1. Overview

In mechanical design, a hygienic / cleanability module is a function module that ensures machine structures in contact with products, raw materials, cleaning water, operators, and the surrounding environment can be maintained in a hygienic condition.

In general machinery, strength, stiffness, accuracy, speed, and productivity are often the main design criteria.
However, in equipment where product contamination is a concern, such as food machinery, pharmaceutical manufacturing equipment, cosmetic manufacturing equipment, and packaging equipment, hygiene and cleanability become part of machine performance.

A hygienic / cleanability module is not simply a matter of using stainless steel.
It is a design area that considers product-contact surfaces, raw material flow paths, areas exposed to cleaning water, spaces where residue can accumulate, drainage direction, disassembly structure, sealing structure, separation of lubricated areas, and the possibility of foreign matter contamination.

In other words, the hygienic / cleanability module is a design module that prevents contamination, enables cleaning, and maintains hygienic conditions after cleaning.

For example, product-contact surfaces, hoppers, chutes, filling nozzles, mixing tanks, transfer belts, product guides, clamp pads, cleaning covers, drainage structures, removable jigs, hygienic seals, stainless steel frames, open structures, sloped surfaces, and cleaning access spaces may all be included in the hygienic / cleanability module.

This module is especially important in food machinery, but it can also be applied to any equipment where product contamination, cleaning, residue, microorganisms, corrosion, or foreign matter contamination may become a problem.

Therefore, the hygienic / cleanability module should not be treated as a cleaning method to be considered after the equipment is completed. It should be reviewed from the early design stage together with the machine structure and functions.

2. Definition

A hygienic / cleanability module is a function module that prevents product contamination, makes product-contact and surrounding structures easy to clean, and ensures that residue, standing water, foreign matter, corrosion, and lubricant contamination do not remain after cleaning.

The core purpose of this module can be summarized as follows:

To design machine structures that contact products or may cause contamination so that they can be maintained hygienically and inspected or cleaned properly.

The hygienic / cleanability module performs the following functions.

The hygienic / cleanability module does not refer to one specific part.
It is a design perspective that includes product-contact structures, frames, covers, piping, drive-unit layout, disassembly structures, drainage structures, and maintenance structures.

3. Role in Mechanical Systems

The hygienic / cleanability module performs the following roles within a mechanical system.

3.1 It Prevents Product Contamination

One of the most important purposes in food machinery is the prevention of product contamination.

Contamination can occur through many routes.

The hygienic / cleanability module must structurally reduce these contamination routes.

Contamination prevention is not simply a matter of cleaning frequently.
It is important to create a structure where contamination is difficult to generate, easy to see, and easy to remove.

3.2 It Creates a Cleanable Structure

To maintain a machine hygienically, the structure must be cleanable.

Cleanability is determined by the following conditions.

• Can the operator reach the area with hands or cleaning tools?

• Can cleaning water reach the contaminated area?

• Can the area be cleaned without disassembly?

• If disassembly is required, can it be done easily?

• Does water drain after cleaning?

• Is residue visible?

• Is reassembly easy after cleaning?

• Are function and position maintained after cleaning?

Good hygienic design is not a structure that merely “looks clean.”
It is a structure that operators can actually clean.

For example, even if a cover is installed, cleanability is low if the inside cannot be accessed.
Even if stainless steel is used, residue can remain if there are many gaps and pockets.
Even if disassembly is possible, proper cleaning is difficult in the field if many tools are required or assembly references are unclear.

3.3 It Reduces Residue and Standing Water

In food machinery, residue and standing water are major causes of hygiene problems.

Structures where residue is likely to remain include:

• Closed pockets

• Deep grooves

• Horizontal surfaces

• Plates without drainage

• Areas around bolts

• Areas around weld beads

• Under linear guide rails

• Under belts

• Around hinges

• Between seals and covers

• Hollow spaces inside frames

• Adjustment slots

• Overlapped sheet-metal areas

If residue remains, it can lead to microbial growth, odor, corrosion, foreign matter contamination, and product contamination.

Therefore, the hygienic / cleanability module should be designed with open structures, sloped surfaces, drainage paths, unobstructed spaces, and cleanable clearances wherever possible.

3.4 It Determines the Quality of Product-Contact Surfaces

Product-contact surfaces are the most important area in hygienic design.

