SAMFA - QUESTIONS ON METAL FINISHING
If you have any inquiry related to metal finishing please feel free to post it here. We will publish all the answers received, and should you wish the answerer to communicate directly with you, we'll put you in touch
QUESTION #6
We are a powder coating company with an iron phosphate cleaning line, we have our procedures and samples tested internally and externally. We are repeatedly having customers send back product that has been laser cut or punched where the mild steel edges are 'exposed' and rusting.
Is this a common problem? How do we overcome it?
We are a powder coating company with an iron phosphate cleaning line, we have our procedures and samples tested internally and externally. We are repeatedly having customers send back product that has been laser cut or punched where the mild steel edges are 'exposed' and rusting.
Is this a common problem? How do we overcome it?
Submitted by: Ant
JHB, South Africa
JHB, South Africa
RESPONSE 1 to QUESTION #6
Laser machining and all machining causes surface changes to metals. In this case I can only suggest a few options if you have not tried them already:
1. Descale your components for longer.
2. Change the ratio of your phosphate.
3. Increase the concentration of the phosphate.
4. Play with temperature, concentration and time to try as best to overcome this.
Laser machining and all machining causes surface changes to metals. In this case I can only suggest a few options if you have not tried them already:
1. Descale your components for longer.
2. Change the ratio of your phosphate.
3. Increase the concentration of the phosphate.
4. Play with temperature, concentration and time to try as best to overcome this.
Response from:
Greg Tearnan
Chemical Supplier
Tel: 082 442 4834
Greg Tearnan
Chemical Supplier
Tel: 082 442 4834
RESPONSE 2 to QUESTION #6
Yes it is common problem to have rust on sharp edges of panels. I have seen even salt spray test panels having had wax or duct tape applied to edges to prevent this "edge rust" affecting the scribed test surface. It is caused by the powder's tendency to be thinner on sharp edges. If you aim for a general coating thickness of 60 to 80 microns on the flat surfaces, the coating thickness on the extreme sharp edges of the same panel will be a small percentage of that. This is thought to be caused by some shrinkage by the powder on drying of course powder dependant. This could also be caused by electrostatic charges on the edges. This lack of coating is leaving that edge exposed to the elements causing the rust. One must remember that phosphate coatings be it iron - as you are using - or even zinc are under paint corrosion protection systems. If there is little or no paint over them, they slow the rust down but u! ltimately will lose the battle.
How to reduce this:
1. Optimize your chemical treatment. Make sure you are getting the best possible corrosion resistance from your chemical plant. I assume that you are removing all heat scale in your system if not, attention should be given to that. You should do this with the close assistance of your supplier as they should be able to give you information on how changing each parameter can affect the quality of the work, and cost to you.
2. Optimize the electrostatic charge on your line. Again this should be done with the assistance of your powder or equipment supplier. We all know how charges can even prevent coverage such as in the case of a Faraday Cage. They should be able to advise on upward or downward movement based on your plant as well as grounding.
3. Check the work for any burring on the edges of punched pieces. This too, would cause problems as you mentioned.
4. Application techniques employed by the gun operator could also influence coverage so maybe spend some time with them. Alternatively some training such as the Powder Coating course offered by SAMFA might fine tune or rectify some possible problems in the spraying process.
If you require any assistance, please feel free to contact me.
Yes it is common problem to have rust on sharp edges of panels. I have seen even salt spray test panels having had wax or duct tape applied to edges to prevent this "edge rust" affecting the scribed test surface. It is caused by the powder's tendency to be thinner on sharp edges. If you aim for a general coating thickness of 60 to 80 microns on the flat surfaces, the coating thickness on the extreme sharp edges of the same panel will be a small percentage of that. This is thought to be caused by some shrinkage by the powder on drying of course powder dependant. This could also be caused by electrostatic charges on the edges. This lack of coating is leaving that edge exposed to the elements causing the rust. One must remember that phosphate coatings be it iron - as you are using - or even zinc are under paint corrosion protection systems. If there is little or no paint over them, they slow the rust down but u! ltimately will lose the battle.
How to reduce this:
1. Optimize your chemical treatment. Make sure you are getting the best possible corrosion resistance from your chemical plant. I assume that you are removing all heat scale in your system if not, attention should be given to that. You should do this with the close assistance of your supplier as they should be able to give you information on how changing each parameter can affect the quality of the work, and cost to you.
2. Optimize the electrostatic charge on your line. Again this should be done with the assistance of your powder or equipment supplier. We all know how charges can even prevent coverage such as in the case of a Faraday Cage. They should be able to advise on upward or downward movement based on your plant as well as grounding.
3. Check the work for any burring on the edges of punched pieces. This too, would cause problems as you mentioned.
4. Application techniques employed by the gun operator could also influence coverage so maybe spend some time with them. Alternatively some training such as the Powder Coating course offered by SAMFA might fine tune or rectify some possible problems in the spraying process.
If you require any assistance, please feel free to contact me.
RESPONSE 4 to QUESTION #6
Atotech the company I represent is currently based in the Western Cape to supply the market directly. We would like to assist you with the current problems you are experiencing. We have a new system based on the exact problem you are experiencing. Please contact our Cape Town office for further discussions on this matter.
Atotech the company I represent is currently based in the Western Cape to supply the market directly. We would like to assist you with the current problems you are experiencing. We have a new system based on the exact problem you are experiencing. Please contact our Cape Town office for further discussions on this matter.
