Mô tả:
Adhesive Manufacturing Processes
Chapter 6: Testing and Quality Assurance
Univ.-Prof. Dr.-Ing. Prof. h.c. Stefan Böhm
Department for Cutting and Joining Manufacturing Processes (tff)
University of Kassel, Germany
Quelle: Wikipedia
Agenda
Introduction
Destructive Testing Methods
Non-Destructive Testing Methods
2
Introduction
Testing & Quality Assurance is especially important
joined elements can either not be reworked or only with much effort
Criteria for the selection of a testing method for an adhesively joined bond:
● parameters that need to be examined
● destructive or non-destructive testing
● circumstances under which the test is to be carried out (i.e. production control or
individual examination)
testing standards and regulations need to be followed
Source: Habenicht
3
Introduction
Important aspects for the quality assurance for adhesive bonding:
1. Planning:
– Training measures for employees,
– Integration of the production of adhesively joined bonds into the construction phase,
– Development of company-specific regulations or production standards,
Source: Habenicht
4
Introduction
2. Adhesives:
– Checking of the supplier´s specifications on the label to avoid confusion
– For further identification of the adhesive, viscosity, density and, if necessary, solids content
and colour should be examined
Checking of rheological characteristics (i.e. viscosity, thixotropy)
– Checking of storing time and temperature
– If necessary, execution of test samples and tests
3. Joint Elements:
– Assessment of the surface quality (how clean, free of grease)
– Testing of the wetting properties (water drop test)
– Assessment of roughness
– Required dimensions, tolerances
Source: Habenicht
5
Introduction
4. Surface Treatment:
– Blasting material (size of grains, free of grease (also the supply air)
– Pureness of the degreasing material
– Composition, concentration and temperature of the pickling and chemical pretreatment
baths
– Pureness of the rinsing baths
5. Application of the Adhesive:
– Preparation of the adhesive
– Degree of mixture and the relation of the components to each other
– Pot life, amount, thickness of the layer, adhesive wetting
– Checking if the system for the application, mixture and dosing functions properly
– Positioning and fixation of the joint elements
Source: Habenicht
6
Introduction
6. Environmental Conditions:
– Cleanliness in the production halls
– Temperature, if necessary, climatisation (adsorption of humidity at the surfaces)
– Degree of humidity in the air
7. Occupational and Environmental Safety (Disposal, Recycling):
– various legal standards, laws and guidelines
8. Documentation:
– Continuous documentation of the parameters that are important for the quality
Source: Habenicht
7
Introduction
Classification of the Testing Methods for Bonds
Testing of the Bond
Destructive Testing
Static
Source: Habenicht
if necessary, inclusion of
specific circumstances
Dynamic
Non-Destructuve
Testing
Highly Dynamic
8
Agenda
Introduction
Destructive Testing Methods
Non-Destructive Testing Methods
9
Destructive Testing Methods
static short-term stress
Shear Stress:
● Shear Test
– According to DIN EN 1465 (DIN 53283): „Determination of the
shear strength of highly strong overlap bonds“
:Bond Strength, Fmax:Maximum Force, A: Bond Area)
Source: Habenicht
10
Destructive Testing
static short-term stress
Shear Stress:
● Disadvantages:
– Influence of the expansion of the joint elements
– Eccentric fixation
– To avoid eccentric stress in testing machines, specimen reinforcement in the fixation
area is done (out of the same specimen material)
● Field of Application:
– Testing method serves to examine the usability and the quality of the adhesive:
– When developing and applying the adhesive,
– When controling the production to ensure the quality
– When comparing adhesives under chemical and physical stress and influence
Source: Habenicht
11
Destructive Testing
static short-term stress
Tensile Stress:
● Shear Stress and Sliding Behaviour
– „Thick“ shear test
– Implementation according to ISO 11003-2 (before DIN 54451)
– No bending moment pure shear stress
– Building elements quite thick
Expansion of joint elements is avoided
Source: Habenicht
12
Destructive Testing
static short-term stress
Torsion Shear Stress:
● Torsion Shear Stress
–
according to: ISO 10033-1 and ISO 11003-2
–
Two pipe sections are twisted longitudinally in opposite directions
–
Advantage: very homogeneous distribution of the shear stress, eliminates
shear and bending stress
–
Disadvantage: elaborate preparation of the specimen to ensure the
concentricity of the hollow cylinder and the compliance to the defined
thickness of the adhesive layer
Source: Habenicht
13
Destructive Testing
static short-term stress
Tensile Stress:
● according to DIN EN 26922 (DIN 53288) „determination of tensile
strength“
● stress under normal forces (this means horizontal to the joint surface)
● advantages: defined stress ratio and information about adhesion and
cohesion behaviour of the bond
Source: Habenicht
14
Destructive Testing
static short-term stress
Compression Shear Stress:
● according to DIN 54452
● determination of shear strength of adhesive rotationally symmetric bond gaps in
axial direction
● especially for anaerobic adhesives for shaft-hub-connections
● advantages: homogeneous distribution of shear stress
(
: shear strength, FB: breaking strength, A: shearing area,
D: bolt diameter, l: case length)
Source: Habenicht
15
Destructive Testing
static short-term stresssche Kurzzeitbeanspruchungen
Torsion Stress:
● also mainly for anaerobic adhesives
● if the geometry is round, it can be tested flatly (1.) or with a thread (2.):
1. Torsion Strength
– apply according to DIN 54455 „ Determination of shear strength of adhesives in a
rotationally symmetric joint gap in tangential direction“
–
(
: torsion shear strength, MB: measured ultimate moment,
r: radius of the joint gap, A: shearing area)
Source: Habenicht
16
Destructive Testing
static short-term stress
Torsion Stress:
● if the geometry is round, it can be tested flatly (1.) or with a thread (2.):
2. Breakaway torque
– according to DIN 54454 on adhesively joined threads (see picture)
– serves to compare the security effect of bonded threads
– the breakaway torque is ascertained from the rotational angle diagram MLB
(relative motion between nut and screw)
Source: Habenicht
17
Destructive Testing
static short-term stress
Peel Stress:
● this stress must be avoided constructively peeling
stress is always the worst for a bond
● examination of adhesion behaviour
● line loads instead of area loading
● testing occurs under constant load or
constant peel speed
Simple peel
stress
Source: Habenicht
18
Destructive Testing
static short-term stress
Peel Stress:
● Four methods for testing:
1. Angle Peel Test:
– according to ISO 11339 and DIN EN 28510 „Determination of the resistance of metal
bonds to peeling forces that occur horizontally to the joint gap“
– mainly to compare adhesives or surface pretreatment methods
smallest differences in the adhesive and cohesive behaviour
can be shown
– advantage: easy to apply
Source: Habenicht
19
Destructive Testing
static short-term stress
Peel Stress:
● Four methods for testing:
Example of a
peeling diagram
1. Angle Peel Test:
– result of the test: peel diagram
– high force at the beginning joint elements have
to be deformed first (absolute peeling resistance)
30 – 90% of the length of the diagram is
necessary to show the inhomogeneity of a bond
– elastic adhesive layers
Kraft F
– continuous peeling (relative peeling resistance)
Middle separating force
Fm
higher peel resistance than brittle layers
Length of
diagram
20
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