Product-contact surfaces should meet the following conditions.

• The material must be suitable for the product.

• The surface must be smooth and cleanable.

• There should be no sharp edges or scratches.

• It must resist corrosion.

• It must withstand cleaning agents and temperature.

• There should be no gaps where raw material can become trapped.

• It should be possible to disassemble and inspect the area.

• Foreign matter should not be generated even after wear.

If product-contact surfaces are not properly designed, product quality and safety can become problematic even if the machine operates normally.

For example, if there is an uncleanable step inside a filling nozzle, previous product may remain.
If a weld inside a hopper is rough, powder or viscous material may adhere to it.
If a product guide has deep scratches, residue can remain and cleaning becomes difficult.

3.5 It Separates Lubricated Areas from Product Areas

Many machine components require lubrication, such as bearings, chains, gears, linear guides, and ball screws.

However, in food machinery, if lubricated areas are close to product areas, the risk of contamination increases.

The following factors should be reviewed.

• Is the lubricated area located above the product?

• Is there a possibility that lubricant may drip?

• Can chain or gear wear particles enter the product?

• If a bearing seal fails, can lubricant enter the product area?

• Can cleaning water enter the lubricated area and wash away lubricant?

• Can lubricated areas be inspected and replaced?

• Does the protective cover trap residue instead of preventing contamination?

If lubricated areas cannot be completely eliminated, they should be separated from product-contact areas, positioned away from drip paths, and reviewed together with covers and drainage structures.

3.6 It Makes Cleaning, Inspection, and Maintenance Easier

The hygienic / cleanability module directly affects cleaning and maintenance work.

The following factors should be reviewed.

• Can operators see the areas that need cleaning?

• Can parts be disassembled easily?

• Can disassembled parts be reassembled accurately?

• Can pads, seals, guides, and nozzles be replaced easily?

• Is tool-less disassembly possible?

• Can the machine dry after cleaning?

• Can inspection intervals be managed?

• Are sensors and electrical components protected during cleaning?

Hygienic structures must be managed repeatedly in the field.
Therefore, designers should consider operator movement, tool use, part weight, disassembly sequence, and reassembly references.

4. Main Types of Hygienic / Cleanability Modules

Hygienic / cleanability modules can be divided into several types according to application area and function.

5. Types of Hygienic / Cleanability Design Methods

5.1 Hygienic Design of Product-Contact Areas

Hygienic design of product-contact areas makes the parts touched directly by products, raw materials, semi-finished products, or packaging materials hygienic.

Typical components include:

• Hopper

• Chute

• Filling nozzle

• Mixing tank

• Product guide

• Transfer belt

• Clamp pad

• Forming mold

• Sealing contact section

• Discharge outlet

Advantages

• Product contamination risk can be directly reduced.

• Cleaning and inspection criteria can be clearly defined.

• It directly contributes to product quality stability.

• It is the most important hygienic area in food machinery.

• Residue problems during product changeover can be reduced.

Points to Consider

• Raw material can remain even in small gaps.

• Residue can adhere to scratches and rough welds.

• Product-contact materials must be suitable.

• Resistance to cleaning agents, temperature, and friction is required.

• Position must be repeatable after disassembly and reassembly.

Design Review Points

• Product-contact range

• Material suitability

• Surface condition

• Weld finishing

• Edge treatment

• Cleaning accessibility

• Disassembly

• Possibility of residue

• Wear and foreign matter generation

• Cleanability after product changeover

5.2 Open-Frame Design

Open-frame design creates frames and structures in an open form that is easy to clean and inspect, rather than in a closed form.

Typical components include:

• Open stainless steel frame

• Lower cleaning space

• Sloped frame top surface

• Unobstructed support structure

• Accessible mounting areas

• Exposed inspection space

Advantages

• Cleaning accessibility is good.

• Residue and foreign matter are easy to identify.

• Internal structures are visible and easy to inspect.

• Standing water can be reduced more easily.

• It is suitable for food machinery structures.

Points to Consider

• If the structure is too open, safety may decrease.

• Stiffness and vibration must be reviewed together.

• Exposed wiring and piping must be managed.

• Product scattering and cleaning-water splashing must be considered.

• Balance with covers and guards is required.

