It grades the mill streams, so high-grade flour can be taken off separately from lower grades.
3. It splits bran, germ and endosperm in wheat and maize processing.

It does not grind, it does not clean incoming grain, and it does not change the baking quality of what the rolls produced. Stones or straw in the incoming grain are dealt with by the pre-cleaning sifter upstream, not by the plansifter.

How sieve and compartment arrangement is usually described

Supplier catalogues describe plansifters in two ways, and both matter when you compare offers.

The first is by how the sieve frames are moved: vibrating plansifters, rotary sifters and gravity plansifters. The second is by how the body is divided: single-section plansifters and multi-section plansifters.

A section, sometimes called a compartment, is one bank of stacked sieve frames sharing a common drive and feed point. A single-section body has one bank; a multi-section body stacks several banks in one frame, so one machine can make several cuts at once. How many sections you need follows from how many separate streams your flow sheet has to produce.

Catalogues do not fix a standard number of sections or frames per body, and in practice it varies between builders and duties. The numbers to ask about are the screen area the body actually provides, and the number of independently fed sections it contains.

The variables that decide sifter performance

Screen area and mesh are the two figures to compare between offers, because throughput and grade both follow from them.

How sifter performance is judged

Judge the sifter as part of the whole sifting section, not as a machine on its own. Five checks are worth putting into a routine:

1. The split between streams. Look at how much material reaches each grade outlet and whether that split still matches your flow sheet.
2. Screening efficiency. Compare what leaves with the coarse streams against what should have passed the mesh.
3. Blinding. Check how quickly the fine sections plug; a blocked mesh changes the grade long before it changes the sound of the machine.
4. Sieve frame condition. Look for torn or slack cloth and worn frames; a small hole behaves like a large mesh change.
5. Consistency between shifts. The same grist should give the same split; drift is a signal.

Record the readings the same way each time; a trend line is more useful than a single reading.

Selection questions to put to any supplier

1. Which category is offered for this duty, vibrating, rotary or gravity, and what decides that choice?
2. How many sections does the body have, and how many separate streams can it deliver?
3. What total screen area does the body provide, and what feed rate is it sized for?
4. What mesh is specified for each section?
5. What is the drive arrangement, and what running settings are specified?
6. Which parts are classed as wear parts, and how are they identified for reordering?
7. What documentation is supplied with the machine?
8. Is the unit offered as a standalone replacement, or as part of a full sifting section?

Ask for the answers in writing: a mesh list and a section layout are what let you compare two offers on the same basis.

Installation and commissioning checks

Work through these before the machine is loaded with stock:

1. Foundation and level. The body should sit level and be supported as specified.
2. Frame seating and gaskets. Check that every frame seats fully and that no seal is pinched.
3. Drive. Confirm the specified settings, and confirm that no frame or cleaner is touching.
4. Feed spouting, aspiration and canopy. Confirm that spouts align with the correct outlets and that the canopy connection is tight.
5. Run empty. Listen for unusual noise or movement before introducing stock.
6. Feed gradually. Bring the feed up in steps and watch the split between streams.

Routine maintenance and what wears out

Sieve cloth and mesh are the fastest-wearing items, followed by frames, cleaners and gaskets. Tensioners, the drive bearings and the feed or discharge connections wear more slowly but still belong on the schedule.

A simple routine works well: inspect the mesh for holes or slack, check cleaners, gaskets and frame condition, and confirm the drive setting is unchanged. Clean the machine to the standard your product requires, and record what you changed and when.

Common problems and what to check first

1. Flour grade drifting coarse. Check the fine-section mesh first for a hole or slack cloth before touching the drive.
2. Capacity falling with unchanged feed. Check for blinding on the fine sections, then the cleaners, then the feed distribution.
3. Material turning up in the wrong outlet. Check gaskets and frame seating before assuming a mesh error.
4. Uneven wear across one sieve. Check whether feed is spread across the full screen width.
5. Rising noise or movement. Check the drive setting, the frame clamps and the foundation.
6. Fine material in the coarse stream. Check the mesh aperture and the frame seal at that section.
7. Dust escaping the body. Check the canopy and the aspiration connection.

Ordering spare parts for the sifter section

Sieve frames, mesh, cleaners, gaskets and tensioners are the items most often reordered, and they are matched on dimensions rather than on a model name. To get a correct match, send the frame dimensions, the mesh specification and photographs of the frame and its fittings. If a part is unmarked, a photograph with a scale beside it is often enough to identify it.

WUXI HASEN matches parts against dimensions, photographs and part numbers, and can supply spares for equipment built by other suppliers. For steel parts, ask the supplier for the mill test certificate; for anything dimensionally critical, ask for the dimensional inspection report. Ask also for the packing list and the commercial invoice, and confirm that wooden packing meets ISPM 15 if crates are used. WUXI HASEN works from the machine on your floor rather than from a fixed catalogue, and consolidates machines, spare parts and accessories from different origins into one shipment.

FAQ

What is a high plansifter used for?

It classifies ground stock into size fractions in the sifting section of a flour mill. In wheat and maize milling it grades flour and separates bran, germ and endosperm into different streams.

Where does it sit in the milling flow?

Immediately after the grinding rolls. Cleaning happens upstream, and the pre-cleaning sifter handles whole grain before grinding.

Are vibrating, rotary and gravity plansifters different machines?

They are categories used in catalogues to describe how the sieve frames are moved. Which one suits a duty depends on the product being sifted and on the cuts required.

What do single-section and multi-section mean?

They describe how the body is divided. A section is one bank of stacked sieve frames sharing a drive and feed point. A multi-section body stacks several banks in one frame, so more cuts can be made in one pass.

How is sifter performance judged?

By the split between the grade outlets, by screening efficiency, by how quickly the mesh blinds, by sieve frame condition, and by how consistent the split stays between shifts.

What wears out first?

Sieve cloth and mesh, then frames, cleaners and gaskets. Drive bearings and the feed and discharge connections wear more slowly.

Can you supply spare parts for a sifter built by another supplier?

Yes. Parts are matched by dimensions, photographs and part numbers, and WUXI HASEN can supply spares for equipment built by other suppliers.

What information do I need before ordering mesh?

The mesh specification, the frame dimensions, and photographs of the frame and its fittings.

What to send us for a precise answer

Send the machine type and its duty, the flow sheet you are working to, the frame dimensions and the mesh specification, and photographs of the sifter and of any part you need matched. If you are replacing a complete sifting line, tell us the grain, the number of streams and the site conditions. With those in hand we can define the requirement, match the parts, arrange inspection before shipment and consolidate the shipment. Reach us through Contact-us, or start from Flour-Mill-Machines, Grain-Machines and Flour-Mill-Parts.