|Ask Joe Powder|
"Ask Joe Powder"
"Ask Joe Powder" is a question and answer column authored by Kevin Biller of the Powder Coating Research Group. Mr. Biller has over 30 years experience formulating and manufacturing powder coatings. He welcomes your questions regarding powder coating technology. Please write to: firstname.lastname@example.org
I work as a sale (service) guy for Gema equipment in Serbia. A customer asked me for a measuring device that is able to measure parts temperature in multiple spots during time spend in polymerization oven.
Which producers are most accurate, for temperatures up to 830 degrees Celsius?
It's nice to hear from Serbia. I hope that your powder coating operation is going well and I am happy to help you. Indeed there are instruments designed to measure the temperature of parts in multiple locations. These devices were developed in the 1980s and are an excellent way to ensure part temperature versus time. This data is essential to knowing if your coating is developing full cure. As you probably know you should adhere to the recommended time and temperature stated on the powder coating Technical Data Sheet provided by your supplier.
The most common instrument is the DataPaq Oven Tracker (see: Scheen Engineering Ltd in Hungary) but there are many other products from other equipment houses such as TQC (Nederlands) and Grant Instruments (see: Tectra Beograd in Serbia).
You mention that you need the instrument to be accurate to 830⁰C which is rather high for a powder coating. This requirement may force you to consider a specialized device to be able to withstand temperatures this high. Most of these instruments use a thermally insulated box to protect the data logger while it is exposed to the heat in the oven. You will have to check with each supplier to see what they offer.
We have been developing new polymers for powder coatings. One of the most critical properties is impact resistance. Our test results have been inconsistent and vary significantly depending on substrate used. In some cases the coating passes 160 inch-lbs. and with other conditions only gets 80 inch-lbs. What could be the cause of this variation? And how can we eliminate these variations?
First of all, kudos to you and your colleagues for developing new polymers. Most advancements in powder coating technology are based on new and improved polymer chemistry. It's tough for us formulators to create new coatings without innovative polymers.
The most common impact resistance test method is described in ASTM D-2794 2794 Standard Test Method for the Rapid Deformation of Organic Coatings (Impact). The values typically quoted in impact resistance are inch-pounds (the metric centric folks use Newton-meters) and refer to the weight times the distance (height) of the impact. Another parameter is the radius of the 'ball' or hemisphere that impacts the surface of the coating. North America typically uses a 5/8 inch diameter ball although some specifications call for a 1/2 inch one. The smaller the diameter, the higher the deformation and hence lower impact resistance.
Besides the coating's inherent flexibility substrate has the most significant influence on film performance. Adhesion is affected by the type of metal, the surface profile, cleanliness and pretreatment. Impact resistance is affected by adhesion so poorly pretreated substrate will cause unexpected impact failure. On the other hand, well pretreated metal will enhance impact resistance by providing a strong bond of the powder to the substrate.
In addition to metal preparation, the gauge and type of substrate significantly influences impact resistance because of the degree of deformation to the substrate. Hence 80 inch-lbs. on a ductile grade of aluminum will have different deformation than carbon steel. And certainly the gauge or thickness of the metal will also influence deformation and therefore impact resistance. Thicker gauge metal will deform less and therefore the coating experiences less stress.
Coating parameters to control are mainly film thickness and degree of cure. Thinner films tend to exhibit higher impact resistance whereas thicker ones are more brittle. Complete cure is highly recommended as undercured powders will usually have lower impact resistance. Make sure your coating receives the time at temperature specified by the coating supplier.
When characterizing a coating for impact resistance the challenge is to use substrate(s) that are relevant to the target market(s). For general industrial end uses, cold rolled steel is relevant whereas the architectural market typically uses various grades of aluminum depending upon the forming and parts requirements. In addition pretreatment type is important. Cold rolled steel is usually pretreated with a phosphate (iron or zinc) or in newer installations a zirconium based product. Aluminum is typically pretreated with chromate, zirconium or sometimes zinc phosphate. For polymer development I suggest that you obtain your substrate from a reputable test panel supplier. A list of them can be found on the PCI website ( www.powdercoating.org ) under 'Members'
Good luck with your polymer chemistry efforts, the industry needs you.
The boss is at it again. He wants me to coat some parts for a 'government'project and I am unsure as to what powder to use. These are 16 inch tubes made out of galvanized aluminum. They are for his boat which obviously means they need to withstand a marine environment. Our shop usually applies an epoxy primer, “gels” it, then follow with a polyester topcoat and then cure with a full bake. Will this be OK for the boss’s parts?
Looks like you need to make sure these work out or you'll be on your boss's wrong side. I'll have to be honest with you, I can't say that I have encountered galvanized aluminum before. I will take your word for it however.