Design Review Points

• Cleaning access direction

• Frame stiffness

• Lower space

• Drainage path

• Need for safety guard

• Wiring and piping arrangement

• Possibility of product scattering

• Frame section treatment

• Foreign matter visibility

• Operator accessibility

5.3 Drainability Design

Drainability design allows cleaning water and raw material residue to drain naturally without remaining inside the machine.

Typical components include:

• Sloped surface

• Drain hole

• Drain

• Open floor structure

• Sloped cover

• Water-accumulation-prevention plate

• Removal of closed pockets

• Lower discharge space

Advantages

• Standing water can be reduced.

• Drying after cleaning becomes easier.

• Microbial growth risk decreases.

• Corrosion risk decreases.

• Cleaning time can be reduced.

Points to Consider

• Drainage direction must match the actual installation condition.

• Water must not remain even after leveling.

• Drains must not clog.

• Products or raw materials must not accumulate in drainage sections.

• Drainage structures must not create safety risks for operators.

Design Review Points

• Slope direction

• Drain location

• Possibility of standing water

• Cleaning water flow

• Drain size

• Drying after drainage

• Influence of installation leveling

• Possibility of raw material residue

• Cleaning accessibility

• Foreign matter prevention in drainage areas

5.4 Disassembly and Tool-Less Cleaning Design

Disassembly and tool-less cleaning design allows parts that require cleaning to be disassembled quickly and repeatedly.

Typical components include:

• Quick clamp

• Hand knob

• Tool-less fastener

• Removable guide

• Detachable nozzle

• Removable belt

• Removable cover

• Positioning pin

• Assembly reference surface

Advantages

• Cleaning time is reduced.

• Operator burden decreases.

• It is advantageous for product changeover.

• Cleaning quality can be improved.

• Inspection and part replacement become easier.

Points to Consider

• Position repeatability is required after repeated disassembly.

• If fastening force is insufficient, parts may loosen during operation.

• Small parts can become foreign matter.

• Storage and management of disassembled parts are required.

• Tool-less structures must not create additional gaps.

Design Review Points

• Areas requiring disassembly

• Disassembly frequency

• Fastening method

• Position repeatability

• Operator usability

• Part weight

• Disassembly sequence

• Possibility of foreign matter contamination

• Reassembly reference after cleaning

• Fastening condition after wear

5.5 Sealing and Gap-Prevention Design

Sealing and gap-prevention design reduces gaps where raw material, cleaning water, microorganisms, or lubricant can enter or remain.

Typical components include:

• Hygienic gasket

• O-ring

• Seal plate

• Clamp connection

• Enclosed cover

• Rounded treatment

• Integrated structure

• Gap-minimizing structure

Advantages

• Residue ingress can be reduced.

• Cleanability can be improved.

• Leakage can be prevented.

• Hygiene of product-contact areas can be improved.

• Possibility of foreign matter contamination decreases.

Points to Consider

• Worn seals can become contamination sources.

• Uncleanable spaces may be created behind seals.

• Excessive sealing can make cleaning and drying difficult.

• Seal material must be suitable for the product and cleaning agents.

• Disassembly and replacement must be possible.

Design Review Points

• Seal position

• Seal material

• Product-contact status

• Cleaning agent resistance

• Temperature resistance

• Disassembly

• Possibility of residue behind seals

• Leakage direction

• Replacement interval

• Possibility of foreign matter generation

5.6 Cleaning-Water Protection Design

Cleaning-water protection design prevents cleaning water and cleaning agents from entering drive units, electrical components, sensors, bearings, and lubricated areas.

Typical components include:

• Waterproof cover

• Cable gland

• Sensor protection cover

• Motor protection cover

• Wiring duct

• Drainage-direction guide plate

• Sealing structure

• Fixed piping protection structure

Advantages

• Electrical failures can be reduced.

• Sensor misdetection can be reduced.

• Bearing and guide service life can be protected.

• Lubricant washout can be reduced.

• Cleaning work can be performed more freely.

Points to Consider

• Water must not accumulate inside protective covers.

• Enclosed structures must not trap heat and moisture.

• Cable and sensor replacement must be possible.

• Protective structures must not create cleaning blind spots.

• Drainage direction must be considered.

