practical test of a Manual powder coating gun
Contents
1. or ange I find two sample metal sheets which are 50 x 50 cm in size First I paint them black then I apply a yellow coat on top On one side I use the normal process and on the other PCC mode It s almost impossible to get full coverage on the first side The faults are clearly visible Now I try the other side with PCC mode I pass the gun four or five times over the sheet There are no faults and you must remember that I m apply ing yellow over black Orange is the next problem colour and here everything goes smoothly too The application efficiency is better with all the colours and the work is easier even with problem powders I can reduce the powder output in all cases and work much faster On top of that the visible results after curing are better for all the colours I ve tested Day 8 On the last day of testing I try me tallic powders After roughly setting up the gun I coat some small parts and two large sheets using RAL 9006 The old settings are not much use with this gun so I switch to PCC mode to see how the powder reacts to my set tings Then I do a bit of fine tuning un til I get the right results It will be inter esting to see what it looks like after cur ing A colleague is the first person to see the parts as they leave the cooling area and he s enthusiastic There is no edge build up and also no stripes All in all it s been a great success It s a pity that there werent more parts w2. past Over the weekend I plan to read the user s manual You can only get a really good result if you know everything about the tools youre using Day 5 I will be experimenting with spe cial colours and metallic coatings over the next few days I m interested to find out how the precise charge control PCC mode functions with metallic powders Id also like to look in more detail at recoating I think I ve now got the right settings for blue and black The results are very good I will keep things as they are and see whether these settings can be used for our en tire range of parts Today Pll be using black and blue alternately I install a new box The powder hangs in the box like a wet rag In the past I ve had to shake it up by hand several times a day Now I put the suction pipe in and watch what hap pens The suction pipe is much narrow er than the previous model The pow der fluidises almost imperceptibly in the box but it all works without prob lems That s true both of black and of Trumpf blue One other excellent feature is that there is much less powder waste In the past we wasted between one and three quarter full sacks every day Now that figure has more than halved which is a significant advantage given today s pow der prices 4 Day 6 Over the weekend I ve read and in wardly digested the user s manual First of all I take a close look at the gun In my view there should be a centra
3. POWDER COATING Report on a User s Experiences Practical Test of a Manual Powder Coating Gun For eight days an expert user tested a new manual powder coating gun The following excerpts from his diary give an insight into his experiences he employees at Trumpf Laser und Systemtechnik GmbH near Stuttgart in Germany have many years of experi ence in powder coating Complex ma chine parts are coated mainly by hand a in a manual booth or in an automatic booth with manual pre coating and fin ishing processes In February 2011 Oskar Heinz head of powder coating at Trumpf de Oskar Heinz head of powder coating at Trumpf in Ditzingen A very successful spray gun 2 cided to invest in a new manual gun OptiFlex from Gema Switzerland GmbH for the first time Compared to the guns previously used by the compa ny this offered significant improvements in overall handling powder consump tion and powder penetration together with better options for setting the coat ing parameters on the control unit In ad dition the new gun produced a much higher quality finish including in the case of metallic powders When Gema introduced its succes sor the OptiFlex2 onto the market six months ago Heinz decided to carry out some practical tests In order to provide the manufacturer with comprehensive feedback he recorded his experiences from the first to the eighth day of the testing period These are excerpts f
4. ating large parts cross beams I start as normal with 85 powder output but I notice immediately that this is too much I reduce the powder output ulti mately by 30 My working speed stays the same The powder cloud seems more even and uniform and I can coat the corners edges and undercuts much more effec tively After reducing the current the cra ters and the build up on the edges dis appears Following the curing phase I look at the parts in the loading and un loading area and it becomes clear that the results are even better I go on exper imenting with different settings on to the limit Its obvious that this gun produces significantly improved results even with difficult powder types 3 POWDER COATING Day 4 Powder coating in the colour RAL 9005 is on the agenda today I reduce the current again Black is the easiest powder to use I choose a specific range of parts for coating with lots of corners edges and areas that are diffi cult to access And of course parts that are very difficult to coat because of their shape I bring in a colleague to find out what he thinks He does the testing him self The result is surprising A variety of parts that in the past always had a nar row uncoated strip are now completely coated We are both amazed The parts look completely uniform and there are no uncoated metal areas at the bottom Also the build up of powder in the cor ners is largely a thing of the
