www.ashton-moore.co.uk

for aerospace metal finishing and

NADCAP chemical processing

t.+44 (0)845 618 8196

12 Smith Street, Birmingham, B19 3EX, W. Midlands, England.

Having traded from the same site for nearly 80 years a management buyout in 2004 allowed the new owners to move the business to premises offering single story open plan facilities with the opportunity to lay out the production units in a more logical, ergonomic and environmentally sound way.

The new premises, ideally situated just a few hundred yards from the Birmingham inner ring and approximately 2 miles from junction 6 of the M6  now allows more efficient production routes, easy access for maintenance to vital equipment and a greater degree of electronic process and quality  control as well as a pleasant working environment. The move, starting January 2006 and completed late Autumn 2007, was accomplished without any significant business interruption or the loss of any approvals despite the requirement for re-accreditation from all of our customers, other bodies such as BSI for our ISO, quality and environmental approvals, Nadcap accredition and the environment agency,

In addition to these benefits we have been able to commission a specialist “solvent free” paint facility which will allow us to take advantage of the new generation of environmentally friendly paints as they are developed. We are also actively involved in projects to reduce the drag out of chemicals from our process lines and to find alternatives for those processes using materials and chemicals currently under threat from the REACH directive (European Community Regulation on chemicals).

Aerospace anodising for corrosion resistant aircraft components.

As aluminium  “rusts” it produces a loose dry white powder, aluminium oxide. The aerospace anodising process artificially produces this film but as a hard, dense wear resistant surface, the two most common ways to produce this film are by passing a dc current through parts immersed in a solution of  either sulphuric acid or chromic acid. The passing of the current liberates high volumes of Oxygen at the surface of the aluminium thus aiding controlled formation of the oxide layer. These processes do not produce a coating, but are a conversion of the surface aluminium to aluminium oxide and therefore are metalurgically bonded.

Both the Chromic and sulphuric acid methods produce a tight but porous layer which, because it is porous, requires a sealing process to close the pores and prevent further natural attack on the aluminium.

Sealing is carried out by immersing the component in near boiling de-mineralised water, which, if required, can have small quantities of other chemicals, such as Nickel acetate or sodium dichromate to further enhance corrosion resistance. Before sealing, immersion in specially formulated dyes can be carried out, the open pores soak up the dye which will then be locked in by the sealing process, this can produce very attractive finishes but will depend on the thickness of the anodised film as the thinner the film the less dye will be absorbed.

A major benefit of aerospace anodising is that, because the oxide film is electrically resistant, the film is distributed across the component very evenly as when the film starts to grow that area becomes more resistive  until all other areas on the component have achieved the same thickness of film so equalising the relative resistivity therefore ensuring even growth over the whole component

Chromic acid anodising.

This method produces comparatively thin but dense oxide films which are usually dark grey in colour, they have very good corrosion resistance but are not really suited to subsequent dyeing. However as they are thin, they do not affect close tolerances and are therefore used extensively in the aerospace and defence industries and, if left unsealed, are an excellent base for subsequent painting operations, as the first coat of paint soaks in to the pores. The thin film also reduces the possibility of fatigue fracture on the component.

A further benefit of the chromic process is that the chromic solution is extremely searching and will seep into even the smallest of flaws and because it is also a browny/orange colour, there will be a stain apparent around the flaw thus acting as a type of non-destructive testing.

Sulphuric acid anodising.

This method can produce much thicker films than the chromic process, and is generally used in corrosion resistance, general engineering,  or decorative applications. Aluminium can be chemically or mechanically polished, satin etched or even left in it’s natural state prior to anodising. Combined with the ability to dye sulphuric anodised films, the process offers a wide variety of visual finishes.

Sulphuric anodising can be found in almost every walk of life, wherever aluminium is used, examples of which can be seen on domestic cookware, hand tools, fascias for computers and televisions.

If used with the correct solution composition, current and temperature can produce extremely hard films. So much so that the process is known as “Hard Anodising”.

Component masking...

Exacting engineering requirements now require that specific areas of components should not be coated; All our divisions carry masking operatives experienced in a variety of masking media to ensure these requirements are met.

Aerospace electroplating

Cadmium Plating for corrosion resistant components.

Cadmium is now strictly controlled under a 1993 environmental act.  It is an offence to use cadmium other than for “Permitted use” and any company offering cadmium plating now has to be licensed by the Environment agency.  Cadmium plating is a crucial aerospace coating, also used in mining and marine applications. Cadmium itself has very high corrosion resistance and, like zinc, is sacrificial when used on ferrous based components. It is, however, much more effective than zinc, as the sacrificial process is much slower. Unlike zinc, Cadmium has low contact potential with many other metals, particularly aluminium and cuprous alloys, thus making it an ideal barrier between steel, aluminium and cuprous alloy component assemblies which without the cadmium interface would rapidly preferentially corrode.