Design Review Points

• Cleaning water direction

• Electrical component location

• Need for sensor protection

• Cable entry

• Cover drainability

• Possibility of internal condensation

• Maintenance accessibility

• Waterproof level

• Effect of cleaning agents

• Protection of lubricated areas

6. Main Design Criteria

The following criteria should be reviewed when designing a hygienic / cleanability module.

6.1 Product-Contact Status

The first factor to review is whether the area directly contacts the product.

Direct product-contact areas require the highest level of hygienic design.
However, even non-contact areas must be reviewed carefully if they are located above the product or if cleaning water can flow from them into the product area.

6.2 Material Selection

Material selection is very important in hygienic / cleanability modules.

Review points include:

• Suitability for product contact

• Corrosion resistance

• Cleaning agent resistance

• Temperature resistance

• Wear resistance

• Surface treatment possibility

• Possibility of foreign matter generation

• Detectability

• Contamination risk in case of breakage

• Cost and machinability

Stainless steel is widely used in food machinery, but making every part from stainless steel is not always the correct answer.
Product characteristics, cleaning conditions, strength, wear, cost, and machinability must be considered together.

6.3 Surface Condition

Surface condition directly affects residue adhesion and cleanability.

Review points include:

• Surface roughness

• Weld finishing

• Machining marks

• Scratches

• Sharp edges

• Oxide layer

• Possibility of coating peeling

• Adhesive residue

• Possibility of corrosion

• Surface change after wear

If the surface is rough or scratched, raw material adheres easily and cleaning becomes difficult.
Viscous materials, powders, proteins, and fats are especially sensitive to surface condition.

6.4 Gaps, Pockets, and Blind Spots

In hygienic design, uncleanable gaps and pockets are typical structures to avoid.

Review points include:

• Between overlapped plates

• Around bolts

• Adjustment slots

• Unwelded gaps

• Deep grooves

• Blind holes

• Inside covers

• Around hinges

• Behind seals

• Hollow spaces inside frames

These areas are difficult to clean and residue can easily remain.
Therefore, the structure should be simplified, opened, made visible, and designed in a cleanable direction wherever possible.

6.5 Drainability and Drying

If water remains after cleaning, hygiene problems may occur.

Review points include:

• Application of sloped surfaces

• Drainage direction

• Possibility of standing water

• Lower discharge space

• Drain location

• Drying time after drainage

• Installation leveling condition

• Cleaning water flow

• Possibility of condensation

• Drainability of internal hollow spaces

Drainability is not determined only by slope on the drawing.
Actual installation condition, leveling, floor slope, and cleaning direction must also be considered.

6.6 Disassembly and Reassembly

Parts that must be disassembled for cleaning should be easy to disassemble and accurately reassembled.

Review points include:

• Need for disassembly

• Disassembly frequency

• Need for tools

• Part weight

• Operator accessibility

• Assembly reference surface

• Positioning pin

• Fastening force confirmation

• Misassembly prevention

• Functional check after cleaning

If disassembly is easy but reassembly is poor, quality problems can occur in the field.
Therefore, disassembly structures should always include position repeatability and misassembly prevention.

6.7 Cleaning Method and Operating Conditions

Hygienic / cleanability design should be reviewed based on the actual cleaning method.

Review points include:

• Dry cleaning or wet cleaning

• High-pressure cleaning

• Type of cleaning agent

• Cleaning temperature

• Cleaning frequency

• Disassembly cleaning

• Automatic cleaning

• Drying after cleaning

• Product changeover frequency

• Possibility of allergen or flavor residue

Even for the same equipment, the required structure changes depending on the cleaning method.
In wet-cleaned equipment, waterproofing, drainability, and corrosion prevention are important.
In dry powder equipment, dust accumulation and moisture absorption prevention may be more important.

6.8 Foreign Matter Prevention

The hygienic / cleanability module must also consider foreign matter prevention.

Review points include:

• Possibility of bolt loosening

• Possibility of nut loss

• Possibility of seal breakage

• Possibility of plastic cover breakage

• Belt wear particles

• Brush bristle loss

• Metal wear particles

• Paint peeling

• Corrosion fragments

• Operator tool ingress

Foreign matter contamination is directly connected to product safety.
Therefore, parts located above the product, repeated-wear parts, disassembled parts, and small fastening parts require special attention.

