Non-Stick Coatings

What are Non-Stick Coatings?

Non-Stick coatings are a complex mix of lubricating pigments in a continuous matrix of a binder. This is normally a tough coating layer providing a low friction resistance surface between two parts. The lubricating pigments fit into two main categories:

  1. Crystalline lattice or lamella type structures, for instance Molybdenum Disulphade & Graphite or
  2. Fluorocarbons, typically PTFE

These varying pigments can be combined with a wide variety of resins to achieve different properties – high load bearing, chemical resistance, high temperature stability, low coefficient of friction.

How might Non-Stick Coatings be used?

Non-Stick coatings are used for many different reasons, but most importantly they are used when a liquid lubricant such as oil or grease cannot be used or it would be beneficial to avoid use. The major problem with liquid lubricants is they have a limited range of use and once exhausted the liquid will often change state (due to temperature, load, wear, migration and debris) becoming a processing or use problem, no longer providing protection.

So take for instance the bread baking process; bread pans might be silicon glaze coated and will require oil/grease to be applied for release of the baked bread. After the baking process the oil/grease will carbonize (burn on) onto the bread pan. Excess oil/grease presents an increase in cleaning requirements and health & safety measures. The baker will need to invest in and maintain oil depositing machinery and finally will incur the extra cost of the oil/grease.

By having the bread pans coated with a Non-Stick Coating all of this can be avoided, bread will be cleaner (not have burnt bits on it), the fat content of the bread will be reduced so making it healthier for consumer and the bakery plant will be a generally cleaner and a safer place to work as well as the financial advantage of not having to purchase oil/grease and the associated coats of running the plant equipment to apply it.

NP.STOCK.01

So how does PTFE Coatings really work?

There are 3 factors which give PTFE its unique Non-Stick capabilities:

  1. PTFE is made from a chain of carbon atoms with 2 large fluorine atoms attached to each carbon atom. The size of the fluorine atoms provides a protective barrier to the carbon atoms and therefore it is almost impossible for chemical structures to gain access to the carbon atom.
  2. The bond strength between the carbon and fluorine atoms is classified as extremely high bond disassociation strength. The strength is measured typically as 544 kj/mol making them almost unbreakable.
  3. Fluorine is a naturally ‘anti-social’ atom which wants to repel other atoms.

The combination of these factors makes PTFE coatings very low coefficient of friction coatings which provide chemical resistance.

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BS EN ISO 9001 : 2008

BS EN ISO 9001 : 2008 is a quality management system (QMS) that should be adopted by a company who make a strategic commitment to such a documented system. There are numerous reasons why an organisation might adopt such QMS:

  1. A way of managing risk in the business environment
  2. A way of managing varying needs within the business
  3. It is a recognised way of the business meeting particular objectives
  4. It provides a framework around the which the business can manage the production of products and services
  5. It provides a process driven framework for operational management
  6. It might be appropriate as an expectation by Clients give the relative size of the company

It is not a system that imply’s that all QMS’s operated are uniform in nature, quite the reverse really. It provides a framework of best practice but how the framework is adopted is entirely up to the company operating the system. The QMS should complement the actual processes and products or services.

By adopting the QMS formally the company opens themselves up to auditing both from internal and external sources of how the QMS is operated. This of itself is no bad thing, it encourages those operating and working within the 9000 environment to meet the standard.

The standard promotes a process approach in development and implementation of the QMS.  It is considered that such an approach will add to improvements in process and effectiveness of processes. Indeed the process approach is a natural way of looking at the linkages active within an organisation, often the output of one process is the input of the next.

The advantage of a process approach lies in the ongoing control possible over the system links between the individual processes and over the combination of the processes. When such an approach is used within a QMS it emphasizes the importance of:

  1. the need to full understand requirements
  2. the need to understand processes in terms of the value they add
  3. what process performance and effectiveness is
  4. how processes are continually improved based on any change in objectives

The route of the process for BS EN ISO 9001 : 2008 is Plan, Do, Check, Act

PLAN:  is about establishing the objectives and processes necessary to deliver the requirements

DO:  implementation of the process(s)

CHECK:  monitoring and measurement of the process and combination of the processes against any policies, objectives and requirements as may be understood to apply

ACT:  take action, make changes if necessary so that objectives and requirements can be met consistently

Following the recent external ISOQAR Audit of Northpoint’s QMS for the coating of pipework I am happy to report that there are no concerns rasied.

