ZinKlad Welcomes…Retsacoat – Portugal

Congratulations to the Retsacoat team seen receiving there new ZinKlad certificate from Daniel Algar and Belina Raposo MacDermid Portugal.

RETSACOATTratamentos de Superficies Metálicas Lda, leading company in thermal and anti-corrosive treatments, started its activity in 2001. Retsacoat is a member of the Pecol business group. This partnership has been essential for the development of our current surface treatments.

To View this article on Retsacoat and ZinKlad in Spanish / online ebook, follow link  

Retsacoat started as lamellar (dip spin) zinc applicators inPortugal. In 2006, as a result of the Cr VI restriction in surface treatments, we became approved for the application of chromium-free lamellar zinc processes.

These thin film anti-corrosive treatments are the best alternative for a great number of parts. For example, the absence of chemical pickling eliminates the risk of hydrogen embrittlement. The thin thickness and integrated lubrication, allows a perfect assembly, even with small metric screws. Lubrication, an increasingly important issue, allows us to meet these market demands.

Recently we completed our portfolio of electrolytic treatments with the implementation of a fully automatic line for zinc, zinc nickel and zinc iron.

The support and collaboration of MacDermid has been fundamental. From the beginning of 2012, we are the first company in Portugal certified with the process ZinKlad 250 and ZinKlad 1000. With these new processes, we offer our customers the best solution in electrolytic finishing processes.

For lubrication of the ZinKlad finishes we offer both Torque ‘n’ Tension 11, and Torque ‘n’ Tension 15. Collectively these provide the optimal controlling the coefficient of friction characteristics.

Strategy

Retsacoat have always been a pioneer in the latest equipment and finishing technology. We have implemented fully automatic lines that allow us to deliver finishes of high quality and consistency, at very competitive prices and with a reduced time for deliveries.

Quality

Quality is always a high priority for us. All surface and thermal treatments require a perfect control, both of the processes and finished product. In our in-house laboratories we carry out the most demanding tests including hardness testing, deposit observations by microscope, neutral spray salt, measurements of thickness by X-ray and also coefficients of friction.

Environment

Our concern for the environment has always been an essential part of the process development. Effluent gases such as liquid heat and finishing treatments are controlled by our in-house treatment equipment.

RETSACOAT – the solution for your mechanical parts.  http://www.retsacoat.pt/

– A Bright Future for Decorative Chromium –

Editorial

Terry Clarke: Global Director, Decorative Products

 

–  A Bright Future for Decorative Chromium  –

Introduction

Decorative Chromium electroplating has remained the most popular and widely specified metallic decorative finish for over 20 years. Its classic looks, worldwide availability and affordability have maintained it as the first choice decorative coating for engineers, designers and stylists across a wide range of decorative applications. Its use extends into many product types, from automotive parts to cell phones and its attributes, as a highly resilient decorative coating, continue to attract many new applications and uses.

Chrome is truly an iconic decorative coating adding high class impact to designs and providing a long lasting durable finish capable of withstanding even the most severe external environmental conditions for many years.

During the past 10 years, decorative chromium has enjoyed increasing appeal through the wider selection and adoption of satin effect finishes. The satin layer uniformly scatters any light falling on its surface, giving a shimmering soft bright metallic appearance. This unique micro satin effect can be adjusted from a fine sheen to a heavier matte finish depending on the design needs. The finish also retains the same performance benefits as bright chrome. Satin finishes have become a highly desirable interior trim finish for many automotive companies and continues to gain popularity as stylists seek to differentiate designs and brands.

Also complementing the bright chrome range are specialist darker chromium coatings delivered using trivalent based plating electrolytes. Finishes like Twilite® are essentially chrome alloys that have a slightly darker and warmer colour than standard chrome. Twilite® is widely used where bright chrome colours would be considered a little too monochrome or when a subtly warmer style is desired. The performance aspects of Twilite® is at least equivalent to standard chromium and in some unusual environmental conditions like Calcium Chloride, out performs standard chromium deposits.

Decoration is all about Style…

20 years ago, electroplated chrome was far less fashionable than it is today and was applied mainly to steel, brass and zinc based die cast components. Its limited appeal was partly a result of the fashions and styles of that era when the use of solid colours and colour uniformity was more popular. It was also due, in part, to the limited performance of single layer nickel/chromium electroplated coatings, especially in outdoor environments.

Today however designers and stylists are far more adventurous in their use of metallic effects, encouraged by the technical development of nickel/chromium electrodeposits, especially when applied to engineering plastics. Performance capabilities today are suited to even the most demanding external applications. Of the 60 million or so vehicles produced each year, very few models roll off the production line without being enhanced by electroplated chromium. And such is it’s styling appeal it is adopted on many of the latest consumer electronic goods as well as furniture and domestic appliances.

