Dimension change after grit blasting
11-23-2012, 03:40 PM, (This post was last modified: 11-23-2012, 03:48 PM by TomasCro.)
#1
Dimension change after grit blasting
Hello everyone. I have one question about grit blast. Is it possible the diameter of piston is changed if the piston before grit blast is lets say 79,50 and after grit blast 79,55-56? Is it possible that the grit blasting add additional mm
Reply
11-23-2012, 04:05 PM,
#2
RE: Dimension change after grit blasting
Hi TomasCro

Sign0016 to the Surface Engineering Forum.

Slight increases in diameter are possible due to fact that your measuring from the peaks in the grit blast texture. There is no increase in volume, in fact grit blasting may reduce volume. Thin section tube I suppose could increase in diameter slightly due to induced work hardening compressive stresses.
Reply
11-25-2012, 11:25 PM,
#3
RE: Dimension change after grit blasting
Hi Tomas,

there is a useful pdf at the following link :

https://www.blast-one.com/lib/Surface%20Preparation.pdf

It covers the requirements etc for surface preparation, it shows the effects of the steel when Grit Blasting using different pressures, grit type and spray distance

When you grit blast steel the it causes the steel to lift slightly and as Gordon mentioned you measure the peak to valley height so it would appear that there has been stock added to the surface but it is not the case.

Hope that helps ?

Cheers

Kev
Reply
11-26-2012, 11:36 AM,
#4
RE: Dimension change after grit blasting
ty on response.. Reason im asking because some aluminum tubes after grit blast got 0.10 increase in diamater .. so from lets say 59.65 after grit were 59.75
Reply
11-26-2012, 10:46 PM,
#5
RE: Dimension change after grit blasting
That would be correct as Aluminium is a softer material therefore the impact of the grit will raise the profile of the aluminium.

Try reducing your air pressure slightly see what effects that has. Another thing to watch for is grit entrapment due to the soft substrate, its a good idea to brush down the surface after blasting with a CLEAN nylon brush and blow down with compressed air.

Cheers

Kev
Reply
11-27-2012, 04:28 AM,
#6
RE: Dimension change after grit blasting
Increases/decreases in OD and ID occur after blast preparation as the surface is ripped up and the 'mechanical fingers' (peaks) for bond interlock are created and add thickness.

The degree of which is down to substrate material, type/size of blast media used and blast pressures. The differences are measurable, relevant and need to be considered especially when spraying thin coatings or thickness specific top coats to size or dimension.

Remember that measuring a blasted/ready for spray component will make this area shiny so coating adherence in this area may be compromised. If dimension deviation is relevant then it is better to anticipate the dimension change of the un-blasted component dimension before.

With Aluminium the best blast profile will be achieved with low nozzle air pressures. Normal blast pressures will result in over-blasting and a poor mechanical key. Low air pressure means less interface contamination (grit entrapment) but as Kev says doesn’t hurt to clean by brush or blow down with clean shop air or Nitrogen. You will need to spray ASAP with this material as it oxidises quickly.
Len Wood
METAL MONSTER LTD
BIGGER BETTER FASTER MORE!
Ph: +64 9 4730705
Fax: +64 9 4730706
Email:: len@metal-monster.com
www.metal-monster.com
Reply
11-27-2012, 09:12 AM,
#7
RE: Dimension change after grit blasting
Thanks guys for reply Smile You helped alot . Cheers
Reply




Possibly Related Threads…
Thread Author Replies Views Last Post
  Grit Blasting Parameters DanyGans 3 4,460 08-20-2018, 04:04 PM
Last Post: darexpl
Bell Dimension of JP5000 parts for computational purpose Lalit 0 2,081 06-16-2015, 09:52 AM
Last Post: Lalit
  Grit blasting epoxy, carbon fibre and titanium in one cabinet? David Churcher 2 4,115 11-30-2012, 01:42 PM
Last Post: MichiganMan
  Surface roughness after grit blasting Leanne 8 21,782 08-15-2012, 05:28 AM
Last Post: Leanne
  Brush instead grit blasting divanis 4 6,015 11-16-2011, 05:32 PM
Last Post: divanis
  Build Up without grit blasting Met.Eng. 5 6,148 09-27-2011, 03:57 AM
Last Post: kschewe
  Dirt in the grit blasting machine Aware 7 7,612 05-20-2011, 05:27 PM
Last Post: Aware
  Grit Blasting Riz 5 12,636 05-10-2011, 01:14 PM
Last Post: MichiganMan
  Chrome Carbide & T800 Coating Property Change after heat treatment Alexangel1226 5 12,953 09-30-2010, 03:04 AM
Last Post: arjfaye06
  Removal of grit after grit-blasting? pulaunias 11 18,360 06-18-2010, 01:52 AM
Last Post: Gordon
  grit Blasting 13cr steel hibberd 3 5,233 04-14-2010, 07:51 PM
Last Post: Gordon
  Increase production rate of Grit Blasting of steel plates Adarsh 4 8,495 07-14-2009, 07:47 PM
Last Post: djewell
  Grit Blasting Titanium rbeale98 3 10,326 04-13-2009, 08:52 PM
Last Post: Gordon
  Alternatives to grit blasting? durkie 8 11,465 03-19-2009, 10:47 PM
Last Post: Gordon
  TBC Coating change to grey mehongbo 1 3,575 03-09-2009, 05:02 PM
Last Post: Gordon



Users browsing this thread: 1 Guest(s)





Surface Engineering Forum Sponsor - Alphatek Hyperformance Coatings Ltd