 

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Pin-holes in Powder Coatings

A common complaint or comment about powder coatings is that they are sometimes pin-holed; a small crater visible, pin-holes in the surface of the finished powder coating.

PIN-HOLES

There are many reasons for pin-holes and not all of them are related with the way the powder coating materials are applied.

De-gassing agent Benzoin if used can prove to be problematic. The substance is a precursor to Benzil, a photoinhibitor and is activated by copper, nitric acid and atmospheric oxygen. So if not fully encapsulated the substance can be the route cause of issues found. Normally this is overcome by the powder coating material manufacturer at the extrusion stage of manufacture.

Other problems at the manufacturing stage are related to contamination by volatile matter; such as high-boiling solvents or low molecular weight resin compounds. Incorrect extruder settings can lead to pin-holing in the finished coating.

Plant conditions at the applicator can be an influence of the eventual finish applied. Cross contamination of the application equipment can have a detrimental effect on the control of pin-holes although not as significant as contamination at the extrusion stage of manufacture. Probably the major contributor from application mistakes is from back-ionization, the effect of particles of powder being thrown back from the surface being coated taking other particles with it and leaving a small crater or pin-hole.

Pin-holes from back-ionization are far more common when coating iron/steel parts than aluminium parts. If this is the case then lowering the Kv may help to overcome this problem.

Other coating plant issues could be related to the quality of the compressed air used, which should be dry and free from oil. Moisture and oil become a contaminant leading to among other problems pin-holes. Emulsions of oil/water; more water give micro-pin-holes and more oil give larger, flatter with fatter borders type pin-holes.

At the pretreatment stage problems can be introduced. Over-pickling and poor de-gassing can be the cause of some pin-holes, this is particularly the case with galvanized steel products. Where substrates have been oxidized and greater then normal pickling is required this can lead to a greater amount of zinc phosphate being attracted. The zinc phosphates applied generally encapsulate molecules of moisture which is then boiled-off during the powder coating cure stage.

Pin-holes are under these conditions the result of gas & steam escaping through the powder coating after the powder has started to flow and skin-over (very similar to the predominately water/oil emulsion effects described above).

In this last case the steel chemistry will heavily influence the pick-up of zinc during galvanizing allowing silicone and phosphorus to migrate to the zinc surface both providing ideal conditions for the incidence of pin-holes. Where the galvanizer has not taken account of condensation or the production of oxidized surface salts from storage and transportation the powder coating applicator is left with a substrate which will have to be over-pickled.

The above is not an exhaustive list of reasons why powder coating pin-holes but gives a range of possible technical reasons why, which suggests that the incidence of pin-holes is far from a simple matter. Control of processes from the powder manufacturer and the galvanizer as well as the steel chemistry have a significant influence of the incidence of pin-holes in the finished powder coating.

Link:  http://powdercc.com/images/pdf/How%20to%20eliminate%20outgassing,%20the%20powder%20coating%20faux%20pas.pdf

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Anti-Corrosion Coating Systems

For a reinforced anti-corrosion coating system Northpoint Ltd have developed powder coating systems based on different protection techniques.

Steel Passivation:  an active protective primer over-coated with a high grade polyester powder coating.  The primer is applied at 60 – 100 microns thickness with a polyester (or hybrid top coat for interior use) top-coat applied at 70 – 120 microns.  This system is dedicated to steel passivation when linked to a phosphate pretreatment.  The passivation is derived from active pigments within the primer and is formulated to provide excellent adhesion between the coating layers.

Barrier Protection:  a high grade barrier protective primer over-coated with a high grade polyester powder coating.  The primer is applied at 60 – 100 microns thickness with a polyester top-coat applied at 70 – 120 microns.  This is a pure epoxy system  providing for the very best, market leading barrier protection when applied over a phosphate pretreatment system.