7. Interface with Other Modules

The hygienic / cleanability module is connected to almost every functional module.

7.1 Relationship with the Material Handling Module

The material handling module often directly contacts the product, so hygiene and cleanability are important.

Review points include:

• Does residue remain inside hoppers and chutes?

• Can the underside of conveyor belts be cleaned?

• Can product guides be disassembled easily?

• Is the product not contaminated during transfer?

• Are there no closed pockets at discharge outlets?

• Is cleaning possible during product changeover?

7.2 Relationship with the Processing / Working Module

The processing / working module changes the state of raw materials, so residue and contamination risks are high.

7.3 Relationship with the Tooling Module

The tooling module often directly contacts the product.

Review points include:

• Is the tool surface cleanable?

• Is position reproduced after tool replacement?

• Does residue not remain between the tool and jig?

• Does worn tooling not generate foreign matter?

• Is tool material suitable for the product and cleaning agents?

• Can the tool be disassembled and cleaned?

7.4 Relationship with the Holding / Clamping Module

The holding / clamping module often directly holds or supports the product.

Review points include:

• Is the clamp pad suitable for the product?

• Does residue not remain on the pad surface?

• Can jig pockets be cleaned?

• Does raw material not become trapped inside clamp gaps?

• Do pads and seals not generate foreign matter after wear?

• Are disassembly and replacement easy?

7.5 Relationship with the Motion / Positioning Module

The motion / positioning module includes guides, ball screws, sensors, and stoppers, so cleanability and separation of lubricated areas are important.

Review points include:

• Are linear guides separated from the product area?

• Can ball screw lubricant drip toward the product?

• Does residue not remain around stoppers?

• Are sensor brackets cleanable?

• Is positional repeatability maintained after cleaning?

• Does the guide cover not trap residue?

7.6 Relationship with the Drive and Power Transmission Modules

Drive sections and power transmission sections involve lubrication, wear, dust, and cleaning-water ingress issues.

Review points include:

• Are motors and reducers protected from cleaning water?

• Are chains and gears separated from the product area?

• Do belt wear particles not enter the product?

• Are bearing lubrication areas isolated?

• Does water not accumulate inside covers?

• Does contamination not occur during maintenance?

7.7 Relationship with the Structural Support Module

The structural support module strongly affects the cleanability and drainability of the entire equipment.

Review points include:

• Does water not accumulate on the frame?

• Is the structure open and cleanable?

• Does residue not remain around bolts and brackets?

• Are welds finished hygienically?

• Can the lower area be cleaned?

• Does the frame material resist corrosion?

7.8 Relationship with the Safety / Guarding Module

The safety / guarding module protects workers, but it can interfere with cleanability.

Review points include:

• Can the cover be opened and cleaned easily?

• Does residue not remain inside transparent covers?

• Are interlock switches waterproof?

• Does the guard not create cleaning blind spots?

• Is there a foreign matter risk if the cover breaks?

• Is the safety function maintained after cleaning?

8. Application in Food Machinery

In food machinery, the hygienic / cleanability module is not optional. It is a basic design condition of the equipment.

Important conditions for hygienic / cleanability modules in food machinery include the following.

In food machinery, the following questions should always be checked.

• Where does the product contact the machine?

• Where does cleaning water flow?

• Where can raw material remain?

• How far can the operator clean?

• Where does water accumulate after cleaning?

• Can lubricant or wear particles move toward the product?

• Are disassembled parts reassembled accurately?

Hygienic / cleanability design affects product quality, food safety, productivity, cleaning time, maintainability, and equipment life.

9. Common Design Mistakes

Common design mistakes in hygienic / cleanability modules include the following.

9.1 Assuming That Stainless Steel Alone Makes the Machine Hygienic

Even if stainless steel is used, the structure is not hygienic if there are gaps, pockets, rough welds, or standing water.

Hygienic design is not only a material issue.
It is also an issue of structure, surface condition, drainability, disassembly, and cleaning accessibility.

9.2 Reviewing Cleanability Too Late in the Design Process

If the equipment structure is completed first and cleanability is reviewed later, inaccessible areas, poor drainage, cover interference, and difficult disassembly are likely to occur.

Cleanability should be determined together with the initial layout and structural design.