My recommendation is to thoroughly clean the galvanized surface with a strong alkaline cleaner and a good, clean rinse. Alternately you could wipe the surface with a good solvent such as acetone. Allow the surface to dry then preheat the part at 375 degree F (part temperature) for a few minutes. This degasses the galvanizing which can harbor moisture and other volatiles that can cause pinhole defects. Allow the tube to cool to around 160 degree F, then apply the epoxy primer. I recommend a standard epoxy primer (not a zinc rich one) as the zinc is overkill on a galvanized surface. 'Gel' the epoxy with a modest bake of around 300 degree F for 5 minutes (again, metal temperature). Cool the part then apply the polyester topcoat and fully cure per the powder manufacturer's Technical Data Sheet. The gel bake of a primer followed by a full cure of the topcoat/primer combination ensures good inter-coat adhesion.
Do this with one part and evaluate the adhesion with a non-destructive test. Tapping on the surface with a small ballpeen hammer should work. If everything looks good then proceed with the rest of the parts. Good luck with the 'government' work. I will have to consult with some of my colleagues to see what they know about galvanized aluminum.
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7th Leading International Trade Fair for Industrial Coating Technology from 17 through 20 April 2018 in Karlsruhe (Germany) with More Exhibition Floor Space
Strong Demand for Booth Locations at PaintExpo 2018
Oberboihingen, November 2016 Although it is only been seven months since PaintExpo 2016 closed with record breaking results, promoters FairFair GmbH are already able to report lively demand for exhibition floor space at the upcoming, leading international trade fair for industrial coating technology: at the beginning of November 2016, 170 companies had already made firm bookings for their booth locations at PaintExpo from the 17th through the 20th of April, 2018. With roughly 75,000 square feet, net exhibition floor space already amounts to more than 50% of the level reached at the last event. And thus for PaintExpo 2018, booth floor space offerings will be significantly increased.
PaintExpo 2016 received top scores and set new standards with regard to exhibitor and visitor numbers, as well as internationalism. With 10,522 visitors from 74 countries, the leading international trade fair for industrial coating technology observed an increase of 14.8%. And it's no wonder, because with its comprehensive overview of the industrial coating technologies market, PaintExpo is meanwhile the number one information and procurement platform for users from all over the world. 'PaintExpo is theglobal showcase of the painting industry, which makes it an absolute must for us. It's the most effective way to present our product range and new developments to international expert visitors, and we'll exhibit again in 2018 as a result', explains Andrea Ortelli, export manager for Italian paint manufacturer Arsonsisi. And the fact that he's not alone with this assessment is already demonstrated by the star studded exhibitor list 17 months before PaintExpo 2018 opens its doors. Roughly 170 companies from 15 countries have already made firm bookings and secured ideal boothlocations. They include nearly all of the national and international heavyweights from the various exhibition segments.
PaintExpo 2018 with Additional Exhibition Hall With roughly 75,000 square feet, net exhibition floor space already amounts to more than 50% of the level reached at the last event. This extremely strong, early demand for booth floor space illustrates the importance of PaintExpo amongst the suppliers of products and services from the field of industrial coating technology. 'We're of course very pleased that the companies are deciding to book so early, and it provides us with the opportunity of clearing the path for further growth. That's why we've increased exhibition floor space offerings to include an additional hall. This is being very well received by the exhibitors so that we've been able to distribute visitor magnets uniformly throughout all of the halls' reports Jurgen Haufmann, managing director of FairFair GmbH.
Procurement Platform for Future-Oriented Painting and Coating
Worldwide demand for optimised painting and coating solutions speaks infavour of strong further development of PaintExpo where visitor numbers areconcerned as well. 'Regardless of where products need to be painted, usersfrom the various regions around the world are generally placing ever higherdemands on finished goods. In addition to optimised quality andproductivity, this also involves more efficient use of materials andresources, as well as sustainability. Beyond this, ever smaller lot sizesand increasing individualisation necessitate more flexible solutions in thefield of coating technology. New challenges for coating job-shops and companies with in-house painting operations are also resulting from the use of new materials, for example fibrous composite materials for lightweight parts, as well as the use of various materials within a single finished product. 'Thanks to an exhibition programme which is focused exclusively on liquid painting, powder coating and coil coating, as well as market-driven, representative and future-oriented exhibitor offerings, PaintExpo 2018 will be a point of departure for the visitors in their search for suitable solutions based on products and processes', states Jurgen Haufmann with confidence.
The exhibition programme covers liquid painting, powder coating and coil coating systems, application systems and spray guns, liquid paints and powdered enamels, automation and conveyor technology, cleaning and pre-treatment, drying and curing, environmental technology, pneumatics, compressed air supply and exhaust purification, water treatment, recycling and disposal, accessories, measuring and test technology, quality assurance, paint stripping, job-shop coating, services and technical literature. Beyond this, downstream process steps such as printing and packaging are covered as well.
Further information and a preliminary exhibitor list can be accessed at
SCHULZ. PRESSE. TEXT, Doris Schulz, (journalist DJV),
Landhausstr. 12, D-70825 Korntal, Germany, phone: +49 (0)711 854085,
email@example.com , www.schulzpressetext.de
FairFair GmbH, Jurgen Haufmann, Max-Eyth-Str. 19, D-72644 Oberboihingen,
Germany, phone :+49 (0)7022 6025510, firstname.lastname@example.org , www.paintexpo.de
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