Duplex (barrier/cathodic protection) System:  a zinc-rich primer over-coated with a high grade polyester powder coating providing a combined barrier and cathodic protection effect.  The zinc-rich primer is applied at 60 – 120 microns thickness with a polyester powder top-coat of 70 – 120 microns thickness.  The zinc particles provide great primer layer conductivity; its very important when these systems are used that the zinc content in the primer is high enough to provide cathodic protection but not so high that it does not bond sufficiently well with the resins.  The pretreatment for this system is critical and should include as part of the process a Zn-Ni phosphate + passivation to give best results.

Reinforced Duplex System:  this is a 3-layer system combining the zinc-rich primer with a barrier primer followed by over-coating with a high grade polyester powder coating.

Criteria for Choice

Powder coating systems are defined by the cleaning and surface pretreatment of the parts and the powder coating itself.  The choice of powder coating system should be made with regard to:  the substrate, the use environment, the parts geometry, any post coating forming, any working constraints and the expected life of the coating.

Northpoint Ltd typically apply polyester powder coatings directly to galvanised steel parts and under normal service conditions this system is adequate for a 10-year life expectancy.  For more aggressive environments or service conditions other more robust systems as described above might be appropriate.

For selection reasons Clients can expect to get a statement of life expectancy on the basis of ISO 12944-5:

Low – 2 to 5 years life expectancy

Medium – 5 – 15 years life expectancy

High – 15 years+ life expectancy

The life expectancy durability statements offered are NOT a guarantee period.  Its a technical indication to select a system and build a maintenance program.

http://www.northpointcoatings.co.uk/wp-content/uploads/2013/01/POLYESTER_DURABILITY1.pdf

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Corrosion Protection – Pt. 2

In my last post we got to the point of corrosion protection by barrier methods and cathodic protection. There are of course other methods.

Protection by Steel Passivation

With paints or powder coatings, it is possible to delay corrosion under the corrosion protection coating layer by the use of inhibitors in the paint which provide a certain passivation of the steel substrate. These passivation inhibitors slow down the reaction of water-oxygen and can neutralize the acid ions caused by humidity.

The effectiveness of these inhibitors varies considerably depending on the coating chemistry and the formulation technique used.

corrosion protection.1

Corrosion Protection by a Duplex System

When a zinc or zinc-rich covering is over-coated with a paint or powder coating, this is often called a duplex coating system.

This two layer approach combines a cathodic corrosion protection system provided by the zinc and a barrier corrosion protection system provided by the top paint or powder coating layer. The 2-layer corrosion protection system brings advantages:

1. a possibility of various finishes and shades

2. a greater corrosion protection when compared to singular cathodic protection such as zinc over steel

Pre-Treatments

Prior to any coating application, a surface pre-treatment is a must.

Typically a pre-treatment has multiple aims:

  1. eliminate any surface dirt or contamination
  2. provide improved surface adhesion characteristics
  3. improve corrosion resistance of the coating system to be applied

Chemical Pre-Treatments

The chemical process is generally made up of a core 5 stages, although many plants will have more processes, Northpoint Ltd for example has 10 stages on each of its two Fence coating lines.

  1. Degreasing – aims to eliminate oil, grease and dust and is used to create a clean surface
  2. Etching – eliminates rust & mill scale to obtain a surface free from oxides
  3. Chemical Conversion – builds a thin layer of well adhering insoluable metallic salts; iron oxids/iron phosphates, zinc phosphates, Mn, Ni phosphates, crystalline Zn-Ni phosphates, tri-cat phosphates, nanoparticles with zirconium
  4. Passivation – to eliminate active salts and to seal the surface
  5. Rinsing – after each operation to eliminate active residues

Anti-Corrosion Performance of Chemical Pre-Treatments

750 hour neutral salt spray on hybrid powder coating steel plate:

  • Fe Phosphating (no passivation) – rust on scribe 7.7 mm
  • Zi + nanoparticles (no post-treatment) – rust on scribe 4.3 mm
  • Fe Phosphating + Cr- Passivation – rust on scribe 4.2 mm
  • Zn Phosphating + Cr- Passivation – rust on scribe 1.7 mm

The Northpoint Ltd system is based on a sophisticated Zn Phos + Cr- Passivation pre-treatment and will meet or exceed 1000 hour neutral salt spray testing.

