VDMA SPECIFICATION 24364 · VDMA SPECIFICATION 24364 Testing for paint wetting impairment...

VDMA SPECIFICATION 24364 Testing for paint wetting impairment substances (PWIS/LABS-conformity)

Simone FrickProfessional Forum parts2clean 24 October, 2019

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Special field elastomers and seals

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10/2019 - SF PWIS/LABS conformity in accordance with VDMA 24364 2

SPECIAL CLEANLINESSPaint-Wetting Impairment Substances


SPECIAL CLEANLINESS


Contamination through paint wetting impairment substances impair the uniform paint application lead to blemishes and so-called craters

LABS is the German acronym for LAckBenetzungsstörende Substanzen PWIS is the equivalent English acronym for Paint-Wetting Impairment Substances

Components for varnishing applications

PWISLacquer

Substrate

PAINT-WETTING IMPAIRMENT

Total wetting: Requires the lacquer’s surface tension to be lower than that of the substrate

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Disturbed wetting: The lacquer’s surface tension is higher than that of PWIS

> The lacquer will retreat from the substrate at the contaminated spots PWIS contaminated surfaces cannot be wetted flawlessly with paint This leads to blemishes and craters


Cause and effect through contamination with PWIS

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>

total wetting

disturbedwetting

FAILURE MODE

Craters are punctual cavities in the lacquer coat Partly surrounded by a bulging margin Size, shape and characteristic can be quite diverse


Images: APO GmbH Industrielackierung

PWIS EFFECTS


Consequences of paint wetting impairments

PWIS disturb the look and the function of the lacquer coat, e.g. corrosion protection Deficiently painted components have to be scraped

or reworked extensively which leads to additional expenses High rework effort Additional expenses Image: APO GmbH Industrielackierung

Image: APO GmbH Industrielackierung

DEFICIENT DEFINITION


Silicone-free Silicones were initially mainly noticed as substances that interfere

with paint wetting The term „freedom from silicones “ is mistakenly still used today Not all PWIS contain silicones

Free of oil and grease Not all PWIS are oils and greases Not all oils and greases interfere with paint wetting

PWIS-free PWIS is no definable group of substances or contaminants

Silicone-free Free of oil and grease PWIS-free

Paint wetting impairment effects depend on the contaminants’ interaction with The paint system The substrate The ambient conditions

A general listing of all PWIS is not possible

When does a contaminant cause paint wetting disturbance?

PAINT-WETTING IMPAIRMENT SUBSTANCES


SOURCES OF CONTAMINATION

In the production Lubricants Residues of drawing and release agents Sealing compounds Plasticizers from polymer components Contamination distributed via the room air technology, process

air technology or the compressed air system Carry-overs from other production areas Operating and auxiliary materials

Cleaning agents Polishing agents Gloves, work clothes, etc.

And more…

10/2019 - SF PWIS/LABS conformity in accordance with VDMA 24364

PWIS are pervasive

10

SOURCES OF CONTAMINATION

Person-related sources Cosmetics, skin and hair care products Eyeglass cleaner Clothing (e.g. impregnation and shoe care products) Food and beverages

Fatty acid esters such as butter, fats Drinking cups from coffee machines (mould release agents)

Plastic bracelets or jewellery, fitness tracker, smartphone cases

And more…


PWIS are pervasive

11

PWIS TESTING

Sample taking Dissolving/extraction of PWIS through suitable media-

adequate method Collecting of PWIS on a suitable substrate Drying

Painting the substrate Analysis of the paintwork


General principle of testing procedures

DEGREE OF CLEANLINESS REQUIRED?


PWIS testing of elastomeric components Example: Insertion of a component in solvents

Dissolution of substances out of an elastomeric component PWIS containing Nowhere usable? Also not in air-ducting applications?

No Dissolution of substances out of a PTFE component PWIS-free Unrestricted use? Also with abrasion?