The long awaited 3rd Dimension – Dark Chrome

As the drive for new styles and differentiation continues, one of the challenges facing chemists and R&D specialists is the development of new fashion finishes that build upon the success of bright and satin chrome. Studies have shown that designers from different industry sectors are looking for extended chrome colour ranges, from subtle grey shades through to intense dark chrome. One of the most widely requested and anticipated development is a genuine dark chrome finish. For the most part, these requirements cannot be satisfied using top coats, lacquers, paints or varnishes even when applied over standard chrome finishes. However with the imminent launch of Moonlite, a new dark chrome finish, the range will extend from bright to satin to dark and of course any combination within these. Moonlite essentially completes the 3rd dimension in the matrix of chrome finishing options.

Beauty and Performance…

The combination of both beauty and performance may be a rare commodity but with the latest chromium coating developments, beauty and performance are truly attainable.

OEM’s recognize the value of decorative finishes and often develop specifications to ensure their specific needs are met. Technical and aesthetic requirements for decorative chromium are continually under review with expectations that higher performances for CASS, NSS, thermal cycling and Calcium Chloride corrosion resistance must be meet by new finishes.

Raising performance requirements typically raises the degree of complexity of the electroplating processes. However with good process control consistent quality is within the reach of many high volume applicators. Bright chromium originally began as a fairly simple electroplating process and has evolved into modern a process utilizing as many as 6 or 8 highly interdependent layered coatings produced using 14 or more chemical process stages. Each of these coating stages requires close chemical and operational control in order to ensure the right surface morphology is optimized to enhance specific characteristics. The final metallic layers work synergistically to optimize corrosion performance, gloss, resilience and colour. A fault at any process step can result in a significant compromise in overall performance, therefore careful process choice and control plan integrity are vital ingredients of a successful decorative plating operation.

Typical automotive OEM bright chrome performance specifications cover most of the performance criteria that electroplated chromium deposits have to offer. As can be seen below, the range of conformance testing extends from thickness measurements through to complex thermal cyclic testing designed to simulate many years of active service life. Understanding the interdependence of each process step is critical, as is operating within a carefully managed control plan. All decorative processes have optimal windows of operation within which they are capable of delivering maximum performance characteristics.

Decorative chromium specification table

Typical OEM Specification for Plastic substrates

High performance nickel/chromium deposits applied to plastic substrates takes more than 3 hours chemical production time. The process route frequently involves 14 or more discrete chemical stages (excluding rinsing) each of which must be operated within close limits to ensure a successful coating.

The complexity of many individual processes involves the management of 3, 4 or 5 separate chemical additives, pH, temperature, agitation mode and applied current that must be controlled within tight operating ranges. This is a highly automated operation supervised by highly skilled technical staff using an increasingly sophisticated array of testing apparatus. Successful management of these systems requires detailed planning and coordination to ensure consistency.

Quality and Assurance…

Complexity adds cost therefore the applicator market is being driven to lower cost regions where labor rates make it easier to justify employing large numbers of trained technicians.

With millions of components being processed each day, the chromium plating industry is increasingly geared towards efficient mass production. Finding lower labor costs is encouraging expansion of chromium electroplating in emerging markets including China, Brazil, India, Korea and SEA. This in itself brings new challenges for a community of applicators not always experienced in working to OEM specification levels. This coupled with the divergence between local and international quality requirements places great emphasis on the technical support structures provided by key chemical suppliers. In order to ensure successful procurement of chromium decorative finishes in emerging markets, the development of supplier/applicators quality partnerships like ZinKlad and Q-Klad is vital.

These programs offer true partnerships between key applicators, technology developers, T1’s and OEM’s in which each takes an active part in ensuring process control plans are developed, implemented, monitored and maintained via agreed protocols. This tried and trusted method of collaboration is proving to be an excellent tool in supply chain management of rapidly emerging markets.

For further information contact us at prodinfo@macdermid.com

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Improving your friction control coatings

The extensive use of topcoats for fasteners began in the 1980’s. The primary need was to enhance corrosion protection and were generically known as leach and seal, due to their ability to turn yellow passivates to an almost silver colour. An improvement to leach and seal was to incorporate dry film lubricants in the coating to lower the coefficient of friction (CoF) of a fastener. With the introduction of high performance trivalent chromium passivates in 2000, the technology evolved into processes applied at room temperature. These were more sympathetic to the underlying passivates, giving high quality black finishes. One major global automotive OEM followed this evolution, moving from hexavalent passivates with leach and seal, to trivalent passivates with a thin film topcoat and lubricant combination.