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Corrosion Protection Coating – Steel; Pt. 1

Corrosion is the deterioration of a material by chemical or electro-chemical reaction; it is the material returning to its natural oxide state. Corrosion can be the result of different processes & can be avoided or minimized by use of an appropriate corrosion protection coating. Methods of corrosion:

  1. Chemical – reaction between the metal and a gas or liquid stage
  2. Electro-chemical – by creating an electro-chemical cell with oxidation of the anode
  3. Biochemcial – by bacterial attack

The chemical formula of RUST:  Fe(OH)2, FeO, Fe(OH)3, Fe2O3

Corrosion can form uniformly or may follow the grain boundaries or may penetrate into the steel in the form of a localised pit. The speed of corrosion depends on the aggressiveness of the environment, the oxidation products structure and behavior of the steel. In the case of steel, the rust doesn’t adhere to the surface and will flake away leaving the steel unprotected and the corrosion propagates continuously.

Rusty-metal-fence1521

ENVIRONMENTAL FACTORS

Interior and Exterior environments may influence the steel in different ways.

Corrosion Protection Coating – Interior Factors

C1 – very low:  heated buildings with clean atmospheres – offices/shops

C2 – low:  unheated buildings where condensation may occur – sports halls

C3 – medium:  production rooms, high humidity and some internal air pollution – food-processing, dairies

C4 – high:  chemical plants, swimming pools, coastal boat-yards

C5I – very high industrial:  buildings with almost permanent condensation and high levels of pollution

C5M – very high marine:  buildings with permanent condensation and high levels of pollution

Corrosion Protection Coating – Exterior Factors

C2 – low:  area of low levels of pollution – rural areas

C3 – medium:  urban areas with moderate sulfur dioxide & coastal areas with low levels of salinity

C4 – high:  industrial areas and coastal areas with moderate levels of salinity

C5I – very high industrial:  industrial areas with high humidity and aggressive atmosphere

C5M – very high marine:  coastal and off-shore areas with high salinity

For details see: http://www.northpointcoatings.co.uk/wp-content/uploads/2013/01/POLYESTER_DURABILITY1.pdf

and

http://www.northpoint.ltd.uk/anti-corrosion-coatings/

CORROSION PROTECTION COATING – METHODS

Barrier Protection

Barrier corrosion protection coating generally works well provided there is no defect in the coating layer.  In the case of a defect corrosion will often spread under the coating layer lifting the coating off allowing an even greater area to be exposed.  Standard corrosion protection coating include, liquid paints and powder coatings offering a barrier protection layer.

To provide a very good level of corrosion protection coating the barrier layer should be impermeable to water. This requires a high level of binder to be in the coating mix. Phosphating pre-treatment before the coating is applied offers a further layer of corrosion protection coating.  A thin layer of metal phosphates provides some protection and improves adhesion.

Cathodic Protection

This is applying a layer of less noble metal over the steel which will oxidize preferentially.  Zinc brings a cathodic protection to iron by electro-chemical effect.  In addition to this cathodic protection zinc offers a shield as well.

In the presence of water and oxygen zinc converts to various zinc salts, insoluble in most natural environments. These salts build to a dense layer  slowing down the rate of corrosion and provides in the case of scratches a sealing effect which also contributes to the slow down of corrosion.

For help, advice and commercial quotes:  http://www.northpoint.ltd.uk/contact-us/

Links:

http://www.northpoint.ltd.uk/

http://www.northpoint.ltd.uk/gallery/?album=1&gallery=1

http://www.northpoint.ltd.uk/services/fence-coating/

 

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Who We Are

NORTHPOINT LOGO

Northpoint is a leading provider and pioneer in application of industrial coatings to steel and other metals.

As one of the most experienced and respected specialists in the coatings application business, you can rely on us to help you manage your colour coating responsibilities more efficiently and effectively.

We are though, about much more than coating application, we give you peace of mind as well. In fact at the very heart of our company is a commitment to the quality and growth of your business too. This means we’re not just a coating company, we offer expert help and advice, we are a trusted sounding board. We’re more than a solution provider, we are a best practice partner to your business. Our core mantra is we will now what we need to do to reduce and simplify complexity – so you can focus on what’s important to your business.