PWIS testing procedures can be too severe or too weak or simply not suitable Rejection of suitable components Admission of unsuitable components

Inspection severity for adequate cleanliness

VDMA SPECIFICATION 24364


ADEQUATE CLEANLINESS

Established by the VDMA* Working Group LABS Experts concerning PWIS from German Industries

Based on PWIS-free requirements from automotive industries Participating companies

ABB, AUDI, DFO, Dürr, Systems, Eisenmann, Festo, Fraunhofer IPA, Freudenberg Filtration Technologies, GSR Ventiltechnik, IngenieurbüroFischer, iLF, KAESER Kompressoren, Krautzberger, Parker Hannifin, Phoenix Contact, plasma technology, SATA, Schmalz, SICK, Siemens, SMC Deutschland, Trelleborg Sealing Solutions, VDMA, Volkswagen, Wildeboer Bauteile, Wörwag (und seals‘n‘finishing)


VDMA specification 24364

15

*VDMA = German engineering federation


For evaluation of the PWIS relevance For the definition of the test requirements for products and substances Distribution of a painting production in three zones*

Critical Zone Areas of pre-treatment, painting and drying Surfaces which are exposed to media

Zone with low PWIS relevance Located within the painting production Outside of the critical zone

Zone with no PWIS relevance Located outside the painting production line


Practical Relevance Zones and Product Groups

*simplified description following VDMA 24364



Product group A Components with direct contact to the lacquer, solvent or to the substrate, normally zone I

Product group B Components with only indirect contact to the lacquer, solvent or to the substrate, normally zone II

Product group C Components which cannot be classified into A or B, e.g. control system, air duct, normally zone II

Product group S Products which cannot be classified into A, B or C Substances which can be transferred to zone I or II or which are applied on the substrate (liquid,

paste, powder, grease, …)

Product group T Products which are used at higher temperatures

Practical Relevance Product Groups*

*abstract from VDMA 24364 definitions

Images: APO GmbH Industrielackierung



Practical Relevance Test Classes*

Classification synonymous to the product group designation Selection of the appropriate sample taking has to be

adjusted to the actual use of the component Combination of test classes possible Differentiation of test classes through the method of

sample taking

18Image: APO GmbH Industrielackierung



Practical Relevance Test Classes* The test class and sample taking shall be selected on the basis of the

exposure when the product is used as intended Test class A

Solvent defined Sample taking through

A1: Rinse off with solvent A2: Rubbing off with solvent A3: Immerse in solvent

Test class B Solvent choice (SHALL – MAY) Sample taking through

B1: Blow off B2: Rinse off with solvent (SHALL for zone I)




Test class C Sample taking through

C1: Dry rubbing off C2: Blow off

Test class S Sample taking through

SHALL: Direct application of the substance onto the test plate in a very thin layer

Dry rubbing off of the hardened substance Test class T

Sample taking through Outgassing Only in conjunction with another testing

Practical Relevance Test Classes*




Practical relevance of PWIS testing to the intended use of a product Especially for polymer components any rejection of suitable

materials through high inspection severity can be avoided Basis for

the standardisation of PWIS-conformity requirements for products the definition of the PWIS-conformity for standard products the prevention of redundant and unnecessary testing economical and ecologically meaningful adjustments of cleaning

processes

Practical Relevance Benefit

Image: APO GmbH Industrielackierung

THE VDMA PWIS MANUAL

Gives information on the topic of PWIS Explains the handling of VDMA 24364 Gives examples for the selection of test classes Explains the different sample taking methods

Illustrated with pictures Gives support for the evaluation of test results

Illustrated with pictures Gives information concerning preventive measures in the

production Free of charge


A practical guide

Cover picture of the VDMA PWIS guide

SOURCES AND CONTACTS


VDMA specification 24364 Via www.beuth.de

VDMA LABS guide Download via VDMA website https://ot.vdma.org/en/viewer/-/v2article/render/26327354

Contact the VDMA* Working Group LABS via VDMA, department surface technology https://ot.vdma.org/en/

Consulting and training concerning PWIS conformity and VDMA 24364 www.seals-and-finishing.com

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VDMA SPECIFICATION 24364 · VDMA SPECIFICATION 24364 Testing for paint wetting impairment...

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