Leach and Seal

Arguably the best known leach and seal process is the MacDermid JS500 system. Used alone, it reduces the CoF range of pure zinc from >0.4 to 0.22 +/- 0.08. Combined with an integral lubricant it reduces the CoF to 0.12 (+/- 0.02). This integrated process (known as JS600) provided the required protection, improvement and lubrication for the majority of their fasteners.

Change instigates higher performance requirements

Around the year 2000, the ELV directive drove many automotive companies to upgrade their existing plated fastener finishes requirements. Typically this was the new specification:

  • Higher corrosion resistance
  • Compatibility with trivalent passivation
  • CoF 0.15 with a deviation of +/- 0.02
  • New CoF requirements for different fastener innovation
  • Identification with an integral UV tracer

The answer was a new breed of topcoats. These mixed inorganic and organic compounds gave thin topcoats which adhered to and respected the underlying passivate, gave significant improvements in neutral salt spray (corrosion) resistance and a very predictable CoF of the desired 0.15. As the topcoat is so thin and transparent, its application can be verified by the presence of tracers, which maybe seen under a UV lamp. Let us review how these new topcoats achieve these performance enhancements.

Higher corrosion resistance

Three effects are taking place to increase the overall protection: (i) water resistance (ii) corrosion inhibition (iii) adhesion to the passivate layer. The first line of defence is that the coating performs as a barrier layer. The topcoat prevents water reaching the surface by providing a strong hydrophobic layer. The homogeneity of the coating also prevents premature swelling of the coating by water absorption. The second defence is the presence of corrosion inhibitors throughout the coating. These help to seal the coating in any areas where minute discontinuities in the film might occur. Thirdly the adhesion to the passivate layer is so strong that any ‘undercutting’ of the film is prevented. This is particularly important on sharp profiles (where the coating will typically be thinner).

Compatibility with trivalent chromium passivates

The original leach and seal coatings were designed around hexavalent chromium passivates. The leach process ensured exceptional adhesion by combining the passivate with topcoat layer. Trivalent passivates are homogenous layers and not so easy to leach. So the new products had to adhere to a smooth and pore / crack free coating. They also had to be compatible with various types including thin film (typically blue) and thick film (iridescent or black) passivates.

Narrow range coefficient of friction

All fasteners have a designed maximum proof load. Creating the correct torque-tension relationship achieves maximum joint security without exceeding the proof load of the fastener. Zinc and zinc alloys have a relatively high and variable coefficient of friction. This can adversely affect the torque-tension properties of fasteners. Additionally passivates offer different levels of CoF. For example, it was noted that hexavalent passivates have an average CoF of 0.4, whereas a high build trivalent could be as high as 0.5.

If fasteners are used without a friction control fluid, the increase in friction results in lower bolt tension for a given torque, resulting in a joint weakness, which leads to poor clamping, insecure joints and, possibly premature bolt fatigue failure. Conversely too much can lead to bolt fracture and thread stripping. This factor becomes even more crucial in safety critical applications, such as wheels, seat belts, steering and suspension component system.

Torque n Tension for zinc nickel coatings

Torque n Tension for zinc nickel coatings

Therefore lubricated topcoats provide both a lower friction coating than simply metal to metal joints; and also makes the relationship more predictable, avoiding too low or too high clamping forces. Returning to our OEM, they changed to the newer topcoats in order to consistently achieve this predictable surface CoF. Another consideration was to ensure that all applicators, across an increasingly global supply chain, conformed to the same standard. Incorporation of the UV tracer permits verification that the right topcoat has been applied.

New range coefficient of friction requirements

As new fastener technology is introduced, new CoF ranges are demanded, whilst still maintaining the corrosion resistance and compatibility with trivalent passivates. The most current dry film lubricant systems can be tailored to meet these new CoF demands, while still returning low variability.

Summary

Dry film lubricants have evolved from leach and seal processes, designed primarily for hexavalent chromium passivates, to non leach systems compatible with trivalent chromium passivates. Coupled with outstanding corrosion resistance, the non-leach technology delivers exceptionally predictable torque-tension relationships without interfering with the dimensional tolerances. Additionally they can be modified to meet newer demands for friction ranges. This technology allowed a major global automotive OEM to improve the effectiveness of the fastener assembly operations by consistently returning desired corrosion and coefficient of friction on zinc and zinc alloy plate and trivalent passivation systems.

http://www.industrial.macdermid.com

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