9.3 Ignoring Standing Water and Drainage Direction

Even if the drawing looks acceptable, water may accumulate in certain areas after the equipment is installed and leveled.

Drainability must consider actual installation condition, leveling, floor condition, and cleaning direction.

9.4 Designing Parts That Can Be Disassembled but Have No Reassembly Reference

Even if parts can be disassembled for cleaning, production quality changes if their position changes after reassembly.

Removable parts need positioning structures, assembly direction indicators, and misassembly prevention structures.

9.5 Allowing Covers and Guards to Create Cleaning Blind Spots

A cover may be installed for safety, but if raw material enters inside it and the area is difficult to clean, it becomes a hygiene problem.

Safety guards should be designed together with cleanability.

9.6 Placing Lubricated Areas Above the Product

If bearings, chains, gears, or linear guides are located above the product, lubricants, wear particles, and cleaning water may fall toward the product.

Lubricated areas should be positioned away from product areas whenever possible.
If this is not possible, isolation structures and drainage structures should be designed together.

10. Design Checklist

The following questions can be used when designing a hygienic / cleanability module.

10.1 Product-Contact Review

• Where do products, raw materials, or semi-finished products directly contact the machine?

• Which areas can indirectly affect the product?

• Which components are located above the product?

• Are product-contact materials suitable?

• Will wear or breakage generate foreign matter?

10.2 Cleanability Review

• Can operators see the areas that need cleaning?

• Can hands, brushes, water, and cleaning agents reach contaminated areas?

• Can the area be cleaned without disassembly?

• If disassembly is required, can it be done easily?

• Is the part reassembled accurately after cleaning?

10.3 Residue Review

• Are there gaps, grooves, pockets, or horizontal surfaces?

• Does raw material accumulate around bolts or adjustment slots?

• Does residue remain inside covers?

• Does raw material adhere around welds and edges?

• Does previous product remain after product changeover?

10.4 Drainability Review

• Does cleaning water drain naturally?

• Are there horizontal surfaces where water can remain?

• Are drains unlikely to clog?

• Does drainage still work after installation and leveling?

• Can the machine dry after cleaning?

10.5 Drive and Lubricated-Area Review

• Are lubricated areas separated from product areas?

• Is there a possibility that lubricant may drip toward the product?

• Does cleaning water not enter bearings, guides, or motors?

• Does the cover protect lubricated areas without trapping residue?

• Does maintenance not create contamination?

10.6 Maintenance and Foreign Matter Prevention Review

• Can seals, pads, belts, and nozzles be replaced easily?

• Can small fastening parts enter the product?

• Can wear parts be inspected easily?

• Is there no possibility of cover breakage or paint peeling?

• Are function and position maintained after cleaning?

11. Summary

A hygienic / cleanability module is a core function module that prevents product contamination, makes product-contact and surrounding structures easy to clean, and ensures that residue, standing water, foreign matter, corrosion, and lubricant contamination do not remain after cleaning.

This module may consist of product-contact surfaces, hoppers, chutes, nozzles, tanks, product guides, clamp pads, cleaning covers, drainage structures, removable jigs, hygienic seals, open frames, waterproof structures, and lubricated-area separation structures.

A hygienic / cleanability module is not simply a matter of using stainless steel.
It is a design area that reviews material, surface condition, structural geometry, gaps, pockets, drainability, disassembly, reassembly, cleaning method, separation of lubricated areas, and foreign matter prevention together.

When designing this module, product-contact status, material, surface smoothness, cleaning accessibility, residue prevention, drainability, drying, disassembly, reassembly, cleaning method, waterproofing, maintainability, and foreign matter prevention must be reviewed comprehensively.

The hygienic / cleanability module is also directly connected to the material handling module, processing / working module, tooling module, holding / clamping module, motion / positioning module, drive module, power transmission module, structural support module, and safety / guarding module.

In food machinery, the hygienic / cleanability module is a basic design condition of the equipment.
Designers should review from the early design stage where the product contacts the machine, where raw material can remain, where cleaning water flows, how far operators can clean, and whether lubricants or foreign matter can enter the product.

Therefore, the hygienic / cleanability module should be understood not as an additional element for cleaning work, but as a core design module that determines product safety, quality stability, productivity, maintainability, and equipment reliability in food machinery.