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SELECTION OF CHEMICALS AND PROCESSES FOR FINE AND ULTRA-FINE CLEANING

Ulrike Kunz – SurTec Deutschland GmbH

Fachforum parts2clean – 24.10.2017

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� What does „Sufficient Parts Cleanliness“ mean?

� Chemicals for fine and ultra-fine cleaning

� Enlarged Sinner‘s Circle

� Requirements for achieving parts cleanliness

� Equipment of plants used for parts with extreme

cleanliness requirements

� Summary

OVERVIEW

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� Sufficient parts cleanliness describes the level of cleanliness of the

parts, which is required for the subsequent process step

� That means: not as clean as possible but as clean as necessary

� Both particle and filmic impurities are considered

WHAT DOES „SUFFICIENT PARTS CLEANLINESS“ MEAN?

source: partikel-scanner.de

source: qe-online.de source: SITA Messtechnik

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Example: Intermediate Cleaning

� Cleaning between different production steps

WHAT DOES „SUFFICIENT PARTS CLEANLINESS“ MEAN?

turning drilling cleaningcleaning

source: www.direct-industry.desource: www.weindorf-metallbearbeitung.de

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Example: „Extended“ intermediate Cleaning

� Cleaning prior to „special“ process steps

WHAT DOES „SUFFICIENT PARTS CLEANLINESS“ MEAN?

coating

heat

treatmentcleaningdeburring cleaning

source: Hildenk.de

source: Cotarko

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Example: Final Cleaning = Fine and Precision Cleaning

� Cleaning before functional coating (PVD/CVD), gluing, or final cleaning

of components of high functional density or medical-technical products

WHAT DOES „SUFFICIENT PARTS CLEANLINESS“ MEAN?

final

inspection

inspection/

installationcleaningpolishing cleaning

source: dd-optic.de source: videoportal.bosch-presse.de

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� If the components are not cleaned properly, problems may occur during

the usage of the components, e.g.:

� Clogging of fine nozzles

� Short in electric circuits

� Jamming of valves

CONSEQUENCES OF INSUFFICIENT PARTS CLEANLINESS

source: focus.de

� Total failure of the component

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� Ultra-fine particles and impurities which

� disturb the following process step

� impair the function of the part

� prevent the function of the part

CONTAMINATIONS IN THE PROCESS CHAIN

minerals metals salts organics/fibres oils/fats

source: RJL Micro&Analytic

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Blasting processes

Mechanical processes

Thermic processes

Special processes

Others

OVERVIEW CLEANING PROCESSES

59%

20%

13%

4%

3%

1%

Wet processes

source: Fraunhofer IPK, 2012

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OVERVIEW CLEANING PROCESSES – WET PROCESSES

76%

7%

8%

6%

3%

aqueous processes

chlorinated hydrocarbons

hydrocarbons

alcohols

special processes

source: Fraunhofer IPK, 2012

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CHEMICALS FOR FINE AND ULTRA-FINE CLEANING SOLVENT CLEANING

Halogenated organic solvents

CHC (chlorinated hydrocarbons)

� perchloroethylene (Per)

� methylene chloride (MeCl)

Non-halogenated organic solvents

HC solvents (hydrocarbon solvents)

� nonpolar solvents

(e.g. isoparaffins, test fuel)

� semi-polar solvents

(e.g. alcoxy propanol, ester)

� polar solvents

(e.g. NMP, alcohols)

� Physical Processes

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ADVANTAGES AND DISADVANTAGES OF SOLVENT CLEANING

Principle: „similar dissolves similar“

Non-polar solvents dissolve non-polar impurities (oils, fats).

Contaminations are removed by dilution.

+ independent of material and geometrical shapes

+ good creeping properties

+ fast drying

- only moderate removal of pigments, particles and inorganic residues (salts)

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CHEMICALS FOR FINE AND ULTRA-FINE CLEANING AQUEOUS CLEANING

Aqueous Detergents

�„Builder“ as basis (neutral, alkaline and acidic)

� Surfactants

� Corrosion inhibitors

� Additives (defoaming agents, inhibitors etc.)

