7.3 Process steps in the production p‌hase2019-05-03T13:00:54+01:00

7.3 Process steps in the production p‌hase

Specific quality assurance measures in the production p‌hase

1. Logistics (transport, goods receipt, storage, availability of special materials, disposal)

  • Dispatch tests and test certificate of the manufacturer
  • Monitor transport
  • Check and test materials (identity, appearance, rheology, composition, usability, expiry date)
  • Labelling of containers (date of receipt)
  • Samples
  • Monitor storage conditions (temperature, humidity, time, light intensity/ radiation)
  • Availability of special materials (e.g. tape for marking areas off, warning signs, “wet adhesive” stickers, silicone-free skin-cleaning and skin-care products)
  • Ban sources of contamination (e.g. silicones; also from gloves, cleaning cloths, lubricants, cleaning and impregnating agents, etc.)
  • Optimise organisational systems (e.g. for storage)
  • Heed specifications

2. Ensure optimum ambient conditions

  • Mark off the area where work is to be carried out and ensure unauthorised persons do not enter the work area
  • Protect the work area from contamination via the air
  • Take measurements in the work area (temperature, humidity, dust, aerosols, gases, light intensity)
  • Avoid draughts

3. Acclimatise the substrates, primer and adhesives

  • Definition of location, temperature, time and tolerances
  • Measurements (ambient temperature, surface temperature, time)

4. Test the accuracy of fit

  • Check the accuracy of fit and tolerances using suitable test and measurement methods (e.g. templates)
  • Check substrates for other damage and abnormalities

5. Cleaning

  • Thoroughly rinse off aggressive cleaning agents
  • Avoid recontamination (e.g. via contaminated cleaning agents, cloths, gloves)
  • Prepare a summary of the dependence of the evaporation time on temperature and humidity
  • When using adhesive tape for masking purposes bear in mind that residues may remain after removing the tape
  • Measurements (time, pressure, temperature, composition, surface contamination)
  • Monitor (settings, appearance)
  • Associated tests (e.g. wetting tests with test inks, contact angle method))
  • Labelling of containers
  • Minimise storage and transport times after cleaning
  • Monitor storage and transport conditions after cleaning

6. Pretreat surfaces

  • Never pretreat contaminated surfaces without cleaning them adequately
  • Only use contamination-free materials (e.g. etching agents, grit for blasting, sandpaper)
  • Thoroughly rinse off any aggressive pretreatment agents (e.g. etchingagent)
  • Measurements (time, pressure, temperature, stress, composition, layer thickness, degree of coverage)
  • Monitor (settings, appearance)
  • Associated tests (e.g. wetting tests with test inks, contact anglemethod)
  • Labelling of containers
  • Minimise storage and transport times after pretreatment
  • Monitor storage and transport conditions

7. Primers (also applies for activators, pre-applied activators, etc.)

  • Strict protection of primers from contamination and moisture, reseal containers immediately
  • Use coloured materials
  • Apply the correct layer thickness, avoid applying excess
  • Prepare a summary of the dependence of the drying time on temperature and humidity
  • Measurements (layer thickness, degree of coverage)
  • Monitor (appearance, rhelogy)
  • Labelling of  containers (e.g. date of first opening, shelf-life after first opening)
  • Minimise storage and transport times after priming
  • Monitor storage and transport conditions
  • Monitor storage and transport times

8. Adhesive stocks

  • Protect adhesive from contamination and moisture, reseal containersimmediately
  • Use coloured adhesives
  • Measurements (temperature, pressure, time, contamination, thorough mixing, rheology, usability)
  • Monitor (settings, appearance, air contact)
  • Labelling of containers (e.g. date of first opening, shelf-life after first opening)
  • Monitor storage and transport conditions
  • Monitor storage and transport times

9. Feeding

  • Protect the adhesive from contamination (e.g. use water-impermeable tubing)
  • Measurements (temperature, pressure, volume, weight, time, rheology)
  • Monitor (settings)

10. Dosing

  • Twin cartridge for manual processing; for automatic processing use 2-C dosing and mixing unit
  • Automatic control circuit sensor-machine
  • Measurements (pressure, volume, weight, time)
  • Monitor (settings)

11. Mixing

    • Use coloured components
    • For small quantities, twin-cartridge with static mixer or use 2-C adhesives premixed by the manufacturer and stored under cool conditions

m‌ixing ratio

  • Check the quality of mixing
  • Stipulate the rinsing interval, maintenance interval, change interval for dynamic mixers
  • Measurements (progress of the curing, usability, rheology, time)
  • Monitor (settings, appearance)

12. Application

  • Definition of quantity to be applied, application pattern and geometry of the bonding area
  • Ensure the correct film thickness is applied, especially for solvent-containing contact adhesives
  • Avoid closed voids which could cause condensation of moisture
  • Stipulate the maximum processing time
  • Stipulate the minimumbcuring time
  • Use coloured / fluorescing adhesives
  • Automatic control circuit sensor-machine
  • Measurements (quantity, position, shape, contamination)
  • Monitor (position, shape)
  • Associated tests (e.g. wetting tests, bead peel test)

13. Joining the substrates

  • Keep the adhesive film thickness within the prescribed tolerance
  • Avoid closed voids where moisture could condense
  • Automatic control circuit sensor-machine
  • Measurements (width, thickness, tolerances, pressure)
  • Visual inspection

14. Fixing

  • Avoid non-permitted stress during and after fixing
  • Automatic control circuit sensor-machine
  • Measurements (tolerances, pressure)
  • Visual inspection

15. Curing

  • Protect from unpermitted loads/stresses during the curing process
  • Prepare summary of the dependence of the curing process on humidity, temperature, pressure and dose
  • Avoid build up of high stress in the bonded joint by optimising the curing parameters
  • Stipulate the strength required for handling
  • For hot-curing adhesives ensure the curing temperature in the joint is reached for the necessary time
  • Automatic control circuit sensor-machine
  • Measurements (temperature, humidity, dose, time, pressure)
  • Monitor (settings)
  • Associated tests (e.g. bead peel test)
  • Samples
  • Final checks:
    • Work samples or random samples: destructive tests to demonstrate that the required and geometry have been achieved strength Random samples or 100%-test: non-destructive tests to demonstrate that the required geometry has been achieved