Chapter 10-11 Flashcards
Describe the properties of abrsive media that effect the surface profile and finish of the final product “
- hardness - mohs’s scale of 1-10 - determine ability to remove layers of rust, mill scale, paint
2, shape - shot (rounded) and grit (angular) , shot good for breaking away brittle coating and mill scale , grit is good cuts for rust, clean faster, product s shaper but uniform profile, good for adhesisive but poor at removing mill scale. Shot for IOZ, can be mixed - size - large and smale particle, large - result in deeping heavier and less uniform profile / small decrease change of removing too much surface material. (use small)
- denisty - affects the cleaning rate and surface profile, higher the density the more productivity.
- friability - how easily the blasting material crumbles or fracture/shatter upon impact . High = low resusability, more crumbling
- usability - expendable / recycleable - concerns with contaminating”
hardness -
mohs’s scale of 1-10 - determine ability to remove layers of rust, mill scale, paint
2, shape
- shot (rounded) and grit (angular) , shot good for breaking away brittle coating and mill scale , grit is good cuts for rust, clean faster, product s shaper but uniform profile, good for adhesisive but poor at removing mill scale. Shot for IOZ, can be mixed
- size -
large and smale particle, large - result in deeping heavier and less uniform profile / small decrease change of removing too much surface material. (use small)
- denisty -
affects the cleaning rate and surface profile, higher the density the more productivity.
- friability -
how easily the blasting material crumbles or fracture/shatter upon impact . High = low resusability, more crumbling
- usability -
expendable / recycleable - concerns with contaminating”
metallic vs non metallic abrasive media affects the resulting finish
“1. metallic - high carbon steel and are often heat trated to different hardless level , appear darker, NOT used on SS , AL , galvanized (only ferrous)
2. non metallic - low initial cost but breakdown rate is higher can be use don ferrour and non ferrous substrate”
“1. metallic -
high carbon steel and are often heat trated to different hardless level , appear darker, NOT used on SS , AL , galvanized (only ferrous)
- non metallic -
low initial cost but breakdown rate is higher can be use don ferrour and non ferrous substrate”
Explain how to perform different QC test that relate to abrasive media “
- Vial Test to test for presence of oil and dust
- pH test - test if abrsive is acidic or alkaline
- Sieve test - compares the particle size received against the data provided by the manufactures
- Soluable salt and conductivity test - test for soluable salt contamination of abrsive”
ASTM D7393
vial test
ASTM C136
Sieve Test - compares the particle size receive against the data provided. Size 10 sieve has 10 holes / in. larger the # = smaller the holes
ASTM D4940
standard test method for conductimetric analysis of water soluble ionic
Abrasives are selected based on (8)
“
“1. kind of surface to be cleaned
2. size and shape of the object
3. type of cleaning facility
4. existing surface condition
5. condition desired after cleaning
6. desired surface profile
7. type of coating to be applied
8. whether or not the abrasive is to be recycles
Documentations (4)
“1. project name and date
2. media type, maufacture,size and batch number
3. specification / std reference
4. QC test/ test frequency/results, acceptance criteria and NC”
Epoxy
“safety covers , co-reaction, multi coat, can be primer , intermediate, top coat , 2 component,
amine blush, chemical, solvent and water resistance, vulnerable to UV”
Latex Emulsions (water based)
“no safety concerns , Coalescence, single or multiple coats , can be primer , intermediate, top coat , 1 component
often used as a top over expoxies , organic and inorganic zinc”