� Chemical-physical Processes

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� Emulsifying of oils and fats

� Saponification of vegetable and animal oils and fats

� Dispersing of particle impurities

� Dissolving/complexing of metals, metal oxides and metal salts

CHEMICAL AND PHYSICAL CLEANING EFFECTS

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ADVANTAGES AND DISADVANTAGES OF AQUEOUS CLEANING

+ good or very good removal of inorganic contaminations

+ good removal of swarfs and particles

+ cleaning by abrasion possible

+ produces highly active surfaces e.g. for further coating

- adaption to material and geometrical shape necessary

- separate drying and corrosion protection required

source: MAV-online.de

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Sinner‘s Circle

FACTORS FOR ACHIEVING PARTS CLEANLINESS

Optimal result

Chemistry

Application

Temperature

Time

Initial contamination Medium cleanliness

Drying air

Interior of the washing plant

Cleaning (maintenance)

cycles of the washing plant

Handling after cleaning

Protection against re-contamination

Medium preparationMedium monitoring

Batch volume

Special

goods carrier

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� Make up with demineralised water

� Completely analysable multi-component cleaning systems

� Usage of demulsifying, recyclable cleaning systems

� Salt-free if possible, for easier maintenance of the subsequent rinsing bath

AQUEOUS CHEMICALS FOR FINE AND ULTRA-FINE CLEANING

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WATER QUALITY FOR FINE AND ULTRA-FINE CLEANING

Possible ingredients of drinking water

calcium, magnesium

� lime spots

chloride, sulfate

� corrosion

sodium, potassium, other salts

� increased salinity

various organics

� stains, foam

watercleaning agent

5 %

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Builder and surfactants are consumed in different amounts

Depending on: oil and dirt contamination

maintenance system (e.g. filtration, oil separator etc.)

For constantly good bath quality and for saving the resources:

Use of recyclable, demulsifying cleaning systems:

WHY USING MULTI-COMPONENT SYSTEMS?

� 2-Component-Systems

Builder

concentr

ati

on [

%]

Week

Surf

acta

nt

concentr

ati

on [

%]

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� In the fine and ultra-fine cleaning sector, efficient rinsing systems are as

important as the cleaning process itself!

� Rinsing off the pre-dissolved impurities

� Achieving low-stain/spot-free surfaces

� The more alkaline the cleaning solution the more difficult the rinse ability

� Salt-free cleaners are easier to rinse off as salt-containing cleaners

Thus: Adapt the rinsing intensity to the cleaning medium!

RINSING SYSTEMS IN THE FINE AND ULTRA-FINE CLEANING

Important: The drag-in of cleaning chemicals into

the rinsing systems and the necessary action for

maintenance has to be considered in order to avoid

stains! source: Kramer-Oberflächenzentrum

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1. Adapted Cleaning Parameters:

� Effective cleaning technique

Spray

Immersion

Immersion/ultra sound

Flooding

CNP

…

PRECONDITIONS FOR GOOD CLEANLINESS RESULTS

Sources (v.o.n.u.): Dürr,

Fotosearch, LPW

source: LPW

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1. Adapted Cleaning Parameters:

� Good accessibility to the parts

PRECONDITIONS FOR GOOD CLEANLINESS RESULTS

source: Metallform

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1. Adapted Cleaning Parameters:

� Appropriate cleaning chemicals

Use of recyclable, multi-component products

Demulsifying if using oil separators

Silicate-free if using evaporators or membrane filtration

PRECONDITIONS FOR GOOD CLEANLINESS RESULTS

source: atech innovation

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2. Effective Discharge of the Dissolved Contamination

� Processing has to be adequately dimensioned

� Adapted facility design

PRECONDITIONS FOR GOOD CLEANLINESS RESULTS

source: Dürr Ecoclean

cleaning cleaning rinsing rinsingDI-

rinsing

oil separator

membrane filterevaporator

drying

warm air

vacuum

Oily Phase

Driving Carriage

Mixed bed

active carbon

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3. Prevention of Re-contamination