5. hich need a metallic coating Pm sure we could make some more minor adjustments Summary This is a very well designed spraying unit with hardly any weak points The new functions are excellent and the whole thing is a step in the right direc tion The gun functions particularly well with difficult powders It would have been good to be able to test metallic powders on a wider range of parts and for a longer time Overall the new gun has a great deal of potential My sum mary after eight days of testing is that once you ve got your hands on this spray gun you wont want to let go of it I Oskar Heinz Trumpf Laser und Systemtechnik GmbH Ditzingen Germany JOT International Surface Technology 2 2012 JOT International Surface Technology 2 2012 5
6. king One of my colleagues says I don t have to go over the parts as often even in the corners and on the edges The cleaning process is very quick Well designed components in clude the new injector the collec tor nozzle and the extension with a locking mechanism The best thing of all is cleaning at the press of a button using the P switch on the gun Day 3 Today I do some fine tuning of the control unit and decide to use our blue problem powder First I try to get rid of back ionisation I keep the powder out put the same to make sure that the coat ing thickness is correct I reduce the cur rent and immediately the back ionisa tion disappears Considerable improve ments are possible even with a difficult powder The unattractive picture frame effect is also significantly reduced After the curing process I take a look at the parts The visual inspection shows Better coverage of undercuts The penetration is significantly im proved even with difficult powder The structure seems stronger My colleagues also feel that if we had had a better blue powder the results would definitely have shown an even JOT International Surface Technology 2 2012 k A i After selecting the program for parts that are difficult to coat The powder moves easily into the corners and the edges There is no powder build up in the corners greater improvement Next we begin co
7. l but ton to allow you to control all the pro grams from the gun Comment This function is now available on volume production models The buttons should also be raised so that they can be used when wearing gloves I try out what I have read about over the weekend using RAL 9005 black powder I press the button on the con trol unit which shows that I have chosen a program for parts that are difficult to coat Straight away I notice that some thing is happening The powder moves into the corners and the edges almost of its own accord It all happens in no time with no powder build up in the corners Two of my colleagues try coating some parts and get the same results When they ask what I ve done I explain to them about the symbols on the control unit Despite the cavity you have total control of the coating process The working speed is right too And one other very important point the quality is top class Day 7 Today s job is coating swarf gates by far the most difficult part to coat First of all I try applying a com plete coating to the parts and it s easy The corners are coated and I dont need to go through the irritating process of coating the parts over and over again until the corners and gaps are proper ly covered This wasn t possible with other spray guns Now we come to the special col ours yellow orange RAL 9002 RAL 5010 In the past we ve had to have one or two extra passes with yellow and
8. rom his diary Day 1 I start up the gun at the beginning of the day using the same settings as the previous model The first thing that strikes me is that this simply isn t right Its using too much powder There is an excessive build up on the edges and the coated surfaces dont look smooth or uniform I reduce the powder output but that alone isn t enough Then I reduce the voltage and the current and things start to look much better Believe it or not I ve cut the powder output by 30 96 after half an hour Now I got used to it and my colleagues want to try the gun out It s a big aha moment Day 2 All the programs are stored For me the design of the gun is a success It s the JOT International Surface Technology 2 2012 small details that really impress me For example the pivoting control unit the new injector and the cleaning function The only minor problem is that the gun is slightly longer than its predecessor and a little top heavy We start by coating smaller parts I notice a few things The penetration is much better than the previous model even with our problem Trumpf blue powder There are noticeable improve ments in the application efficiency The appearance of the coating is better The picture frame effect is less re duced There is almost no build up on the edges Trumpf blue Ifthe powder were better the re sults would be even more stri
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