Cadmium, whilst being relatively hard, so not being too susceptible to abrasion, is also highly ductile and therefore is suitable for applications where flexibility is required e.g. where the extreme temperature changes experienced by aircraft during flight and landing produce expansion and contraction of components.

Cadmium when plated is a matt silvery colour and, although chemicals can be added to the plating bath to brighten the deposit, these additions are forbidden by many specifiers as they can make the deposit brittle and impart brittleness to the component. Correct control of the non brightened solution can, in most cases provide a semi bright deposit which is aesthetically acceptable for most applications. The cadmium can be further treated, using chrome based dips, which increase the corrosion resistance even further, as well as providing a good key for subsequent component painting operations which are frequently required.

Aerospace silver plating.

Silver’s natural lubricity and conductivity make it an ideal product for use in aerospace and defence applications. Modern applications use a high number of stainless steel and nickel based alloy components, but these materials tend to gall when assembled together. A thin film of silver plating on at least half of any assembly allows successful disassembly and reassembly, thus saving costly downtime and the possibility of unnecessary early replacement. A deposit of silver on electrical contacts improves conductivity dramatically.

Like Cadmium plating, the addition of brightening agents to the silver bath can adversely affect the deposit and/or impart embrittlement of the component, therefore the silver plating offered by Ashton and Moore is pure and un-brightened.

Lead component coatings & Indium.

Lead coatings on big end and other similar bearings has been used extensively for many years but is used now mainly for overhaul and repair of older engines. Pure lead is deposited onto the bronze bearing bush. Not only is the lead highly lubricative and slow wearing, but because it is very soft and the coating is relatively thick, around 0.005”/0.010”, it absorbs and captures the minute metal particles worn from other parts of the engine preventing them from abrading other parts of the engine. This extends engine life dramatically. Unfortunately in this type of application lead readily oxidises and wears away. To prevent this, a thin film of pure Indium is plated on top of the lead and the two metals are “fused” together by soaking in a near boiling oil bath. This fusion forms lead indium alloy coatings which do not oxidise, thereby lasting for many years, durable component coatings.

Aerospace stainless steel electropolishing.

Aerospace electropolishing is carried out in the same way as electroplating, but because the component is made anodic, instead of material being deposited, it is electrolytically removed. During the process three things happen. Firstly, high spots on the component attract a greater proportion of the current, thereby removing those high spots preferentially. This smoothes out the surface, resulting in a brightening of that surface. Secondly, much of the tarnish or contamination on the surface of the component will tend to be removed as the metal is removed (see Pickling below), further enhancing the brightening of the component. Finally, as electrolysis produces oxygen at the anode, the component gets scrubbed with free oxygen, enhancing the natural protective oxide layer, which gives stainless steel it’s stainless properties. The combination of these three events is that the electropolished component becomes cleaner, brighter, and achieves it’s maximum stainless properties.

The success of the electropolishing process is very alloy dependant and whilst specific solution variants can be formulated to deal with other alloys, the process offered by Ashton & Moore is designed to deal with Austenitic stainless steel e.g. 316 stainless or 304 stainless.

Aerospace Pickling.

Many stainless steels are fabricated, welded or cast, these manufacturing processes can impart soils and scales, such as burnt on oils or carbon films or casting “crust”, these contaminants can be inert to the usual pre-cleaning methods and therefore interfere with the electropolishing process, so need to be removed by pickling with strong acids or by the use of “Pickling pastes”, before the actual polishing is carried out. Ashton & Moore do offer these pickling processes, but it is worth noting that they can impart additional time and cost to the job and frequently, these contaminants can be eliminated by good practice in the manufacturing stage.

Aircraft component painting.

Modern high performance products require high performance protection frequently from specially formulated products with specific performance attributes and aircraft component painting is no exception.

The aircraft industry requires paints which will resist fire, heat, wear, corrosion, as well as attack from fuels and hydraulic fluids as well as abrasion and impact from everyday use.

Ashton & Moore’s expertise in this field allows us to offer a paint for almost any application. Whether a specific system, as would be the case for aircraft or defence equipment, or whether we are offering solutions to companies who require a given performance, but need advice on a system to attain that performance, we offer all aerospace component paints and coatings.

This includes epoxy, acrylic, polyurethane systems, along with dry film lubricants such as PTFE and molybdenum disulphide, intumescent paints for fire resistance, infra red reflective paints for weaponry, high temperature/high corrosion resistant paints for severe applications and even paints which, in some applications, can be used as a replacement for cadmium plating.

Exacting engineering requirements now require that specific areas of components should not be coated; As with our other divisions, our painting division carries masking operatives experienced in a variety of masking media to ensure these requirements are met.