We’ve been immersed in our Clients business’ for years, and honestly, we find your business to be an inspiration to how we run ours. Your needs helps us set our standards for quality of product, speed of service, and the support we offer.

Knowing whats needed in today’s business environment is one thing, being able to spot and address tomorrow’s needs is another. Through the hundreds of thousands of conversations we have with our Clients every year we identify trends and help to future-proof your products with our world leading coating applications. Northpoint’s coatings, peace of mind, timely advice and new processes introduced aimed at simplifying the coating process.

Your business + Northpoint = a winning combination!

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Fence coating – How You Benefit

We at Northpoint Ltd have been passionate champions of professionally applied polyester powder fence coating over galvanized steel fencing parts for over 30 years. But that’s only part of the story.

For what we’ve learnt along the way is that applying the coating to meet recognized International Standards, making the management of the process easier for the customer can unlock an array of additional commercial advantages for the Client.

It goes without saying that we have automated the application process and the coating tasks so that the process is as tight as possible. Quality is high and consistent, indeed we are often used as the market example of best practice and best coating. There’s the added knock on effect of these automated and streamlined processes that encourages clear thinking and consistent action from all our staff meaning that problems are pre-empted and crises avoided.

But there’s more to be gained, turning our compliance to the International Standards from a burden into a bonus. Our experience shows that enabling you to give your Clients compliant coatings, backed in all cases by documented evidence and in some cases where required life expectancy guarantees underwritten by the powder manufacturer, meeting your commercial objectives protects both your business and ours.

The Northpoint Fence Coating systems allows you to:

Reduce Risks

The fence coating applied meet Internationally Recognized Standards; BS 1722: Pt 16 2009 & BS EN 13438 2005 . Coating applied in the right way minimizing financial and reputation risks.

Save Time

By automating many of the fence coating tasks and processes means we can turn work around quickly but without the risk of inconsistent coatings being applied.

Controls Costs

For those customers who have a price list they can work out what the fence coating cost will be at the bid stage.

Future Proofing

Northpoint Ltd consistently stay at the forefront of coating technologies meaning you always get our market leading quality of coating.

Boost Productivity

By using Northpoint Ltd fence coatings you know that the fence coating will do what its designed to do. The potential for coating failure is massively reduced.

Business Growth

With Northpoint Ltd covering the detail of the fence coating, you have the time and the energy to focus on your bigger picture, developing your company.

The Northpoint fence coating advantage is all about taking away complexity and bringing you a wealth of business benefits. By bringing together our insights and innovations we simplify complexity for Fencing Manufactures

.McARTHUR.18.01.2012.C

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Northpoint appoint MBA Students as Consultants

In a link with Manchester Business School, Northpoint Ltd are proud to announce that we are appointing 2 MBA Students from this year’s cohort.

Ke Jiang will join Northpoint Ltd from the end of September 2013, looking at the developing service range for our fence coating plants.  Her remit is to seek out additional opportunities that Northpoint Ltd could take advantage of, utilising the existing equipment. Her remit will include new markets and equipment redevelopment to allow Northpoint to enter related markets. ke jiang

We are more than pleased with her appointment.

Hicham Labiad joins early September 2013 and will be concentrating on developing our functional coating reach.  He will be looking at opportunities in the oil, gas and associated industries, as well as supply into the pharmaceutical industry.  His remit will be to look at plant development, specifically related to giving Northpoint a European reach for coating of industrial pipework. hicham labiad

We are confident that Hicham will deliver on his project give his assured performance at the interviews.

 

Both Ke and Hicham are undertaking this part-time consultancy for Northpoint over a 3 month period. The results will be used by them to meet the academic criteria of the MBA programme they are studying for.

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Pipe Protection

Northpoint Ltd pipe chemical coatings recently completed the FBE coating of a 1800 NB Duck-Foot Bend. Nothing unusual there you would think. But we were then asked to protect the external coating with a protective tape, the picture tells the story:

G.Green

For more details on pipe coating and pictures go to:  http://pinterest.com/georgegreenltd/1800nb-duckfoot-bend/

If you have that awkward to handle, difficult to coat job, give us a call or e.mail howard@northpoint.ltd.uk and we’ll give you our best price and delivery doing the work.

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