Response from:
Jade Cupido
Process Chemicals Supplier
Cape Town
Tel 021 385 0030
Jade Cupido
Process Chemicals Supplier
Cape Town
Tel 021 385 0030
Response from:
Ray Orlik
Chemical Supply House
Tel: 082 375 6187
Ray Orlik
Chemical Supply House
Tel: 082 375 6187
Is there anyone that would be willing to give me a call to arrange a discussion with the manager of the department that might want to share his/her knowledge?
QUESTION #7
We recently installed a plating facility at our Cape Town office. The department is struggling with chrome plating of cast aluminium products. The products are mostly homeware and table top products.
We recently installed a plating facility at our Cape Town office. The department is struggling with chrome plating of cast aluminium products. The products are mostly homeware and table top products.
It appears as if the problem experienced may be with the composition of the aluminium cast items.
Submitted by: Aliwiya
Cape Town, South Africa
Posted October 30, 2011
Cape Town, South Africa
Posted October 30, 2011
RESPONSE 3 to QUESTION #6
This is a common problem. There are only 2 solutions
1. Mechanical removal of scale by sandblasting or brushing
2. Chemical removal by wiping or brushing on edges just prior to entry into phosphate
This is a common problem. There are only 2 solutions
1. Mechanical removal of scale by sandblasting or brushing
2. Chemical removal by wiping or brushing on edges just prior to entry into phosphate
Response from:
Peter von Holdt
Pre-Treatment Chemical Supplier
Tel 012 345 2215
Peter von Holdt
Pre-Treatment Chemical Supplier
Tel 012 345 2215
RESPONSE 2 to QUESTION #7
If your supplier set up the line to plate aluminium then you will have the proper etching and de-smutting in the line. You will only have to make sure the aluminium is clean and treated correctly before plating. Different castings might need different de-smutting containing fluorides.
If your supplier set up the line to plate aluminium then you will have the proper etching and de-smutting in the line. You will only have to make sure the aluminium is clean and treated correctly before plating. Different castings might need different de-smutting containing fluorides.
RESPONSE 1 to QUESTION #7
Atotech the company I represent is currently positioned in the Western Cape to supply the market directly. We would be more than happy to assist you in the current challenges you are experiencing. Please contact us for further discussion.
Atotech the company I represent is currently positioned in the Western Cape to supply the market directly. We would be more than happy to assist you in the current challenges you are experiencing. Please contact us for further discussion.
Response from:
Trudy Kastner
Plant & Chemical Supplier
Durban
Tel 083 281 9896
Trudy Kastner
Plant & Chemical Supplier
Durban
Tel 083 281 9896
Response from:
Matthew Bronslow
Process Chemicals Supplier
Cape Town
Tel 021 385 0030
Matthew Bronslow
Process Chemicals Supplier
Cape Town
Tel 021 385 0030
RESPONSE 3 to QUESTION #7
You do not say what your problems are but chrome plating of aluminium castings will not be a problem if you have the correct set - up for pretreatment. Send me say 10 samples and I will plate them for you free of charge. If you approve the samples I will further help you.We chrome plate aluminium all day every day almost trouble free..
You do not say what your problems are but chrome plating of aluminium castings will not be a problem if you have the correct set - up for pretreatment. Send me say 10 samples and I will plate them for you free of charge. If you approve the samples I will further help you.We chrome plate aluminium all day every day almost trouble free..
Response from:
Trevor Fox
Jobbing Plating Shop
Boksburg RSA
Tel 011 894 2046
Trevor Fox
Jobbing Plating Shop
Boksburg RSA
Tel 011 894 2046
QUESTION #8
We manufacture audio amplifiers which have alu 6082 T6 machined front panels fitted. Sometimes these are ordered as black, and in 16 years of manufacturing, we still have to find a company to anodize black properly. The black almost always go bluish/purplish or some funny shade over a short time. We would now like to try the E-COAT process in black. Where in the Pretoria area can this be done, bearing in mind that these items are limited quantites of no more than 5 units at a time. PLEASE, we need help!
We manufacture audio amplifiers which have alu 6082 T6 machined front panels fitted. Sometimes these are ordered as black, and in 16 years of manufacturing, we still have to find a company to anodize black properly. The black almost always go bluish/purplish or some funny shade over a short time. We would now like to try the E-COAT process in black. Where in the Pretoria area can this be done, bearing in mind that these items are limited quantites of no more than 5 units at a time. PLEASE, we need help!
Submitted by: Schalk
Pretoria, South Africa
Posted December 7, 2011
Pretoria, South Africa
Posted December 7, 2011
RESPONSE 1 to QUESTION #8
Hi, In my opinion sealing failure can lead to the deterioration of the finish, so test the sealing;
request electro-colour black instead, although special jigging will be required for this process, but a far longer lifespan of the finish will be achieved.
Feel free to give me a call should you wish to discuss this matter further.
Hi, In my opinion sealing failure can lead to the deterioration of the finish, so test the sealing;
request electro-colour black instead, although special jigging will be required for this process, but a far longer lifespan of the finish will be achieved.
Feel free to give me a call should you wish to discuss this matter further.
Response from:
Mark Coetzee
Astro Holdings
Sebenza RSA
Tel 011 452 9748
Mark Coetzee
Astro Holdings
Sebenza RSA
Tel 011 452 9748
QUESTION #9
I cannot find anyone in SA that is willing and able to Platinum plate 316 stainless steel mesh. I found one company in PE that is able, but they are not interested. I have an American company willing to help, but time is the problem. Can anyone help?
Submitted by: George Anagos
Johannesburg. RSA
Posted February 2, 2012
Johannesburg. RSA
Posted February 2, 2012