Aerospace Phosphating.

Phosphating is the application of porous crystalline coatings, usually applied to ferrous based materials. The process is non electrolytic, with the phosphate layers being produced  by catalytic action between the component material and the phosphating solutions. This catalytic action produces an exceptionally strong bond of the phosphate layer to the component surface.

The coating produced is crystalline and porous and forms a very good base for subsequent applications. As an undercoat for paints, it dramatically improves adhesion of the painted layer and the application of specialised oils and greases will enhance the corrosion performance of the component or provide lubricity for subsequent manufacturing operations.

Although most commonly applied to ferrous materials, it can also be applied to zinc or zinc plated bases where, prior to subsequent painting operations, both corrosion performance and adhesion are considerably improved.

Ashton & Moore offer two types of aerospace phosphating, Zinc Phosphate which gives a finer grain with a wider range of thicknesses being achievable, or Manganese Phosphate which is limited to heavier films, The Manganese phosphate coatings also have different crystalline structure to zinc phosphate. This structure is laminar rather than columner. It is compressive and imparts greater corrosion resistance and lubricity without the need for additional coating, although these can be specified if required. Manganese phosphating is particularly good for components where “wearing/running in” is required, and because it is a compressive coating, it continues to offer lubricative properties for extended life.

Aerospace Non Destructive Testing NADCAP approved.

Our NDT department offers magnetic particle and fluorescent dye penetrant  services, having Nadcap approvals plus an extensive range  of aerospace and industrial specifiers (see “our approvals” page on our website for detailed list.)

As well as being a “stand alone” service, this facility, complementing our plating, anodising and painting services offers our Aerospace, defence and other specialist clients the opportunity for single source procurement, bringing the benefits of reduced lead times, costs and logistical problems.

All of our NDT operatives are at least level 11 qualified technicians and our MD,  Dr Keith Tucker, holds level 111 NDT status, accepted by all the approval bodies that we work for .

Two of the main forms of NDT, both of which are employed at Ashton and Moore, are fluorescent penetrant inspection and magnetic particle inspection.  They are used primarily for the non-destructive examination of components, usually prior to the application of component protective coatings, to find inherent flaws in the base material or those which arise from the formation of the component. They may also be used in the examination of in-service components for fatigue defects, in either case ensuring the aircraft components’ suitability for purpose.

Liquid Penetrant Inspection.

Ashton and Moore utilise fluorescent penetrants to detect surface breaking flaws such as cracks, porosity, etc., in components made from non-porous materials.  They are typically applied to the surfaces under inspection, following suitable pre-cleaning/degreasing and given a long enough dwell time to be drawn into any flaw present.  The excess penetrant is then removed, the surface(s) are dried and a finely divided developer powder is applied.  This developer assists in drawing the residual penetrant from the flaw, thereby revealing the location when viewed under an ultraviolet light in a darkened inspection area.

Magnetic Particle Inspection

Magnetic particle inspection is employed at Ashton and Moore, using paraffin based fluorescent ink containing fine ferromagnetic particles and a fixed bench MPI unit, in order to discover not only surface breaking flaws, but also those up to 2 – 3mm below the surface, on components made from ferromagnetic material.  Typically, a magnetic field is introduced into the component under test, whilst the ink is applied.  Any flaw in the area tested which cuts across the magnetic field will create a leakage field with both south and north pole on either side of it, and therefore will attract the ferromagnetic particles in great numbers, producing a visible indication, when viewed under ultraviolet light in a darkened inspection area.  To inspect any surface completely, at least two fields will have to be applied at 90 degrees to each other.

For further information about this and other benefits we can offer contact our sales department at 0845 618 8196 or e-mail ndt@ashton-moore.co.uk.

Awards attributable to Ashton & Moore.

Ashton & Moore have been strong supporters of the Surface engineering industry and have been active with their trade association for many years. The company sits on both the national committee and various sub committees of firstly the Metal Finishing Association (MFA) and now the Surface Engineering Association (SEA) which was formed to include other surface engineering sector trade associations. Ashton & Moore executives, in conjunction with the SEA sit on the defence standards committee and also lobby for UK manufacturing interests at Westminster and European level.

During our association with these trade associations we have been fortunate enough to gain several successes at their biennial awards ceremonies, they are as follows

1997 MFA awards   Winner marketing category.

1999 SEA awards    Winner Quality category

2004 SEA awards    Winner Quality category

2008 SEA awards    Winner Outstanding company achievement, Winner Ray Alford Memorial award for outstanding personal achievement, Runners up in both quality and environmental categories.

The directors have also been listed in the 2009 Who’s Who of successful businessmen.

www.ashton-moore.co.uk