� Clean drying air

� Optimised handling of the cleaned parts

PRECONDITIONS FOR GOOD CLEANLINESS RESULTS

source: Antalis

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4. Monitoring the Bath Parameter

� Cleaner concentration (Builder and Surfactant)

source: SITA

PRECONDITIONS FOR GOOD CLEANLINESS RESULTS

source: pce-instruments

source: Hach

source: Sensaction

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4. Monitoring the Bath Parameter

� Bath condition (degree of contamination)

PRECONDITIONS FOR GOOD CLEANLINESS RESULTS

source: Sita

UV beam

Opticalfilter

Light guide rod Bath

contamination, e.g. oil drops

Fluorescence

UV light source

Photo diode

bath contamination particle

Softened laser light

Continuous flow bath sample

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EQUIPMENT OF LINES FOR PARTS WITH EXTREME CLEANLINESS REQUIREMENTS

� Adapted facility design (without etches/corners to avoid particles to gather in)

� Specially adapted racks for cleaning, reduced filling volume

� Increased ultra sonic power (should be adapted to the residual dirt analysis)

� Extended application times

� Limited contamination input e.g. by pre-cleaning in a second line

� Exclusive usage of the line for final cleaning

source: upl-service.desource: sauberkeit-und-reinraum.com

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EQUIPMENT OF LINES FOR PARTS WITH EXTREME CLEANLINESS REQUIREMENTS

� Needle-felt filter inserts for high particle separation

� Filter units phased from 25 µm to 1 µm; if necessary: ultra or micro filtration

� Additionally use of magnet cores

source: Mahle Industriefiltration

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EQUIPMENT OF LINES FOR PARTS WITH EXTREME CLEANLINESS REQUIREMENTS

� Filtration of the drying air

� Counting the particle number in the baths

� Monitoring of the oily contamination in the baths

� Overpressure to prevent the intrusion of ambient air

� Separation of the cleaned parts from the environment by using tunnels,

direct interlinking into the controlled clean areas or clean room

source: Epcos.de

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EXAMPLE FOR PRODUCTION PROCESSES WITH OPTIMIZED CLEANLINESS

Process without special requirements

Drawing

Cleaning (standard system)

Hardening inclusive cleaning and

tempering

Installation

Conservation

Packaging (standard)

Process for enhanced cleanliness

requirements

Drawing

Cleaning (special system)

Hardening inclusive cleaning and

tempering

Vibratory finishing

Cleaning (special system)

Installation

Cleaning of the installed part (special system)

Packaging (special packaging)

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CLEANLINESS REQUIREMENTS � PLANT DESIGN

200 µm 400 µm 600 µm 800 µm 1000 µm

Cleaning system for extreme cleanliness requirements

Clean room required

Controlled clean areas + additional measures

Controlled clean areas required

Cleaning system for enhanced cleanliness requirements

Cleaning system for standard cleanliness requirements

Maximum allowed particle size

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COSTS CAUSED BY ENHANCED CLEANLINESS REQUIREMENTS

Standard cleanliness

Enhanced requirements

Extreme requirements

Plant investment 1 + 30% + 50 %

Cycle time 1 factor 2 factor 4

Baskets / washing racks 1 factor 10 factor 20

Filling volume 1 50 % 25 %

Utilisation rate (down time due to filter change / new make-up)

100 % 90 % 80 %

Effort for parts handling 100 % 100 % 125 %

Additional working steps no yes/no yes/no

Overall assessment 1 factor 5 - 10 factor 15 - 20

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� The selection of chemicals and the decision for a process is based on the

knowledge of the sufficient parts cleanliness

� For fine cleaning the „wet cleaning“ method is the most common kind of cleaning procedure

� Cleaning chemicals, plant engineering and processing methods must be

coordinated

� Extreme requirements concerning the parts cleanliness require special

additional measures and cause higher investment costs

SUMMARY

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THANK YOU!

Further information:

Ulrike.Kunz@SurTec.com

Tel: 06251/171-712

www.SurTec.com